[compiler] Standarize CompilerDiagnostic descriptions (trailing periods)

Separated this out into its own PR since it's really a cosmetic change.

CompilerErrorDetail and CompilerDiagnostic now both expect `reason`/`category` and `description` to *not* have trailing periods.

.eslintignore

@@ -28,6 +28,3 @@ packages/react-devtools-shared/src/hooks/__tests__/__source__/__untransformed__/
 packages/react-devtools-shell/dist
 packages/react-devtools-timeline/dist
 packages/react-devtools-timeline/static
-
-# Imported third-party Flow types
-flow-typed/

.eslintrc.js

@@ -468,7 +468,6 @@ module.exports = {
       files: ['packages/react-server-dom-webpack/**/*.js'],
       globals: {
         __webpack_chunk_load__: 'readonly',
-        __webpack_get_script_filename__: 'readonly',
         __webpack_require__: 'readonly',
       },
     },
@@ -547,10 +546,13 @@ module.exports = {
   },
 
   globals: {
+    $Call: 'readonly',
+    $ElementType: 'readonly',
     $Flow$ModuleRef: 'readonly',
     $FlowFixMe: 'readonly',
     $Keys: 'readonly',
     $NonMaybeType: 'readonly',
+    $PropertyType: 'readonly',
     $ReadOnly: 'readonly',
     $ReadOnlyArray: 'readonly',
     $ArrayBufferView: 'readonly',
@@ -565,7 +567,6 @@ module.exports = {
     BigInt: 'readonly',
     BigInt64Array: 'readonly',
     BigUint64Array: 'readonly',
-    CacheType: 'readonly',
     Class: 'readonly',
     ClientRect: 'readonly',
     CopyInspectedElementPath: 'readonly',
@@ -580,15 +581,13 @@ module.exports = {
     IteratorResult: 'readonly',
     JSONValue: 'readonly',
     JSResourceReference: 'readonly',
-    mixin$Animatable: 'readonly',
     MouseEventHandler: 'readonly',
     NavigateEvent: 'readonly',
-    PerformanceMeasureOptions: 'readonly',
     PropagationPhases: 'readonly',
     PropertyDescriptor: 'readonly',
-    PropertyDescriptorMap: 'readonly',
-    Proxy$traps: 'readonly',
+    React$AbstractComponent: 'readonly',
     React$Component: 'readonly',
+    React$ComponentType: 'readonly',
     React$Config: 'readonly',
     React$Context: 'readonly',
     React$Element: 'readonly',
@@ -620,6 +619,7 @@ module.exports = {
     PropertyIndexedKeyframes: 'readonly',
     KeyframeAnimationOptions: 'readonly',
     GetAnimationsOptions: 'readonly',
+    Animatable: 'readonly',
     ScrollTimeline: 'readonly',
     EventListenerOptionsOrUseCapture: 'readonly',
     FocusOptions: 'readonly',

.github/workflows/compiler_playground.yml

@@ -57,6 +57,8 @@ jobs:
           key: playwright-browsers-v6-${{ runner.arch }}-${{ runner.os }}-${{ steps.playwright_version.outputs.playwright_version }}
       - run: npx playwright install --with-deps chromium
         if: steps.cache_playwright_browsers.outputs.cache-hit != 'true'
+      - run: npx playwright install-deps
+        if: steps.cache_playwright_browsers.outputs.cache-hit == 'true'
       - run: CI=true yarn test
       - run: ls -R test-results
         if: '!cancelled()'

.github/workflows/runtime_build_and_test.yml

@@ -316,7 +316,7 @@ jobs:
         if: steps.node_modules.outputs.cache-hit != 'true'
       - run: ./scripts/react-compiler/build-compiler.sh && ./scripts/react-compiler/link-compiler.sh
       - run: yarn workspace eslint-plugin-react-hooks test
-
+        
   # ----- BUILD -----
   build_and_lint:
     name: yarn build and lint
@@ -811,18 +811,9 @@ jobs:
           pattern: _build_*
           path: build
           merge-multiple: true
-      - name: Check Playwright version
-        id: playwright_version
-        run: echo "playwright_version=$(npm ls @playwright/test | grep @playwright | sed 's/.*@//' | head -1)" >> "$GITHUB_OUTPUT"
-      - name: Cache Playwright Browsers for version ${{ steps.playwright_version.outputs.playwright_version }}
-        id: cache_playwright_browsers
-        uses: actions/cache@v4
-        with:
-          path: ~/.cache/ms-playwright
-          key: playwright-browsers-v6-${{ runner.arch }}-${{ runner.os }}-${{ steps.playwright_version.outputs.playwright_version }}
-      - name: Playwright install deps
-        if: steps.cache_playwright_browsers.outputs.cache-hit != 'true'
-        run: npx playwright install --with-deps chromium
+      - run: |
+          npx playwright install
+          sudo npx playwright install-deps
       - run: ./scripts/ci/run_devtools_e2e_tests.js
         env:
           RELEASE_CHANNEL: experimental

.github/workflows/shared_close_direct_sync_branch_prs.yml

@@ -18,7 +18,6 @@ jobs:
     permissions:
       # Used to create a review and close PRs
       pull-requests: write
-      contents: write
     steps:
       - name: Close PR
         uses: actions/github-script@v7

babel.config-ts.js

@@ -8,7 +8,6 @@ module.exports = {
     '@babel/plugin-syntax-jsx',
     '@babel/plugin-transform-flow-strip-types',
     ['@babel/plugin-transform-class-properties', {loose: true}],
-    ['@babel/plugin-transform-private-methods', {loose: true}],
     '@babel/plugin-transform-classes',
   ],
   presets: [

compiler/apps/playground/components/Editor/ConfigEditor.tsx

@@ -1,103 +0,0 @@
-/**
- * Copyright (c) Meta Platforms, Inc. and affiliates.
- *
- * This source code is licensed under the MIT license found in the
- * LICENSE file in the root directory of this source tree.
- */
-
-import MonacoEditor, {loader, type Monaco} from '@monaco-editor/react';
-import {parseConfigPragmaAsString} from 'babel-plugin-react-compiler';
-import type {editor} from 'monaco-editor';
-import * as monaco from 'monaco-editor';
-import parserBabel from 'prettier/plugins/babel';
-import * as prettierPluginEstree from 'prettier/plugins/estree';
-import * as prettier from 'prettier/standalone';
-import {useState, useEffect} from 'react';
-import {Resizable} from 're-resizable';
-import {useStore} from '../StoreContext';
-import {monacoOptions} from './monacoOptions';
-
-loader.config({monaco});
-
-export default function ConfigEditor(): JSX.Element {
-  const [, setMonaco] = useState<Monaco | null>(null);
-  const store = useStore();
-
-  // Parse string-based override config from pragma comment and format it
-  const [configJavaScript, setConfigJavaScript] = useState('');
-
-  useEffect(() => {
-    const pragma = store.source.substring(0, store.source.indexOf('\n'));
-    const configString = `(${parseConfigPragmaAsString(pragma)})`;
-
-    prettier
-      .format(configString, {
-        semi: true,
-        parser: 'babel-ts',
-        plugins: [parserBabel, prettierPluginEstree],
-      })
-      .then(formatted => {
-        setConfigJavaScript(formatted);
-      })
-      .catch(error => {
-        console.error('Error formatting config:', error);
-        setConfigJavaScript('({})'); // Return empty object if not valid for now
-        //TODO: Add validation and error handling for config
-      });
-    console.log('Config:', configString);
-  }, [store.source]);
-
-  const handleChange: (value: string | undefined) => void = value => {
-    if (!value) return;
-
-    // TODO: Implement sync logic to update pragma comments in the source
-    console.log('Config changed:', value);
-  };
-
-  const handleMount: (
-    _: editor.IStandaloneCodeEditor,
-    monaco: Monaco,
-  ) => void = (_, monaco) => {
-    setMonaco(monaco);
-
-    const uri = monaco.Uri.parse(`file:///config.js`);
-    const model = monaco.editor.getModel(uri);
-    if (model) {
-      model.updateOptions({tabSize: 2});
-    }
-  };
-
-  return (
-    <div className="relative flex flex-col flex-none border-r border-gray-200">
-      <h2 className="p-4 duration-150 ease-in border-b cursor-default border-grey-200 font-light text-secondary">
-        Config Overrides
-      </h2>
-      <Resizable
-        minWidth={300}
-        maxWidth={600}
-        defaultSize={{width: 350, height: 'auto'}}
-        enable={{right: true}}
-        className="!h-[calc(100vh_-_3.5rem_-_4rem)]">
-        <MonacoEditor
-          path={'config.js'}
-          language={'javascript'}
-          value={configJavaScript}
-          onMount={handleMount}
-          onChange={handleChange}
-          options={{
-            ...monacoOptions,
-            readOnly: true,
-            lineNumbers: 'off',
-            folding: false,
-            renderLineHighlight: 'none',
-            scrollBeyondLastLine: false,
-            hideCursorInOverviewRuler: true,
-            overviewRulerBorder: false,
-            overviewRulerLanes: 0,
-            fontSize: 12,
-          }}
-        />
-      </Resizable>
-    </div>
-  );
-}

compiler/apps/playground/components/Editor/EditorImpl.tsx

@@ -37,7 +37,6 @@ import {
   type Store,
 } from '../../lib/stores';
 import {useStore, useStoreDispatch} from '../StoreContext';
-import ConfigEditor from './ConfigEditor';
 import Input from './Input';
 import {
   CompilerOutput,
@@ -47,7 +46,6 @@ import {
 } from './Output';
 import {transformFromAstSync} from '@babel/core';
 import {LoggerEvent} from 'babel-plugin-react-compiler/dist/Entrypoint';
-import {useSearchParams} from 'next/navigation';
 
 function parseInput(
   input: string,
@@ -293,13 +291,7 @@ export default function Editor(): JSX.Element {
     [deferredStore.source],
   );
 
-  // TODO: Remove this once the config editor is more stable
-  const searchParams = useSearchParams();
-  const search = searchParams.get('showConfig');
-  const shouldShowConfig = search === 'true';
-
   useMountEffect(() => {
-    // Initialize store
     let mountStore: Store;
     try {
       mountStore = initStoreFromUrlOrLocalStorage();
@@ -336,7 +328,6 @@ export default function Editor(): JSX.Element {
   return (
     <>
       <div className="relative flex basis top-14">
-        {shouldShowConfig && <ConfigEditor />}
         <div className={clsx('relative sm:basis-1/4')}>
           <Input language={language} errors={errors} />
         </div>

compiler/package.json

@@ -19,8 +19,7 @@
     "test": "yarn workspaces run test",
     "snap": "yarn workspace babel-plugin-react-compiler run snap",
     "snap:build": "yarn workspace snap run build",
-    "npm:publish": "node scripts/release/publish",
-    "eslint-docs": "yarn workspace babel-plugin-react-compiler build && node scripts/build-eslint-docs.js"
+    "npm:publish": "node scripts/release/publish"
   },
   "dependencies": {
     "fs-extra": "^4.0.2",

compiler/packages/babel-plugin-react-compiler/src/CompilerError.ts

@@ -7,68 +7,36 @@
 
 import * as t from '@babel/types';
 import {codeFrameColumns} from '@babel/code-frame';
-import {type SourceLocation} from './HIR';
+import type {SourceLocation} from './HIR';
 import {Err, Ok, Result} from './Utils/Result';
 import {assertExhaustive} from './Utils/utils';
-import invariant from 'invariant';
-
-export enum ErrorSeverity {
-  /**
-   * Invalid JS syntax, or valid syntax that is semantically invalid which may indicate some
-   * misunderstanding on the user’s part.
-   */
-  InvalidJS = 'InvalidJS',
-  /**
-   * JS syntax that is not supported and which we do not plan to support. Developers should
-   * rewrite to use supported forms.
-   */
-  UnsupportedJS = 'UnsupportedJS',
-  /**
-   * Code that breaks the rules of React.
-   */
-  InvalidReact = 'InvalidReact',
-  /**
-   * Incorrect configuration of the compiler.
-   */
-  InvalidConfig = 'InvalidConfig',
-  /**
-   * Code that can reasonably occur and that doesn't break any rules, but is unsafe to preserve
-   * memoization.
-   */
-  CannotPreserveMemoization = 'CannotPreserveMemoization',
-  /**
-   * Unhandled syntax that we don't support yet.
-   */
-  Todo = 'Todo',
-  /**
-   * An unexpected internal error in the compiler that indicates critical issues that can panic
-   * the compiler.
-   */
-  Invariant = 'Invariant',
-}
+import {ErrorSeverity} from './Utils/CompilerErrorSeverity';
+import {
+  ErrorCode,
+  ErrorCodeDetails,
+  LinterCategory,
+} from './Utils/CompilerErrorCodes';
+export {ErrorSeverity};
+export {ErrorCode, ErrorCodeDetails, LinterCategory};
 
 export type CompilerDiagnosticOptions = {
-  category: ErrorCategory;
   severity: ErrorSeverity;
-  reason: string;
-  description: string;
+  category: string;
+  description?: string | null | undefined;
   details: Array<CompilerDiagnosticDetail>;
   suggestions?: Array<CompilerSuggestion> | null | undefined;
+  linterCategory?: LinterCategory | null | undefined;
 };
 
 export type CompilerDiagnosticDetail =
   /**
    * A/the source of the error
    */
-  | {
-      kind: 'error';
-      loc: SourceLocation | null;
-      message: string;
-    }
-  | {
-      kind: 'hint';
-      message: string;
-    };
+  {
+    kind: 'error';
+    loc: SourceLocation | null;
+    message: string;
+  };
 
 export enum CompilerSuggestionOperation {
   InsertBefore,
@@ -92,14 +60,28 @@ export type CompilerSuggestion =
       description: string;
     };
 
-export type CompilerErrorDetailOptions = {
-  category: ErrorCategory;
-  severity: ErrorSeverity;
+export type PlainCompilerErrorDetailOptions = {
+  errorCode?: void;
   reason: string;
   description?: string | null | undefined;
+  severity:
+    | ErrorSeverity.Invariant
+    | ErrorSeverity.Todo
+    | ErrorSeverity.InvalidConfig;
   loc: SourceLocation | null;
   suggestions?: Array<CompilerSuggestion> | null | undefined;
 };
+export type CodedCompilerErrorDetailOptions = {
+  errorCode: ErrorCode;
+  description?: string | null | undefined;
+  loc: SourceLocation | null;
+  suggestions?: Array<CompilerSuggestion> | null | undefined;
+  linterCategory?: LinterCategory | null | undefined;
+};
+
+export type CompilerErrorDetailOptions =
+  | PlainCompilerErrorDetailOptions
+  | CodedCompilerErrorDetailOptions;
 
 export type PrintErrorMessageOptions = {
   /**
@@ -109,21 +91,74 @@ export type PrintErrorMessageOptions = {
   eslint: boolean;
 };
 
+export function makeCompilerDiagnostic(
+  code: ErrorCode,
+  options?: {
+    description?: string;
+    suggestions?: Array<CompilerSuggestion> | null | undefined;
+  },
+): CompilerDiagnostic {
+  return makeCompilerDiagnostic(code, options);
+}
+
 export class CompilerDiagnostic {
   options: CompilerDiagnosticOptions;
 
-  constructor(options: CompilerDiagnosticOptions) {
+  /**
+   * Constructor is private to enforce that we either only create invariant diagnostics
+   * or use ErrorCodes
+   */
+  private constructor(options: CompilerDiagnosticOptions) {
     this.options = options;
   }
 
-  static create(
-    options: Omit<CompilerDiagnosticOptions, 'details'>,
-  ): CompilerDiagnostic {
+  static create<
+    T extends CompilerDiagnosticOptions & {severity: ErrorSeverity.Invariant},
+  >(options: Omit<T, 'details'>): CompilerDiagnostic {
     return new CompilerDiagnostic({...options, details: []});
   }
 
-  get reason(): CompilerDiagnosticOptions['reason'] {
-    return this.options.reason;
+  static fromCode(
+    code: ErrorCode,
+    options?: {
+      description?: string;
+      suggestions?: Array<CompilerSuggestion> | null | undefined;
+      details?: Array<CompilerDiagnosticDetail> | null | undefined;
+    },
+  ): CompilerDiagnostic {
+    const errorEntry = ErrorCodeDetails[code];
+    let description = undefined;
+    if (errorEntry.description != null) {
+      description = endWithPeriod(errorEntry.description);
+    }
+    if (options?.description != null && options.description.length > 0) {
+      if (description != null && description.length > 0) {
+        description += ' ';
+      } else {
+        description = '';
+      }
+      description += endWithPeriod(options.description);
+    }
+
+    const diagnosticOptions: CompilerDiagnosticOptions = {
+      severity: errorEntry.severity,
+      category: errorEntry.reason,
+      description,
+      linterCategory: errorEntry.linterCategory,
+      suggestions: options?.suggestions,
+      details: options?.details ?? [],
+    };
+
+    return new CompilerDiagnostic(diagnosticOptions);
+  }
+
+  // TODO: remove after converting test fixtures to use printErrorMessage
+  serialize(): unknown {
+    return {options: {...this.options, linterCategory: undefined}};
+  }
+
+  get category(): CompilerDiagnosticOptions['category'] {
+    return this.options.category;
   }
   get description(): CompilerDiagnosticOptions['description'] {
     return this.options.description;
@@ -134,8 +169,8 @@ export class CompilerDiagnostic {
   get suggestions(): CompilerDiagnosticOptions['suggestions'] {
     return this.options.suggestions;
   }
-  get category(): ErrorCategory {
-    return this.options.category;
+  get linterCategory(): CompilerDiagnosticOptions['linterCategory'] {
+    return this.options.linterCategory;
   }
 
   withDetail(detail: CompilerDiagnosticDetail): CompilerDiagnostic {
@@ -144,20 +179,14 @@ export class CompilerDiagnostic {
   }
 
   primaryLocation(): SourceLocation | null {
-    const firstErrorDetail = this.options.details.filter(
-      d => d.kind === 'error',
-    )[0];
-    return firstErrorDetail != null && firstErrorDetail.kind === 'error'
-      ? firstErrorDetail.loc
-      : null;
+    return this.options.details.filter(d => d.kind === 'error')[0]?.loc ?? null;
   }
 
   printErrorMessage(source: string, options: PrintErrorMessageOptions): string {
-    const buffer = [
-      printErrorSummary(this.severity, this.reason),
-      '\n\n',
-      this.description,
-    ];
+    const buffer = [printErrorSummary(this.severity, this.category)];
+    if (this.description != null) {
+      buffer.push(`\n\n${endWithPeriod(this.description)}`);
+    }
     for (const detail of this.options.details) {
       switch (detail.kind) {
         case 'error': {
@@ -182,14 +211,9 @@ export class CompilerDiagnostic {
           buffer.push(codeFrame);
           break;
         }
-        case 'hint': {
-          buffer.push('\n\n');
-          buffer.push(detail.message);
-          break;
-        }
         default: {
           assertExhaustive(
-            detail,
+            detail.kind,
             `Unexpected detail kind ${(detail as any).kind}`,
           );
         }
@@ -199,9 +223,9 @@ export class CompilerDiagnostic {
   }
 
   toString(): string {
-    const buffer = [printErrorSummary(this.severity, this.reason)];
+    const buffer = [printErrorSummary(this.severity, this.category)];
     if (this.description != null) {
-      buffer.push(`. ${this.description}.`);
+      buffer.push(`. ${endWithPeriod(this.description)}`);
     }
     const loc = this.primaryLocation();
     if (loc != null && typeof loc !== 'symbol') {
@@ -222,13 +246,68 @@ export class CompilerErrorDetail {
     this.options = options;
   }
 
-  get reason(): CompilerErrorDetailOptions['reason'] {
-    return this.options.reason;
+  static fromCode(
+    code: ErrorCode,
+    details?: {
+      description?: string | null;
+      loc?: SourceLocation | null;
+      suggestions?: Array<CompilerSuggestion> | null | undefined;
+    },
+  ): CompilerErrorDetail {
+    return new CompilerErrorDetail({
+      ...details,
+      errorCode: code,
+    } as CodedCompilerErrorDetailOptions);
   }
-  get description(): CompilerErrorDetailOptions['description'] {
-    return this.options.description;
+
+  // TODO: remove after converting test fixtures to use printErrorMessage
+  serialize(): unknown {
+    return {
+      options: {
+        reason: this.reason,
+        description: this.description,
+        severity: this.severity,
+        loc: this.loc,
+        suggestions: this.suggestions,
+      },
+    };
   }
-  get severity(): CompilerErrorDetailOptions['severity'] {
+
+  get reason(): string {
+    if (this.options.errorCode != null) {
+      return ErrorCodeDetails[this.options.errorCode].reason;
+    } else {
+      return this.options.reason;
+    }
+  }
+  get description(): string | null | undefined {
+    if (this.options.errorCode != null) {
+      let description = undefined;
+      const errorEntry = ErrorCodeDetails[this.options.errorCode];
+      if (errorEntry.description != null) {
+        description = endWithPeriod(errorEntry.description);
+      }
+      if (
+        this.options.description != null &&
+        this.options.description.length > 0
+      ) {
+        if (description != null && description.length > 0) {
+          description += ' ';
+        } else {
+          description = '';
+        }
+        description += endWithPeriod(this.options.description);
+      }
+      return description;
+    }
+    return this.options.description != null
+      ? endWithPeriod(this.options.description)
+      : this.options.description;
+  }
+  get severity(): ErrorSeverity {
+    if (this.options.errorCode != null) {
+      return ErrorCodeDetails[this.options.errorCode].severity;
+    }
     return this.options.severity;
   }
   get loc(): CompilerErrorDetailOptions['loc'] {
@@ -237,8 +316,11 @@ export class CompilerErrorDetail {
   get suggestions(): CompilerErrorDetailOptions['suggestions'] {
     return this.options.suggestions;
   }
-  get category(): ErrorCategory {
-    return this.options.category;
+  get linterCategory(): LinterCategory | null | undefined {
+    if (this.options.errorCode != null) {
+      return ErrorCodeDetails[this.options.errorCode].linterCategory;
+    }
+    return undefined;
   }
 
   primaryLocation(): SourceLocation | null {
@@ -248,7 +330,7 @@ export class CompilerErrorDetail {
   printErrorMessage(source: string, options: PrintErrorMessageOptions): string {
     const buffer = [printErrorSummary(this.severity, this.reason)];
     if (this.description != null) {
-      buffer.push(`\n\n${this.description}.`);
+      buffer.push(`\n\n${endWithPeriod(this.description)}`);
     }
     const loc = this.loc;
     if (loc != null && typeof loc !== 'symbol') {
@@ -273,7 +355,7 @@ export class CompilerErrorDetail {
   toString(): string {
     const buffer = [printErrorSummary(this.severity, this.reason)];
     if (this.description != null) {
-      buffer.push(`. ${this.description}.`);
+      buffer.push(`. ${endWithPeriod(this.description)}`);
     }
     const loc = this.loc;
     if (loc != null && typeof loc !== 'symbol') {
@@ -289,14 +371,13 @@ export class CompilerError extends Error {
 
   static invariant(
     condition: unknown,
-    options: Omit<CompilerErrorDetailOptions, 'severity' | 'category'>,
+    options: Omit<PlainCompilerErrorDetailOptions, 'severity'>,
   ): asserts condition {
     if (!condition) {
       const errors = new CompilerError();
       errors.pushErrorDetail(
         new CompilerErrorDetail({
           ...options,
-          category: ErrorCategory.Invariant,
           severity: ErrorSeverity.Invariant,
         }),
       );
@@ -304,62 +385,43 @@ export class CompilerError extends Error {
     }
   }
 
-  static throwDiagnostic(options: CompilerDiagnosticOptions): never {
+  static throwDiagnostic(diagnostic: CompilerDiagnostic): never {
     const errors = new CompilerError();
-    errors.pushDiagnostic(new CompilerDiagnostic(options));
+    errors.pushDiagnostic(diagnostic);
     throw errors;
   }
 
   static throwTodo(
-    options: Omit<CompilerErrorDetailOptions, 'severity' | 'category'>,
+    options: Omit<PlainCompilerErrorDetailOptions, 'severity'>,
   ): never {
     const errors = new CompilerError();
     errors.pushErrorDetail(
-      new CompilerErrorDetail({
-        ...options,
-        severity: ErrorSeverity.Todo,
-        category: ErrorCategory.Todo,
-      }),
+      new CompilerErrorDetail({...options, severity: ErrorSeverity.Todo}),
     );
     throw errors;
   }
 
-  static throwInvalidJS(
-    options: Omit<CompilerErrorDetailOptions, 'severity' | 'category'>,
+  static throwFromCode(
+    code: ErrorCode,
+    options?: {
+      description?: string | null;
+      loc?: SourceLocation | null;
+      suggestions?: Array<CompilerSuggestion> | null | undefined;
+    },
   ): never {
     const errors = new CompilerError();
-    errors.pushErrorDetail(
-      new CompilerErrorDetail({
-        ...options,
-        severity: ErrorSeverity.InvalidJS,
-        category: ErrorCategory.Syntax,
-      }),
-    );
-    throw errors;
-  }
-
-  static throwInvalidReact(
-    options: Omit<CompilerErrorDetailOptions, 'severity'>,
-  ): never {
-    const errors = new CompilerError();
-    errors.pushErrorDetail(
-      new CompilerErrorDetail({
-        ...options,
-        severity: ErrorSeverity.InvalidReact,
-      }),
-    );
+    errors.pushErrorDetail(CompilerErrorDetail.fromCode(code, options));
     throw errors;
   }
 
   static throwInvalidConfig(
-    options: Omit<CompilerErrorDetailOptions, 'severity' | 'category'>,
+    options: Omit<PlainCompilerErrorDetailOptions, 'severity'>,
   ): never {
     const errors = new CompilerError();
     errors.pushErrorDetail(
       new CompilerErrorDetail({
         ...options,
         severity: ErrorSeverity.InvalidConfig,
-        category: ErrorCategory.Config,
       }),
     );
     throw errors;
@@ -422,14 +484,10 @@ export class CompilerError extends Error {
   }
 
   push(options: CompilerErrorDetailOptions): CompilerErrorDetail {
-    const detail = new CompilerErrorDetail({
-      category: options.category,
-      reason: options.reason,
-      description: options.description ?? null,
-      severity: options.severity,
-      suggestions: options.suggestions,
-      loc: typeof options.loc === 'symbol' ? null : options.loc,
-    });
+    if (options instanceof CompilerErrorDetail) {
+      return this.pushErrorDetail(options);
+    }
+    const detail = new CompilerErrorDetail(options);
     return this.pushErrorDetail(detail);
   }
 
@@ -438,6 +496,19 @@ export class CompilerError extends Error {
     return detail;
   }
 
+  pushErrorCode(
+    code: ErrorCode,
+    details?: {
+      description?: string | null;
+      loc?: SourceLocation | null;
+      suggestions?: Array<CompilerSuggestion> | null | undefined;
+    },
+  ): CompilerErrorDetail {
+    const detail = CompilerErrorDetail.fromCode(code, details);
+    this.details.push(detail);
+    return detail;
+  }
+
   hasErrors(): boolean {
     return this.details.length > 0;
   }
@@ -525,357 +596,9 @@ function printErrorSummary(severity: ErrorSeverity, message: string): string {
   return `${severityCategory}: ${message}`;
 }
 
-/**
- * See getRuleForCategory() for how these map to ESLint rules
- */
-export enum ErrorCategory {
-  // Checking for valid hooks usage (non conditional, non-first class, non reactive, etc)
-  Hooks = 'Hooks',
-
-  // Checking for no capitalized calls (not definitively an error, hence separating)
-  CapitalizedCalls = 'CapitalizedCalls',
-
-  // Checking for static components
-  StaticComponents = 'StaticComponents',
-
-  // Checking for valid usage of manual memoization
-  UseMemo = 'UseMemo',
-
-  // Checking for higher order functions acting as factories for components/hooks
-  Factories = 'Factories',
-
-  // Checks that manual memoization is preserved
-  PreserveManualMemo = 'PreserveManualMemo',
-
-  // Checking for no mutations of props, hook arguments, hook return values
-  Immutability = 'Immutability',
-
-  // Checking for assignments to globals
-  Globals = 'Globals',
-
-  // Checking for valid usage of refs, ie no access during render
-  Refs = 'Refs',
-
-  // Checks for memoized effect deps
-  EffectDependencies = 'EffectDependencies',
-
-  // Checks for no setState in effect bodies
-  EffectSetState = 'EffectSetState',
-
-  EffectDerivationsOfState = 'EffectDerivationsOfState',
-
-  // Validates against try/catch in place of error boundaries
-  ErrorBoundaries = 'ErrorBoundaries',
-
-  // Checking for pure functions
-  Purity = 'Purity',
-
-  // Validates against setState in render
-  RenderSetState = 'RenderSetState',
-
-  // Internal invariants
-  Invariant = 'Invariant',
-
-  // Todos
-  Todo = 'Todo',
-
-  // Syntax errors
-  Syntax = 'Syntax',
-
-  // Checks for use of unsupported syntax
-  UnsupportedSyntax = 'UnsupportedSyntax',
-
-  // Config errors
-  Config = 'Config',
-
-  // Gating error
-  Gating = 'Gating',
-
-  // Suppressions
-  Suppression = 'Suppression',
-
-  // Issues with auto deps
-  AutomaticEffectDependencies = 'AutomaticEffectDependencies',
-
-  // Issues with `fire`
-  Fire = 'Fire',
-
-  // fbt-specific issues
-  FBT = 'FBT',
-}
-
-export type LintRule = {
-  // Stores the category the rule corresponds to, used to filter errors when reporting
-  category: ErrorCategory;
-
-  /**
-   * The "name" of the rule as it will be used by developers to enable/disable, eg
-   * "eslint-disable-nest line <name>"
-   */
-  name: string;
-
-  /**
-   * A description of the rule that appears somewhere in ESLint. This does not affect
-   * how error messages are formatted
-   */
-  description: string;
-
-  /**
-   * If true, this rule will automatically appear in the default, "recommended" ESLint
-   * rule set. Otherwise it will be part of an `allRules` export that developers can
-   * use to opt-in to showing output of all possible rules.
-   *
-   * NOTE: not all validations are enabled by default! Setting this flag only affects
-   * whether a given rule is part of the recommended set. The corresponding validation
-   * also should be enabled by default if you want the error to actually show up!
-   */
-  recommended: boolean;
-};
-
-const RULE_NAME_PATTERN = /^[a-z]+(-[a-z]+)*$/;
-
-export function getRuleForCategory(category: ErrorCategory): LintRule {
-  const rule = getRuleForCategoryImpl(category);
-  invariant(
-    RULE_NAME_PATTERN.test(rule.name),
-    `Invalid rule name, got '${rule.name}' but rules must match ${RULE_NAME_PATTERN.toString()}`,
-  );
-  return rule;
-}
-
-function getRuleForCategoryImpl(category: ErrorCategory): LintRule {
-  switch (category) {
-    case ErrorCategory.AutomaticEffectDependencies: {
-      return {
-        category,
-        name: 'automatic-effect-dependencies',
-        description:
-          'Verifies that automatic effect dependencies are compiled if opted-in',
-        recommended: false,
-      };
-    }
-    case ErrorCategory.CapitalizedCalls: {
-      return {
-        category,
-        name: 'capitalized-calls',
-        description:
-          'Validates against calling capitalized functions/methods instead of using JSX',
-        recommended: false,
-      };
-    }
-    case ErrorCategory.Config: {
-      return {
-        category,
-        name: 'config',
-        description: 'Validates the compiler configuration options',
-        recommended: true,
-      };
-    }
-    case ErrorCategory.EffectDependencies: {
-      return {
-        category,
-        name: 'memoized-effect-dependencies',
-        description: 'Validates that effect dependencies are memoized',
-        recommended: false,
-      };
-    }
-    case ErrorCategory.EffectDerivationsOfState: {
-      return {
-        category,
-        name: 'no-deriving-state-in-effects',
-        description:
-          'Validates against deriving values from state in an effect',
-        recommended: false,
-      };
-    }
-    case ErrorCategory.EffectSetState: {
-      return {
-        category,
-        name: 'set-state-in-effect',
-        description:
-          'Validates against calling setState synchronously in an effect, which can lead to re-renders that degrade performance',
-        recommended: true,
-      };
-    }
-    case ErrorCategory.ErrorBoundaries: {
-      return {
-        category,
-        name: 'error-boundaries',
-        description:
-          'Validates usage of error boundaries instead of try/catch for errors in child components',
-        recommended: true,
-      };
-    }
-    case ErrorCategory.Factories: {
-      return {
-        category,
-        name: 'component-hook-factories',
-        description:
-          'Validates against higher order functions defining nested components or hooks. ' +
-          'Components and hooks should be defined at the module level',
-        recommended: true,
-      };
-    }
-    case ErrorCategory.FBT: {
-      return {
-        category,
-        name: 'fbt',
-        description: 'Validates usage of fbt',
-        recommended: false,
-      };
-    }
-    case ErrorCategory.Fire: {
-      return {
-        category,
-        name: 'fire',
-        description: 'Validates usage of `fire`',
-        recommended: false,
-      };
-    }
-    case ErrorCategory.Gating: {
-      return {
-        category,
-        name: 'gating',
-        description:
-          'Validates configuration of [gating mode](https://react.dev/reference/react-compiler/gating)',
-        recommended: true,
-      };
-    }
-    case ErrorCategory.Globals: {
-      return {
-        category,
-        name: 'globals',
-        description:
-          'Validates against assignment/mutation of globals during render, part of ensuring that ' +
-          '[side effects must render outside of render](https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)',
-        recommended: true,
-      };
-    }
-    case ErrorCategory.Hooks: {
-      return {
-        category,
-        name: 'hooks',
-        description: 'Validates the rules of hooks',
-        /**
-         * TODO: the "Hooks" rule largely reimplements the "rules-of-hooks" non-compiler rule.
-         * We need to dedeupe these (moving the remaining bits into the compiler) and then enable
-         * this rule.
-         */
-        recommended: false,
-      };
-    }
-    case ErrorCategory.Immutability: {
-      return {
-        category,
-        name: 'immutability',
-        description:
-          'Validates against mutating props, state, and other values that [are immutable](https://react.dev/reference/rules/components-and-hooks-must-be-pure#props-and-state-are-immutable)',
-        recommended: true,
-      };
-    }
-    case ErrorCategory.Invariant: {
-      return {
-        category,
-        name: 'invariant',
-        description: 'Internal invariants',
-        recommended: false,
-      };
-    }
-    case ErrorCategory.PreserveManualMemo: {
-      return {
-        category,
-        name: 'preserve-manual-memoization',
-        description:
-          'Validates that existing manual memoized is preserved by the compiler. ' +
-          'React Compiler will only compile components and hooks if its inference ' +
-          '[matches or exceeds the existing manual memoization](https://react.dev/learn/react-compiler/introduction#what-should-i-do-about-usememo-usecallback-and-reactmemo)',
-        recommended: true,
-      };
-    }
-    case ErrorCategory.Purity: {
-      return {
-        category,
-        name: 'purity',
-        description:
-          'Validates that [components/hooks are pure](https://react.dev/reference/rules/components-and-hooks-must-be-pure) by checking that they do not call known-impure functions',
-        recommended: true,
-      };
-    }
-    case ErrorCategory.Refs: {
-      return {
-        category,
-        name: 'refs',
-        description:
-          'Validates correct usage of refs, not reading/writing during render. See the "pitfalls" section in [`useRef()` usage](https://react.dev/reference/react/useRef#usage)',
-        recommended: true,
-      };
-    }
-    case ErrorCategory.RenderSetState: {
-      return {
-        category,
-        name: 'set-state-in-render',
-        description:
-          'Validates against setting state during render, which can trigger additional renders and potential infinite render loops',
-        recommended: true,
-      };
-    }
-    case ErrorCategory.StaticComponents: {
-      return {
-        category,
-        name: 'static-components',
-        description:
-          'Validates that components are static, not recreated every render. Components that are recreated dynamically can reset state and trigger excessive re-rendering',
-        recommended: true,
-      };
-    }
-    case ErrorCategory.Suppression: {
-      return {
-        category,
-        name: 'rule-suppression',
-        description: 'Validates against suppression of other rules',
-        recommended: false,
-      };
-    }
-    case ErrorCategory.Syntax: {
-      return {
-        category,
-        name: 'syntax',
-        description: 'Validates against invalid syntax',
-        recommended: false,
-      };
-    }
-    case ErrorCategory.Todo: {
-      return {
-        category,
-        name: 'todo',
-        description: 'Unimplemented features',
-        recommended: false,
-      };
-    }
-    case ErrorCategory.UnsupportedSyntax: {
-      return {
-        category,
-        name: 'unsupported-syntax',
-        description:
-          'Validates against syntax that we do not plan to support in React Compiler',
-        recommended: true,
-      };
-    }
-    case ErrorCategory.UseMemo: {
-      return {
-        category,
-        name: 'use-memo',
-        description:
-          'Validates usage of the useMemo() hook against common mistakes. See [`useMemo()` docs](https://react.dev/reference/react/useMemo) for more information.',
-        recommended: true,
-      };
-    }
-    default: {
-      assertExhaustive(category, `Unsupported category ${category}`);
-    }
+function endWithPeriod(s: string): string {
+  if (s === '' || s.endsWith('.')) {
+    return s;
   }
+  return `${s.replace(/\.+$/, '')}.`;
 }
-
-export const LintRules: Array<LintRule> = Object.keys(ErrorCategory).map(
-  category => getRuleForCategory(category as any),
-);

compiler/packages/babel-plugin-react-compiler/src/Entrypoint/Imports.ts

@@ -9,7 +9,7 @@ import {NodePath} from '@babel/core';
 import * as t from '@babel/types';
 import {Scope as BabelScope} from '@babel/traverse';
 
-import {CompilerError, ErrorCategory, ErrorSeverity} from '../CompilerError';
+import {CompilerError, ErrorSeverity} from '../CompilerError';
 import {
   EnvironmentConfig,
   GeneratedSource,
@@ -38,11 +38,10 @@ export function validateRestrictedImports(
     ImportDeclaration(importDeclPath) {
       if (restrictedImports.has(importDeclPath.node.source.value)) {
         error.push({
-          category: ErrorCategory.Todo,
-          severity: ErrorSeverity.Todo,
           reason: 'Bailing out due to blocklisted import',
           description: `Import from module ${importDeclPath.node.source.value}`,
           loc: importDeclPath.node.loc ?? null,
+          severity: ErrorSeverity.Todo,
         });
       }
     },
@@ -206,11 +205,10 @@ export class ProgramContext {
     }
     const error = new CompilerError();
     error.push({
-      category: ErrorCategory.Todo,
-      severity: ErrorSeverity.Todo,
       reason: 'Encountered conflicting global in generated program',
       description: `Conflict from local binding ${name}`,
       loc: scope.getBinding(name)?.path.node.loc ?? null,
+      severity: ErrorSeverity.Todo,
       suggestions: null,
     });
     return Err(error);

compiler/packages/babel-plugin-react-compiler/src/Entrypoint/Options.ts

@@ -11,7 +11,7 @@ import {
   CompilerDiagnostic,
   CompilerError,
   CompilerErrorDetail,
-  CompilerErrorDetailOptions,
+  PlainCompilerErrorDetailOptions,
 } from '../CompilerError';
 import {
   EnvironmentConfig,
@@ -107,6 +107,8 @@ export type PluginOptions = {
    * passes.
    *
    * Defaults to false
+   *
+   * TODO: rename this to lintOnly or something similar
    */
   noEmit: boolean;
 
@@ -234,7 +236,10 @@ export type CompileErrorEvent = {
 export type CompileDiagnosticEvent = {
   kind: 'CompileDiagnostic';
   fnLoc: t.SourceLocation | null;
-  detail: Omit<Omit<CompilerErrorDetailOptions, 'severity'>, 'suggestions'>;
+  detail: Omit<
+    Omit<PlainCompilerErrorDetailOptions, 'severity'>,
+    'suggestions'
+  >;
 };
 export type CompileSuccessEvent = {
   kind: 'CompileSuccess';

compiler/packages/babel-plugin-react-compiler/src/Entrypoint/Pipeline.ts

@@ -33,7 +33,9 @@ import {findContextIdentifiers} from '../HIR/FindContextIdentifiers';
 import {
   analyseFunctions,
   dropManualMemoization,
+  inferMutableRanges,
   inferReactivePlaces,
+  inferReferenceEffects,
   inlineImmediatelyInvokedFunctionExpressions,
   inferEffectDependencies,
 } from '../Inference';
@@ -171,7 +173,7 @@ function runWithEnvironment(
     !env.config.disableMemoizationForDebugging &&
     !env.config.enableChangeDetectionForDebugging
   ) {
-    dropManualMemoization(hir).unwrap();
+    env.logOrThrowErrors(dropManualMemoization(hir));
     log({kind: 'hir', name: 'DropManualMemoization', value: hir});
   }
 
@@ -204,10 +206,10 @@ function runWithEnvironment(
 
   if (env.isInferredMemoEnabled) {
     if (env.config.validateHooksUsage) {
-      validateHooksUsage(hir).unwrap();
+      env.logOrThrowErrors(validateHooksUsage(hir));
     }
-    if (env.config.validateNoCapitalizedCalls) {
-      validateNoCapitalizedCalls(hir).unwrap();
+    if (env.config.validateNoCapitalizedCalls != null) {
+      env.logOrThrowErrors(validateNoCapitalizedCalls(hir));
     }
   }
 
@@ -226,12 +228,23 @@ function runWithEnvironment(
   analyseFunctions(hir);
   log({kind: 'hir', name: 'AnalyseFunctions', value: hir});
 
-  const mutabilityAliasingErrors = inferMutationAliasingEffects(hir);
-  log({kind: 'hir', name: 'InferMutationAliasingEffects', value: hir});
-  if (env.isInferredMemoEnabled) {
-    if (mutabilityAliasingErrors.isErr()) {
-      throw mutabilityAliasingErrors.unwrapErr();
+  if (!env.config.enableNewMutationAliasingModel) {
+    const fnEffectResult = inferReferenceEffects(hir);
+
+    if (env.isInferredMemoEnabled) {
+      env.logOrThrowErrors(fnEffectResult);
     }
+    log({kind: 'hir', name: 'InferReferenceEffects', value: hir});
+  } else {
+    const mutabilityAliasingErrors = inferMutationAliasingEffects(hir);
+    log({kind: 'hir', name: 'InferMutationAliasingEffects', value: hir});
+    if (env.isInferredMemoEnabled) {
+      env.logOrThrowErrors(mutabilityAliasingErrors);
+    }
+  }
+
+  if (!env.config.enableNewMutationAliasingModel) {
+    validateLocalsNotReassignedAfterRender(hir);
   }
 
   // Note: Has to come after infer reference effects because "dead" code may still affect inference
@@ -246,15 +259,18 @@ function runWithEnvironment(
   pruneMaybeThrows(hir);
   log({kind: 'hir', name: 'PruneMaybeThrows', value: hir});
 
-  const mutabilityAliasingRangeErrors = inferMutationAliasingRanges(hir, {
-    isFunctionExpression: false,
-  });
-  log({kind: 'hir', name: 'InferMutationAliasingRanges', value: hir});
-  if (env.isInferredMemoEnabled) {
-    if (mutabilityAliasingRangeErrors.isErr()) {
-      throw mutabilityAliasingRangeErrors.unwrapErr();
+  if (!env.config.enableNewMutationAliasingModel) {
+    inferMutableRanges(hir);
+    log({kind: 'hir', name: 'InferMutableRanges', value: hir});
+  } else {
+    const mutabilityAliasingErrors = inferMutationAliasingRanges(hir, {
+      isFunctionExpression: false,
+    });
+    log({kind: 'hir', name: 'InferMutationAliasingRanges', value: hir});
+    if (env.isInferredMemoEnabled) {
+      env.logOrThrowErrors(mutabilityAliasingErrors.map(() => undefined));
+      env.logOrThrowErrors(validateLocalsNotReassignedAfterRender(hir));
     }
-    validateLocalsNotReassignedAfterRender(hir);
   }
 
   if (env.isInferredMemoEnabled) {
@@ -263,15 +279,15 @@ function runWithEnvironment(
     }
 
     if (env.config.validateRefAccessDuringRender) {
-      validateNoRefAccessInRender(hir).unwrap();
+      env.logOrThrowErrors(validateNoRefAccessInRender(hir));
     }
 
     if (env.config.validateNoSetStateInRender) {
-      validateNoSetStateInRender(hir).unwrap();
+      env.logOrThrowErrors(validateNoSetStateInRender(hir));
     }
 
     if (env.config.validateNoDerivedComputationsInEffects) {
-      validateNoDerivedComputationsInEffects(hir);
+      env.logOrThrowErrors(validateNoDerivedComputationsInEffects(hir));
     }
 
     if (env.config.validateNoSetStateInEffects) {
@@ -281,12 +297,19 @@ function runWithEnvironment(
     if (env.config.validateNoJSXInTryStatements) {
       env.logErrors(validateNoJSXInTryStatement(hir));
     }
-
-    if (env.config.validateNoImpureFunctionsInRender) {
-      validateNoImpureFunctionsInRender(hir).unwrap();
+    if (
+      env.config.validateNoImpureFunctionsInRender &&
+      !env.config.enableNewMutationAliasingModel
+    ) {
+      env.logOrThrowErrors(validateNoImpureFunctionsInRender(hir));
     }
 
-    validateNoFreezingKnownMutableFunctions(hir).unwrap();
+    if (
+      env.config.validateNoFreezingKnownMutableFunctions ||
+      env.config.enableNewMutationAliasingModel
+    ) {
+      env.logOrThrowErrors(validateNoFreezingKnownMutableFunctions(hir));
+    }
   }
 
   inferReactivePlaces(hir);

compiler/packages/babel-plugin-react-compiler/src/Entrypoint/Program.ts

@@ -7,12 +7,7 @@
 
 import {NodePath} from '@babel/core';
 import * as t from '@babel/types';
-import {
-  CompilerError,
-  CompilerErrorDetail,
-  ErrorCategory,
-  ErrorSeverity,
-} from '../CompilerError';
+import {CompilerError, ErrorSeverity} from '../CompilerError';
 import {ExternalFunction, ReactFunctionType} from '../HIR/Environment';
 import {CodegenFunction} from '../ReactiveScopes';
 import {isComponentDeclaration} from '../Utils/ComponentDeclaration';
@@ -33,6 +28,7 @@ import {
 } from './Suppression';
 import {GeneratedSource} from '../HIR';
 import {Err, Ok, Result} from '../Utils/Result';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 
 export type CompilerPass = {
   opts: PluginOptions;
@@ -102,13 +98,9 @@ function findDirectivesDynamicGating(
       if (t.isValidIdentifier(maybeMatch[1])) {
         result.push({directive, match: maybeMatch[1]});
       } else {
-        errors.push({
-          reason: `Dynamic gating directive is not a valid JavaScript identifier`,
+        errors.pushErrorCode(ErrorCode.DYNAMIC_GATING_IS_NOT_IDENTIFIER, {
           description: `Found '${directive.value.value}'`,
-          severity: ErrorSeverity.InvalidReact,
-          category: ErrorCategory.Gating,
           loc: directive.loc ?? null,
-          suggestions: null,
         });
       }
     }
@@ -117,15 +109,11 @@ function findDirectivesDynamicGating(
     return Err(errors);
   } else if (result.length > 1) {
     const error = new CompilerError();
-    error.push({
-      reason: `Multiple dynamic gating directives found`,
+    error.pushErrorCode(ErrorCode.DYNAMIC_GATING_MULTIPLE_DIRECTIVES, {
       description: `Expected a single directive but found [${result
         .map(r => r.directive.value.value)
         .join(', ')}]`,
-      severity: ErrorSeverity.InvalidReact,
-      category: ErrorCategory.Gating,
       loc: result[0].directive.loc ?? null,
-      suggestions: null,
     });
     return Err(error);
   } else if (result.length === 1) {
@@ -454,15 +442,12 @@ export function compileProgram(
   if (programContext.hasModuleScopeOptOut) {
     if (compiledFns.length > 0) {
       const error = new CompilerError();
-      error.pushErrorDetail(
-        new CompilerErrorDetail({
-          reason:
-            'Unexpected compiled functions when module scope opt-out is present',
-          severity: ErrorSeverity.Invariant,
-          category: ErrorCategory.Invariant,
-          loc: null,
-        }),
-      );
+      error.push({
+        reason:
+          'Unexpected compiled functions when module scope opt-out is present',
+        severity: ErrorSeverity.Invariant,
+        loc: null,
+      });
       handleError(error, programContext, null);
     }
     return null;
@@ -494,20 +479,7 @@ function findFunctionsToCompile(
 ): Array<CompileSource> {
   const queue: Array<CompileSource> = [];
   const traverseFunction = (fn: BabelFn, pass: CompilerPass): void => {
-    // In 'all' mode, compile only top level functions
-    if (
-      pass.opts.compilationMode === 'all' &&
-      fn.scope.getProgramParent() !== fn.scope.parent
-    ) {
-      return;
-    }
-
     const fnType = getReactFunctionType(fn, pass);
-
-    if (pass.opts.environment.validateNoDynamicallyCreatedComponentsOrHooks) {
-      validateNoDynamicallyCreatedComponentsOrHooks(fn, pass, programContext);
-    }
-
     if (fnType === null || programContext.alreadyCompiled.has(fn.node)) {
       return;
     }
@@ -608,9 +580,7 @@ function processFn(
   let compiledFn: CodegenFunction;
   const compileResult = tryCompileFunction(fn, fnType, programContext);
   if (compileResult.kind === 'error') {
-    if (directives.optOut != null) {
-      logError(compileResult.error, programContext, fn.node.loc ?? null);
-    } else {
+    if (directives.optOut == null) {
       handleError(compileResult.error, programContext, fn.node.loc ?? null);
     }
     const retryResult = retryCompileFunction(fn, fnType, programContext);
@@ -709,7 +679,7 @@ function tryCompileFunction(
         fn,
         programContext.opts.environment,
         fnType,
-        'all_features',
+        programContext.opts.noEmit ? 'lint_only' : 'all_features',
         programContext,
         programContext.opts.logger,
         programContext.filename,
@@ -822,16 +792,7 @@ function shouldSkipCompilation(
   if (pass.opts.sources) {
     if (pass.filename === null) {
       const error = new CompilerError();
-      error.pushErrorDetail(
-        new CompilerErrorDetail({
-          reason: `Expected a filename but found none.`,
-          description:
-            "When the 'sources' config options is specified, the React compiler will only compile files with a name",
-          severity: ErrorSeverity.InvalidConfig,
-          category: ErrorCategory.Config,
-          loc: null,
-        }),
-      );
+      error.pushErrorCode(ErrorCode.FILENAME_NOT_SET);
       handleError(error, pass, null);
       return true;
     }
@@ -852,73 +813,6 @@ function shouldSkipCompilation(
   return false;
 }
 
-/**
- * Validates that Components/Hooks are always defined at module level. This prevents scope reference
- * errors that occur when the compiler attempts to optimize the nested component/hook while its
- * parent function remains uncompiled.
- */
-function validateNoDynamicallyCreatedComponentsOrHooks(
-  fn: BabelFn,
-  pass: CompilerPass,
-  programContext: ProgramContext,
-): void {
-  const parentNameExpr = getFunctionName(fn);
-  const parentName =
-    parentNameExpr !== null && parentNameExpr.isIdentifier()
-      ? parentNameExpr.node.name
-      : '<anonymous>';
-
-  const validateNestedFunction = (
-    nestedFn: NodePath<
-      t.FunctionDeclaration | t.FunctionExpression | t.ArrowFunctionExpression
-    >,
-  ): void => {
-    if (
-      nestedFn.node === fn.node ||
-      programContext.alreadyCompiled.has(nestedFn.node)
-    ) {
-      return;
-    }
-
-    if (nestedFn.scope.getProgramParent() !== nestedFn.scope.parent) {
-      const nestedFnType = getReactFunctionType(nestedFn as BabelFn, pass);
-      const nestedFnNameExpr = getFunctionName(nestedFn as BabelFn);
-      const nestedName =
-        nestedFnNameExpr !== null && nestedFnNameExpr.isIdentifier()
-          ? nestedFnNameExpr.node.name
-          : '<anonymous>';
-      if (nestedFnType === 'Component' || nestedFnType === 'Hook') {
-        CompilerError.throwDiagnostic({
-          category: ErrorCategory.Factories,
-          severity: ErrorSeverity.InvalidReact,
-          reason: `Components and hooks cannot be created dynamically`,
-          description: `The function \`${nestedName}\` appears to be a React ${nestedFnType.toLowerCase()}, but it's defined inside \`${parentName}\`. Components and Hooks should always be declared at module scope`,
-          details: [
-            {
-              kind: 'error',
-              message: 'this function dynamically created a component/hook',
-              loc: parentNameExpr?.node.loc ?? fn.node.loc ?? null,
-            },
-            {
-              kind: 'error',
-              message: 'the component is created here',
-              loc: nestedFnNameExpr?.node.loc ?? nestedFn.node.loc ?? null,
-            },
-          ],
-        });
-      }
-    }
-
-    nestedFn.skip();
-  };
-
-  fn.traverse({
-    FunctionDeclaration: validateNestedFunction,
-    FunctionExpression: validateNestedFunction,
-    ArrowFunctionExpression: validateNestedFunction,
-  });
-}
-
 function getReactFunctionType(
   fn: BabelFn,
   pass: CompilerPass,
@@ -957,6 +851,11 @@ function getReactFunctionType(
       return componentSyntaxType;
     }
     case 'all': {
+      // Compile only top level functions
+      if (fn.scope.getProgramParent() !== fn.scope.parent) {
+        return null;
+      }
+
       return getComponentOrHookLike(fn, hookPattern) ?? 'Other';
     }
     default: {

compiler/packages/babel-plugin-react-compiler/src/Entrypoint/Suppression.ts

@@ -11,8 +11,7 @@ import {
   CompilerDiagnostic,
   CompilerError,
   CompilerSuggestionOperation,
-  ErrorCategory,
-  ErrorSeverity,
+  ErrorCode,
 } from '../CompilerError';
 import {assertExhaustive} from '../Utils/utils';
 import {GeneratedSource} from '../HIR';
@@ -166,14 +165,12 @@ export function suppressionsToCompilerError(
     let reason, suggestion;
     switch (suppressionRange.source) {
       case 'Eslint':
-        reason =
-          'React Compiler has skipped optimizing this component because one or more React ESLint rules were disabled';
+        reason = ErrorCode.BAILOUT_ESLINT_SUPPRESSION;
         suggestion =
           'Remove the ESLint suppression and address the React error';
         break;
       case 'Flow':
-        reason =
-          'React Compiler has skipped optimizing this component because one or more React rule violations were reported by Flow';
+        reason = ErrorCode.BAILOUT_FLOW_SUPPRESSION;
         suggestion = 'Remove the Flow suppression and address the React error';
         break;
       default:
@@ -183,11 +180,8 @@ export function suppressionsToCompilerError(
         );
     }
     error.pushDiagnostic(
-      CompilerDiagnostic.create({
-        reason: reason,
-        description: `React Compiler only works when your components follow all the rules of React, disabling them may result in unexpected or incorrect behavior. Found suppression \`${suppressionRange.disableComment.value.trim()}\``,
-        severity: ErrorSeverity.InvalidReact,
-        category: ErrorCategory.Suppression,
+      CompilerDiagnostic.fromCode(reason, {
+        description: `Found suppression \`${suppressionRange.disableComment.value.trim()}\``,
         suggestions: [
           {
             description: suggestion,

compiler/packages/babel-plugin-react-compiler/src/Entrypoint/ValidateNoUntransformedReferences.ts

@@ -8,31 +8,24 @@
 import {NodePath} from '@babel/core';
 import * as t from '@babel/types';
 
-import {CompilerError, EnvironmentConfig, ErrorSeverity, Logger} from '..';
+import {CompilerError, EnvironmentConfig, Logger} from '..';
 import {getOrInsertWith} from '../Utils/utils';
 import {Environment, GeneratedSource} from '../HIR';
 import {DEFAULT_EXPORT} from '../HIR/Environment';
 import {CompileProgramMetadata} from './Program';
-import {
-  CompilerDiagnostic,
-  CompilerDiagnosticOptions,
-  ErrorCategory,
-} from '../CompilerError';
+import {CompilerDiagnostic} from '../CompilerError';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 
-function throwInvalidReact(
-  options: Omit<CompilerDiagnosticOptions, 'severity'>,
+function logAndThrowDiagnostic(
+  diagnostic: CompilerDiagnostic,
   {logger, filename}: TraversalState,
 ): never {
-  const detail: CompilerDiagnosticOptions = {
-    severity: ErrorSeverity.InvalidReact,
-    ...options,
-  };
   logger?.logEvent(filename, {
     kind: 'CompileError',
     fnLoc: null,
-    detail: new CompilerDiagnostic(detail),
+    detail: diagnostic,
   });
-  CompilerError.throwDiagnostic(detail);
+  CompilerError.throwDiagnostic(diagnostic);
 }
 
 function isAutodepsSigil(
@@ -94,14 +87,9 @@ function assertValidEffectImportReference(
          * as it may have already been transformed by the compiler (and not
          * memoized).
          */
-        throwInvalidReact(
-          {
-            category: ErrorCategory.AutomaticEffectDependencies,
-            reason:
-              'Cannot infer dependencies of this effect. This will break your build!',
-            description:
-              'To resolve, either pass a dependency array or fix reported compiler bailout diagnostics.' +
-              (maybeErrorDiagnostic ? ` ${maybeErrorDiagnostic}` : ''),
+        logAndThrowDiagnostic(
+          CompilerDiagnostic.fromCode(ErrorCode.DID_NOT_INFER_DEPS, {
+            description: maybeErrorDiagnostic ? `${maybeErrorDiagnostic}` : '',
             details: [
               {
                 kind: 'error',
@@ -109,7 +97,7 @@ function assertValidEffectImportReference(
                 loc: parent.node.loc ?? GeneratedSource,
               },
             ],
-          },
+          }),
           context,
         );
       }
@@ -126,10 +114,8 @@ function assertValidFireImportReference(
       paths[0],
       context.transformErrors,
     );
-    throwInvalidReact(
-      {
-        category: ErrorCategory.Fire,
-        reason: '[Fire] Untransformed reference to compiler-required feature.',
+    logAndThrowDiagnostic(
+      CompilerDiagnostic.fromCode(ErrorCode.CANNOT_COMPILE_FIRE, {
         description:
           'Either remove this `fire` call or ensure it is successfully transformed by the compiler' +
           maybeErrorDiagnostic
@@ -142,7 +128,7 @@ function assertValidFireImportReference(
             loc: paths[0].node.loc ?? GeneratedSource,
           },
         ],
-      },
+      }),
       context,
     );
   }

compiler/packages/babel-plugin-react-compiler/src/Flood/TypeErrors.ts

@@ -1,4 +1,5 @@
 import {CompilerError, SourceLocation} from '..';
+import {ErrorCode} from '../CompilerError';
 import {
   ConcreteType,
   printConcrete,
@@ -12,8 +13,8 @@ export function unsupportedLanguageFeature(
   desc: string,
   loc: SourceLocation,
 ): never {
-  CompilerError.throwInvalidJS({
-    reason: `Typedchecker does not currently support language feature: ${desc}`,
+  CompilerError.throwFromCode(ErrorCode.INVALID_JAVASCRIPT_AST, {
+    description: `Typedchecker does not currently support language feature: ${desc}`,
     loc,
   });
 }
@@ -49,16 +50,16 @@ export function raiseUnificationErrors(
         loc,
       });
     } else if (errs.length === 1) {
-      CompilerError.throwInvalidJS({
-        reason: `Unable to unify types because ${printUnificationError(errs[0])}`,
+      CompilerError.throwFromCode(ErrorCode.INVALID_JAVASCRIPT_AST, {
+        description: `Unable to unify types because ${printUnificationError(errs[0])}`,
         loc,
       });
     } else {
       const messages = errs
         .map(err => `\t* ${printUnificationError(err)}`)
         .join('\n');
-      CompilerError.throwInvalidJS({
-        reason: `Unable to unify types because:\n${messages}`,
+      CompilerError.throwFromCode(ErrorCode.INVALID_JAVASCRIPT_AST, {
+        description: `Unable to unify types because:\n${messages}`,
         loc,
       });
     }
@@ -69,21 +70,21 @@ export function unresolvableTypeVariable(
   id: VariableId,
   loc: SourceLocation,
 ): never {
-  CompilerError.throwInvalidJS({
-    reason: `Unable to resolve free variable ${id} to a concrete type`,
+  CompilerError.throwFromCode(ErrorCode.INVALID_JAVASCRIPT_AST, {
+    description: `Unable to resolve free variable ${id} to a concrete type`,
     loc,
   });
 }
 
 export function cannotAddVoid(explicit: boolean, loc: SourceLocation): never {
   if (explicit) {
-    CompilerError.throwInvalidJS({
-      reason: `Undefined is not a valid operand of \`+\``,
+    CompilerError.throwFromCode(ErrorCode.INVALID_JAVASCRIPT_AST, {
+      description: `Undefined is not a valid operand of \`+\``,
       loc,
     });
   } else {
-    CompilerError.throwInvalidJS({
-      reason: `Value may be undefined, which is not a valid operand of \`+\``,
+    CompilerError.throwFromCode(ErrorCode.INVALID_JAVASCRIPT_AST, {
+      description: `Value may be undefined, which is not a valid operand of \`+\``,
       loc,
     });
   }
@@ -93,8 +94,8 @@ export function unsupportedTypeAnnotation(
   desc: string,
   loc: SourceLocation,
 ): never {
-  CompilerError.throwInvalidJS({
-    reason: `Typedchecker does not currently support type annotation: ${desc}`,
+  CompilerError.throwFromCode(ErrorCode.INVALID_JAVASCRIPT_AST, {
+    description: `Typedchecker does not currently support type annotation: ${desc}`,
     loc,
   });
 }
@@ -106,16 +107,16 @@ export function checkTypeArgumentArity(
   loc: SourceLocation,
 ): void {
   if (expected !== actual) {
-    CompilerError.throwInvalidJS({
-      reason: `Expected ${desc} to have ${expected} type parameters, got ${actual}`,
+    CompilerError.throwFromCode(ErrorCode.INVALID_JAVASCRIPT_AST, {
+      description: `Expected ${desc} to have ${expected} type parameters, got ${actual}`,
       loc,
     });
   }
 }
 
 export function notAFunction(desc: string, loc: SourceLocation): void {
-  CompilerError.throwInvalidJS({
-    reason: `Cannot call ${desc} because it is not a function`,
+  CompilerError.throwFromCode(ErrorCode.INVALID_JAVASCRIPT_AST, {
+    description: `Cannot call ${desc} because it is not a function`,
     loc,
   });
 }
@@ -124,8 +125,8 @@ export function notAPolymorphicFunction(
   desc: string,
   loc: SourceLocation,
 ): void {
-  CompilerError.throwInvalidJS({
-    reason: `Cannot call ${desc} with type arguments because it is not a polymorphic function`,
+  CompilerError.throwFromCode(ErrorCode.INVALID_JAVASCRIPT_AST, {
+    description: `Cannot call ${desc} with type arguments because it is not a polymorphic function`,
     loc,
   });
 }

compiler/packages/babel-plugin-react-compiler/src/HIR/BuildHIR.ts

@@ -12,7 +12,7 @@ import {
   CompilerDiagnostic,
   CompilerError,
   CompilerSuggestionOperation,
-  ErrorCategory,
+  ErrorCode,
   ErrorSeverity,
 } from '../CompilerError';
 import {Err, Ok, Result} from '../Utils/Result';
@@ -109,8 +109,7 @@ export function lower(
         builder.errors.pushDiagnostic(
           CompilerDiagnostic.create({
             severity: ErrorSeverity.Invariant,
-            category: ErrorCategory.Invariant,
-            reason: 'Could not find binding',
+            category: 'Could not find binding',
             description: `[BuildHIR] Could not find binding for param \`${param.node.name}\`.`,
           }).withDetail({
             kind: 'error',
@@ -172,15 +171,12 @@ export function lower(
       );
     } else {
       builder.errors.pushDiagnostic(
-        CompilerDiagnostic.create({
-          severity: ErrorSeverity.Todo,
-          category: ErrorCategory.Todo,
-          reason: `Handle ${param.node.type} parameters`,
+        CompilerDiagnostic.fromCode(ErrorCode.UNKNOWN_FUNCTION_PARAMETERS, {
           description: `[BuildHIR] Add support for ${param.node.type} parameters.`,
         }).withDetail({
           kind: 'error',
           loc: param.node.loc ?? null,
-          message: 'Unsupported parameter type',
+          message: `Unsupported parameter type: ${param.node.type}`,
         }),
       );
     }
@@ -204,15 +200,12 @@ export function lower(
     directives = body.get('directives').map(d => d.node.value.value);
   } else {
     builder.errors.pushDiagnostic(
-      CompilerDiagnostic.create({
-        severity: ErrorSeverity.InvalidJS,
-        category: ErrorCategory.Syntax,
-        reason: `Unexpected function body kind`,
+      CompilerDiagnostic.fromCode(ErrorCode.INVALID_JAVASCRIPT_AST, {
         description: `Expected function body to be an expression or a block statement, got \`${body.type}\`.`,
       }).withDetail({
         kind: 'error',
         loc: body.node.loc ?? null,
-        message: 'Expected a block statement or expression',
+        message: 'Change this to a block statement or expression',
       }),
     );
   }
@@ -277,7 +270,6 @@ function lowerStatement(
           reason:
             '(BuildHIR::lowerStatement) Support ThrowStatement inside of try/catch',
           severity: ErrorSeverity.Todo,
-          category: ErrorCategory.Todo,
           loc: stmt.node.loc ?? null,
           suggestions: null,
         });
@@ -465,7 +457,6 @@ function lowerStatement(
           } else if (!binding.path.isVariableDeclarator()) {
             builder.errors.push({
               severity: ErrorSeverity.Todo,
-              category: ErrorCategory.Todo,
               reason: 'Unsupported declaration type for hoisting',
               description: `variable "${binding.identifier.name}" declared with ${binding.path.type}`,
               suggestions: null,
@@ -475,7 +466,6 @@ function lowerStatement(
           } else {
             builder.errors.push({
               severity: ErrorSeverity.Todo,
-              category: ErrorCategory.Todo,
               reason: 'Handle non-const declarations for hoisting',
               description: `variable "${binding.identifier.name}" declared with ${binding.kind}`,
               suggestions: null,
@@ -556,7 +546,6 @@ function lowerStatement(
             reason:
               '(BuildHIR::lowerStatement) Handle non-variable initialization in ForStatement',
             severity: ErrorSeverity.Todo,
-            category: ErrorCategory.Todo,
             loc: stmt.node.loc ?? null,
             suggestions: null,
           });
@@ -629,7 +618,6 @@ function lowerStatement(
         builder.errors.push({
           reason: `(BuildHIR::lowerStatement) Handle empty test in ForStatement`,
           severity: ErrorSeverity.Todo,
-          category: ErrorCategory.Todo,
           loc: stmt.node.loc ?? null,
           suggestions: null,
         });
@@ -778,13 +766,12 @@ function lowerStatement(
         const testExpr = case_.get('test');
         if (testExpr.node == null) {
           if (hasDefault) {
-            builder.errors.push({
-              reason: `Expected at most one \`default\` branch in a switch statement, this code should have failed to parse`,
-              severity: ErrorSeverity.InvalidJS,
-              category: ErrorCategory.Syntax,
-              loc: case_.node.loc ?? null,
-              suggestions: null,
-            });
+            builder.errors.pushErrorCode(
+              ErrorCode.INVALID_SYNTAX_MULTIPLE_DEFAULTS,
+              {
+                loc: case_.node.loc ?? null,
+              },
+            );
             break;
           }
           hasDefault = true;
@@ -854,7 +841,6 @@ function lowerStatement(
         builder.errors.push({
           reason: `(BuildHIR::lowerStatement) Handle ${nodeKind} kinds in VariableDeclaration`,
           severity: ErrorSeverity.Todo,
-          category: ErrorCategory.Todo,
           loc: stmt.node.loc ?? null,
           suggestions: null,
         });
@@ -883,7 +869,6 @@ function lowerStatement(
             builder.errors.push({
               reason: `(BuildHIR::lowerAssignment) Could not find binding for declaration.`,
               severity: ErrorSeverity.Invariant,
-              category: ErrorCategory.Invariant,
               loc: id.node.loc ?? null,
               suggestions: null,
             });
@@ -898,20 +883,20 @@ function lowerStatement(
             if (builder.isContextIdentifier(id)) {
               if (kind === InstructionKind.Const) {
                 const declRangeStart = declaration.parentPath.node.start!;
-                builder.errors.push({
-                  reason: `Expect \`const\` declaration not to be reassigned`,
-                  severity: ErrorSeverity.InvalidJS,
-                  category: ErrorCategory.Syntax,
-                  loc: id.node.loc ?? null,
-                  suggestions: [
-                    {
-                      description: 'Change to a `let` declaration',
-                      op: CompilerSuggestionOperation.Replace,
-                      range: [declRangeStart, declRangeStart + 5], // "const".length
-                      text: 'let',
-                    },
-                  ],
-                });
+                builder.errors.pushErrorCode(
+                  ErrorCode.INVALID_SYNTAX_REASSIGNED_CONST,
+                  {
+                    loc: id.node.loc ?? null,
+                    suggestions: [
+                      {
+                        description: 'Change to a `let` declaration',
+                        op: CompilerSuggestionOperation.Replace,
+                        range: [declRangeStart, declRangeStart + 5], // "const".length
+                        text: 'let',
+                      },
+                    ],
+                  },
+                );
               }
               lowerValueToTemporary(builder, {
                 kind: 'DeclareContext',
@@ -945,14 +930,13 @@ function lowerStatement(
             }
           }
         } else {
-          builder.errors.push({
-            reason: `Expected variable declaration to be an identifier if no initializer was provided`,
-            description: `Got a \`${id.type}\``,
-            severity: ErrorSeverity.InvalidJS,
-            category: ErrorCategory.Syntax,
-            loc: stmt.node.loc ?? null,
-            suggestions: null,
-          });
+          builder.errors.pushErrorCode(
+            ErrorCode.INVALID_SYNTAX_BAD_VARIABLE_DECL,
+            {
+              description: `Got a \`${id.type}\``,
+              loc: stmt.node.loc ?? null,
+            },
+          );
         }
       }
       return;
@@ -1058,7 +1042,6 @@ function lowerStatement(
         builder.errors.push({
           reason: `(BuildHIR::lowerStatement) Handle for-await loops`,
           severity: ErrorSeverity.Todo,
-          category: ErrorCategory.Todo,
           loc: stmt.node.loc ?? null,
           suggestions: null,
         });
@@ -1291,7 +1274,6 @@ function lowerStatement(
         builder.errors.push({
           reason: `(BuildHIR::lowerStatement) Handle TryStatement without a catch clause`,
           severity: ErrorSeverity.Todo,
-          category: ErrorCategory.Todo,
           loc: stmt.node.loc ?? null,
           suggestions: null,
         });
@@ -1301,7 +1283,6 @@ function lowerStatement(
         builder.errors.push({
           reason: `(BuildHIR::lowerStatement) Handle TryStatement with a finalizer ('finally') clause`,
           severity: ErrorSeverity.Todo,
-          category: ErrorCategory.Todo,
           loc: stmt.node.loc ?? null,
           suggestions: null,
         });
@@ -1391,13 +1372,8 @@ function lowerStatement(
       return;
     }
     case 'WithStatement': {
-      builder.errors.push({
-        reason: `JavaScript 'with' syntax is not supported`,
-        description: `'with' syntax is considered deprecated and removed from JavaScript standards, consider alternatives`,
-        severity: ErrorSeverity.UnsupportedJS,
-        category: ErrorCategory.UnsupportedSyntax,
+      builder.errors.pushErrorCode(ErrorCode.UNSUPPORTED_WITH, {
         loc: stmtPath.node.loc ?? null,
-        suggestions: null,
       });
       lowerValueToTemporary(builder, {
         kind: 'UnsupportedNode',
@@ -1412,13 +1388,8 @@ function lowerStatement(
        * and complex enough to support that we don't anticipate supporting anytime soon. Developers
        * are encouraged to lift classes out of component/hook declarations.
        */
-      builder.errors.push({
-        reason: 'Inline `class` declarations are not supported',
-        description: `Move class declarations outside of components/hooks`,
-        severity: ErrorSeverity.UnsupportedJS,
-        category: ErrorCategory.UnsupportedSyntax,
+      builder.errors.pushErrorCode(ErrorCode.UNSUPPORTED_INNER_CLASS, {
         loc: stmtPath.node.loc ?? null,
-        suggestions: null,
       });
       lowerValueToTemporary(builder, {
         kind: 'UnsupportedNode',
@@ -1442,13 +1413,8 @@ function lowerStatement(
     case 'ImportDeclaration':
     case 'TSExportAssignment':
     case 'TSImportEqualsDeclaration': {
-      builder.errors.push({
-        reason:
-          'JavaScript `import` and `export` statements may only appear at the top level of a module',
-        severity: ErrorSeverity.InvalidJS,
-        category: ErrorCategory.Syntax,
+      builder.errors.pushErrorCode(ErrorCode.INVALID_IMPORT_EXPORT, {
         loc: stmtPath.node.loc ?? null,
-        suggestions: null,
       });
       lowerValueToTemporary(builder, {
         kind: 'UnsupportedNode',
@@ -1458,13 +1424,8 @@ function lowerStatement(
       return;
     }
     case 'TSNamespaceExportDeclaration': {
-      builder.errors.push({
-        reason:
-          'TypeScript `namespace` statements may only appear at the top level of a module',
-        severity: ErrorSeverity.InvalidJS,
-        category: ErrorCategory.Syntax,
+      builder.errors.pushErrorCode(ErrorCode.INVALID_TS_NAMESPACE, {
         loc: stmtPath.node.loc ?? null,
-        suggestions: null,
       });
       lowerValueToTemporary(builder, {
         kind: 'UnsupportedNode',
@@ -1541,7 +1502,6 @@ function lowerObjectPropertyKey(
       builder.errors.push({
         reason: `(BuildHIR::lowerExpression) Expected Identifier, got ${key.type} key in ObjectExpression`,
         severity: ErrorSeverity.Todo,
-        category: ErrorCategory.Todo,
         loc: key.node.loc ?? null,
         suggestions: null,
       });
@@ -1567,7 +1527,6 @@ function lowerObjectPropertyKey(
   builder.errors.push({
     reason: `(BuildHIR::lowerExpression) Expected Identifier, got ${key.type} key in ObjectExpression`,
     severity: ErrorSeverity.Todo,
-    category: ErrorCategory.Todo,
     loc: key.node.loc ?? null,
     suggestions: null,
   });
@@ -1625,7 +1584,6 @@ function lowerExpression(
             builder.errors.push({
               reason: `(BuildHIR::lowerExpression) Handle ${valuePath.type} values in ObjectExpression`,
               severity: ErrorSeverity.Todo,
-              category: ErrorCategory.Todo,
               loc: valuePath.node.loc ?? null,
               suggestions: null,
             });
@@ -1652,7 +1610,6 @@ function lowerExpression(
             builder.errors.push({
               reason: `(BuildHIR::lowerExpression) Handle ${propertyPath.node.kind} functions in ObjectExpression`,
               severity: ErrorSeverity.Todo,
-              category: ErrorCategory.Todo,
               loc: propertyPath.node.loc ?? null,
               suggestions: null,
             });
@@ -1674,7 +1631,6 @@ function lowerExpression(
           builder.errors.push({
             reason: `(BuildHIR::lowerExpression) Handle ${propertyPath.type} properties in ObjectExpression`,
             severity: ErrorSeverity.Todo,
-            category: ErrorCategory.Todo,
             loc: propertyPath.node.loc ?? null,
             suggestions: null,
           });
@@ -1708,7 +1664,6 @@ function lowerExpression(
           builder.errors.push({
             reason: `(BuildHIR::lowerExpression) Handle ${element.type} elements in ArrayExpression`,
             severity: ErrorSeverity.Todo,
-            category: ErrorCategory.Todo,
             loc: element.node.loc ?? null,
             suggestions: null,
           });
@@ -1725,13 +1680,8 @@ function lowerExpression(
       const expr = exprPath as NodePath<t.NewExpression>;
       const calleePath = expr.get('callee');
       if (!calleePath.isExpression()) {
-        builder.errors.push({
-          reason: `Expected an expression as the \`new\` expression receiver (v8 intrinsics are not supported)`,
-          description: `Got a \`${calleePath.node.type}\``,
-          severity: ErrorSeverity.InvalidJS,
-          category: ErrorCategory.Syntax,
+        builder.errors.pushErrorCode(ErrorCode.UNSUPPORTED_NEW_EXPRESSION, {
           loc: calleePath.node.loc ?? null,
-          suggestions: null,
         });
         return {kind: 'UnsupportedNode', node: exprNode, loc: exprLoc};
       }
@@ -1756,7 +1706,6 @@ function lowerExpression(
         builder.errors.push({
           reason: `Expected Expression, got ${calleePath.type} in CallExpression (v8 intrinsics not supported). This error is likely caused by a bug in React Compiler. Please file an issue`,
           severity: ErrorSeverity.Todo,
-          category: ErrorCategory.Todo,
           loc: calleePath.node.loc ?? null,
           suggestions: null,
         });
@@ -1791,7 +1740,6 @@ function lowerExpression(
         builder.errors.push({
           reason: `(BuildHIR::lowerExpression) Expected Expression, got ${leftPath.type} lval in BinaryExpression`,
           severity: ErrorSeverity.Todo,
-          category: ErrorCategory.Todo,
           loc: leftPath.node.loc ?? null,
           suggestions: null,
         });
@@ -1804,7 +1752,6 @@ function lowerExpression(
         builder.errors.push({
           reason: `(BuildHIR::lowerExpression) Pipe operator not supported`,
           severity: ErrorSeverity.Todo,
-          category: ErrorCategory.Todo,
           loc: leftPath.node.loc ?? null,
           suggestions: null,
         });
@@ -1831,13 +1778,12 @@ function lowerExpression(
           last = lowerExpressionToTemporary(builder, item);
         }
         if (last === null) {
-          builder.errors.push({
-            reason: `Expected sequence expression to have at least one expression`,
-            severity: ErrorSeverity.InvalidJS,
-            category: ErrorCategory.Syntax,
-            loc: expr.node.loc ?? null,
-            suggestions: null,
-          });
+          builder.errors.pushErrorCode(
+            ErrorCode.UNSUPPORTED_EMPTY_SEQUENCE_EXPRESSION,
+            {
+              loc: expr.node.loc ?? null,
+            },
+          );
         } else {
           lowerValueToTemporary(builder, {
             kind: 'StoreLocal',
@@ -2047,7 +1993,6 @@ function lowerExpression(
             reason: `(BuildHIR::lowerExpression) Unsupported syntax on the left side of an AssignmentExpression`,
             description: `Expected an LVal, got: ${left.type}`,
             severity: ErrorSeverity.Todo,
-            category: ErrorCategory.Todo,
             loc: left.node.loc ?? null,
             suggestions: null,
           });
@@ -2076,7 +2021,6 @@ function lowerExpression(
         builder.errors.push({
           reason: `(BuildHIR::lowerExpression) Handle ${operator} operators in AssignmentExpression`,
           severity: ErrorSeverity.Todo,
-          category: ErrorCategory.Todo,
           loc: expr.node.loc ?? null,
           suggestions: null,
         });
@@ -2176,7 +2120,6 @@ function lowerExpression(
           builder.errors.push({
             reason: `(BuildHIR::lowerExpression) Expected Identifier or MemberExpression, got ${expr.type} lval in AssignmentExpression`,
             severity: ErrorSeverity.Todo,
-            category: ErrorCategory.Todo,
             loc: expr.node.loc ?? null,
             suggestions: null,
           });
@@ -2216,7 +2159,6 @@ function lowerExpression(
           builder.errors.push({
             reason: `(BuildHIR::lowerExpression) Handle ${attribute.type} attributes in JSXElement`,
             severity: ErrorSeverity.Todo,
-            category: ErrorCategory.Todo,
             loc: attribute.node.loc ?? null,
             suggestions: null,
           });
@@ -2230,7 +2172,6 @@ function lowerExpression(
             builder.errors.push({
               reason: `(BuildHIR::lowerExpression) Unexpected colon in attribute name \`${propName}\``,
               severity: ErrorSeverity.Todo,
-              category: ErrorCategory.Todo,
               loc: namePath.node.loc ?? null,
               suggestions: null,
             });
@@ -2261,7 +2202,6 @@ function lowerExpression(
             builder.errors.push({
               reason: `(BuildHIR::lowerExpression) Handle ${valueExpr.type} attribute values in JSXElement`,
               severity: ErrorSeverity.Todo,
-              category: ErrorCategory.Todo,
               loc: valueExpr.node?.loc ?? null,
               suggestions: null,
             });
@@ -2272,7 +2212,6 @@ function lowerExpression(
             builder.errors.push({
               reason: `(BuildHIR::lowerExpression) Handle ${expression.type} expressions in JSXExpressionContainer within JSXElement`,
               severity: ErrorSeverity.Todo,
-              category: ErrorCategory.Todo,
               loc: valueExpr.node.loc ?? null,
               suggestions: null,
             });
@@ -2328,19 +2267,18 @@ function lowerExpression(
         });
         for (const [name, locations] of Object.entries(fbtLocations)) {
           if (locations.length > 1) {
-            CompilerError.throwDiagnostic({
-              severity: ErrorSeverity.Todo,
-              category: ErrorCategory.FBT,
-              reason: 'Support duplicate fbt tags',
-              description: `Support \`<${tagName}>\` tags with multiple \`<${tagName}:${name}>\` values`,
-              details: locations.map(loc => {
-                return {
-                  kind: 'error',
-                  message: `Multiple \`<${tagName}:${name}>\` tags found`,
-                  loc,
-                };
+            CompilerError.throwDiagnostic(
+              CompilerDiagnostic.fromCode(ErrorCode.TODO_DUPLICATE_FBT_TAGS, {
+                description: `Support \`<${tagName}>\` tags with multiple \`<${tagName}:${name}>\` values`,
+                details: locations.map(loc => {
+                  return {
+                    kind: 'error',
+                    message: `Multiple \`<${tagName}:${name}>\` tags found`,
+                    loc,
+                  };
+                }),
               }),
-            });
+            );
           }
         }
       }
@@ -2392,7 +2330,6 @@ function lowerExpression(
           reason:
             '(BuildHIR::lowerExpression) Handle tagged template with interpolations',
           severity: ErrorSeverity.Todo,
-          category: ErrorCategory.Todo,
           loc: exprPath.node.loc ?? null,
           suggestions: null,
         });
@@ -2411,7 +2348,6 @@ function lowerExpression(
           reason:
             '(BuildHIR::lowerExpression) Handle tagged template where cooked value is different from raw value',
           severity: ErrorSeverity.Todo,
-          category: ErrorCategory.Todo,
           loc: exprPath.node.loc ?? null,
           suggestions: null,
         });
@@ -2431,12 +2367,8 @@ function lowerExpression(
       const quasis = expr.get('quasis');
 
       if (subexprs.length !== quasis.length - 1) {
-        builder.errors.push({
-          reason: `Unexpected quasi and subexpression lengths in template literal`,
-          severity: ErrorSeverity.InvalidJS,
-          category: ErrorCategory.Syntax,
+        builder.errors.pushErrorCode(ErrorCode.INVALID_QUASI_LENGTHS, {
           loc: exprPath.node.loc ?? null,
-          suggestions: null,
         });
         return {kind: 'UnsupportedNode', node: exprNode, loc: exprLoc};
       }
@@ -2445,7 +2377,6 @@ function lowerExpression(
         builder.errors.push({
           reason: `(BuildHIR::lowerAssignment) Handle TSType in TemplateLiteral.`,
           severity: ErrorSeverity.Todo,
-          category: ErrorCategory.Todo,
           loc: exprPath.node.loc ?? null,
           suggestions: null,
         });
@@ -2485,26 +2416,23 @@ function lowerExpression(
             };
           }
         } else {
-          builder.errors.push({
-            reason: `Only object properties can be deleted`,
-            severity: ErrorSeverity.InvalidJS,
-            category: ErrorCategory.Syntax,
-            loc: expr.node.loc ?? null,
-            suggestions: [
-              {
-                description: 'Remove this line',
-                range: [expr.node.start!, expr.node.end!],
-                op: CompilerSuggestionOperation.Remove,
-              },
-            ],
-          });
+          builder.errors.pushErrorCode(
+            ErrorCode.INVALID_SYNTAX_DELETE_EXPRESSION,
+            {
+              loc: expr.node.loc ?? null,
+              suggestions: [
+                {
+                  description: 'Remove this line',
+                  range: [expr.node.start!, expr.node.end!],
+                  op: CompilerSuggestionOperation.Remove,
+                },
+              ],
+            },
+          );
           return {kind: 'UnsupportedNode', node: expr.node, loc: exprLoc};
         }
       } else if (expr.node.operator === 'throw') {
-        builder.errors.push({
-          reason: `Throw expressions are not supported`,
-          severity: ErrorSeverity.InvalidJS,
-          category: ErrorCategory.Syntax,
+        builder.errors.pushErrorCode(ErrorCode.UNSUPPORTED_THROW_EXPRESSION, {
           loc: expr.node.loc ?? null,
           suggestions: [
             {
@@ -2626,7 +2554,6 @@ function lowerExpression(
         builder.errors.push({
           reason: `(BuildHIR::lowerExpression) Handle UpdateExpression with ${argument.type} argument`,
           severity: ErrorSeverity.Todo,
-          category: ErrorCategory.Todo,
           loc: exprPath.node.loc ?? null,
           suggestions: null,
         });
@@ -2635,7 +2562,6 @@ function lowerExpression(
         builder.errors.push({
           reason: `(BuildHIR::lowerExpression) Handle UpdateExpression to variables captured within lambdas.`,
           severity: ErrorSeverity.Todo,
-          category: ErrorCategory.Todo,
           loc: exprPath.node.loc ?? null,
           suggestions: null,
         });
@@ -2656,7 +2582,6 @@ function lowerExpression(
           builder.errors.push({
             reason: `(BuildHIR::lowerExpression) Found an invalid UpdateExpression without a previously reported error`,
             severity: ErrorSeverity.Invariant,
-            category: ErrorCategory.Invariant,
             loc: exprLoc,
             suggestions: null,
           });
@@ -2666,7 +2591,6 @@ function lowerExpression(
         builder.errors.push({
           reason: `(BuildHIR::lowerExpression) Support UpdateExpression where argument is a global`,
           severity: ErrorSeverity.Todo,
-          category: ErrorCategory.Todo,
           loc: exprLoc,
           suggestions: null,
         });
@@ -2722,7 +2646,6 @@ function lowerExpression(
       builder.errors.push({
         reason: `(BuildHIR::lowerExpression) Handle MetaProperty expressions other than import.meta`,
         severity: ErrorSeverity.Todo,
-        category: ErrorCategory.Todo,
         loc: exprPath.node.loc ?? null,
         suggestions: null,
       });
@@ -2732,7 +2655,6 @@ function lowerExpression(
       builder.errors.push({
         reason: `(BuildHIR::lowerExpression) Handle ${exprPath.type} expressions`,
         severity: ErrorSeverity.Todo,
-        category: ErrorCategory.Todo,
         loc: exprPath.node.loc ?? null,
         suggestions: null,
       });
@@ -3030,7 +2952,6 @@ function lowerReorderableExpression(
     builder.errors.push({
       reason: `(BuildHIR::node.lowerReorderableExpression) Expression type \`${expr.type}\` cannot be safely reordered`,
       severity: ErrorSeverity.Todo,
-      category: ErrorCategory.Todo,
       loc: expr.node.loc ?? null,
       suggestions: null,
     });
@@ -3227,7 +3148,6 @@ function lowerArguments(
       builder.errors.push({
         reason: `(BuildHIR::lowerExpression) Handle ${argPath.type} arguments in CallExpression`,
         severity: ErrorSeverity.Todo,
-        category: ErrorCategory.Todo,
         loc: argPath.node.loc ?? null,
         suggestions: null,
       });
@@ -3263,7 +3183,6 @@ function lowerMemberExpression(
       builder.errors.push({
         reason: `(BuildHIR::lowerMemberExpression) Handle ${propertyNode.type} property`,
         severity: ErrorSeverity.Todo,
-        category: ErrorCategory.Todo,
         loc: propertyNode.node.loc ?? null,
         suggestions: null,
       });
@@ -3285,7 +3204,6 @@ function lowerMemberExpression(
       builder.errors.push({
         reason: `(BuildHIR::lowerMemberExpression) Expected Expression, got ${propertyNode.type} property`,
         severity: ErrorSeverity.Todo,
-        category: ErrorCategory.Todo,
         loc: propertyNode.node.loc ?? null,
         suggestions: null,
       });
@@ -3341,11 +3259,8 @@ function lowerJsxElementName(
     const name = exprPath.node.name.name;
     const tag = `${namespace}:${name}`;
     if (namespace.indexOf(':') !== -1 || name.indexOf(':') !== -1) {
-      builder.errors.push({
-        reason: `Expected JSXNamespacedName to have no colons in the namespace or name`,
+      builder.errors.pushErrorCode(ErrorCode.INVALID_JSX_NAMESPACED_NAME, {
         description: `Got \`${namespace}\` : \`${name}\``,
-        severity: ErrorSeverity.InvalidJS,
-        category: ErrorCategory.Syntax,
         loc: exprPath.node.loc ?? null,
         suggestions: null,
       });
@@ -3360,7 +3275,6 @@ function lowerJsxElementName(
     builder.errors.push({
       reason: `(BuildHIR::lowerJsxElementName) Handle ${exprPath.type} tags`,
       severity: ErrorSeverity.Todo,
-      category: ErrorCategory.Todo,
       loc: exprPath.node.loc ?? null,
       suggestions: null,
     });
@@ -3459,7 +3373,6 @@ function lowerJsxElement(
     builder.errors.push({
       reason: `(BuildHIR::lowerJsxElement) Unhandled JsxElement, got: ${exprPath.type}`,
       severity: ErrorSeverity.Todo,
-      category: ErrorCategory.Todo,
       loc: exprPath.node.loc ?? null,
       suggestions: null,
     });
@@ -3642,12 +3555,7 @@ function lowerIdentifier(
     }
     default: {
       if (binding.kind === 'Global' && binding.name === 'eval') {
-        builder.errors.push({
-          reason: `The 'eval' function is not supported`,
-          description:
-            'Eval is an anti-pattern in JavaScript, and the code executed cannot be evaluated by React Compiler',
-          severity: ErrorSeverity.UnsupportedJS,
-          category: ErrorCategory.UnsupportedSyntax,
+        builder.errors.pushErrorCode(ErrorCode.UNSUPPORTED_EVAL, {
           loc: exprPath.node.loc ?? null,
           suggestions: null,
         });
@@ -3704,7 +3612,6 @@ function lowerIdentifierForAssignment(
       builder.errors.push({
         reason: `(BuildHIR::lowerAssignment) Could not find binding for declaration.`,
         severity: ErrorSeverity.Invariant,
-        category: ErrorCategory.Invariant,
         loc: path.node.loc ?? null,
         suggestions: null,
       });
@@ -3714,10 +3621,7 @@ function lowerIdentifierForAssignment(
     binding.bindingKind === 'const' &&
     kind === InstructionKind.Reassign
   ) {
-    builder.errors.push({
-      reason: `Cannot reassign a \`const\` variable`,
-      severity: ErrorSeverity.InvalidJS,
-      category: ErrorCategory.Syntax,
+    builder.errors.pushErrorCode(ErrorCode.INVALID_SYNTAX_REASSIGNED_CONST, {
       loc: path.node.loc ?? null,
       description:
         binding.identifier.name != null
@@ -3772,13 +3676,13 @@ function lowerAssignment(
       let temporary;
       if (builder.isContextIdentifier(lvalue)) {
         if (kind === InstructionKind.Const && !isHoistedIdentifier) {
-          builder.errors.push({
-            reason: `Expected \`const\` declaration not to be reassigned`,
-            severity: ErrorSeverity.InvalidJS,
-            category: ErrorCategory.Syntax,
-            loc: lvalue.node.loc ?? null,
-            suggestions: null,
-          });
+          builder.errors.pushErrorCode(
+            ErrorCode.INVALID_SYNTAX_REASSIGNED_CONST,
+            {
+              loc: lvalue.node.loc ?? null,
+              suggestions: null,
+            },
+          );
         }
 
         if (
@@ -3789,8 +3693,8 @@ function lowerAssignment(
         ) {
           builder.errors.push({
             reason: `Unexpected context variable kind`,
-            severity: ErrorSeverity.InvalidJS,
-            category: ErrorCategory.Syntax,
+            description: `Expected one of Const, Reassign, Let, Function, got ${kind}`,
+            severity: ErrorSeverity.Invariant,
             loc: lvalue.node.loc ?? null,
             suggestions: null,
           });
@@ -3862,7 +3766,6 @@ function lowerAssignment(
           builder.errors.push({
             reason: `(BuildHIR::lowerAssignment) Handle ${property.type} properties in MemberExpression`,
             severity: ErrorSeverity.Todo,
-            category: ErrorCategory.Todo,
             loc: property.node.loc ?? null,
             suggestions: null,
           });
@@ -3875,7 +3778,6 @@ function lowerAssignment(
             reason:
               '(BuildHIR::lowerAssignment) Expected private name to appear as a non-computed property',
             severity: ErrorSeverity.Todo,
-            category: ErrorCategory.Todo,
             loc: property.node.loc ?? null,
             suggestions: null,
           });
@@ -3941,7 +3843,6 @@ function lowerAssignment(
             } else if (identifier.kind === 'Global') {
               builder.errors.push({
                 severity: ErrorSeverity.Todo,
-                category: ErrorCategory.Todo,
                 reason:
                   'Expected reassignment of globals to enable forceTemporaries',
                 loc: element.node.loc ?? GeneratedSource,
@@ -3981,7 +3882,6 @@ function lowerAssignment(
           } else if (identifier.kind === 'Global') {
             builder.errors.push({
               severity: ErrorSeverity.Todo,
-              category: ErrorCategory.Todo,
               reason:
                 'Expected reassignment of globals to enable forceTemporaries',
               loc: element.node.loc ?? GeneratedSource,
@@ -4055,7 +3955,6 @@ function lowerAssignment(
             builder.errors.push({
               reason: `(BuildHIR::lowerAssignment) Handle ${argument.node.type} rest element in ObjectPattern`,
               severity: ErrorSeverity.Todo,
-              category: ErrorCategory.Todo,
               loc: argument.node.loc ?? null,
               suggestions: null,
             });
@@ -4087,7 +3986,6 @@ function lowerAssignment(
             } else if (identifier.kind === 'Global') {
               builder.errors.push({
                 severity: ErrorSeverity.Todo,
-                category: ErrorCategory.Todo,
                 reason:
                   'Expected reassignment of globals to enable forceTemporaries',
                 loc: property.node.loc ?? GeneratedSource,
@@ -4105,7 +4003,6 @@ function lowerAssignment(
             builder.errors.push({
               reason: `(BuildHIR::lowerAssignment) Handle ${property.type} properties in ObjectPattern`,
               severity: ErrorSeverity.Todo,
-              category: ErrorCategory.Todo,
               loc: property.node.loc ?? null,
               suggestions: null,
             });
@@ -4115,7 +4012,6 @@ function lowerAssignment(
             builder.errors.push({
               reason: `(BuildHIR::lowerAssignment) Handle computed properties in ObjectPattern`,
               severity: ErrorSeverity.Todo,
-              category: ErrorCategory.Todo,
               loc: property.node.loc ?? null,
               suggestions: null,
             });
@@ -4130,7 +4026,6 @@ function lowerAssignment(
             builder.errors.push({
               reason: `(BuildHIR::lowerAssignment) Expected object property value to be an LVal, got: ${element.type}`,
               severity: ErrorSeverity.Todo,
-              category: ErrorCategory.Todo,
               loc: element.node.loc ?? null,
               suggestions: null,
             });
@@ -4153,7 +4048,6 @@ function lowerAssignment(
             } else if (identifier.kind === 'Global') {
               builder.errors.push({
                 severity: ErrorSeverity.Todo,
-                category: ErrorCategory.Todo,
                 reason:
                   'Expected reassignment of globals to enable forceTemporaries',
                 loc: element.node.loc ?? GeneratedSource,
@@ -4303,7 +4197,6 @@ function lowerAssignment(
       builder.errors.push({
         reason: `(BuildHIR::lowerAssignment) Handle ${lvaluePath.type} assignments`,
         severity: ErrorSeverity.Todo,
-        category: ErrorCategory.Todo,
         loc: lvaluePath.node.loc ?? null,
         suggestions: null,
       });

compiler/packages/babel-plugin-react-compiler/src/HIR/Environment.ts

@@ -93,7 +93,7 @@ export const MacroSchema = z.union([
   z.tuple([z.string(), z.array(MacroMethodSchema)]),
 ]);
 
-export type CompilerMode = 'all_features' | 'no_inferred_memo';
+export type CompilerMode = 'all_features' | 'no_inferred_memo' | 'lint_only';
 
 export type Macro = z.infer<typeof MacroSchema>;
 export type MacroMethod = z.infer<typeof MacroMethodSchema>;
@@ -250,6 +250,11 @@ export const EnvironmentConfigSchema = z.object({
    */
   flowTypeProvider: z.nullable(z.function().args(z.string())).default(null),
 
+  /**
+   * Enable a new model for mutability and aliasing inference
+   */
+  enableNewMutationAliasingModel: z.boolean().default(true),
+
   /**
    * Enables inference of optional dependency chains. Without this flag
    * a property chain such as `props?.items?.foo` will infer as a dep on
@@ -650,13 +655,6 @@ export const EnvironmentConfigSchema = z.object({
    *   useMemo(() => { ... }, [...]);
    */
   validateNoVoidUseMemo: z.boolean().default(false),
-
-  /**
-   * Validates that Components/Hooks are always defined at module level. This prevents scope
-   * reference errors that occur when the compiler attempts to optimize the nested component/hook
-   * while its parent function remains uncompiled.
-   */
-  validateNoDynamicallyCreatedComponentsOrHooks: z.boolean().default(false),
 });
 
 export type EnvironmentConfig = z.infer<typeof EnvironmentConfigSchema>;
@@ -831,6 +829,14 @@ export class Environment {
     }
   }
 
+  logOrThrowErrors(errors: Result<void, CompilerError>): void {
+    if (this.compilerMode === 'lint_only') {
+      this.logErrors(errors);
+    } else {
+      errors.unwrap();
+    }
+  }
+
   isContextIdentifier(node: t.Identifier): boolean {
     return this.#contextIdentifiers.has(node);
   }

compiler/packages/babel-plugin-react-compiler/src/HIR/HIR.ts

@@ -7,7 +7,7 @@
 
 import {BindingKind} from '@babel/traverse';
 import * as t from '@babel/types';
-import {CompilerError} from '../CompilerError';
+import {CompilerError, CompilerErrorDetailOptions} from '../CompilerError';
 import {assertExhaustive} from '../Utils/utils';
 import {Environment, ReactFunctionType} from './Environment';
 import type {HookKind} from './ObjectShape';
@@ -15,6 +15,7 @@ import {Type, makeType} from './Types';
 import {z} from 'zod';
 import type {AliasingEffect} from '../Inference/AliasingEffects';
 import {isReservedWord} from '../Utils/Keyword';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 
 /*
  * *******************************************************************************************
@@ -282,13 +283,30 @@ export type HIRFunction = {
   returnTypeAnnotation: t.FlowType | t.TSType | null;
   returns: Place;
   context: Array<Place>;
+  effects: Array<FunctionEffect> | null;
   body: HIR;
   generator: boolean;
   async: boolean;
   directives: Array<string>;
-  aliasingEffects: Array<AliasingEffect> | null;
+  aliasingEffects?: Array<AliasingEffect> | null;
 };
 
+export type FunctionEffect =
+  | {
+      kind: 'GlobalMutation';
+      error: CompilerErrorDetailOptions;
+    }
+  | {
+      kind: 'ReactMutation';
+      error: CompilerErrorDetailOptions;
+    }
+  | {
+      kind: 'ContextMutation';
+      places: ReadonlySet<Place>;
+      effect: Effect;
+      loc: SourceLocation;
+    };
+
 /*
  * Each reactive scope may have its own control-flow, so the instructions form
  * a control-flow graph. The graph comprises a set of basic blocks which reference
@@ -1305,18 +1323,18 @@ export function forkTemporaryIdentifier(
  */
 export function makeIdentifierName(name: string): ValidatedIdentifier {
   if (isReservedWord(name)) {
-    CompilerError.throwInvalidJS({
-      reason: 'Expected a non-reserved identifier name',
-      loc: GeneratedSource,
-      description: `\`${name}\` is a reserved word in JavaScript and cannot be used as an identifier name`,
-      suggestions: null,
-    });
+    CompilerError.throwFromCode(
+      ErrorCode.INVALID_SYNTAX_RESERVED_VARIABLE_NAME,
+      {
+        loc: GeneratedSource,
+        description: `\`${name}\` is a reserved word in JavaScript and cannot be used as an identifier name`,
+      },
+    );
   } else {
     CompilerError.invariant(t.isValidIdentifier(name), {
       reason: `Expected a valid identifier name`,
       loc: GeneratedSource,
       description: `\`${name}\` is not a valid JavaScript identifier`,
-      suggestions: null,
     });
   }
   return {

compiler/packages/babel-plugin-react-compiler/src/HIR/HIRBuilder.ts

@@ -7,7 +7,7 @@
 
 import {Binding, NodePath} from '@babel/traverse';
 import * as t from '@babel/types';
-import {CompilerError, ErrorCategory, ErrorSeverity} from '../CompilerError';
+import {CompilerDiagnostic, CompilerError} from '../CompilerError';
 import {Environment} from './Environment';
 import {
   BasicBlock,
@@ -37,6 +37,7 @@ import {
   mapTerminalSuccessors,
   terminalFallthrough,
 } from './visitors';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 
 /*
  * *******************************************************************************************
@@ -308,36 +309,17 @@ export default class HIRBuilder {
 
   resolveBinding(node: t.Identifier): Identifier {
     if (node.name === 'fbt') {
-      CompilerError.throwDiagnostic({
-        severity: ErrorSeverity.Todo,
-        category: ErrorCategory.FBT,
-        reason: 'Support local variables named `fbt`',
-        description:
-          'Local variables named `fbt` may conflict with the fbt plugin and are not yet supported',
-        details: [
-          {
-            kind: 'error',
-            message: 'Rename to avoid conflict with fbt plugin',
-            loc: node.loc ?? GeneratedSource,
-          },
-        ],
-      });
-    }
-    if (node.name === 'this') {
-      CompilerError.throwDiagnostic({
-        severity: ErrorSeverity.UnsupportedJS,
-        category: ErrorCategory.UnsupportedSyntax,
-        reason: '`this` is not supported syntax',
-        description:
-          'React Compiler does not support compiling functions that use `this`',
-        details: [
-          {
-            kind: 'error',
-            message: '`this` was used here',
-            loc: node.loc ?? GeneratedSource,
-          },
-        ],
-      });
+      CompilerError.throwDiagnostic(
+        CompilerDiagnostic.fromCode(ErrorCode.TODO_CONFLICTING_FBT_IDENTIFIER, {
+          details: [
+            {
+              kind: 'error',
+              message: 'Rename to avoid conflict with fbt plugin',
+              loc: node.loc ?? GeneratedSource,
+            },
+          ],
+        }),
+      );
     }
     const originalName = node.name;
     let name = originalName;

compiler/packages/babel-plugin-react-compiler/src/HIR/PrintHIR.ts

@@ -554,11 +554,23 @@ export function printInstructionValue(instrValue: ReactiveValue): string {
       const context = instrValue.loweredFunc.func.context
         .map(dep => printPlace(dep))
         .join(',');
+      const effects =
+        instrValue.loweredFunc.func.effects
+          ?.map(effect => {
+            if (effect.kind === 'ContextMutation') {
+              return `ContextMutation places=[${[...effect.places]
+                .map(place => printPlace(place))
+                .join(', ')}] effect=${effect.effect}`;
+            } else {
+              return `GlobalMutation`;
+            }
+          })
+          .join(', ') ?? '';
       const aliasingEffects =
         instrValue.loweredFunc.func.aliasingEffects
           ?.map(printAliasingEffect)
           ?.join(', ') ?? '';
-      value = `${kind} ${name} @context[${context}] @aliasingEffects=[${aliasingEffects}]\n${fn}`;
+      value = `${kind} ${name} @context[${context}] @effects[${effects}] @aliasingEffects=[${aliasingEffects}]\n${fn}`;
       break;
     }
     case 'TaggedTemplateExpression': {
@@ -880,8 +892,7 @@ export function printType(type: Type): string {
   if (type.kind === 'Object' && type.shapeId != null) {
     return `:T${type.kind}<${type.shapeId}>`;
   } else if (type.kind === 'Function' && type.shapeId != null) {
-    const returnType = printType(type.return);
-    return `:T${type.kind}<${type.shapeId}>()${returnType !== '' ? `:  ${returnType}` : ''}`;
+    return `:T${type.kind}<${type.shapeId}>`;
   } else {
     return `:T${type.kind}`;
   }
@@ -984,16 +995,16 @@ export function printAliasingEffect(effect: AliasingEffect): string {
     case 'MutateConditionally':
     case 'MutateTransitive':
     case 'MutateTransitiveConditionally': {
-      return `${effect.kind} ${printPlaceForAliasEffect(effect.value)}${effect.kind === 'Mutate' && effect.reason?.kind === 'AssignCurrentProperty' ? ' (assign `.current`)' : ''}`;
+      return `${effect.kind} ${printPlaceForAliasEffect(effect.value)}`;
     }
     case 'MutateFrozen': {
-      return `MutateFrozen ${printPlaceForAliasEffect(effect.place)} reason=${JSON.stringify(effect.error.reason)}`;
+      return `MutateFrozen ${printPlaceForAliasEffect(effect.place)} reason=${JSON.stringify(effect.error.category)}`;
     }
     case 'MutateGlobal': {
-      return `MutateGlobal ${printPlaceForAliasEffect(effect.place)} reason=${JSON.stringify(effect.error.reason)}`;
+      return `MutateGlobal ${printPlaceForAliasEffect(effect.place)} reason=${JSON.stringify(effect.error.category)}`;
     }
     case 'Impure': {
-      return `Impure ${printPlaceForAliasEffect(effect.place)} reason=${JSON.stringify(effect.error.reason)}`;
+      return `Impure ${printPlaceForAliasEffect(effect.place)} reason=${JSON.stringify(effect.error.category)}`;
     }
     case 'Render': {
       return `Render ${printPlaceForAliasEffect(effect.place)}`;

compiler/packages/babel-plugin-react-compiler/src/Inference/AliasingEffects.ts

@@ -50,7 +50,7 @@ export type AliasingEffect =
   /**
    * Mutate the value and any direct aliases (not captures). Errors if the value is not mutable.
    */
-  | {kind: 'Mutate'; value: Place; reason?: MutationReason | null}
+  | {kind: 'Mutate'; value: Place}
   /**
    * Mutate the value and any direct aliases (not captures), but only if the value is known mutable.
    * This should be rare.
@@ -174,8 +174,6 @@ export type AliasingEffect =
       place: Place;
     };
 
-export type MutationReason = {kind: 'AssignCurrentProperty'};
-
 export function hashEffect(effect: AliasingEffect): string {
   switch (effect.kind) {
     case 'Apply': {
@@ -231,7 +229,7 @@ export function hashEffect(effect: AliasingEffect): string {
         effect.kind,
         effect.place.identifier.id,
         effect.error.severity,
-        effect.error.reason,
+        effect.error.category,
         effect.error.description,
         printSourceLocation(effect.error.primaryLocation() ?? GeneratedSource),
       ].join(':');

compiler/packages/babel-plugin-react-compiler/src/Inference/AnalyseFunctions.ts

@@ -6,10 +6,20 @@
  */
 
 import {CompilerError} from '../CompilerError';
-import {Effect, HIRFunction, IdentifierId, makeInstructionId} from '../HIR';
+import {
+  Effect,
+  HIRFunction,
+  Identifier,
+  IdentifierId,
+  LoweredFunction,
+  isRefOrRefValue,
+  makeInstructionId,
+} from '../HIR';
 import {deadCodeElimination} from '../Optimization';
 import {inferReactiveScopeVariables} from '../ReactiveScopes';
 import {rewriteInstructionKindsBasedOnReassignment} from '../SSA';
+import {inferMutableRanges} from './InferMutableRanges';
+import inferReferenceEffects from './InferReferenceEffects';
 import {assertExhaustive} from '../Utils/utils';
 import {inferMutationAliasingEffects} from './InferMutationAliasingEffects';
 import {inferMutationAliasingRanges} from './InferMutationAliasingRanges';
@@ -20,7 +30,12 @@ export default function analyseFunctions(func: HIRFunction): void {
       switch (instr.value.kind) {
         case 'ObjectMethod':
         case 'FunctionExpression': {
-          lowerWithMutationAliasing(instr.value.loweredFunc.func);
+          if (!func.env.config.enableNewMutationAliasingModel) {
+            lower(instr.value.loweredFunc.func);
+            infer(instr.value.loweredFunc);
+          } else {
+            lowerWithMutationAliasing(instr.value.loweredFunc.func);
+          }
 
           /**
            * Reset mutable range for outer inferReferenceEffects
@@ -125,3 +140,58 @@ function lowerWithMutationAliasing(fn: HIRFunction): void {
     value: fn,
   });
 }
+
+function lower(func: HIRFunction): void {
+  analyseFunctions(func);
+  inferReferenceEffects(func, {isFunctionExpression: true});
+  deadCodeElimination(func);
+  inferMutableRanges(func);
+  rewriteInstructionKindsBasedOnReassignment(func);
+  inferReactiveScopeVariables(func);
+  func.env.logger?.debugLogIRs?.({
+    kind: 'hir',
+    name: 'AnalyseFunction (inner)',
+    value: func,
+  });
+}
+
+function infer(loweredFunc: LoweredFunction): void {
+  for (const operand of loweredFunc.func.context) {
+    const identifier = operand.identifier;
+    CompilerError.invariant(operand.effect === Effect.Unknown, {
+      reason:
+        '[AnalyseFunctions] Expected Function context effects to not have been set',
+      loc: operand.loc,
+    });
+    if (isRefOrRefValue(identifier)) {
+      /*
+       * TODO: this is a hack to ensure we treat functions which reference refs
+       * as having a capture and therefore being considered mutable. this ensures
+       * the function gets a mutable range which accounts for anywhere that it
+       * could be called, and allows us to help ensure it isn't called during
+       * render
+       */
+      operand.effect = Effect.Capture;
+    } else if (isMutatedOrReassigned(identifier)) {
+      /**
+       * Reflects direct reassignments, PropertyStores, and ConditionallyMutate
+       * (directly or through maybe-aliases)
+       */
+      operand.effect = Effect.Capture;
+    } else {
+      operand.effect = Effect.Read;
+    }
+  }
+}
+
+function isMutatedOrReassigned(id: Identifier): boolean {
+  /*
+   * This check checks for mutation and reassingnment, so the usual check for
+   * mutation (ie, `mutableRange.end - mutableRange.start > 1`) isn't quite
+   * enough.
+   *
+   * We need to track re-assignments in context refs as we need to reflect the
+   * re-assignment back to the captured refs.
+   */
+  return id.mutableRange.end > id.mutableRange.start;
+}

compiler/packages/babel-plugin-react-compiler/src/Inference/DropManualMemoization.ts

@@ -5,13 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {
-  CompilerDiagnostic,
-  CompilerError,
-  ErrorSeverity,
-  SourceLocation,
-} from '..';
-import {ErrorCategory} from '../CompilerError';
+import {CompilerDiagnostic, CompilerError, SourceLocation} from '..';
 import {
   CallExpression,
   Effect,
@@ -36,6 +30,7 @@ import {
   makeInstructionId,
 } from '../HIR';
 import {createTemporaryPlace, markInstructionIds} from '../HIR/HIRBuilder';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 import {Result} from '../Utils/Result';
 
 type ManualMemoCallee = {
@@ -300,13 +295,11 @@ function extractManualMemoizationArgs(
   >;
   if (fnPlace == null) {
     errors.pushDiagnostic(
-      CompilerDiagnostic.create({
-        category: ErrorCategory.UseMemo,
-        severity: ErrorSeverity.InvalidReact,
-        reason: `Expected a callback function to be passed to ${kind}`,
-        description: `Expected a callback function to be passed to ${kind}`,
-        suggestions: null,
-      }).withDetail({
+      CompilerDiagnostic.fromCode(
+        kind === 'useMemo'
+          ? ErrorCode.INVALID_USE_MEMO_NO_ARG0
+          : ErrorCode.INVALID_USE_CALLBACK_NO_ARG0,
+      ).withDetail({
         kind: 'error',
         loc: instr.value.loc,
         message: `Expected a callback function to be passed to ${kind}`,
@@ -316,13 +309,11 @@ function extractManualMemoizationArgs(
   }
   if (fnPlace.kind === 'Spread' || depsListPlace?.kind === 'Spread') {
     errors.pushDiagnostic(
-      CompilerDiagnostic.create({
-        category: ErrorCategory.UseMemo,
-        severity: ErrorSeverity.InvalidReact,
-        reason: `Unexpected spread argument to ${kind}`,
-        description: `Unexpected spread argument to ${kind}`,
-        suggestions: null,
-      }).withDetail({
+      CompilerDiagnostic.fromCode(
+        fnPlace.kind === 'Spread'
+          ? ErrorCode.DYNAMIC_USE_MEMO_SPREAD_ARGUMENT
+          : ErrorCode.DYNAMIC_USE_CALLBACK_SPREAD_ARGUMENT,
+      ).withDetail({
         kind: 'error',
         loc: instr.value.loc,
         message: `Unexpected spread argument to ${kind}`,
@@ -337,13 +328,9 @@ function extractManualMemoizationArgs(
     );
     if (maybeDepsList == null) {
       errors.pushDiagnostic(
-        CompilerDiagnostic.create({
-          category: ErrorCategory.UseMemo,
-          severity: ErrorSeverity.InvalidReact,
-          reason: `Expected the dependency list for ${kind} to be an array literal`,
-          description: `Expected the dependency list for ${kind} to be an array literal`,
-          suggestions: null,
-        }).withDetail({
+        CompilerDiagnostic.fromCode(
+          ErrorCode.DYNAMIC_MANUAL_MEMO_DEPENDENCY_LIST,
+        ).withDetail({
           kind: 'error',
           loc: depsListPlace.loc,
           message: `Expected the dependency list for ${kind} to be an array literal`,
@@ -356,13 +343,9 @@ function extractManualMemoizationArgs(
       const maybeDep = sidemap.maybeDeps.get(dep.identifier.id);
       if (maybeDep == null) {
         errors.pushDiagnostic(
-          CompilerDiagnostic.create({
-            category: ErrorCategory.UseMemo,
-            severity: ErrorSeverity.InvalidReact,
-            reason: `Expected the dependency list to be an array of simple expressions (e.g. \`x\`, \`x.y.z\`, \`x?.y?.z\`)`,
-            description: `Expected the dependency list to be an array of simple expressions (e.g. \`x\`, \`x.y.z\`, \`x?.y?.z\`)`,
-            suggestions: null,
-          }).withDetail({
+          CompilerDiagnostic.fromCode(
+            ErrorCode.COMPLEX_MANUAL_MEMO_DEPENDENCY_LIST_ENTRY,
+          ).withDetail({
             kind: 'error',
             loc: dep.loc,
             message: `Expected the dependency list to be an array of simple expressions (e.g. \`x\`, \`x.y.z\`, \`x?.y?.z\`)`,
@@ -462,17 +445,16 @@ export function dropManualMemoization(
             if (funcToCheck !== undefined && funcToCheck.loweredFunc.func) {
               if (!hasNonVoidReturn(funcToCheck.loweredFunc.func)) {
                 errors.pushDiagnostic(
-                  CompilerDiagnostic.create({
-                    severity: ErrorSeverity.InvalidReact,
-                    category: ErrorCategory.UseMemo,
-                    reason: 'useMemo() callbacks must return a value',
-                    description: `This ${
-                      manualMemo.loadInstr.value.kind === 'PropertyLoad'
-                        ? 'React.useMemo'
-                        : 'useMemo'
-                    } callback doesn't return a value. useMemo is for computing and caching values, not for arbitrary side effects.`,
-                    suggestions: null,
-                  }).withDetail({
+                  CompilerDiagnostic.fromCode(
+                    ErrorCode.INVALID_USE_MEMO_CALLBACK_RETURN,
+                    {
+                      description: `This ${
+                        manualMemo.loadInstr.value.kind === 'PropertyLoad'
+                          ? 'React.useMemo'
+                          : 'useMemo'
+                      } callback doesn't return a value. useMemo is for computing and caching values, not for arbitrary side effects.`,
+                    },
+                  ).withDetail({
                     kind: 'error',
                     loc: instr.value.loc,
                     message: 'useMemo() callbacks must return a value',
@@ -503,13 +485,9 @@ export function dropManualMemoization(
              */
             if (!sidemap.functions.has(fnPlace.identifier.id)) {
               errors.pushDiagnostic(
-                CompilerDiagnostic.create({
-                  category: ErrorCategory.UseMemo,
-                  severity: ErrorSeverity.InvalidReact,
-                  reason: `Expected the first argument to be an inline function expression`,
-                  description: `Expected the first argument to be an inline function expression`,
-                  suggestions: [],
-                }).withDetail({
+                CompilerDiagnostic.fromCode(
+                  ErrorCode.DYNAMIC_MANUAL_MEMO_CALLBACK,
+                ).withDetail({
                   kind: 'error',
                   loc: fnPlace.loc,
                   message: `Expected the first argument to be an inline function expression`,

compiler/packages/babel-plugin-react-compiler/src/Inference/InerAliasForUncalledFunctions.ts

@@ -0,0 +1,134 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {
+  Effect,
+  HIRFunction,
+  Identifier,
+  isMutableEffect,
+  isRefOrRefLikeMutableType,
+  makeInstructionId,
+} from '../HIR/HIR';
+import {eachInstructionValueOperand} from '../HIR/visitors';
+import {isMutable} from '../ReactiveScopes/InferReactiveScopeVariables';
+import DisjointSet from '../Utils/DisjointSet';
+
+/**
+ * If a function captures a mutable value but never gets called, we don't infer a
+ * mutable range for that function. This means that we also don't alias the function
+ * with its mutable captures.
+ *
+ * This case is tricky, because we don't generally know for sure what is a mutation
+ * and what may just be a normal function call. For example:
+ *
+ * ```
+ * hook useFoo() {
+ *   const x = makeObject();
+ *   return () => {
+ *     return readObject(x); // could be a mutation!
+ *   }
+ * }
+ * ```
+ *
+ * If we pessimistically assume that all such cases are mutations, we'd have to group
+ * lots of memo scopes together unnecessarily. However, if there is definitely a mutation:
+ *
+ * ```
+ * hook useFoo(createEntryForKey) {
+ *   const cache = new WeakMap();
+ *   return (key) => {
+ *     let entry = cache.get(key);
+ *     if (entry == null) {
+ *       entry = createEntryForKey(key);
+ *       cache.set(key, entry); // known mutation!
+ *     }
+ *     return entry;
+ *   }
+ * }
+ * ```
+ *
+ * Then we have to ensure that the function and its mutable captures alias together and
+ * end up in the same scope. However, aliasing together isn't enough if the function
+ * and operands all have empty mutable ranges (end = start + 1).
+ *
+ * This pass finds function expressions and object methods that have an empty mutable range
+ * and known-mutable operands which also don't have a mutable range, and ensures that the
+ * function and those operands are aliased together *and* that their ranges are updated to
+ * end after the function expression. This is sufficient to ensure that a reactive scope is
+ * created for the alias set.
+ */
+export function inferAliasForUncalledFunctions(
+  fn: HIRFunction,
+  aliases: DisjointSet<Identifier>,
+): void {
+  for (const block of fn.body.blocks.values()) {
+    instrs: for (const instr of block.instructions) {
+      const {lvalue, value} = instr;
+      if (
+        value.kind !== 'ObjectMethod' &&
+        value.kind !== 'FunctionExpression'
+      ) {
+        continue;
+      }
+      /*
+       * If the function is known to be mutated, we will have
+       * already aliased any mutable operands with it
+       */
+      const range = lvalue.identifier.mutableRange;
+      if (range.end > range.start + 1) {
+        continue;
+      }
+      /*
+       * If the function already has operands with an active mutable range,
+       * then we don't need to do anything — the function will have already
+       * been visited and included in some mutable alias set. This case can
+       * also occur due to visiting the same function in an earlier iteration
+       * of the outer fixpoint loop.
+       */
+      for (const operand of eachInstructionValueOperand(value)) {
+        if (isMutable(instr, operand)) {
+          continue instrs;
+        }
+      }
+      const operands: Set<Identifier> = new Set();
+      for (const effect of value.loweredFunc.func.effects ?? []) {
+        if (effect.kind !== 'ContextMutation') {
+          continue;
+        }
+        /*
+         * We're looking for known-mutations only, so we look at the effects
+         * rather than function context
+         */
+        if (effect.effect === Effect.Store || effect.effect === Effect.Mutate) {
+          for (const operand of effect.places) {
+            /*
+             * It's possible that function effect analysis thinks there was a context mutation,
+             * but then InferReferenceEffects figures out some operands are globals and therefore
+             * creates a non-mutable effect for those operands.
+             * We should change InferReferenceEffects to swap the ContextMutation for a global
+             * mutation in that case, but for now we just filter them out here
+             */
+            if (
+              isMutableEffect(operand.effect, operand.loc) &&
+              !isRefOrRefLikeMutableType(operand.identifier.type)
+            ) {
+              operands.add(operand.identifier);
+            }
+          }
+        }
+      }
+      if (operands.size !== 0) {
+        operands.add(lvalue.identifier);
+        aliases.union([...operands]);
+        // Update mutable ranges, if the ranges are empty then a reactive scope isn't created
+        for (const operand of operands) {
+          operand.mutableRange.end = makeInstructionId(instr.id + 1);
+        }
+      }
+    }
+  }
+}

compiler/packages/babel-plugin-react-compiler/src/Inference/InferAlias.ts

@@ -0,0 +1,68 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {
+  HIRFunction,
+  Identifier,
+  Instruction,
+  isPrimitiveType,
+  Place,
+} from '../HIR/HIR';
+import DisjointSet from '../Utils/DisjointSet';
+
+export type AliasSet = Set<Identifier>;
+
+export function inferAliases(func: HIRFunction): DisjointSet<Identifier> {
+  const aliases = new DisjointSet<Identifier>();
+  for (const [_, block] of func.body.blocks) {
+    for (const instr of block.instructions) {
+      inferInstr(instr, aliases);
+    }
+  }
+
+  return aliases;
+}
+
+function inferInstr(
+  instr: Instruction,
+  aliases: DisjointSet<Identifier>,
+): void {
+  const {lvalue, value: instrValue} = instr;
+  let alias: Place | null = null;
+  switch (instrValue.kind) {
+    case 'LoadLocal':
+    case 'LoadContext': {
+      if (isPrimitiveType(instrValue.place.identifier)) {
+        return;
+      }
+      alias = instrValue.place;
+      break;
+    }
+    case 'StoreLocal':
+    case 'StoreContext': {
+      alias = instrValue.value;
+      break;
+    }
+    case 'Destructure': {
+      alias = instrValue.value;
+      break;
+    }
+    case 'ComputedLoad':
+    case 'PropertyLoad': {
+      alias = instrValue.object;
+      break;
+    }
+    case 'TypeCastExpression': {
+      alias = instrValue.value;
+      break;
+    }
+    default:
+      return;
+  }
+
+  aliases.union([lvalue.identifier, alias.identifier]);
+}

compiler/packages/babel-plugin-react-compiler/src/Inference/InferAliasForPhis.ts

@@ -0,0 +1,27 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {HIRFunction, Identifier} from '../HIR/HIR';
+import DisjointSet from '../Utils/DisjointSet';
+
+export function inferAliasForPhis(
+  func: HIRFunction,
+  aliases: DisjointSet<Identifier>,
+): void {
+  for (const [_, block] of func.body.blocks) {
+    for (const phi of block.phis) {
+      const isPhiMutatedAfterCreation: boolean =
+        phi.place.identifier.mutableRange.end >
+        (block.instructions.at(0)?.id ?? block.terminal.id);
+      if (isPhiMutatedAfterCreation) {
+        for (const [, operand] of phi.operands) {
+          aliases.union([phi.place.identifier, operand.identifier]);
+        }
+      }
+    }
+  }
+}

compiler/packages/babel-plugin-react-compiler/src/Inference/InferAliasForStores.ts

@@ -0,0 +1,68 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {
+  Effect,
+  HIRFunction,
+  Identifier,
+  InstructionId,
+  Place,
+} from '../HIR/HIR';
+import {
+  eachInstructionLValue,
+  eachInstructionValueOperand,
+} from '../HIR/visitors';
+import DisjointSet from '../Utils/DisjointSet';
+
+export function inferAliasForStores(
+  func: HIRFunction,
+  aliases: DisjointSet<Identifier>,
+): void {
+  for (const [_, block] of func.body.blocks) {
+    for (const instr of block.instructions) {
+      const {value, lvalue} = instr;
+      const isStore =
+        lvalue.effect === Effect.Store ||
+        /*
+         * Some typed functions annotate callees or arguments
+         * as Effect.Store.
+         */
+        ![...eachInstructionValueOperand(value)].every(
+          operand => operand.effect !== Effect.Store,
+        );
+
+      if (!isStore) {
+        continue;
+      }
+      for (const operand of eachInstructionLValue(instr)) {
+        maybeAlias(aliases, lvalue, operand, instr.id);
+      }
+      for (const operand of eachInstructionValueOperand(value)) {
+        if (
+          operand.effect === Effect.Capture ||
+          operand.effect === Effect.Store
+        ) {
+          maybeAlias(aliases, lvalue, operand, instr.id);
+        }
+      }
+    }
+  }
+}
+
+function maybeAlias(
+  aliases: DisjointSet<Identifier>,
+  lvalue: Place,
+  rvalue: Place,
+  id: InstructionId,
+): void {
+  if (
+    lvalue.identifier.mutableRange.end > id + 1 ||
+    rvalue.identifier.mutableRange.end > id
+  ) {
+    aliases.union([lvalue.identifier, rvalue.identifier]);
+  }
+}

compiler/packages/babel-plugin-react-compiler/src/Inference/InferFunctionEffects.ts

@@ -0,0 +1,347 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {
+  CompilerError,
+  CompilerErrorDetailOptions,
+  ErrorSeverity,
+  ValueKind,
+} from '..';
+import {
+  AbstractValue,
+  BasicBlock,
+  Effect,
+  Environment,
+  FunctionEffect,
+  Instruction,
+  InstructionValue,
+  Place,
+  ValueReason,
+  getHookKind,
+  isRefOrRefValue,
+} from '../HIR';
+import {eachInstructionOperand, eachTerminalOperand} from '../HIR/visitors';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
+import {assertExhaustive} from '../Utils/utils';
+
+interface State {
+  kind(place: Place): AbstractValue;
+  values(place: Place): Array<InstructionValue>;
+  isDefined(place: Place): boolean;
+}
+
+function inferOperandEffect(state: State, place: Place): null | FunctionEffect {
+  const value = state.kind(place);
+  CompilerError.invariant(value != null, {
+    reason: 'Expected operand to have a kind',
+    loc: null,
+  });
+
+  switch (place.effect) {
+    case Effect.Store:
+    case Effect.Mutate: {
+      if (isRefOrRefValue(place.identifier)) {
+        break;
+      } else if (value.kind === ValueKind.Context) {
+        CompilerError.invariant(value.context.size > 0, {
+          reason:
+            "[InferFunctionEffects] Expected Context-kind value's capture list to be non-empty.",
+          loc: place.loc,
+        });
+        return {
+          kind: 'ContextMutation',
+          loc: place.loc,
+          effect: place.effect,
+          places: value.context,
+        };
+      } else if (
+        value.kind !== ValueKind.Mutable &&
+        // We ignore mutations of primitives since this is not a React-specific problem
+        value.kind !== ValueKind.Primitive
+      ) {
+        let errorCode = getWriteErrorReason(value);
+        return {
+          kind:
+            value.reason.size === 1 && value.reason.has(ValueReason.Global)
+              ? 'GlobalMutation'
+              : 'ReactMutation',
+          error: {
+            errorCode,
+            description:
+              place.identifier.name !== null &&
+              place.identifier.name.kind === 'named'
+                ? `Found mutation of \`${place.identifier.name.value}\``
+                : null,
+            loc: place.loc,
+          },
+        };
+      }
+      break;
+    }
+  }
+  return null;
+}
+
+function inheritFunctionEffects(
+  state: State,
+  place: Place,
+): Array<FunctionEffect> {
+  const effects = inferFunctionInstrEffects(state, place);
+
+  return effects
+    .flatMap(effect => {
+      if (effect.kind === 'GlobalMutation' || effect.kind === 'ReactMutation') {
+        return [effect];
+      } else {
+        const effects: Array<FunctionEffect | null> = [];
+        CompilerError.invariant(effect.kind === 'ContextMutation', {
+          reason: 'Expected ContextMutation',
+          loc: null,
+        });
+        /**
+         * Contextual effects need to be replayed against the current inference
+         * state, which may know more about the value to which the effect applied.
+         * The main cases are:
+         * 1. The mutated context value is _still_ a context value in the current scope,
+         *    so we have to continue propagating the original context mutation.
+         * 2. The mutated context value is a mutable value in the current scope,
+         *    so the context mutation was fine and we can skip propagating the effect.
+         * 3. The mutated context value  is an immutable value in the current scope,
+         *    resulting in a non-ContextMutation FunctionEffect. We propagate that new,
+         *    more detailed effect to the current function context.
+         */
+        for (const place of effect.places) {
+          if (state.isDefined(place)) {
+            const replayedEffect = inferOperandEffect(state, {
+              ...place,
+              loc: effect.loc,
+              effect: effect.effect,
+            });
+            if (replayedEffect != null) {
+              if (replayedEffect.kind === 'ContextMutation') {
+                // Case 1, still a context value so propagate the original effect
+                effects.push(effect);
+              } else {
+                // Case 3, immutable value so propagate the more precise effect
+                effects.push(replayedEffect);
+              }
+            } // else case 2, local mutable value so this effect was fine
+          }
+        }
+        return effects;
+      }
+    })
+    .filter((effect): effect is FunctionEffect => effect != null);
+}
+
+function inferFunctionInstrEffects(
+  state: State,
+  place: Place,
+): Array<FunctionEffect> {
+  const effects: Array<FunctionEffect> = [];
+  const instrs = state.values(place);
+  CompilerError.invariant(instrs != null, {
+    reason: 'Expected operand to have instructions',
+    loc: null,
+  });
+
+  for (const instr of instrs) {
+    if (
+      (instr.kind === 'FunctionExpression' || instr.kind === 'ObjectMethod') &&
+      instr.loweredFunc.func.effects != null
+    ) {
+      effects.push(...instr.loweredFunc.func.effects);
+    }
+  }
+
+  return effects;
+}
+
+function operandEffects(
+  state: State,
+  place: Place,
+  filterRenderSafe: boolean,
+): Array<FunctionEffect> {
+  const functionEffects: Array<FunctionEffect> = [];
+  const effect = inferOperandEffect(state, place);
+  effect && functionEffects.push(effect);
+  functionEffects.push(...inheritFunctionEffects(state, place));
+  if (filterRenderSafe) {
+    return functionEffects.filter(effect => !isEffectSafeOutsideRender(effect));
+  } else {
+    return functionEffects;
+  }
+}
+
+export function inferInstructionFunctionEffects(
+  env: Environment,
+  state: State,
+  instr: Instruction,
+): Array<FunctionEffect> {
+  const functionEffects: Array<FunctionEffect> = [];
+  switch (instr.value.kind) {
+    case 'JsxExpression': {
+      if (instr.value.tag.kind === 'Identifier') {
+        functionEffects.push(...operandEffects(state, instr.value.tag, false));
+      }
+      instr.value.children?.forEach(child =>
+        functionEffects.push(...operandEffects(state, child, false)),
+      );
+      for (const attr of instr.value.props) {
+        if (attr.kind === 'JsxSpreadAttribute') {
+          functionEffects.push(...operandEffects(state, attr.argument, false));
+        } else {
+          functionEffects.push(...operandEffects(state, attr.place, true));
+        }
+      }
+      break;
+    }
+    case 'ObjectMethod':
+    case 'FunctionExpression': {
+      /**
+       * If this function references other functions, propagate the referenced function's
+       * effects to this function.
+       *
+       * ```
+       * let f = () => global = true;
+       * let g = () => f();
+       * g();
+       * ```
+       *
+       * In this example, because `g` references `f`, we propagate the GlobalMutation from
+       * `f` to `g`. Thus, referencing `g` in `g()` will evaluate the GlobalMutation in the outer
+       * function effect context and report an error. But if instead we do:
+       *
+       * ```
+       * let f = () => global = true;
+       * let g = () => f();
+       * useEffect(() => g(), [g])
+       * ```
+       *
+       * Now `g`'s effects will be discarded since they're in a useEffect.
+       */
+      for (const operand of eachInstructionOperand(instr)) {
+        instr.value.loweredFunc.func.effects ??= [];
+        instr.value.loweredFunc.func.effects.push(
+          ...inferFunctionInstrEffects(state, operand),
+        );
+      }
+      break;
+    }
+    case 'MethodCall':
+    case 'CallExpression': {
+      let callee;
+      if (instr.value.kind === 'MethodCall') {
+        callee = instr.value.property;
+        functionEffects.push(
+          ...operandEffects(state, instr.value.receiver, false),
+        );
+      } else {
+        callee = instr.value.callee;
+      }
+      functionEffects.push(...operandEffects(state, callee, false));
+      let isHook = getHookKind(env, callee.identifier) != null;
+      for (const arg of instr.value.args) {
+        const place = arg.kind === 'Identifier' ? arg : arg.place;
+        /*
+         * Join the effects of the argument with the effects of the enclosing function,
+         * unless the we're detecting a global mutation inside a useEffect hook
+         */
+        functionEffects.push(...operandEffects(state, place, isHook));
+      }
+      break;
+    }
+    case 'StartMemoize':
+    case 'FinishMemoize':
+    case 'LoadLocal':
+    case 'StoreLocal': {
+      break;
+    }
+    case 'StoreGlobal': {
+      functionEffects.push({
+        kind: 'GlobalMutation',
+        error: {
+          errorCode: ErrorCode.INVALID_WRITE_GLOBAL,
+          loc: instr.loc,
+        },
+      });
+      break;
+    }
+    default: {
+      for (const operand of eachInstructionOperand(instr)) {
+        functionEffects.push(...operandEffects(state, operand, false));
+      }
+    }
+  }
+  return functionEffects;
+}
+
+export function inferTerminalFunctionEffects(
+  state: State,
+  block: BasicBlock,
+): Array<FunctionEffect> {
+  const functionEffects: Array<FunctionEffect> = [];
+  for (const operand of eachTerminalOperand(block.terminal)) {
+    functionEffects.push(...operandEffects(state, operand, true));
+  }
+  return functionEffects;
+}
+
+export function transformFunctionEffectErrors(
+  functionEffects: Array<FunctionEffect>,
+): Array<CompilerErrorDetailOptions> {
+  return functionEffects.map(eff => {
+    switch (eff.kind) {
+      case 'ReactMutation':
+      case 'GlobalMutation': {
+        return eff.error;
+      }
+      case 'ContextMutation': {
+        return {
+          severity: ErrorSeverity.Invariant,
+          reason: `Unexpected ContextMutation in top-level function effects`,
+          loc: eff.loc,
+        };
+      }
+      default:
+        assertExhaustive(
+          eff,
+          `Unexpected function effect kind \`${(eff as any).kind}\``,
+        );
+    }
+  });
+}
+
+function isEffectSafeOutsideRender(effect: FunctionEffect): boolean {
+  return effect.kind === 'GlobalMutation';
+}
+
+export function getWriteErrorReason(abstractValue: AbstractValue): ErrorCode {
+  if (abstractValue.reason.has(ValueReason.Global)) {
+    return ErrorCode.INVALID_WRITE_GLOBAL;
+  } else if (abstractValue.reason.has(ValueReason.JsxCaptured)) {
+    return ErrorCode.INVALID_WRITE_FROZEN_VALUE_JSX;
+  } else if (abstractValue.reason.has(ValueReason.Context)) {
+    return ErrorCode.INVALID_WRITE_IMMUTABLE_VALUE_USE_CONTEXT;
+  } else if (abstractValue.reason.has(ValueReason.KnownReturnSignature)) {
+    return ErrorCode.INVALID_WRITE_IMMUTABLE_VALUE_KNOWN_SIGNATURE;
+  } else if (abstractValue.reason.has(ValueReason.ReactiveFunctionArgument)) {
+    return ErrorCode.INVALID_WRITE_IMMUTABLE_ARGS;
+  } else if (abstractValue.reason.has(ValueReason.State)) {
+    return ErrorCode.INVALID_WRITE_STATE;
+  } else if (abstractValue.reason.has(ValueReason.ReducerState)) {
+    return ErrorCode.INVALID_WRITE_REDUCER_STATE;
+  } else if (abstractValue.reason.has(ValueReason.Effect)) {
+    return ErrorCode.INVALID_WRITE_EFFECT_DEPENDENCY;
+  } else if (abstractValue.reason.has(ValueReason.HookCaptured)) {
+    return ErrorCode.INVALID_WRITE_HOOK_CAPTURED;
+  } else if (abstractValue.reason.has(ValueReason.HookReturn)) {
+    return ErrorCode.INVALID_WRITE_HOOK_RETURN;
+  } else {
+    return ErrorCode.INVALID_WRITE_GENERIC;
+  }
+}

compiler/packages/babel-plugin-react-compiler/src/Inference/InferMutableLifetimes.ts

@@ -0,0 +1,218 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {
+  Effect,
+  HIRFunction,
+  Identifier,
+  InstructionId,
+  InstructionKind,
+  isArrayType,
+  isMapType,
+  isRefOrRefValue,
+  isSetType,
+  makeInstructionId,
+  Place,
+} from '../HIR/HIR';
+import {printPlace} from '../HIR/PrintHIR';
+import {
+  eachInstructionLValue,
+  eachInstructionOperand,
+  eachTerminalOperand,
+} from '../HIR/visitors';
+import {assertExhaustive} from '../Utils/utils';
+
+/*
+ * For each usage of a value in the given function, determines if the usage
+ * may be succeeded by a mutable usage of that same value and if so updates
+ * the usage to be mutable.
+ *
+ * Stated differently, this inference ensures that inferred capabilities of
+ * each reference are as follows:
+ * - freeze: the value is frozen at this point
+ * - readonly: the value is not modified at this point *or any subsequent
+ *    point*
+ * - mutable: the value is modified at this point *or some subsequent point*.
+ *
+ * Note that this refines the capabilities inferered by InferReferenceCapability,
+ * which looks at individual references and not the lifetime of a value's mutability.
+ *
+ * == Algorithm
+ *
+ * TODO:
+ * 1. Forward data-flow analysis to determine aliasing. Unlike InferReferenceCapability
+ *     which only tracks aliasing of top-level variables (`y = x`), this analysis needs
+ *     to know if a value is aliased anywhere (`y.x = x`). The forward data flow tracks
+ *     all possible locations which may have aliased a value. The concrete result is
+ *     a mapping of each Place to the set of possibly-mutable values it may alias.
+ *
+ * ```
+ * const x = []; // {x: v0; v0: mutable []}
+ * const y = {}; // {x: v0, y: v1; v0: mutable [], v1: mutable []}
+ * y.x = x;      // {x: v0, y: v1; v0: mutable [v1], v1: mutable [v0]}
+ * read(x);      // {x: v0, y: v1; v0: mutable [v1], v1: mutable [v0]}
+ * mutate(y);    // can infer that y mutates v0 and v1
+ * ```
+ *
+ * DONE:
+ * 2. Forward data-flow analysis to compute mutability liveness. Walk forwards over
+ *     the CFG and track which values are mutated in a successor.
+ *
+ * ```
+ * mutate(y);    // mutable y => v0, v1 mutated
+ * read(x);      // x maps to v0, v1, those are in the mutated-later set, so x is mutable here
+ * ...
+ * ```
+ */
+
+function infer(place: Place, instrId: InstructionId): void {
+  if (!isRefOrRefValue(place.identifier)) {
+    place.identifier.mutableRange.end = makeInstructionId(instrId + 1);
+  }
+}
+
+function inferPlace(
+  place: Place,
+  instrId: InstructionId,
+  inferMutableRangeForStores: boolean,
+): void {
+  switch (place.effect) {
+    case Effect.Unknown: {
+      throw new Error(`Found an unknown place ${printPlace(place)}}!`);
+    }
+    case Effect.Capture:
+    case Effect.Read:
+    case Effect.Freeze:
+      return;
+    case Effect.Store:
+      if (inferMutableRangeForStores) {
+        infer(place, instrId);
+      }
+      return;
+    case Effect.ConditionallyMutateIterator: {
+      const identifier = place.identifier;
+      if (
+        !isArrayType(identifier) &&
+        !isSetType(identifier) &&
+        !isMapType(identifier)
+      ) {
+        infer(place, instrId);
+      }
+      return;
+    }
+    case Effect.ConditionallyMutate:
+    case Effect.Mutate: {
+      infer(place, instrId);
+      return;
+    }
+    default:
+      assertExhaustive(place.effect, `Unexpected ${printPlace(place)} effect`);
+  }
+}
+
+export function inferMutableLifetimes(
+  func: HIRFunction,
+  inferMutableRangeForStores: boolean,
+): void {
+  /*
+   * Context variables only appear to mutate where they are assigned, but we need
+   * to force their range to start at their declaration. Track the declaring instruction
+   * id so that the ranges can be extended if/when they are reassigned
+   */
+  const contextVariableDeclarationInstructions = new Map<
+    Identifier,
+    InstructionId
+  >();
+  for (const [_, block] of func.body.blocks) {
+    for (const phi of block.phis) {
+      const isPhiMutatedAfterCreation: boolean =
+        phi.place.identifier.mutableRange.end >
+        (block.instructions.at(0)?.id ?? block.terminal.id);
+      if (
+        inferMutableRangeForStores &&
+        isPhiMutatedAfterCreation &&
+        phi.place.identifier.mutableRange.start === 0
+      ) {
+        for (const [, operand] of phi.operands) {
+          if (phi.place.identifier.mutableRange.start === 0) {
+            phi.place.identifier.mutableRange.start =
+              operand.identifier.mutableRange.start;
+          } else {
+            phi.place.identifier.mutableRange.start = makeInstructionId(
+              Math.min(
+                phi.place.identifier.mutableRange.start,
+                operand.identifier.mutableRange.start,
+              ),
+            );
+          }
+        }
+      }
+    }
+
+    for (const instr of block.instructions) {
+      for (const operand of eachInstructionLValue(instr)) {
+        const lvalueId = operand.identifier;
+
+        /*
+         * lvalue start being mutable when they're initially assigned a
+         * value.
+         */
+        lvalueId.mutableRange.start = instr.id;
+
+        /*
+         * Let's be optimistic and assume this lvalue is not mutable by
+         * default.
+         */
+        lvalueId.mutableRange.end = makeInstructionId(instr.id + 1);
+      }
+      for (const operand of eachInstructionOperand(instr)) {
+        inferPlace(operand, instr.id, inferMutableRangeForStores);
+      }
+
+      if (
+        instr.value.kind === 'DeclareContext' ||
+        (instr.value.kind === 'StoreContext' &&
+          instr.value.lvalue.kind !== InstructionKind.Reassign &&
+          !contextVariableDeclarationInstructions.has(
+            instr.value.lvalue.place.identifier,
+          ))
+      ) {
+        /**
+         * Save declarations of context variables if they hasn't already been
+         * declared (due to hoisted declarations).
+         */
+        contextVariableDeclarationInstructions.set(
+          instr.value.lvalue.place.identifier,
+          instr.id,
+        );
+      } else if (instr.value.kind === 'StoreContext') {
+        /*
+         * Else this is a reassignment, extend the range from the declaration (if present).
+         * Note that declarations may not be present for context variables that are reassigned
+         * within a function expression before (or without) a read of the same variable
+         */
+        const declaration = contextVariableDeclarationInstructions.get(
+          instr.value.lvalue.place.identifier,
+        );
+        if (
+          declaration != null &&
+          !isRefOrRefValue(instr.value.lvalue.place.identifier)
+        ) {
+          const range = instr.value.lvalue.place.identifier.mutableRange;
+          if (range.start === 0) {
+            range.start = declaration;
+          } else {
+            range.start = makeInstructionId(Math.min(range.start, declaration));
+          }
+        }
+      }
+    }
+    for (const operand of eachTerminalOperand(block.terminal)) {
+      inferPlace(operand, block.terminal.id, inferMutableRangeForStores);
+    }
+  }
+}

compiler/packages/babel-plugin-react-compiler/src/Inference/InferMutableRanges.ts

@@ -0,0 +1,102 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {HIRFunction, Identifier} from '../HIR/HIR';
+import {inferAliasForUncalledFunctions} from './InerAliasForUncalledFunctions';
+import {inferAliases} from './InferAlias';
+import {inferAliasForPhis} from './InferAliasForPhis';
+import {inferAliasForStores} from './InferAliasForStores';
+import {inferMutableLifetimes} from './InferMutableLifetimes';
+import {inferMutableRangesForAlias} from './InferMutableRangesForAlias';
+import {inferTryCatchAliases} from './InferTryCatchAliases';
+
+export function inferMutableRanges(ir: HIRFunction): void {
+  // Infer mutable ranges for non fields
+  inferMutableLifetimes(ir, false);
+
+  // Calculate aliases
+  const aliases = inferAliases(ir);
+  /*
+   * Calculate aliases for try/catch, where any value created
+   * in the try block could be aliased to the catch param
+   */
+  inferTryCatchAliases(ir, aliases);
+
+  /*
+   * Eagerly canonicalize so that if nothing changes we can bail out
+   * after a single iteration
+   */
+  let prevAliases: Map<Identifier, Identifier> = aliases.canonicalize();
+  while (true) {
+    // Infer mutable ranges for aliases that are not fields
+    inferMutableRangesForAlias(ir, aliases);
+
+    // Update aliasing information of fields
+    inferAliasForStores(ir, aliases);
+
+    // Update aliasing information of phis
+    inferAliasForPhis(ir, aliases);
+
+    const nextAliases = aliases.canonicalize();
+    if (areEqualMaps(prevAliases, nextAliases)) {
+      break;
+    }
+    prevAliases = nextAliases;
+  }
+
+  // Re-infer mutable ranges for all values
+  inferMutableLifetimes(ir, true);
+
+  /**
+   * The second inferMutableLifetimes() call updates mutable ranges
+   * of values to account for Store effects. Now we need to update
+   * all aliases of such values to extend their ranges as well. Note
+   * that the store only mutates the the directly aliased value and
+   * not any of its inner captured references. For example:
+   *
+   * ```
+   * let y;
+   * if (cond) {
+   *   y = [];
+   * } else {
+   *   y = [{}];
+   * }
+   * y.push(z);
+   * ```
+   *
+   * The Store effect from the `y.push` modifies the values that `y`
+   * directly aliases - the two arrays from the if/else branches -
+   * but does not modify values that `y` "contains" such as the
+   * object literal or `z`.
+   */
+  prevAliases = aliases.canonicalize();
+  while (true) {
+    inferMutableRangesForAlias(ir, aliases);
+    inferAliasForPhis(ir, aliases);
+    inferAliasForUncalledFunctions(ir, aliases);
+    const nextAliases = aliases.canonicalize();
+    if (areEqualMaps(prevAliases, nextAliases)) {
+      break;
+    }
+    prevAliases = nextAliases;
+  }
+}
+
+function areEqualMaps<T, U>(a: Map<T, U>, b: Map<T, U>): boolean {
+  if (a.size !== b.size) {
+    return false;
+  }
+  for (const [key, value] of a) {
+    if (!b.has(key)) {
+      return false;
+    }
+    if (b.get(key) !== value) {
+      return false;
+    }
+  }
+  return true;
+}

compiler/packages/babel-plugin-react-compiler/src/Inference/InferMutableRangesForAlias.ts

@@ -0,0 +1,54 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {
+  HIRFunction,
+  Identifier,
+  InstructionId,
+  isRefOrRefValue,
+} from '../HIR/HIR';
+import DisjointSet from '../Utils/DisjointSet';
+
+export function inferMutableRangesForAlias(
+  _fn: HIRFunction,
+  aliases: DisjointSet<Identifier>,
+): void {
+  const aliasSets = aliases.buildSets();
+  for (const aliasSet of aliasSets) {
+    /*
+     * Update mutableRange.end only if the identifiers have actually been
+     * mutated.
+     */
+    const mutatingIdentifiers = [...aliasSet].filter(
+      id =>
+        id.mutableRange.end - id.mutableRange.start > 1 && !isRefOrRefValue(id),
+    );
+
+    if (mutatingIdentifiers.length > 0) {
+      // Find final instruction which mutates this alias set.
+      let lastMutatingInstructionId = 0;
+      for (const id of mutatingIdentifiers) {
+        if (id.mutableRange.end > lastMutatingInstructionId) {
+          lastMutatingInstructionId = id.mutableRange.end;
+        }
+      }
+
+      /*
+       * Update mutableRange.end for all aliases in this set ending before the
+       * last mutation.
+       */
+      for (const alias of aliasSet) {
+        if (
+          alias.mutableRange.end < lastMutatingInstructionId &&
+          !isRefOrRefValue(alias)
+        ) {
+          alias.mutableRange.end = lastMutatingInstructionId as InstructionId;
+        }
+      }
+    }
+  }
+}

compiler/packages/babel-plugin-react-compiler/src/Inference/InferMutationAliasingEffects.ts

@@ -9,7 +9,6 @@ import {
   CompilerDiagnostic,
   CompilerError,
   Effect,
-  ErrorSeverity,
   SourceLocation,
   ValueKind,
 } from '..';
@@ -19,14 +18,13 @@ import {
   DeclarationId,
   Environment,
   FunctionExpression,
-  GeneratedSource,
   HIRFunction,
   Hole,
   IdentifierId,
   Instruction,
   InstructionKind,
+  InstructionValue,
   isArrayType,
-  isJsxType,
   isMapType,
   isPrimitiveType,
   isRefOrRefValue,
@@ -35,7 +33,6 @@ import {
   Phi,
   Place,
   SpreadPattern,
-  Type,
   ValueReason,
 } from '../HIR';
 import {
@@ -45,6 +42,12 @@ import {
   eachTerminalSuccessor,
 } from '../HIR/visitors';
 import {Ok, Result} from '../Utils/Result';
+import {
+  getArgumentEffect,
+  getFunctionCallSignature,
+  isKnownMutableEffect,
+  mergeValueKinds,
+} from './InferReferenceEffects';
 import {
   assertExhaustive,
   getOrInsertDefault,
@@ -56,19 +59,16 @@ import {
   printAliasingSignature,
   printIdentifier,
   printInstruction,
+  printInstructionValue,
   printPlace,
   printSourceLocation,
 } from '../HIR/PrintHIR';
 import {FunctionSignature} from '../HIR/ObjectShape';
+import {getWriteErrorReason} from './InferFunctionEffects';
 import prettyFormat from 'pretty-format';
 import {createTemporaryPlace} from '../HIR/HIRBuilder';
-import {
-  AliasingEffect,
-  AliasingSignature,
-  hashEffect,
-  MutationReason,
-} from './AliasingEffects';
-import {ErrorCategory} from '../CompilerError';
+import {AliasingEffect, AliasingSignature, hashEffect} from './AliasingEffects';
+import {ErrorCode, ErrorCodeDetails} from '../Utils/CompilerErrorCodes';
 
 const DEBUG = false;
 
@@ -106,11 +106,11 @@ export function inferMutationAliasingEffects(
   const statesByBlock: Map<BlockId, InferenceState> = new Map();
 
   for (const ref of fn.context) {
-    const value: AliasingEffect = {
-      kind: 'Create',
-      into: ref,
-      value: ValueKind.Context,
-      reason: ValueReason.Other,
+    // TODO: using InstructionValue as a bit of a hack, but it's pragmatic
+    const value: InstructionValue = {
+      kind: 'ObjectExpression',
+      properties: [],
+      loc: ref.loc,
     };
     initialState.initialize(value, {
       kind: ValueKind.Context,
@@ -143,11 +143,10 @@ export function inferMutationAliasingEffects(
     }
     if (ref != null) {
       const place = ref.kind === 'Identifier' ? ref : ref.place;
-      const value: AliasingEffect = {
-        kind: 'Create',
-        into: place,
-        value: ValueKind.Mutable,
-        reason: ValueReason.Other,
+      const value: InstructionValue = {
+        kind: 'ObjectExpression',
+        properties: [],
+        loc: place.loc,
       };
       initialState.initialize(value, {
         kind: ValueKind.Mutable,
@@ -264,6 +263,8 @@ function findHoistedContextDeclarations(
 class Context {
   internedEffects: Map<string, AliasingEffect> = new Map();
   instructionSignatureCache: Map<Instruction, InstructionSignature> = new Map();
+  effectInstructionValueCache: Map<AliasingEffect, InstructionValue> =
+    new Map();
   applySignatureCache: Map<
     AliasingSignature,
     Map<AliasingEffect, Array<AliasingEffect> | null>
@@ -315,11 +316,10 @@ function inferParam(
   paramKind: AbstractValue,
 ): void {
   const place = param.kind === 'Identifier' ? param : param.place;
-  const value: AliasingEffect = {
-    kind: 'Create',
-    into: place,
-    value: paramKind.kind,
-    reason: ValueReason.Other,
+  const value: InstructionValue = {
+    kind: 'Primitive',
+    loc: place.loc,
+    value: undefined,
   };
   initialState.initialize(value, paramKind);
   initialState.define(place, value);
@@ -442,38 +442,27 @@ function applySignature(
         const value = state.kind(effect.value);
         switch (value.kind) {
           case ValueKind.Frozen: {
-            const reason = getWriteErrorReason({
+            const errorCode = getWriteErrorReason({
               kind: value.kind,
               reason: value.reason,
+              context: new Set(),
             });
             const variable =
               effect.value.identifier.name !== null &&
               effect.value.identifier.name.kind === 'named'
                 ? `\`${effect.value.identifier.name.value}\``
                 : 'value';
-            const diagnostic = CompilerDiagnostic.create({
-              category: ErrorCategory.Immutability,
-              severity: ErrorSeverity.InvalidReact,
-              reason: 'This value cannot be modified',
-              description: `${reason}.`,
-            }).withDetail({
-              kind: 'error',
-              loc: effect.value.loc,
-              message: `${variable} cannot be modified`,
-            });
-            if (
-              effect.kind === 'Mutate' &&
-              effect.reason?.kind === 'AssignCurrentProperty'
-            ) {
-              diagnostic.withDetail({
-                kind: 'hint',
-                message: `Hint: If this value is a Ref (value returned by \`useRef()\`), rename the variable to end in "Ref".`,
-              });
-            }
             effects.push({
               kind: 'MutateFrozen',
               place: effect.value,
-              error: diagnostic,
+              // TODO: remove ERROR_CODE.INVALID_WRITE and update test fixtures
+              error: CompilerDiagnostic.fromCode(ErrorCode.INVALID_WRITE, {
+                description: ErrorCodeDetails[errorCode].reason,
+              }).withDetail({
+                kind: 'error',
+                loc: effect.value.loc,
+                message: `${variable} cannot be modified`,
+              }),
             });
           }
         }
@@ -540,11 +529,20 @@ function applyEffect(
       });
       initialized.add(effect.into.identifier.id);
 
-      state.initialize(effect, {
+      let value = context.effectInstructionValueCache.get(effect);
+      if (value == null) {
+        value = {
+          kind: 'ObjectExpression',
+          properties: [],
+          loc: effect.into.loc,
+        };
+        context.effectInstructionValueCache.set(effect, value);
+      }
+      state.initialize(value, {
         kind: effect.value,
         reason: new Set([effect.reason]),
       });
-      state.define(effect.into, effect);
+      state.define(effect.into, value);
       effects.push(effect);
       break;
     }
@@ -571,11 +569,20 @@ function applyEffect(
       initialized.add(effect.into.identifier.id);
 
       const fromValue = state.kind(effect.from);
-      state.initialize(effect, {
+      let value = context.effectInstructionValueCache.get(effect);
+      if (value == null) {
+        value = {
+          kind: 'ObjectExpression',
+          properties: [],
+          loc: effect.into.loc,
+        };
+        context.effectInstructionValueCache.set(effect, value);
+      }
+      state.initialize(value, {
         kind: fromValue.kind,
         reason: new Set(fromValue.reason),
       });
-      state.define(effect.into, effect);
+      state.define(effect.into, value);
       switch (fromValue.kind) {
         case ValueKind.Primitive:
         case ValueKind.Global: {
@@ -663,11 +670,11 @@ function applyEffect(
           operand.effect = Effect.Read;
         }
       }
-      state.initialize(effect, {
+      state.initialize(effect.function, {
         kind: isMutable ? ValueKind.Mutable : ValueKind.Frozen,
         reason: new Set([]),
       });
-      state.define(effect.into, effect);
+      state.define(effect.into, effect.function);
       for (const capture of effect.captures) {
         applyEffect(
           context,
@@ -773,20 +780,38 @@ function applyEffect(
             initialized,
             effects,
           );
-          state.initialize(effect, {
+          let value = context.effectInstructionValueCache.get(effect);
+          if (value == null) {
+            value = {
+              kind: 'Primitive',
+              value: undefined,
+              loc: effect.from.loc,
+            };
+            context.effectInstructionValueCache.set(effect, value);
+          }
+          state.initialize(value, {
             kind: fromKind,
             reason: new Set(fromValue.reason),
           });
-          state.define(effect.into, effect);
+          state.define(effect.into, value);
           break;
         }
         case ValueKind.Global:
         case ValueKind.Primitive: {
-          state.initialize(effect, {
+          let value = context.effectInstructionValueCache.get(effect);
+          if (value == null) {
+            value = {
+              kind: 'Primitive',
+              value: undefined,
+              loc: effect.from.loc,
+            };
+            context.effectInstructionValueCache.set(effect, value);
+          }
+          state.initialize(value, {
             kind: fromKind,
             reason: new Set(fromValue.reason),
           });
-          state.define(effect.into, effect);
+          state.define(effect.into, value);
           break;
         }
         default: {
@@ -801,15 +826,14 @@ function applyEffect(
       const functionValues = state.values(effect.function);
       if (
         functionValues.length === 1 &&
-        functionValues[0].kind === 'CreateFunction' &&
-        functionValues[0].function.kind === 'FunctionExpression' &&
-        functionValues[0].function.loweredFunc.func.aliasingEffects != null
+        functionValues[0].kind === 'FunctionExpression' &&
+        functionValues[0].loweredFunc.func.aliasingEffects != null
       ) {
         /*
          * We're calling a locally declared function, we already know it's effects!
          * We just have to substitute in the args for the params
          */
-        const functionExpr = functionValues[0].function;
+        const functionExpr = functionValues[0];
         let signature = context.functionSignatureCache.get(functionExpr);
         if (signature == null) {
           signature = buildSignatureFromFunctionExpression(
@@ -1001,23 +1025,20 @@ function applyEffect(
           const hoistedAccess = context.hoistedContextDeclarations.get(
             effect.value.identifier.declarationId,
           );
-          const diagnostic = CompilerDiagnostic.create({
-            category: ErrorCategory.Immutability,
-            severity: ErrorSeverity.InvalidReact,
-            reason: 'Cannot access variable before it is declared',
-            description: `${variable ?? 'This variable'} is accessed before it is declared, which prevents the earlier access from updating when this value changes over time.`,
-          });
+          const diagnostic = CompilerDiagnostic.fromCode(
+            ErrorCode.INVALID_ACCESS_BEFORE_INIT,
+          );
           if (hoistedAccess != null && hoistedAccess.loc != effect.value.loc) {
             diagnostic.withDetail({
               kind: 'error',
               loc: hoistedAccess.loc,
-              message: `${variable ?? 'variable'} accessed before it is declared`,
+              message: `${variable ?? 'This variable'} is accessed before it is declared`,
             });
           }
           diagnostic.withDetail({
             kind: 'error',
             loc: effect.value.loc,
-            message: `${variable ?? 'variable'} is declared here`,
+            message: `${variable ?? 'This variable'} is declared here`,
           });
 
           applyEffect(
@@ -1032,34 +1053,16 @@ function applyEffect(
             effects,
           );
         } else {
-          const reason = getWriteErrorReason({
+          const errorCode = getWriteErrorReason({
             kind: value.kind,
             reason: value.reason,
+            context: new Set(),
           });
           const variable =
             effect.value.identifier.name !== null &&
             effect.value.identifier.name.kind === 'named'
               ? `\`${effect.value.identifier.name.value}\``
               : 'value';
-          const diagnostic = CompilerDiagnostic.create({
-            category: ErrorCategory.Immutability,
-            severity: ErrorSeverity.InvalidReact,
-            reason: 'This value cannot be modified',
-            description: `${reason}.`,
-          }).withDetail({
-            kind: 'error',
-            loc: effect.value.loc,
-            message: `${variable} cannot be modified`,
-          });
-          if (
-            effect.kind === 'Mutate' &&
-            effect.reason?.kind === 'AssignCurrentProperty'
-          ) {
-            diagnostic.withDetail({
-              kind: 'hint',
-              message: `Hint: If this value is a Ref (value returned by \`useRef()\`), rename the variable to end in "Ref".`,
-            });
-          }
           applyEffect(
             context,
             state,
@@ -1069,7 +1072,14 @@ function applyEffect(
                   ? 'MutateFrozen'
                   : 'MutateGlobal',
               place: effect.value,
-              error: diagnostic,
+              // TODO: remove ERROR_CODE.INVALID_WRITE and update test fixtures
+              error: CompilerDiagnostic.fromCode(ErrorCode.INVALID_WRITE, {
+                description: ErrorCodeDetails[errorCode].reason,
+              }).withDetail({
+                kind: 'error',
+                loc: effect.value.loc,
+                message: `${variable} cannot be modified`,
+              }),
             },
             initialized,
             effects,
@@ -1099,19 +1109,19 @@ class InferenceState {
   #isFunctionExpression: boolean;
 
   // The kind of each value, based on its allocation site
-  #values: Map<AliasingEffect, AbstractValue>;
+  #values: Map<InstructionValue, AbstractValue>;
   /*
    * The set of values pointed to by each identifier. This is a set
    * to accomodate phi points (where a variable may have different
    * values from different control flow paths).
    */
-  #variables: Map<IdentifierId, Set<AliasingEffect>>;
+  #variables: Map<IdentifierId, Set<InstructionValue>>;
 
   constructor(
     env: Environment,
     isFunctionExpression: boolean,
-    values: Map<AliasingEffect, AbstractValue>,
-    variables: Map<IdentifierId, Set<AliasingEffect>>,
+    values: Map<InstructionValue, AbstractValue>,
+    variables: Map<IdentifierId, Set<InstructionValue>>,
   ) {
     this.env = env;
     this.#isFunctionExpression = isFunctionExpression;
@@ -1131,11 +1141,18 @@ class InferenceState {
   }
 
   // (Re)initializes a @param value with its default @param kind.
-  initialize(value: AliasingEffect, kind: AbstractValue): void {
+  initialize(value: InstructionValue, kind: AbstractValue): void {
+    CompilerError.invariant(value.kind !== 'LoadLocal', {
+      reason:
+        '[InferMutationAliasingEffects] Expected all top-level identifiers to be defined as variables, not values',
+      description: null,
+      loc: value.loc,
+      suggestions: null,
+    });
     this.#values.set(value, kind);
   }
 
-  values(place: Place): Array<AliasingEffect> {
+  values(place: Place): Array<InstructionValue> {
     const values = this.#variables.get(place.identifier.id);
     CompilerError.invariant(values != null, {
       reason: `[InferMutationAliasingEffects] Expected value kind to be initialized`,
@@ -1198,13 +1215,13 @@ class InferenceState {
   }
 
   // Defines (initializing or updating) a variable with a specific kind of value.
-  define(place: Place, value: AliasingEffect): void {
+  define(place: Place, value: InstructionValue): void {
     CompilerError.invariant(this.#values.has(value), {
       reason: `[InferMutationAliasingEffects] Expected value to be initialized at '${printSourceLocation(
-        place.loc,
+        value.loc,
       )}'`,
-      description: printAliasingEffect(value),
-      loc: place.loc,
+      description: printInstructionValue(value),
+      loc: value.loc,
       suggestions: null,
     });
     this.#variables.set(place.identifier.id, new Set([value]));
@@ -1244,17 +1261,17 @@ class InferenceState {
     }
   }
 
-  freezeValue(value: AliasingEffect, reason: ValueReason): void {
+  freezeValue(value: InstructionValue, reason: ValueReason): void {
     this.#values.set(value, {
       kind: ValueKind.Frozen,
       reason: new Set([reason]),
     });
     if (
-      value.kind === 'CreateFunction' &&
+      value.kind === 'FunctionExpression' &&
       (this.env.config.enablePreserveExistingMemoizationGuarantees ||
         this.env.config.enableTransitivelyFreezeFunctionExpressions)
     ) {
-      for (const place of value.function.loweredFunc.func.context) {
+      for (const place of value.loweredFunc.func.context) {
         this.freeze(place, reason);
       }
     }
@@ -1329,8 +1346,8 @@ class InferenceState {
    * termination.
    */
   merge(other: InferenceState): InferenceState | null {
-    let nextValues: Map<AliasingEffect, AbstractValue> | null = null;
-    let nextVariables: Map<IdentifierId, Set<AliasingEffect>> | null = null;
+    let nextValues: Map<InstructionValue, AbstractValue> | null = null;
+    let nextVariables: Map<IdentifierId, Set<InstructionValue>> | null = null;
 
     for (const [id, thisValue] of this.#values) {
       const otherValue = other.#values.get(id);
@@ -1354,7 +1371,7 @@ class InferenceState {
     for (const [id, thisValues] of this.#variables) {
       const otherValues = other.#variables.get(id);
       if (otherValues !== undefined) {
-        let mergedValues: Set<AliasingEffect> | null = null;
+        let mergedValues: Set<InstructionValue> | null = null;
         for (const otherValue of otherValues) {
           if (!thisValues.has(otherValue)) {
             mergedValues = mergedValues ?? new Set(thisValues);
@@ -1407,8 +1424,8 @@ class InferenceState {
    */
   debug(): any {
     const result: any = {values: {}, variables: {}};
-    const objects: Map<AliasingEffect, number> = new Map();
-    function identify(value: AliasingEffect): number {
+    const objects: Map<InstructionValue, number> = new Map();
+    function identify(value: InstructionValue): number {
       let id = objects.get(value);
       if (id == null) {
         id = objects.size;
@@ -1420,7 +1437,7 @@ class InferenceState {
       const id = identify(value);
       result.values[id] = {
         abstract: this.debugAbstractValue(kind),
-        value: printAliasingEffect(value),
+        value: printInstructionValue(value),
       };
     }
     for (const [variable, values] of this.#variables) {
@@ -1437,7 +1454,7 @@ class InferenceState {
   }
 
   inferPhi(phi: Phi): void {
-    const values: Set<AliasingEffect> = new Set();
+    const values: Set<InstructionValue> = new Set();
     for (const [_, operand] of phi.operands) {
       const operandValues = this.#variables.get(operand.identifier.id);
       // This is a backedge that will be handled later by State.merge
@@ -1659,15 +1676,7 @@ function computeSignatureForInstruction(
     }
     case 'PropertyStore':
     case 'ComputedStore': {
-      const mutationReason: MutationReason | null =
-        value.kind === 'PropertyStore' && value.property === 'current'
-          ? {kind: 'AssignCurrentProperty'}
-          : null;
-      effects.push({
-        kind: 'Mutate',
-        value: value.object,
-        reason: mutationReason,
-      });
+      effects.push({kind: 'Mutate', value: value.object});
       effects.push({
         kind: 'Capture',
         from: value.value,
@@ -1828,23 +1837,6 @@ function computeSignatureForInstruction(
             });
           }
         }
-        for (const prop of value.props) {
-          if (
-            prop.kind === 'JsxAttribute' &&
-            prop.place.identifier.type.kind === 'Function' &&
-            (isJsxType(prop.place.identifier.type.return) ||
-              (prop.place.identifier.type.return.kind === 'Phi' &&
-                prop.place.identifier.type.return.operands.some(operand =>
-                  isJsxType(operand),
-                )))
-          ) {
-            // Any props which return jsx are assumed to be called during render
-            effects.push({
-              kind: 'Render',
-              place: prop.place,
-            });
-          }
-        }
       }
       break;
     }
@@ -2010,16 +2002,12 @@ function computeSignatureForInstruction(
       effects.push({
         kind: 'MutateGlobal',
         place: value.value,
-        error: CompilerDiagnostic.create({
-          category: ErrorCategory.Globals,
-          severity: ErrorSeverity.InvalidReact,
-          reason:
-            'Cannot reassign variables declared outside of the component/hook',
-          description: `Variable ${variable} is declared outside of the component/hook. Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)`,
-        }).withDetail({
+        error: CompilerDiagnostic.fromCode(
+          ErrorCode.INVALID_WRITE_GLOBAL,
+        ).withDetail({
           kind: 'error',
           loc: instr.loc,
-          message: `${variable} cannot be reassigned`,
+          message: `${variable} should not be reassigned`,
         }),
       });
       effects.push({kind: 'Assign', from: value.value, into: lvalue});
@@ -2110,20 +2098,16 @@ function computeEffectsForLegacySignature(
     effects.push({
       kind: 'Impure',
       place: receiver,
-      error: CompilerDiagnostic.create({
-        category: ErrorCategory.Purity,
-        severity: ErrorSeverity.InvalidReact,
-        reason: 'Cannot call impure function during render',
-        description:
-          (signature.canonicalName != null
-            ? `\`${signature.canonicalName}\` is an impure function. `
-            : '') +
-          'Calling an impure function can produce unstable results that update unpredictably when the component happens to re-render. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#components-and-hooks-must-be-idempotent)',
-      }).withDetail({
-        kind: 'error',
-        loc,
-        message: 'Cannot call impure function',
-      }),
+      error: CompilerDiagnostic.fromCode(ErrorCode.IMPURE_FUNCTIONS).withDetail(
+        {
+          kind: 'error',
+          loc,
+          message:
+            signature.canonicalName != null
+              ? `\`${signature.canonicalName}\` is an impure function. `
+              : 'This is an impure function.',
+        },
+      ),
     });
   }
   const stores: Array<Place> = [];
@@ -2303,9 +2287,8 @@ function areArgumentsImmutableAndNonMutating(
     const values = state.values(place);
     for (const value of values) {
       if (
-        value.kind === 'CreateFunction' &&
-        value.function.kind === 'FunctionExpression' &&
-        value.function.loweredFunc.func.params.some(param => {
+        value.kind === 'FunctionExpression' &&
+        value.loweredFunc.func.params.some(param => {
           const place = param.kind === 'Identifier' ? param : param.place;
           const range = place.identifier.mutableRange;
           return range.end > range.start + 1;
@@ -2498,47 +2481,10 @@ function computeEffectsForSignature(
         break;
       }
       case 'CreateFunction': {
-        const applyInto = substitutions.get(effect.into.identifier.id);
-        if (applyInto == null || applyInto.length !== 1) {
-          return null;
-        }
-        const captures: Array<Place> = [];
-        for (let i = 0; i < effect.captures.length; i++) {
-          const substitution = substitutions.get(
-            effect.captures[i].identifier.id,
-          );
-          if (substitution == null || substitution.length !== 1) {
-            return null;
-          }
-          captures.push(substitution[0]);
-        }
-        const context: Array<Place> = [];
-        const originalContext = effect.function.loweredFunc.func.context;
-        for (let i = 0; i < originalContext.length; i++) {
-          const substitution = substitutions.get(
-            originalContext[i].identifier.id,
-          );
-          if (substitution == null || substitution.length !== 1) {
-            return null;
-          }
-          context.push(substitution[0]);
-        }
-        effects.push({
-          kind: 'CreateFunction',
-          into: applyInto[0],
-          function: {
-            ...effect.function,
-            loweredFunc: {
-              ...effect.function.loweredFunc,
-              func: {
-                ...effect.function.loweredFunc.func,
-                context,
-              },
-            },
-          },
-          captures,
+        CompilerError.throwTodo({
+          reason: `Support CreateFrom effects in signatures`,
+          loc: receiver.loc,
         });
-        break;
       }
       default: {
         assertExhaustive(
@@ -2578,196 +2524,3 @@ export type AbstractValue = {
   kind: ValueKind;
   reason: ReadonlySet<ValueReason>;
 };
-
-export function getWriteErrorReason(abstractValue: AbstractValue): string {
-  if (abstractValue.reason.has(ValueReason.Global)) {
-    return 'Modifying a variable defined outside a component or hook is not allowed. Consider using an effect';
-  } else if (abstractValue.reason.has(ValueReason.JsxCaptured)) {
-    return 'Modifying a value used previously in JSX is not allowed. Consider moving the modification before the JSX';
-  } else if (abstractValue.reason.has(ValueReason.Context)) {
-    return `Modifying a value returned from 'useContext()' is not allowed.`;
-  } else if (abstractValue.reason.has(ValueReason.KnownReturnSignature)) {
-    return 'Modifying a value returned from a function whose return value should not be mutated';
-  } else if (abstractValue.reason.has(ValueReason.ReactiveFunctionArgument)) {
-    return 'Modifying component props or hook arguments is not allowed. Consider using a local variable instead';
-  } else if (abstractValue.reason.has(ValueReason.State)) {
-    return "Modifying a value returned from 'useState()', which should not be modified directly. Use the setter function to update instead";
-  } else if (abstractValue.reason.has(ValueReason.ReducerState)) {
-    return "Modifying a value returned from 'useReducer()', which should not be modified directly. Use the dispatch function to update instead";
-  } else if (abstractValue.reason.has(ValueReason.Effect)) {
-    return 'Modifying a value used previously in an effect function or as an effect dependency is not allowed. Consider moving the modification before calling useEffect()';
-  } else if (abstractValue.reason.has(ValueReason.HookCaptured)) {
-    return 'Modifying a value previously passed as an argument to a hook is not allowed. Consider moving the modification before calling the hook';
-  } else if (abstractValue.reason.has(ValueReason.HookReturn)) {
-    return 'Modifying a value returned from a hook is not allowed. Consider moving the modification into the hook where the value is constructed';
-  } else {
-    return 'This modifies a variable that React considers immutable';
-  }
-}
-
-function getArgumentEffect(
-  signatureEffect: Effect | null,
-  arg: Place | SpreadPattern,
-): Effect {
-  if (signatureEffect != null) {
-    if (arg.kind === 'Identifier') {
-      return signatureEffect;
-    } else if (
-      signatureEffect === Effect.Mutate ||
-      signatureEffect === Effect.ConditionallyMutate
-    ) {
-      return signatureEffect;
-    } else {
-      // see call-spread-argument-mutable-iterator test fixture
-      if (signatureEffect === Effect.Freeze) {
-        CompilerError.throwTodo({
-          reason: 'Support spread syntax for hook arguments',
-          loc: arg.place.loc,
-        });
-      }
-      // effects[i] is Effect.Capture | Effect.Read | Effect.Store
-      return Effect.ConditionallyMutateIterator;
-    }
-  } else {
-    return Effect.ConditionallyMutate;
-  }
-}
-
-export function getFunctionCallSignature(
-  env: Environment,
-  type: Type,
-): FunctionSignature | null {
-  if (type.kind !== 'Function') {
-    return null;
-  }
-  return env.getFunctionSignature(type);
-}
-
-export function isKnownMutableEffect(effect: Effect): boolean {
-  switch (effect) {
-    case Effect.Store:
-    case Effect.ConditionallyMutate:
-    case Effect.ConditionallyMutateIterator:
-    case Effect.Mutate: {
-      return true;
-    }
-
-    case Effect.Unknown: {
-      CompilerError.invariant(false, {
-        reason: 'Unexpected unknown effect',
-        description: null,
-        loc: GeneratedSource,
-        suggestions: null,
-      });
-    }
-    case Effect.Read:
-    case Effect.Capture:
-    case Effect.Freeze: {
-      return false;
-    }
-    default: {
-      assertExhaustive(effect, `Unexpected effect \`${effect}\``);
-    }
-  }
-}
-
-/**
- * Joins two values using the following rules:
- * == Effect Transitions ==
- *
- * Freezing an immutable value has not effect:
- *                ┌───────────────┐
- *                │               │
- *                ▼               │ Freeze
- * ┌──────────────────────────┐  │
- * │        Immutable         │──┘
- * └──────────────────────────┘
- *
- * Freezing a mutable or maybe-frozen value makes it frozen. Freezing a frozen
- * value has no effect:
- *                                                     ┌───────────────┐
- * ┌─────────────────────────┐     Freeze             │               │
- * │       MaybeFrozen       │────┐                   ▼               │ Freeze
- * └─────────────────────────┘    │     ┌──────────────────────────┐  │
- *                                 ├────▶│          Frozen          │──┘
- *                                 │     └──────────────────────────┘
- * ┌─────────────────────────┐    │
- * │         Mutable         │────┘
- * └─────────────────────────┘
- *
- * == Join Lattice ==
- * - immutable | mutable => mutable
- *     The justification is that immutable and mutable values are different types,
- *     and functions can introspect them to tell the difference (if the argument
- *     is null return early, else if its an object mutate it).
- * - frozen | mutable => maybe-frozen
- *     Frozen values are indistinguishable from mutable values at runtime, so callers
- *     cannot dynamically avoid mutation of "frozen" values. If a value could be
- *     frozen we have to distinguish it from a mutable value. But it also isn't known
- *     frozen yet, so we distinguish as maybe-frozen.
- * - immutable | frozen => frozen
- *     This is subtle and falls out of the above rules. If a value could be any of
- *     immutable, mutable, or frozen, then at runtime it could either be a primitive
- *     or a reference type, and callers can't distinguish frozen or not for reference
- *     types. To ensure that any sequence of joins btw those three states yields the
- *     correct maybe-frozen, these two have to produce a frozen value.
- * - <any> | maybe-frozen => maybe-frozen
- * - immutable | context => context
- * - mutable | context => context
- * - frozen | context => maybe-frozen
- *
- * ┌──────────────────────────┐
- * │        Immutable         │───┐
- * └──────────────────────────┘   │
- *                                 │    ┌─────────────────────────┐
- *                                 ├───▶│         Frozen          │──┐
- * ┌──────────────────────────┐   │    └─────────────────────────┘  │
- * │          Frozen          │───┤                                 │  ┌─────────────────────────┐
- * └──────────────────────────┘   │                                 ├─▶│       MaybeFrozen       │
- *                                 │    ┌─────────────────────────┐  │  └─────────────────────────┘
- *                                 ├───▶│       MaybeFrozen       │──┘
- * ┌──────────────────────────┐   │    └─────────────────────────┘
- * │         Mutable          │───┘
- * └──────────────────────────┘
- */
-function mergeValueKinds(a: ValueKind, b: ValueKind): ValueKind {
-  if (a === b) {
-    return a;
-  } else if (a === ValueKind.MaybeFrozen || b === ValueKind.MaybeFrozen) {
-    return ValueKind.MaybeFrozen;
-    // after this a and b differ and neither are MaybeFrozen
-  } else if (a === ValueKind.Mutable || b === ValueKind.Mutable) {
-    if (a === ValueKind.Frozen || b === ValueKind.Frozen) {
-      // frozen | mutable
-      return ValueKind.MaybeFrozen;
-    } else if (a === ValueKind.Context || b === ValueKind.Context) {
-      // context | mutable
-      return ValueKind.Context;
-    } else {
-      // mutable | immutable
-      return ValueKind.Mutable;
-    }
-  } else if (a === ValueKind.Context || b === ValueKind.Context) {
-    if (a === ValueKind.Frozen || b === ValueKind.Frozen) {
-      // frozen | context
-      return ValueKind.MaybeFrozen;
-    } else {
-      // context | immutable
-      return ValueKind.Context;
-    }
-  } else if (a === ValueKind.Frozen || b === ValueKind.Frozen) {
-    return ValueKind.Frozen;
-  } else if (a === ValueKind.Global || b === ValueKind.Global) {
-    return ValueKind.Global;
-  } else {
-    CompilerError.invariant(
-      a === ValueKind.Primitive && b == ValueKind.Primitive,
-      {
-        reason: `Unexpected value kind in mergeValues()`,
-        description: `Found kinds ${a} and ${b}`,
-        loc: GeneratedSource,
-      },
-    );
-    return ValueKind.Primitive;
-  }
-}

compiler/packages/babel-plugin-react-compiler/src/Inference/InferMutationAliasingRanges.ts

@@ -27,7 +27,7 @@ import {
 } from '../HIR/visitors';
 import {assertExhaustive, getOrInsertWith} from '../Utils/utils';
 import {Err, Ok, Result} from '../Utils/Result';
-import {AliasingEffect, MutationReason} from './AliasingEffects';
+import {AliasingEffect} from './AliasingEffects';
 
 /**
  * This pass builds an abstract model of the heap and interprets the effects of the
@@ -101,7 +101,6 @@ export function inferMutationAliasingRanges(
     transitive: boolean;
     kind: MutationKind;
     place: Place;
-    reason: MutationReason | null;
   }> = [];
   const renders: Array<{index: number; place: Place}> = [];
 
@@ -141,7 +140,7 @@ export function inferMutationAliasingRanges(
         } else if (effect.kind === 'CreateFunction') {
           state.create(effect.into, {
             kind: 'Function',
-            effect,
+            function: effect.function.loweredFunc.func,
           });
         } else if (effect.kind === 'CreateFrom') {
           state.createFrom(index++, effect.from, effect.into);
@@ -156,7 +155,7 @@ export function inferMutationAliasingRanges(
            * invariant here.
            */
           if (!state.nodes.has(effect.into.identifier)) {
-            state.create(effect.into, {kind: 'Assign'});
+            state.create(effect.into, {kind: 'Object'});
           }
           state.assign(index++, effect.from, effect.into);
         } else if (effect.kind === 'Alias') {
@@ -177,7 +176,6 @@ export function inferMutationAliasingRanges(
               effect.kind === 'MutateTransitive'
                 ? MutationKind.Definite
                 : MutationKind.Conditional,
-            reason: null,
             place: effect.value,
           });
         } else if (
@@ -192,7 +190,6 @@ export function inferMutationAliasingRanges(
               effect.kind === 'Mutate'
                 ? MutationKind.Definite
                 : MutationKind.Conditional,
-            reason: effect.kind === 'Mutate' ? (effect.reason ?? null) : null,
             place: effect.value,
           });
         } else if (
@@ -244,7 +241,6 @@ export function inferMutationAliasingRanges(
       mutation.transitive,
       mutation.kind,
       mutation.place.loc,
-      mutation.reason,
       errors,
     );
   }
@@ -271,7 +267,6 @@ export function inferMutationAliasingRanges(
         functionEffects.push({
           kind: 'Mutate',
           value: {...place, loc: node.local.loc},
-          reason: node.mutationReason,
         });
       }
     }
@@ -474,99 +469,6 @@ export function inferMutationAliasingRanges(
     }
   }
 
-  const tracked: Array<Place> = [];
-  for (const param of [...fn.params, ...fn.context, fn.returns]) {
-    const place = param.kind === 'Identifier' ? param : param.place;
-    tracked.push(place);
-  }
-
-  const returned: Set<Node> = new Set();
-  const queue: Array<Node> = [state.nodes.get(fn.returns.identifier)!];
-  const seen: Set<Node> = new Set();
-  while (queue.length !== 0) {
-    const node = queue.pop()!;
-    if (seen.has(node)) {
-      continue;
-    }
-    seen.add(node);
-    for (const id of node.aliases.keys()) {
-      queue.push(state.nodes.get(id)!);
-    }
-    for (const id of node.createdFrom.keys()) {
-      queue.push(state.nodes.get(id)!);
-    }
-    if (node.id.id === fn.returns.identifier.id) {
-      continue;
-    }
-    switch (node.value.kind) {
-      case 'Assign':
-      case 'CreateFrom': {
-        break;
-      }
-      case 'Phi':
-      case 'Object':
-      case 'Function': {
-        returned.add(node);
-        break;
-      }
-      default: {
-        assertExhaustive(
-          node.value,
-          `Unexpected node value kind '${(node.value as any).kind}'`,
-        );
-      }
-    }
-  }
-  const returnedValues = [...returned];
-  if (
-    returnedValues.length === 1 &&
-    returnedValues[0].value.kind === 'Object' &&
-    tracked.some(place => place.identifier.id === returnedValues[0].id.id)
-  ) {
-    const from = tracked.find(
-      place => place.identifier.id === returnedValues[0].id.id,
-    )!;
-    functionEffects.push({
-      kind: 'Assign',
-      from,
-      into: fn.returns,
-    });
-  } else if (
-    returnedValues.length === 1 &&
-    returnedValues[0].value.kind === 'Function'
-  ) {
-    const outerContext = new Set(fn.context.map(p => p.identifier.id));
-    const effect = returnedValues[0].value.effect;
-    functionEffects.push({
-      kind: 'CreateFunction',
-      function: {
-        ...effect.function,
-        loweredFunc: {
-          func: {
-            ...effect.function.loweredFunc.func,
-            context: effect.function.loweredFunc.func.context.filter(p =>
-              outerContext.has(p.identifier.id),
-            ),
-          },
-        },
-      },
-      captures: effect.captures.filter(p => outerContext.has(p.identifier.id)),
-      into: fn.returns,
-    });
-  } else {
-    const returns = fn.returns.identifier;
-    functionEffects.push({
-      kind: 'Create',
-      into: fn.returns,
-      value: isPrimitiveType(returns)
-        ? ValueKind.Primitive
-        : isJsxType(returns.type)
-          ? ValueKind.Frozen
-          : ValueKind.Mutable,
-      reason: ValueReason.KnownReturnSignature,
-    });
-  }
-
   /**
    * Part 3
    * Finish populating the externally visible effects. Above we bubble-up the side effects
@@ -574,12 +476,28 @@ export function inferMutationAliasingRanges(
    * Here we populate an effect to create the return value as well as populating alias/capture
    * effects for how data flows between the params, context vars, and return.
    */
+  const returns = fn.returns.identifier;
+  functionEffects.push({
+    kind: 'Create',
+    into: fn.returns,
+    value: isPrimitiveType(returns)
+      ? ValueKind.Primitive
+      : isJsxType(returns.type)
+        ? ValueKind.Frozen
+        : ValueKind.Mutable,
+    reason: ValueReason.KnownReturnSignature,
+  });
   /**
    * Determine precise data-flow effects by simulating transitive mutations of the params/
    * captures and seeing what other params/context variables are affected. Anything that
    * would be transitively mutated needs a capture relationship.
    */
+  const tracked: Array<Place> = [];
   const ignoredErrors = new CompilerError();
+  for (const param of [...fn.params, ...fn.context, fn.returns]) {
+    const place = param.kind === 'Identifier' ? param : param.place;
+    tracked.push(place);
+  }
   for (const into of tracked) {
     const mutationIndex = index++;
     state.mutate(
@@ -589,7 +507,6 @@ export function inferMutationAliasingRanges(
       true,
       MutationKind.Conditional,
       into.loc,
-      null,
       ignoredErrors,
     );
     for (const from of tracked) {
@@ -663,16 +580,10 @@ type Node = {
   transitive: {kind: MutationKind; loc: SourceLocation} | null;
   local: {kind: MutationKind; loc: SourceLocation} | null;
   lastMutated: number;
-  mutationReason: MutationReason | null;
   value:
-    | {kind: 'Assign'}
-    | {kind: 'CreateFrom'}
     | {kind: 'Object'}
     | {kind: 'Phi'}
-    | {
-        kind: 'Function';
-        effect: Extract<AliasingEffect, {kind: 'CreateFunction'}>;
-      };
+    | {kind: 'Function'; function: HIRFunction};
 };
 class AliasingState {
   nodes: Map<Identifier, Node> = new Map();
@@ -688,13 +599,12 @@ class AliasingState {
       transitive: null,
       local: null,
       lastMutated: 0,
-      mutationReason: null,
       value,
     });
   }
 
   createFrom(index: number, from: Place, into: Place): void {
-    this.create(into, {kind: 'CreateFrom'});
+    this.create(into, {kind: 'Object'});
     const fromNode = this.nodes.get(from.identifier);
     const toNode = this.nodes.get(into.identifier);
     if (fromNode == null || toNode == null) {
@@ -756,10 +666,7 @@ class AliasingState {
         continue;
       }
       if (node.value.kind === 'Function') {
-        appendFunctionErrors(
-          errors,
-          node.value.effect.function.loweredFunc.func,
-        );
+        appendFunctionErrors(errors, node.value.function);
       }
       for (const [alias, when] of node.createdFrom) {
         if (when >= index) {
@@ -790,7 +697,6 @@ class AliasingState {
     transitive: boolean,
     startKind: MutationKind,
     loc: SourceLocation,
-    reason: MutationReason | null,
     errors: CompilerError,
   ): void {
     const seen = new Map<Identifier, MutationKind>();
@@ -811,7 +717,6 @@ class AliasingState {
       if (node == null) {
         continue;
       }
-      node.mutationReason ??= reason;
       node.lastMutated = Math.max(node.lastMutated, index);
       if (end != null) {
         node.id.mutableRange.end = makeInstructionId(
@@ -823,10 +728,7 @@ class AliasingState {
         node.transitive == null &&
         node.local == null
       ) {
-        appendFunctionErrors(
-          errors,
-          node.value.effect.function.loweredFunc.func,
-        );
+        appendFunctionErrors(errors, node.value.function);
       }
       if (transitive) {
         if (node.transitive == null || node.transitive.kind < kind) {

compiler/packages/babel-plugin-react-compiler/src/Inference/InferTryCatchAliases.ts

@@ -0,0 +1,49 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {BlockId, HIRFunction, Identifier} from '../HIR';
+import DisjointSet from '../Utils/DisjointSet';
+
+/*
+ * Any values created within a try/catch block could be aliased to the try handler.
+ * Our lowering ensures that every instruction within a try block will be lowered into a
+ * basic block ending in a maybe-throw terminal that points to its catch block, so we can
+ * iterate such blocks and alias their instruction lvalues to the handler's param (if present).
+ */
+export function inferTryCatchAliases(
+  fn: HIRFunction,
+  aliases: DisjointSet<Identifier>,
+): void {
+  const handlerParams: Map<BlockId, Identifier> = new Map();
+  for (const [_, block] of fn.body.blocks) {
+    if (
+      block.terminal.kind === 'try' &&
+      block.terminal.handlerBinding !== null
+    ) {
+      handlerParams.set(
+        block.terminal.handler,
+        block.terminal.handlerBinding.identifier,
+      );
+    } else if (block.terminal.kind === 'maybe-throw') {
+      const handlerParam = handlerParams.get(block.terminal.handler);
+      if (handlerParam === undefined) {
+        /*
+         * There's no catch clause param, nothing to alias to so
+         * skip this block
+         */
+        continue;
+      }
+      /*
+       * Otherwise alias all values created in this block to the
+       * catch clause param
+       */
+      for (const instr of block.instructions) {
+        aliases.union([handlerParam, instr.lvalue.identifier]);
+      }
+    }
+  }
+}

compiler/packages/babel-plugin-react-compiler/src/Inference/index.ts

@@ -7,6 +7,8 @@
 
 export {default as analyseFunctions} from './AnalyseFunctions';
 export {dropManualMemoization} from './DropManualMemoization';
+export {inferMutableRanges} from './InferMutableRanges';
 export {inferReactivePlaces} from './InferReactivePlaces';
+export {default as inferReferenceEffects} from './InferReferenceEffects';
 export {inlineImmediatelyInvokedFunctionExpressions} from './InlineImmediatelyInvokedFunctionExpressions';
 export {inferEffectDependencies} from './InferEffectDependencies';

compiler/packages/babel-plugin-react-compiler/src/Optimization/InlineJsxTransform.ts

@@ -42,7 +42,6 @@ import {
   mapInstructionValueOperands,
   mapTerminalOperands,
 } from '../HIR/visitors';
-import {ErrorCategory} from '../CompilerError';
 
 type InlinedJsxDeclarationMap = Map<
   DeclarationId,
@@ -84,7 +83,6 @@ export function inlineJsxTransform(
           kind: 'CompileDiagnostic',
           fnLoc: null,
           detail: {
-            category: ErrorCategory.Todo,
             reason: 'JSX Inlining is not supported on value blocks',
             loc: instr.loc,
           },

compiler/packages/babel-plugin-react-compiler/src/Optimization/LowerContextAccess.ts

@@ -255,6 +255,7 @@ function emitSelectorFn(env: Environment, keys: Array<string>): Instruction {
     returnTypeAnnotation: null,
     returns: createTemporaryPlace(env, GeneratedSource),
     context: [],
+    effects: null,
     body: {
       entry: block.id,
       blocks: new Map([[block.id, block]]),
@@ -262,7 +263,6 @@ function emitSelectorFn(env: Environment, keys: Array<string>): Instruction {
     generator: false,
     async: false,
     directives: [],
-    aliasingEffects: [],
   };
 
   reversePostorderBlocks(fn.body);

compiler/packages/babel-plugin-react-compiler/src/Optimization/OutlineJsx.ts

@@ -370,6 +370,7 @@ function emitOutlinedFn(
     returnTypeAnnotation: null,
     returns: createTemporaryPlace(env, GeneratedSource),
     context: [],
+    effects: null,
     body: {
       entry: block.id,
       blocks: new Map([[block.id, block]]),
@@ -377,7 +378,6 @@ function emitOutlinedFn(
     generator: false,
     async: false,
     directives: [],
-    aliasingEffects: [],
   };
   return fn;
 }

compiler/packages/babel-plugin-react-compiler/src/ReactiveScopes/CodegenReactiveFunction.ts

@@ -13,7 +13,7 @@ import {
   pruneUnusedLabels,
   renameVariables,
 } from '.';
-import {CompilerError, ErrorCategory, ErrorSeverity} from '../CompilerError';
+import {CompilerError, ErrorSeverity} from '../CompilerError';
 import {Environment, ExternalFunction} from '../HIR';
 import {
   ArrayPattern,
@@ -2185,7 +2185,6 @@ function codegenInstructionValue(
                 (declarator.id as t.Identifier).name
               }'`,
               severity: ErrorSeverity.Todo,
-              category: ErrorCategory.Todo,
               loc: declarator.loc ?? null,
               suggestions: null,
             });
@@ -2194,7 +2193,6 @@ function codegenInstructionValue(
             cx.errors.push({
               reason: `(CodegenReactiveFunction::codegenInstructionValue) Handle conversion of ${stmt.type} to expression`,
               severity: ErrorSeverity.Todo,
-              category: ErrorCategory.Todo,
               loc: stmt.loc ?? null,
               suggestions: null,
             });

compiler/packages/babel-plugin-react-compiler/src/ReactiveScopes/PruneNonEscapingScopes.ts

@@ -24,6 +24,7 @@ import {
   getHookKind,
   isMutableEffect,
 } from '../HIR';
+import {getFunctionCallSignature} from '../Inference/InferReferenceEffects';
 import {assertExhaustive, getOrInsertDefault} from '../Utils/utils';
 import {getPlaceScope, ReactiveScope} from '../HIR/HIR';
 import {
@@ -34,7 +35,6 @@ import {
   visitReactiveFunction,
 } from './visitors';
 import {printPlace} from '../HIR/PrintHIR';
-import {getFunctionCallSignature} from '../Inference/InferMutationAliasingEffects';
 
 /*
  * This pass prunes reactive scopes that are not necessary to bound downstream computation.

compiler/packages/babel-plugin-react-compiler/src/Transform/TransformFire.ts

@@ -42,7 +42,7 @@ import {
 import {eachInstructionOperand} from '../HIR/visitors';
 import {printSourceLocationLine} from '../HIR/PrintHIR';
 import {USE_FIRE_FUNCTION_NAME} from '../HIR/Environment';
-import {ErrorCategory} from '../CompilerError';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 
 /*
  * TODO(jmbrown):
@@ -51,8 +51,6 @@ import {ErrorCategory} from '../CompilerError';
  *   - React.useEffect calls
  */
 
-const CANNOT_COMPILE_FIRE = 'Cannot compile `fire`';
-
 export function transformFire(fn: HIRFunction): void {
   const context = new Context(fn.env);
   replaceFireFunctions(fn, context);
@@ -134,7 +132,6 @@ function replaceFireFunctions(fn: HIRFunction, context: Context): void {
                   loc: value.loc,
                   description: null,
                   severity: ErrorSeverity.Invariant,
-                  category: ErrorCategory.Invariant,
                   reason: '[InsertFire] No LoadGlobal found for useEffect call',
                   suggestions: null,
                 });
@@ -180,10 +177,7 @@ function replaceFireFunctions(fn: HIRFunction, context: Context): void {
                 loc: value.args[1].loc,
                 description:
                   'You must use an array literal for an effect dependency array when that effect uses `fire()`',
-                severity: ErrorSeverity.Invariant,
-                category: ErrorCategory.Fire,
-                reason: CANNOT_COMPILE_FIRE,
-                suggestions: null,
+                errorCode: ErrorCode.CANNOT_COMPILE_FIRE,
               });
             }
           } else if (value.args.length > 1 && value.args[1].kind === 'Spread') {
@@ -191,10 +185,7 @@ function replaceFireFunctions(fn: HIRFunction, context: Context): void {
               loc: value.args[1].place.loc,
               description:
                 'You must use an array literal for an effect dependency array when that effect uses `fire()`',
-              severity: ErrorSeverity.Invariant,
-              category: ErrorCategory.Fire,
-              reason: CANNOT_COMPILE_FIRE,
-              suggestions: null,
+              errorCode: ErrorCode.CANNOT_COMPILE_FIRE,
             });
           }
         }
@@ -227,7 +218,6 @@ function replaceFireFunctions(fn: HIRFunction, context: Context): void {
                 loc: value.loc,
                 description: null,
                 severity: ErrorSeverity.Invariant,
-                category: ErrorCategory.Invariant,
                 reason:
                   '[InsertFire] No loadLocal found for fire call argument',
                 suggestions: null,
@@ -248,12 +238,9 @@ function replaceFireFunctions(fn: HIRFunction, context: Context): void {
           } else {
             context.pushError({
               loc: value.loc,
+              errorCode: ErrorCode.CANNOT_COMPILE_FIRE,
               description:
                 '`fire()` can only receive a function call such as `fire(fn(a,b)). Method calls and other expressions are not allowed',
-              severity: ErrorSeverity.InvalidReact,
-              category: ErrorCategory.Fire,
-              reason: CANNOT_COMPILE_FIRE,
-              suggestions: null,
             });
           }
         } else {
@@ -268,11 +255,8 @@ function replaceFireFunctions(fn: HIRFunction, context: Context): void {
           }
           context.pushError({
             loc: value.loc,
+            errorCode: ErrorCode.CANNOT_COMPILE_FIRE,
             description,
-            severity: ErrorSeverity.InvalidReact,
-            category: ErrorCategory.Fire,
-            reason: CANNOT_COMPILE_FIRE,
-            suggestions: null,
           });
         }
       } else if (value.kind === 'CallExpression') {
@@ -401,10 +385,7 @@ function ensureNoRemainingCalleeCaptures(
         description: `All uses of ${calleeName} must be either used with a fire() call in \
 this effect or not used with a fire() call at all. ${calleeName} was used with fire() on line \
 ${printSourceLocationLine(calleeInfo.fireLoc)} in this effect`,
-        severity: ErrorSeverity.InvalidReact,
-        category: ErrorCategory.Fire,
-        reason: CANNOT_COMPILE_FIRE,
-        suggestions: null,
+        errorCode: ErrorCode.CANNOT_COMPILE_FIRE,
       });
     }
   }
@@ -419,10 +400,7 @@ function ensureNoMoreFireUses(fn: HIRFunction, context: Context): void {
       context.pushError({
         loc: place.identifier.loc,
         description: 'Cannot use `fire` outside of a useEffect function',
-        category: ErrorCategory.Fire,
-        severity: ErrorSeverity.Invariant,
-        reason: CANNOT_COMPILE_FIRE,
-        suggestions: null,
+        errorCode: ErrorCode.CANNOT_COMPILE_FIRE,
       });
     }
   }

compiler/packages/babel-plugin-react-compiler/src/TypeInference/InferTypes.ts

@@ -777,15 +777,6 @@ class Unifier {
       return {kind: 'Phi', operands: type.operands.map(o => this.get(o))};
     }
 
-    if (type.kind === 'Function') {
-      return {
-        kind: 'Function',
-        isConstructor: type.isConstructor,
-        shapeId: type.shapeId,
-        return: this.get(type.return),
-      };
-    }
-
     return type;
   }
 }

compiler/packages/babel-plugin-react-compiler/src/Utils/CompilerErrorCodes.ts

@@ -0,0 +1,624 @@
+import {ErrorSeverity} from './CompilerErrorSeverity';
+
+export enum LinterCategory {
+  RULES_OF_HOOKS = 'rules-of-hooks',
+  IMPURE_FUNCTIONS = 'impure-functions',
+  JSX_IN_TRY = 'jsx-in-try',
+  NO_REF_ACCESS_IN_RENDER = 'no-ref-access-in-render',
+  VALIDATE_MANUAL_MEMO = 'validate-manual-memo',
+  DYNAMIC_MANUAL_MEMO = 'dynamic-manual-memo',
+
+  EXHAUSTIVE_DEPS = 'exhaustive-deps',
+  MEMOIZED_DEPENDENCIES = 'memoized-dependencies', // not real!
+  INVALID_WRITE = 'invalid-write',
+  CAPITALIZED_CALLS = 'capitalized-calls',
+  STATIC_COMPONENTS = 'static-components',
+  NO_SET_STATE_IN_RENDER = 'no-set-state-in-render',
+  NO_SET_STATE_IN_EFFECTS = 'no-set-state-in-effects',
+  UNNECESSARY_EFFECTS = 'unnecessary-effects',
+
+  UNSUPPORTED_SYNTAX = 'unsupported-syntax',
+
+  TODO_SYNTAX = 'todo-syntax',
+
+  COMPILER_CONFIG = 'compiler-config',
+}
+
+export enum ErrorCode {
+  HOOK_CALL_STATIC,
+  HOOK_INVALID_REFERENCE,
+  HOOK_CALL_REACTIVE,
+  HOOK_CALL_NOT_TOP_LEVEL,
+  IMPURE_FUNCTIONS,
+  JSX_IN_TRY,
+  NO_REF_ACCESS_IN_RENDER,
+  WRITE_AFTER_RENDER,
+  REASSIGN_AFTER_RENDER,
+  REASSIGN_IN_ASYNC,
+  INVALID_WRITE,
+  CAPITALIZED_CALLS,
+  STATIC_COMPONENTS,
+  INVALID_USE_MEMO_CALLBACK_RETURN,
+  INVALID_USE_MEMO_CALLBACK_PARAMETERS,
+  INVALID_USE_MEMO_CALLBACK_ASYNC,
+  INVALID_USE_MEMO_NO_ARG0,
+  INVALID_USE_CALLBACK_NO_ARG0,
+  DYNAMIC_MANUAL_MEMO_CALLBACK,
+  DYNAMIC_USE_MEMO_SPREAD_ARGUMENT,
+  DYNAMIC_USE_CALLBACK_SPREAD_ARGUMENT,
+  DYNAMIC_MANUAL_MEMO_DEPENDENCY_LIST,
+  COMPLEX_MANUAL_MEMO_DEPENDENCY_LIST_ENTRY,
+
+  INVALID_SET_STATE_IN_RENDER,
+  INVALID_SET_STATE_IN_MEMO,
+  INVALID_SET_STATE_IN_EFFECTS,
+
+  NO_DERIVED_COMPUTATIONS_IN_EFFECTS,
+
+  DYNAMIC_GATING_IS_NOT_IDENTIFIER,
+  DYNAMIC_GATING_MULTIPLE_DIRECTIVES,
+  FILENAME_NOT_SET,
+
+  INVALID_WRITE_GLOBAL,
+  INVALID_WRITE_FROZEN_VALUE_JSX,
+  INVALID_WRITE_IMMUTABLE_VALUE_USE_CONTEXT,
+  INVALID_WRITE_IMMUTABLE_VALUE_KNOWN_SIGNATURE,
+  INVALID_WRITE_IMMUTABLE_ARGS,
+  INVALID_WRITE_STATE,
+  INVALID_WRITE_REDUCER_STATE,
+  INVALID_WRITE_EFFECT_DEPENDENCY,
+  INVALID_WRITE_HOOK_CAPTURED,
+  INVALID_WRITE_HOOK_RETURN,
+  INVALID_ACCESS_BEFORE_INIT,
+  INVALID_WRITE_GENERIC,
+
+  MEMOIZED_EFFECT_DEPENDENCIES,
+
+  INVALID_SYNTAX_MULTIPLE_DEFAULTS,
+  INVALID_SYNTAX_REASSIGNED_CONST,
+  INVALID_SYNTAX_BAD_VARIABLE_DECL,
+  UNSUPPORTED_WITH,
+  UNSUPPORTED_INNER_CLASS,
+  INVALID_IMPORT_EXPORT,
+  INVALID_TS_NAMESPACE,
+  UNSUPPORTED_NEW_EXPRESSION,
+  UNSUPPORTED_EMPTY_SEQUENCE_EXPRESSION,
+  INVALID_QUASI_LENGTHS,
+  INVALID_SYNTAX_DELETE_EXPRESSION,
+  UNSUPPORTED_THROW_EXPRESSION,
+  INVALID_JSX_NAMESPACED_NAME,
+  UNSUPPORTED_EVAL,
+  INVALID_SYNTAX_RESERVED_VARIABLE_NAME,
+  INVALID_JAVASCRIPT_AST,
+  BAILOUT_ESLINT_SUPPRESSION,
+  BAILOUT_FLOW_SUPPRESSION,
+  MANUAL_MEMO_MUTATED_LATER,
+  MANUAL_MEMO_REMOVED,
+  MANUAL_MEMO_DEPENDENCIES_CONFLICT,
+
+  CANNOT_COMPILE_FIRE,
+  DID_NOT_INFER_DEPS,
+
+  /** Todo syntax */
+  TODO_CONFLICTING_FBT_IDENTIFIER,
+  TODO_DUPLICATE_FBT_TAGS,
+  UNKNOWN_FUNCTION_PARAMETERS,
+}
+
+type ErrorCodeType = {
+  code: ErrorCode;
+  description?: string;
+  severity: ErrorSeverity;
+  reason: string;
+  linterCategory: LinterCategory | null;
+};
+
+export const ErrorCodeDetails: Record<ErrorCode, ErrorCodeType> = {
+  [ErrorCode.HOOK_CALL_STATIC]: {
+    code: ErrorCode.HOOK_CALL_STATIC,
+    severity: ErrorSeverity.InvalidReact,
+    reason:
+      'Hooks must always be called in a consistent order, and may not be called conditionally. See the Rules of Hooks (https://react.dev/warnings/invalid-hook-call-warning)',
+    linterCategory: LinterCategory.RULES_OF_HOOKS,
+  },
+  [ErrorCode.HOOK_INVALID_REFERENCE]: {
+    code: ErrorCode.HOOK_INVALID_REFERENCE,
+    severity: ErrorSeverity.InvalidReact,
+    reason:
+      'Hooks may not be referenced as normal values, they must be called. See https://react.dev/reference/rules/react-calls-components-and-hooks#never-pass-around-hooks-as-regular-values',
+    linterCategory: LinterCategory.RULES_OF_HOOKS,
+  },
+  [ErrorCode.HOOK_CALL_REACTIVE]: {
+    code: ErrorCode.HOOK_CALL_REACTIVE,
+    severity: ErrorSeverity.InvalidReact,
+    reason:
+      'Hooks must be the same function on every render, but this value may change over time to a different function. See https://react.dev/reference/rules/react-calls-components-and-hooks#dont-dynamically-use-hooks',
+    linterCategory: LinterCategory.RULES_OF_HOOKS,
+  },
+  [ErrorCode.HOOK_CALL_NOT_TOP_LEVEL]: {
+    code: ErrorCode.HOOK_CALL_NOT_TOP_LEVEL,
+    severity: ErrorSeverity.InvalidReact,
+    reason:
+      'Hooks must be called at the top level in the body of a function component or custom hook, and may not be called within function expressions. See the Rules of Hooks (https://react.dev/warnings/invalid-hook-call-warning)',
+    linterCategory: LinterCategory.RULES_OF_HOOKS,
+  },
+  [ErrorCode.IMPURE_FUNCTIONS]: {
+    code: ErrorCode.IMPURE_FUNCTIONS,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'Cannot call impure functions during render',
+    description:
+      'Calling an impure function can produce unstable results that update unpredictably when the component happens to re-render. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#components-and-hooks-must-be-idempotent)',
+    linterCategory: LinterCategory.IMPURE_FUNCTIONS,
+  },
+  [ErrorCode.JSX_IN_TRY]: {
+    code: ErrorCode.JSX_IN_TRY,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'Avoid constructing JSX within try/catch',
+    description: `React does not immediately render components when JSX is rendered, so any errors from this component will not be caught by the try/catch. To catch errors in rendering a given component, wrap that component in an error boundary. (https://react.dev/reference/react/Component#catching-rendering-errors-with-an-error-boundary)`,
+    linterCategory: LinterCategory.JSX_IN_TRY,
+  },
+  [ErrorCode.NO_REF_ACCESS_IN_RENDER]: {
+    code: ErrorCode.NO_REF_ACCESS_IN_RENDER,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'Cannot access refs during render',
+    description:
+      'React refs are values that are not needed for rendering. Refs should only be accessed ' +
+      'outside of render, such as in event handlers or effects. ' +
+      'Accessing a ref value (the `current` property) during render can cause your component ' +
+      'not to update as expected (https://react.dev/reference/react/useRef)',
+    linterCategory: LinterCategory.NO_REF_ACCESS_IN_RENDER,
+  },
+  [ErrorCode.INVALID_SET_STATE_IN_EFFECTS]: {
+    code: ErrorCode.INVALID_SET_STATE_IN_EFFECTS,
+    severity: ErrorSeverity.InvalidReact,
+    reason:
+      'Calling setState synchronously within an effect can trigger cascading renders',
+    description:
+      'Effects are intended to synchronize state between React and external systems such as manually updating the DOM, state management libraries, or other platform APIs. ' +
+      'In general, the body of an effect should do one or both of the following:\n' +
+      '* Update external systems with the latest state from React.\n' +
+      '* Subscribe for updates from some external system, calling setState in a callback function when external state changes.\n\n' +
+      'Calling setState synchronously within an effect body causes cascading renders that can hurt performance, and is not recommended. ' +
+      '(https://react.dev/learn/you-might-not-need-an-effect)',
+    linterCategory: LinterCategory.NO_SET_STATE_IN_EFFECTS,
+  },
+  [ErrorCode.WRITE_AFTER_RENDER]: {
+    code: ErrorCode.WRITE_AFTER_RENDER,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'Cannot modify local variables after render completes',
+    description: `This argument is a function which may reassign or mutate a variable after render, which can cause inconsistent behavior on subsequent renders. Consider using state instead`,
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+  [ErrorCode.REASSIGN_AFTER_RENDER]: {
+    code: ErrorCode.REASSIGN_AFTER_RENDER,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'Cannot reassign local variables after render completes',
+    description: `Reassigning local variables after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead`,
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+  [ErrorCode.REASSIGN_IN_ASYNC]: {
+    code: ErrorCode.REASSIGN_IN_ASYNC,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'Cannot reassign variable in async function',
+    description:
+      'Reassigning a variable in an async function can cause inconsistent behavior on subsequent renders. Consider using state instead',
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+  [ErrorCode.INVALID_WRITE]: {
+    code: ErrorCode.INVALID_WRITE,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'This value cannot be modified',
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+  [ErrorCode.CAPITALIZED_CALLS]: {
+    code: ErrorCode.CAPITALIZED_CALLS,
+    severity: ErrorSeverity.InvalidReact,
+    reason:
+      'Capitalized functions are reserved for components, which must be invoked with JSX. If this is a component, render it with JSX. Otherwise, ensure that it has no hook calls and rename it to begin with a lowercase letter. Alternatively, if you know for a fact that this function is not a component, you can allowlist it via the compiler config',
+    linterCategory: LinterCategory.CAPITALIZED_CALLS,
+  },
+  [ErrorCode.STATIC_COMPONENTS]: {
+    code: ErrorCode.STATIC_COMPONENTS,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'Cannot create components during render',
+    linterCategory: LinterCategory.STATIC_COMPONENTS,
+  },
+  [ErrorCode.INVALID_USE_MEMO_NO_ARG0]: {
+    code: ErrorCode.INVALID_USE_MEMO_NO_ARG0,
+    severity: ErrorSeverity.InvalidReact,
+    reason: `Expected a callback function to be passed to useMemo`,
+    linterCategory: LinterCategory.VALIDATE_MANUAL_MEMO,
+  },
+  [ErrorCode.INVALID_USE_CALLBACK_NO_ARG0]: {
+    code: ErrorCode.INVALID_USE_CALLBACK_NO_ARG0,
+    severity: ErrorSeverity.InvalidReact,
+    reason: `Expected a callback function to be passed to useCallback`,
+    linterCategory: LinterCategory.VALIDATE_MANUAL_MEMO,
+  },
+  [ErrorCode.DYNAMIC_USE_MEMO_SPREAD_ARGUMENT]: {
+    code: ErrorCode.DYNAMIC_USE_MEMO_SPREAD_ARGUMENT,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'Unexpected spread argument to useMemo',
+    linterCategory: LinterCategory.DYNAMIC_MANUAL_MEMO,
+  },
+
+  [ErrorCode.DYNAMIC_USE_CALLBACK_SPREAD_ARGUMENT]: {
+    code: ErrorCode.DYNAMIC_USE_CALLBACK_SPREAD_ARGUMENT,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'Unexpected spread argument to useCallback',
+    linterCategory: LinterCategory.DYNAMIC_MANUAL_MEMO,
+  },
+  [ErrorCode.INVALID_USE_MEMO_CALLBACK_PARAMETERS]: {
+    code: ErrorCode.INVALID_USE_MEMO_CALLBACK_PARAMETERS,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'useMemo() callbacks may not accept parameters',
+    description:
+      'useMemo() callbacks are called by React to cache calculations across re-renders. They should not take parameters. Instead, directly reference the props, state, or local variables needed for the computation',
+    linterCategory: LinterCategory.VALIDATE_MANUAL_MEMO,
+  },
+  [ErrorCode.INVALID_USE_MEMO_CALLBACK_ASYNC]: {
+    code: ErrorCode.INVALID_USE_MEMO_CALLBACK_ASYNC,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'useMemo() callbacks may not be async or generator functions',
+    description:
+      'useMemo() callbacks are called once and must synchronously return a value',
+    linterCategory: LinterCategory.VALIDATE_MANUAL_MEMO,
+  },
+  [ErrorCode.INVALID_USE_MEMO_CALLBACK_RETURN]: {
+    code: ErrorCode.INVALID_USE_MEMO_CALLBACK_RETURN,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'useMemo() callbacks must return a value',
+    linterCategory: LinterCategory.VALIDATE_MANUAL_MEMO,
+  },
+  [ErrorCode.DYNAMIC_MANUAL_MEMO_CALLBACK]: {
+    code: ErrorCode.DYNAMIC_MANUAL_MEMO_CALLBACK,
+    severity: ErrorSeverity.InvalidReact,
+    reason: `Expected the first argument to be an inline function expression`,
+    linterCategory: LinterCategory.DYNAMIC_MANUAL_MEMO,
+  },
+  [ErrorCode.DYNAMIC_MANUAL_MEMO_DEPENDENCY_LIST]: {
+    code: ErrorCode.DYNAMIC_MANUAL_MEMO_DEPENDENCY_LIST,
+    severity: ErrorSeverity.InvalidReact,
+    reason: `Expected the dependency list of useMemo or useCallback to be an array literal`,
+    linterCategory: LinterCategory.DYNAMIC_MANUAL_MEMO,
+  },
+  [ErrorCode.COMPLEX_MANUAL_MEMO_DEPENDENCY_LIST_ENTRY]: {
+    code: ErrorCode.COMPLEX_MANUAL_MEMO_DEPENDENCY_LIST_ENTRY,
+    severity: ErrorSeverity.InvalidReact,
+    reason: `Expected the dependency list to be an array of simple expressions (e.g. \`x\`, \`x.y.z\`, \`x?.y?.z\`)`,
+    linterCategory: LinterCategory.DYNAMIC_MANUAL_MEMO,
+  },
+  [ErrorCode.INVALID_SET_STATE_IN_RENDER]: {
+    code: ErrorCode.INVALID_SET_STATE_IN_RENDER,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'Calling setState during render may trigger an infinite loop',
+    description:
+      'Calling setState during render will trigger another render, and can lead to infinite loops. (https://react.dev/reference/react/useState)',
+    linterCategory: LinterCategory.NO_SET_STATE_IN_RENDER,
+  },
+  [ErrorCode.INVALID_SET_STATE_IN_MEMO]: {
+    code: ErrorCode.INVALID_SET_STATE_IN_MEMO,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'Calling setState from useMemo may trigger an infinite loop',
+    description:
+      'Each time the memo callback is evaluated it will change state. This can cause a memoization dependency to change, running the memo function again and causing an infinite loop. Instead of setting state in useMemo(), prefer deriving the value during render. (https://react.dev/reference/react/useState)',
+    linterCategory: LinterCategory.NO_SET_STATE_IN_RENDER,
+  },
+  [ErrorCode.NO_DERIVED_COMPUTATIONS_IN_EFFECTS]: {
+    code: ErrorCode.NO_DERIVED_COMPUTATIONS_IN_EFFECTS,
+    severity: ErrorSeverity.InvalidReact,
+    reason:
+      'Values derived from props and state should be calculated during render, not in an effect. (https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state)',
+    linterCategory: LinterCategory.UNNECESSARY_EFFECTS,
+  },
+
+  /** Invalid writes */
+  [ErrorCode.INVALID_WRITE_GLOBAL]: {
+    code: ErrorCode.INVALID_WRITE_GLOBAL,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'Cannot reassign variables declared outside of the component/hook',
+    description:
+      'Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)',
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+  [ErrorCode.INVALID_WRITE_FROZEN_VALUE_JSX]: {
+    code: ErrorCode.INVALID_WRITE_FROZEN_VALUE_JSX,
+    severity: ErrorSeverity.InvalidReact,
+    reason:
+      'Modifying a value used previously in JSX is not allowed. Consider moving the modification before the JSX',
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+  [ErrorCode.INVALID_WRITE_IMMUTABLE_VALUE_USE_CONTEXT]: {
+    code: ErrorCode.INVALID_WRITE_IMMUTABLE_VALUE_USE_CONTEXT,
+    severity: ErrorSeverity.InvalidReact,
+    reason: `Modifying a value returned from 'useContext()' is not allowed`,
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+  [ErrorCode.INVALID_WRITE_IMMUTABLE_VALUE_KNOWN_SIGNATURE]: {
+    code: ErrorCode.INVALID_WRITE_IMMUTABLE_VALUE_KNOWN_SIGNATURE,
+    severity: ErrorSeverity.InvalidReact,
+    reason:
+      'Modifying a value returned from a function whose return value should not be mutated',
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+  [ErrorCode.INVALID_WRITE_IMMUTABLE_ARGS]: {
+    code: ErrorCode.INVALID_WRITE_IMMUTABLE_ARGS,
+    severity: ErrorSeverity.InvalidReact,
+    reason:
+      'Modifying component props or hook arguments is not allowed. Consider using a local variable instead',
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+  [ErrorCode.INVALID_WRITE_STATE]: {
+    code: ErrorCode.INVALID_WRITE_STATE,
+    severity: ErrorSeverity.InvalidReact,
+    reason:
+      "Modifying a value returned from 'useState()', which should not be modified directly. Use the setter function to update instead",
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+  [ErrorCode.INVALID_WRITE_REDUCER_STATE]: {
+    code: ErrorCode.INVALID_WRITE_REDUCER_STATE,
+    severity: ErrorSeverity.InvalidReact,
+    reason:
+      "Modifying a value returned from 'useReducer()', which should not be modified directly. Use the dispatch function to update instead",
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+  [ErrorCode.INVALID_WRITE_EFFECT_DEPENDENCY]: {
+    code: ErrorCode.INVALID_WRITE_EFFECT_DEPENDENCY,
+    severity: ErrorSeverity.InvalidReact,
+    reason:
+      'Modifying a value used previously in an effect function or as an effect dependency is not allowed. Consider moving the modification before calling useEffect()',
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+  [ErrorCode.INVALID_WRITE_HOOK_CAPTURED]: {
+    code: ErrorCode.INVALID_WRITE_HOOK_CAPTURED,
+    severity: ErrorSeverity.InvalidReact,
+    reason:
+      'Modifying a value previously passed as an argument to a hook is not allowed. Consider moving the modification before calling the hook',
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+  [ErrorCode.INVALID_WRITE_HOOK_RETURN]: {
+    code: ErrorCode.INVALID_WRITE_HOOK_RETURN,
+    severity: ErrorSeverity.InvalidReact,
+    reason:
+      'Modifying a value returned from a hook is not allowed. Consider moving the modification into the hook where the value is constructed',
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+  [ErrorCode.INVALID_ACCESS_BEFORE_INIT]: {
+    code: ErrorCode.INVALID_ACCESS_BEFORE_INIT,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'Cannot access variable before it is declared',
+    description: `Reading a variable before it is initialized will prevent the earlier access from updating when this value changes over time. Instead, move the variable access to after it has been initialized`,
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+  [ErrorCode.INVALID_WRITE_GENERIC]: {
+    code: ErrorCode.INVALID_WRITE_GENERIC,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'This modifies a variable that React considers immutable',
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+
+  /** Compiler Config */
+  [ErrorCode.DYNAMIC_GATING_IS_NOT_IDENTIFIER]: {
+    code: ErrorCode.DYNAMIC_GATING_IS_NOT_IDENTIFIER,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'Dynamic gating directive is not a valid JavaScript identifier',
+    linterCategory: LinterCategory.COMPILER_CONFIG,
+  },
+  [ErrorCode.DYNAMIC_GATING_MULTIPLE_DIRECTIVES]: {
+    code: ErrorCode.DYNAMIC_GATING_MULTIPLE_DIRECTIVES,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'Expected a single dynamic gating directive',
+    linterCategory: LinterCategory.COMPILER_CONFIG,
+  },
+  [ErrorCode.FILENAME_NOT_SET]: {
+    code: ErrorCode.FILENAME_NOT_SET,
+    severity: ErrorSeverity.InvalidConfig,
+    reason: `Expected a filename but found none`,
+    description:
+      "When the 'sources' config options is specified, the React compiler will only compile files with a name",
+    linterCategory: LinterCategory.COMPILER_CONFIG,
+  },
+
+  /** Effect dependencies */
+  [ErrorCode.MEMOIZED_EFFECT_DEPENDENCIES]: {
+    code: ErrorCode.MEMOIZED_EFFECT_DEPENDENCIES,
+    reason:
+      'React Compiler has skipped optimizing this component because the effect dependencies could not be memoized. Unmemoized effect dependencies can trigger an infinite loop or other unexpected behavior',
+    severity: ErrorSeverity.CannotPreserveMemoization,
+    linterCategory: LinterCategory.MEMOIZED_DEPENDENCIES,
+  },
+
+  /** Invalid / unsupported syntax */
+  [ErrorCode.INVALID_SYNTAX_MULTIPLE_DEFAULTS]: {
+    code: ErrorCode.INVALID_SYNTAX_MULTIPLE_DEFAULTS,
+    reason: `Expected at most one \`default\` branch in a switch statement, this code should have failed to parse`,
+    severity: ErrorSeverity.InvalidJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.INVALID_SYNTAX_REASSIGNED_CONST]: {
+    code: ErrorCode.INVALID_SYNTAX_REASSIGNED_CONST,
+    reason: `Expect \`const\` declaration not to be reassigned`,
+    severity: ErrorSeverity.InvalidJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.INVALID_SYNTAX_BAD_VARIABLE_DECL]: {
+    code: ErrorCode.INVALID_SYNTAX_BAD_VARIABLE_DECL,
+    reason: `Expected variable declaration to be an identifier if no initializer was provided`,
+    severity: ErrorSeverity.InvalidJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.UNSUPPORTED_WITH]: {
+    code: ErrorCode.UNSUPPORTED_WITH,
+    reason: `JavaScript 'with' syntax is not supported`,
+    description: `'with' syntax is considered deprecated and removed from JavaScript standards, consider alternatives`,
+    severity: ErrorSeverity.UnsupportedJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.UNSUPPORTED_INNER_CLASS]: {
+    code: ErrorCode.UNSUPPORTED_INNER_CLASS,
+    reason: 'Inline `class` declarations are not supported',
+    description: `Move class declarations outside of components/hooks`,
+    severity: ErrorSeverity.UnsupportedJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.INVALID_IMPORT_EXPORT]: {
+    code: ErrorCode.INVALID_IMPORT_EXPORT,
+    reason:
+      'JavaScript `import` and `export` statements may only appear at the top level of a module',
+    severity: ErrorSeverity.InvalidJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.INVALID_TS_NAMESPACE]: {
+    code: ErrorCode.INVALID_TS_NAMESPACE,
+    reason:
+      'TypeScript `namespace` statements may only appear at the top level of a module',
+    severity: ErrorSeverity.InvalidJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.UNSUPPORTED_NEW_EXPRESSION]: {
+    code: ErrorCode.UNSUPPORTED_NEW_EXPRESSION,
+    reason: `Expected an expression as the \`new\` expression receiver (v8 intrinsics are not supported)`,
+    severity: ErrorSeverity.InvalidJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.UNSUPPORTED_EMPTY_SEQUENCE_EXPRESSION]: {
+    code: ErrorCode.UNSUPPORTED_EMPTY_SEQUENCE_EXPRESSION,
+    reason: `Expected sequence expression to have at least one expression`,
+    severity: ErrorSeverity.InvalidJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.INVALID_QUASI_LENGTHS]: {
+    code: ErrorCode.INVALID_QUASI_LENGTHS,
+    reason: `Unexpected quasi and subexpression lengths in template literal`,
+    severity: ErrorSeverity.InvalidJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.INVALID_SYNTAX_DELETE_EXPRESSION]: {
+    code: ErrorCode.INVALID_SYNTAX_DELETE_EXPRESSION,
+    reason: `Only object properties can be deleted`,
+    severity: ErrorSeverity.InvalidJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.UNSUPPORTED_THROW_EXPRESSION]: {
+    code: ErrorCode.UNSUPPORTED_THROW_EXPRESSION,
+    reason: `Throw expressions are not supported`,
+    severity: ErrorSeverity.InvalidJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.INVALID_JSX_NAMESPACED_NAME]: {
+    code: ErrorCode.INVALID_JSX_NAMESPACED_NAME,
+    reason: `Expected JSXNamespacedName to have no colons in the namespace or name`,
+    severity: ErrorSeverity.InvalidJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.UNSUPPORTED_EVAL]: {
+    code: ErrorCode.UNSUPPORTED_EVAL,
+    reason: `The 'eval' function is not supported`,
+    description:
+      'Eval is an anti-pattern in JavaScript, and the code executed cannot be evaluated by React Compiler',
+    severity: ErrorSeverity.UnsupportedJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.INVALID_SYNTAX_RESERVED_VARIABLE_NAME]: {
+    code: ErrorCode.INVALID_SYNTAX_RESERVED_VARIABLE_NAME,
+    reason: 'Expected a non-reserved identifier name',
+    severity: ErrorSeverity.InvalidJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.INVALID_JAVASCRIPT_AST]: {
+    code: ErrorCode.INVALID_JAVASCRIPT_AST,
+    reason: 'Encountered invalid JavaScript',
+    severity: ErrorSeverity.InvalidJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.BAILOUT_ESLINT_SUPPRESSION]: {
+    code: ErrorCode.BAILOUT_ESLINT_SUPPRESSION,
+    reason:
+      'React Compiler has skipped optimizing this component because one or more React ESLint rules were disabled',
+    description:
+      'React Compiler only works when your components follow all the rules of React, disabling them may result in unexpected or incorrect behavior',
+    severity: ErrorSeverity.InvalidReact,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.MANUAL_MEMO_REMOVED]: {
+    code: ErrorCode.MANUAL_MEMO_REMOVED,
+    reason:
+      'Compilation skipped because existing memoization could not be preserved',
+    description:
+      'React Compiler has skipped optimizing this component because the existing manual memoization could not be preserved. This value was memoized in source but not in compilation output',
+    severity: ErrorSeverity.CannotPreserveMemoization,
+    linterCategory: LinterCategory.TODO_SYNTAX,
+  },
+
+  /**
+   * This is left vague as fire is very experimental
+   */
+  [ErrorCode.CANNOT_COMPILE_FIRE]: {
+    code: ErrorCode.CANNOT_COMPILE_FIRE,
+    reason: 'Cannot compile `fire`',
+    severity: ErrorSeverity.InvalidReact,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.DID_NOT_INFER_DEPS]: {
+    code: ErrorCode.DID_NOT_INFER_DEPS,
+    reason:
+      'Cannot infer dependencies of this effect. This will break your build!',
+    description:
+      'To resolve, either pass a dependency array or fix reported compiler bailout diagnostics',
+    severity: ErrorSeverity.InvalidReact,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+
+  [ErrorCode.BAILOUT_FLOW_SUPPRESSION]: {
+    code: ErrorCode.BAILOUT_FLOW_SUPPRESSION,
+    reason:
+      'React Compiler has skipped optimizing this component because one or more React rule violations were reported by Flow',
+    description:
+      'React Compiler only works when your components follow all the rules of React, disabling them may result in unexpected or incorrect behavior',
+    severity: ErrorSeverity.InvalidReact,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+
+  /** Syntax React Compiler may eventually support */
+  [ErrorCode.TODO_CONFLICTING_FBT_IDENTIFIER]: {
+    code: ErrorCode.TODO_CONFLICTING_FBT_IDENTIFIER,
+    reason: 'Support local variables named `fbt`',
+    description:
+      'Local variables named `fbt` may conflict with the fbt plugin and are not yet supported',
+    severity: ErrorSeverity.Todo,
+    linterCategory: LinterCategory.TODO_SYNTAX,
+  },
+  [ErrorCode.TODO_DUPLICATE_FBT_TAGS]: {
+    code: ErrorCode.TODO_DUPLICATE_FBT_TAGS,
+    reason: 'Support duplicate fbt tags',
+    severity: ErrorSeverity.Todo,
+    linterCategory: LinterCategory.TODO_SYNTAX,
+  },
+  [ErrorCode.UNKNOWN_FUNCTION_PARAMETERS]: {
+    code: ErrorCode.UNKNOWN_FUNCTION_PARAMETERS,
+    severity: ErrorSeverity.Todo,
+    reason: 'Currently unsupported function parameter syntax',
+    linterCategory: LinterCategory.TODO_SYNTAX,
+  },
+  [ErrorCode.MANUAL_MEMO_MUTATED_LATER]: {
+    code: ErrorCode.MANUAL_MEMO_MUTATED_LATER,
+    reason:
+      'Compilation skipped because existing memoization could not be preserved',
+    description: [
+      'React Compiler has skipped optimizing this component because the existing manual memoization could not be preserved. ',
+      'This dependency may be mutated later, which could cause the value to change unexpectedly',
+    ].join(''),
+    severity: ErrorSeverity.CannotPreserveMemoization,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.MANUAL_MEMO_DEPENDENCIES_CONFLICT]: {
+    code: ErrorCode.MANUAL_MEMO_DEPENDENCIES_CONFLICT,
+    reason:
+      'Compilation skipped because existing memoization could not be preserved',
+    description:
+      'React Compiler has skipped optimizing this component because the existing manual memoization could not be preserved. ' +
+      'The inferred dependencies did not match the manually specified dependencies, which could cause the value to change more or less frequently than expected',
+    severity: ErrorSeverity.CannotPreserveMemoization,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+};

compiler/packages/babel-plugin-react-compiler/src/Utils/CompilerErrorSeverity.ts

@@ -0,0 +1,34 @@
+export enum ErrorSeverity {
+  /**
+   * Invalid JS syntax, or valid syntax that is semantically invalid which may indicate some
+   * misunderstanding on the user’s part.
+   */
+  InvalidJS = 'InvalidJS',
+  /**
+   * JS syntax that is not supported and which we do not plan to support. Developers should
+   * rewrite to use supported forms.
+   */
+  UnsupportedJS = 'UnsupportedJS',
+  /**
+   * Code that breaks the rules of React.
+   */
+  InvalidReact = 'InvalidReact',
+  /**
+   * Incorrect configuration of the compiler.
+   */
+  InvalidConfig = 'InvalidConfig',
+  /**
+   * Code that can reasonably occur and that doesn't break any rules, but is unsafe to preserve
+   * memoization.
+   */
+  CannotPreserveMemoization = 'CannotPreserveMemoization',
+  /**
+   * Unhandled syntax that we don't support yet.
+   */
+  Todo = 'Todo',
+  /**
+   * An unexpected internal error in the compiler that indicates critical issues that can panic
+   * the compiler.
+   */
+  Invariant = 'Invariant',
+}

compiler/packages/babel-plugin-react-compiler/src/Utils/Result.ts

@@ -90,13 +90,10 @@ export function Ok<T>(val: T): OkImpl<T> {
 }
 
 class OkImpl<T> implements Result<T, never> {
-  #val: T;
-  constructor(val: T) {
-    this.#val = val;
-  }
+  constructor(private val: T) {}
 
   map<U>(fn: (val: T) => U): Result<U, never> {
-    return new OkImpl(fn(this.#val));
+    return new OkImpl(fn(this.val));
   }
 
   mapErr<F>(_fn: (val: never) => F): Result<T, F> {
@@ -104,15 +101,15 @@ class OkImpl<T> implements Result<T, never> {
   }
 
   mapOr<U>(_fallback: U, fn: (val: T) => U): U {
-    return fn(this.#val);
+    return fn(this.val);
   }
 
   mapOrElse<U>(_fallback: () => U, fn: (val: T) => U): U {
-    return fn(this.#val);
+    return fn(this.val);
   }
 
   andThen<U>(fn: (val: T) => Result<U, never>): Result<U, never> {
-    return fn(this.#val);
+    return fn(this.val);
   }
 
   and<U>(res: Result<U, never>): Result<U, never> {
@@ -136,30 +133,30 @@ class OkImpl<T> implements Result<T, never> {
   }
 
   expect(_msg: string): T {
-    return this.#val;
+    return this.val;
   }
 
   expectErr(msg: string): never {
-    throw new Error(`${msg}: ${this.#val}`);
+    throw new Error(`${msg}: ${this.val}`);
   }
 
   unwrap(): T {
-    return this.#val;
+    return this.val;
   }
 
   unwrapOr(_fallback: T): T {
-    return this.#val;
+    return this.val;
   }
 
   unwrapOrElse(_fallback: (val: never) => T): T {
-    return this.#val;
+    return this.val;
   }
 
   unwrapErr(): never {
-    if (this.#val instanceof Error) {
-      throw this.#val;
+    if (this.val instanceof Error) {
+      throw this.val;
     }
-    throw new Error(`Can't unwrap \`Ok\` to \`Err\`: ${this.#val}`);
+    throw new Error(`Can't unwrap \`Ok\` to \`Err\`: ${this.val}`);
   }
 }
 
@@ -168,17 +165,14 @@ export function Err<E>(val: E): ErrImpl<E> {
 }
 
 class ErrImpl<E> implements Result<never, E> {
-  #val: E;
-  constructor(val: E) {
-    this.#val = val;
-  }
+  constructor(private val: E) {}
 
   map<U>(_fn: (val: never) => U): Result<U, E> {
     return this;
   }
 
   mapErr<F>(fn: (val: E) => F): Result<never, F> {
-    return new ErrImpl(fn(this.#val));
+    return new ErrImpl(fn(this.val));
   }
 
   mapOr<U>(fallback: U, _fn: (val: never) => U): U {
@@ -202,7 +196,7 @@ class ErrImpl<E> implements Result<never, E> {
   }
 
   orElse<F>(fn: (val: E) => ErrImpl<F>): Result<never, F> {
-    return fn(this.#val);
+    return fn(this.val);
   }
 
   isOk(): this is OkImpl<never> {
@@ -214,18 +208,18 @@ class ErrImpl<E> implements Result<never, E> {
   }
 
   expect(msg: string): never {
-    throw new Error(`${msg}: ${this.#val}`);
+    throw new Error(`${msg}: ${this.val}`);
   }
 
   expectErr(_msg: string): E {
-    return this.#val;
+    return this.val;
   }
 
   unwrap(): never {
-    if (this.#val instanceof Error) {
-      throw this.#val;
+    if (this.val instanceof Error) {
+      throw this.val;
     }
-    throw new Error(`Can't unwrap \`Err\` to \`Ok\`: ${this.#val}`);
+    throw new Error(`Can't unwrap \`Err\` to \`Ok\`: ${this.val}`);
   }
 
   unwrapOr<T>(fallback: T): T {
@@ -233,10 +227,10 @@ class ErrImpl<E> implements Result<never, E> {
   }
 
   unwrapOrElse<T>(fallback: (val: E) => T): T {
-    return fallback(this.#val);
+    return fallback(this.val);
   }
 
   unwrapErr(): E {
-    return this.#val;
+    return this.val;
   }
 }

compiler/packages/babel-plugin-react-compiler/src/Utils/TestUtils.ts

@@ -182,11 +182,6 @@ export function parseConfigPragmaForTests(
     environment?: PartialEnvironmentConfig;
   },
 ): PluginOptions {
-  const overridePragma = parseConfigPragmaAsString(pragma);
-  if (overridePragma !== '') {
-    return parseConfigStringAsJS(overridePragma, defaults);
-  }
-
   const environment = parseConfigPragmaEnvironmentForTest(
     pragma,
     defaults.environment ?? {},
@@ -222,104 +217,3 @@ export function parseConfigPragmaForTests(
   }
   return parsePluginOptions(options);
 }
-
-export function parseConfigPragmaAsString(pragma: string): string {
-  // Check if it's in JS override format
-  for (const {key, value: val} of splitPragma(pragma)) {
-    if (key === 'OVERRIDE' && val != null) {
-      return val;
-    }
-  }
-  return '';
-}
-
-function parseConfigStringAsJS(
-  configString: string,
-  defaults: {
-    compilationMode: CompilationMode;
-    environment?: PartialEnvironmentConfig;
-  },
-): PluginOptions {
-  let parsedConfig: any;
-  try {
-    // Parse the JavaScript object literal
-    parsedConfig = new Function(`return ${configString}`)();
-  } catch (error) {
-    CompilerError.invariant(false, {
-      reason: 'Failed to parse config pragma as JavaScript object',
-      description: `Could not parse: ${configString}. Error: ${error}`,
-      loc: null,
-      suggestions: null,
-    });
-  }
-
-  console.log('OVERRIDE:', parsedConfig);
-
-  const options: Record<keyof PluginOptions, unknown> = {
-    ...defaultOptions,
-    panicThreshold: 'all_errors',
-    compilationMode: defaults.compilationMode,
-    environment: defaults.environment ?? defaultOptions.environment,
-  };
-
-  // Apply parsed config, merging environment if it exists
-  if (parsedConfig.environment) {
-    const mergedEnvironment = {
-      ...(options.environment as Record<string, unknown>),
-      ...parsedConfig.environment,
-    };
-
-    // Apply complex defaults for environment flags that are set to true
-    const environmentConfig: Partial<Record<keyof EnvironmentConfig, unknown>> =
-      {};
-    for (const [key, value] of Object.entries(mergedEnvironment)) {
-      if (hasOwnProperty(EnvironmentConfigSchema.shape, key)) {
-        if (value === true && key in testComplexConfigDefaults) {
-          environmentConfig[key] = testComplexConfigDefaults[key];
-        } else {
-          environmentConfig[key] = value;
-        }
-      }
-    }
-
-    // Validate environment config
-    const validatedEnvironment =
-      EnvironmentConfigSchema.safeParse(environmentConfig);
-    if (!validatedEnvironment.success) {
-      CompilerError.invariant(false, {
-        reason: 'Invalid environment configuration in config pragma',
-        description: `${fromZodError(validatedEnvironment.error)}`,
-        loc: null,
-        suggestions: null,
-      });
-    }
-
-    if (validatedEnvironment.data.enableResetCacheOnSourceFileChanges == null) {
-      validatedEnvironment.data.enableResetCacheOnSourceFileChanges = false;
-    }
-
-    options.environment = validatedEnvironment.data;
-  }
-
-  // Apply other config options
-  for (const [key, value] of Object.entries(parsedConfig)) {
-    if (key === 'environment') {
-      continue;
-    }
-
-    if (hasOwnProperty(defaultOptions, key)) {
-      if (value === true && key in testComplexPluginOptionDefaults) {
-        options[key] = testComplexPluginOptionDefaults[key];
-      } else if (key === 'target' && value === 'donotuse_meta_internal') {
-        options[key] = {
-          kind: value,
-          runtimeModule: 'react',
-        };
-      } else {
-        options[key] = value;
-      }
-    }
-  }
-
-  return parsePluginOptions(options);
-}

compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateHooksUsage.ts

@@ -6,12 +6,7 @@
  */
 
 import * as t from '@babel/types';
-import {
-  CompilerError,
-  CompilerErrorDetail,
-  ErrorCategory,
-  ErrorSeverity,
-} from '../CompilerError';
+import {CompilerError, CompilerErrorDetail} from '../CompilerError';
 import {computeUnconditionalBlocks} from '../HIR/ComputeUnconditionalBlocks';
 import {isHookName} from '../HIR/Environment';
 import {
@@ -28,6 +23,7 @@ import {
 } from '../HIR/visitors';
 import {assertExhaustive} from '../Utils/utils';
 import {Result} from '../Utils/Result';
+import {ErrorCode, ErrorCodeDetails} from '../Utils/CompilerErrorCodes';
 
 /**
  * Represents the possible kinds of value which may be stored at a given Place during
@@ -112,8 +108,6 @@ export function validateHooksUsage(
     // Once a particular hook has a conditional call error, don't report any further issues for this hook
     setKind(place, Kind.Error);
 
-    const reason =
-      'Hooks must always be called in a consistent order, and may not be called conditionally. See the Rules of Hooks (https://react.dev/warnings/invalid-hook-call-warning)';
     const previousError =
       typeof place.loc !== 'symbol' ? errorsByPlace.get(place.loc) : undefined;
 
@@ -121,16 +115,15 @@ export function validateHooksUsage(
      * In some circumstances such as optional calls, we may first encounter a "hook may not be referenced as normal values" error.
      * If that same place is also used as a conditional call, upgrade the error to a conditonal hook error
      */
-    if (previousError === undefined || previousError.reason !== reason) {
+    if (
+      previousError === undefined ||
+      previousError.reason !==
+        ErrorCodeDetails[ErrorCode.HOOK_CALL_STATIC].reason
+    ) {
       recordError(
         place.loc,
-        new CompilerErrorDetail({
-          category: ErrorCategory.Hooks,
-          description: null,
-          reason,
+        CompilerErrorDetail.fromCode(ErrorCode.HOOK_CALL_STATIC, {
           loc: place.loc,
-          severity: ErrorSeverity.InvalidReact,
-          suggestions: null,
         }),
       );
     }
@@ -141,14 +134,8 @@ export function validateHooksUsage(
     if (previousError === undefined) {
       recordError(
         place.loc,
-        new CompilerErrorDetail({
-          category: ErrorCategory.Hooks,
-          description: null,
-          reason:
-            'Hooks may not be referenced as normal values, they must be called. See https://react.dev/reference/rules/react-calls-components-and-hooks#never-pass-around-hooks-as-regular-values',
+        CompilerErrorDetail.fromCode(ErrorCode.HOOK_INVALID_REFERENCE, {
           loc: place.loc,
-          severity: ErrorSeverity.InvalidReact,
-          suggestions: null,
         }),
       );
     }
@@ -159,15 +146,12 @@ export function validateHooksUsage(
     if (previousError === undefined) {
       recordError(
         place.loc,
-        new CompilerErrorDetail({
-          category: ErrorCategory.Hooks,
-          description: null,
-          reason:
-            'Hooks must be the same function on every render, but this value may change over time to a different function. See https://react.dev/reference/rules/react-calls-components-and-hooks#dont-dynamically-use-hooks',
-          loc: place.loc,
-          severity: ErrorSeverity.InvalidReact,
-          suggestions: null,
-        }),
+        CompilerErrorDetail.fromCode(
+          ErrorCodeDetails[ErrorCode.HOOK_CALL_REACTIVE].code,
+          {
+            loc: place.loc,
+          },
+        ),
       );
     }
   }
@@ -450,17 +434,10 @@ function visitFunctionExpression(errors: CompilerError, fn: HIRFunction): void {
               : instr.value.property;
           const hookKind = getHookKind(fn.env, callee.identifier);
           if (hookKind != null) {
-            errors.pushErrorDetail(
-              new CompilerErrorDetail({
-                category: ErrorCategory.Hooks,
-                severity: ErrorSeverity.InvalidReact,
-                reason:
-                  'Hooks must be called at the top level in the body of a function component or custom hook, and may not be called within function expressions. See the Rules of Hooks (https://react.dev/warnings/invalid-hook-call-warning)',
-                loc: callee.loc,
-                description: `Cannot call ${hookKind === 'Custom' ? 'hook' : hookKind} within a function expression`,
-                suggestions: null,
-              }),
-            );
+            errors.pushErrorCode(ErrorCode.HOOK_CALL_NOT_TOP_LEVEL, {
+              loc: callee.loc,
+              description: `Cannot call ${hookKind === 'Custom' ? 'hook' : hookKind} within a function expression`,
+            });
           }
           break;
         }

compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateLocalsNotReassignedAfterRender.ts

@@ -5,22 +5,25 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {CompilerDiagnostic, CompilerError, Effect, ErrorSeverity} from '..';
-import {ErrorCategory} from '../CompilerError';
+import {CompilerDiagnostic, CompilerError, Effect} from '..';
 import {HIRFunction, IdentifierId, Place} from '../HIR';
 import {
   eachInstructionLValue,
   eachInstructionValueOperand,
   eachTerminalOperand,
 } from '../HIR/visitors';
-import {getFunctionCallSignature} from '../Inference/InferMutationAliasingEffects';
+import {getFunctionCallSignature} from '../Inference/InferReferenceEffects';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
+import {Ok, Result} from '../Utils/Result';
 
 /**
  * Validates that local variables cannot be reassigned after render.
  * This prevents a category of bugs in which a closure captures a
  * binding from one render but does not update
  */
-export function validateLocalsNotReassignedAfterRender(fn: HIRFunction): void {
+export function validateLocalsNotReassignedAfterRender(
+  fn: HIRFunction,
+): Result<void, CompilerError> {
   const contextVariables = new Set<IdentifierId>();
   const reassignment = getContextReassignment(
     fn,
@@ -36,19 +39,15 @@ export function validateLocalsNotReassignedAfterRender(fn: HIRFunction): void {
         ? `\`${reassignment.identifier.name.value}\``
         : 'variable';
     errors.pushDiagnostic(
-      CompilerDiagnostic.create({
-        category: ErrorCategory.Immutability,
-        severity: ErrorSeverity.InvalidReact,
-        reason: 'Cannot reassign variable after render completes',
-        description: `Reassigning ${variable} after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead.`,
-      }).withDetail({
+      CompilerDiagnostic.fromCode(ErrorCode.REASSIGN_AFTER_RENDER).withDetail({
         kind: 'error',
         loc: reassignment.loc,
         message: `Cannot reassign ${variable} after render completes`,
       }),
     );
-    throw errors;
+    return errors.asResult();
   }
+  return Ok(undefined);
 }
 
 function getContextReassignment(
@@ -92,13 +91,9 @@ function getContextReassignment(
                   ? `\`${reassignment.identifier.name.value}\``
                   : 'variable';
               errors.pushDiagnostic(
-                CompilerDiagnostic.create({
-                  category: ErrorCategory.Immutability,
-                  severity: ErrorSeverity.InvalidReact,
-                  reason: 'Cannot reassign variable in async function',
-                  description:
-                    'Reassigning a variable in an async function can cause inconsistent behavior on subsequent renders. Consider using state instead',
-                }).withDetail({
+                CompilerDiagnostic.fromCode(
+                  ErrorCode.REASSIGN_IN_ASYNC,
+                ).withDetail({
                   kind: 'error',
                   loc: reassignment.loc,
                   message: `Cannot reassign ${variable}`,

compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateMemoizedEffectDependencies.ts

@@ -5,8 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {CompilerError, ErrorSeverity} from '..';
-import {ErrorCategory} from '../CompilerError';
+import {CompilerError} from '..';
 import {
   Identifier,
   Instruction,
@@ -23,6 +22,7 @@ import {
   ReactiveFunctionVisitor,
   visitReactiveFunction,
 } from '../ReactiveScopes/visitors';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 import {Result} from '../Utils/Result';
 
 /**
@@ -109,13 +109,8 @@ class Visitor extends ReactiveFunctionVisitor<CompilerError> {
           isUnmemoized(deps.identifier, this.scopes))
       ) {
         state.push({
-          category: ErrorCategory.EffectDependencies,
-          reason:
-            'React Compiler has skipped optimizing this component because the effect dependencies could not be memoized. Unmemoized effect dependencies can trigger an infinite loop or other unexpected behavior',
-          description: null,
-          severity: ErrorSeverity.CannotPreserveMemoization,
+          errorCode: ErrorCode.MEMOIZED_EFFECT_DEPENDENCIES,
           loc: typeof instruction.loc !== 'symbol' ? instruction.loc : null,
-          suggestions: null,
         });
       }
     }

compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateNoCapitalizedCalls.ts

@@ -5,10 +5,10 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {CompilerError, EnvironmentConfig, ErrorSeverity} from '..';
-import {ErrorCategory} from '../CompilerError';
+import {CompilerError, EnvironmentConfig} from '..';
 import {HIRFunction, IdentifierId} from '../HIR';
 import {DEFAULT_GLOBALS} from '../HIR/Globals';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 import {Result} from '../Utils/Result';
 
 export function validateNoCapitalizedCalls(
@@ -34,8 +34,6 @@ export function validateNoCapitalizedCalls(
   const errors = new CompilerError();
   const capitalLoadGlobals = new Map<IdentifierId, string>();
   const capitalizedProperties = new Map<IdentifierId, string>();
-  const reason =
-    'Capitalized functions are reserved for components, which must be invoked with JSX. If this is a component, render it with JSX. Otherwise, ensure that it has no hook calls and rename it to begin with a lowercase letter. Alternatively, if you know for a fact that this function is not a component, you can allowlist it via the compiler config';
   for (const [, block] of fn.body.blocks) {
     for (const {lvalue, value} of block.instructions) {
       switch (value.kind) {
@@ -56,12 +54,9 @@ export function validateNoCapitalizedCalls(
           const calleeIdentifier = value.callee.identifier.id;
           const calleeName = capitalLoadGlobals.get(calleeIdentifier);
           if (calleeName != null) {
-            CompilerError.throwInvalidReact({
-              category: ErrorCategory.CapitalizedCalls,
-              reason,
+            errors.pushErrorCode(ErrorCode.CAPITALIZED_CALLS, {
               description: `${calleeName} may be a component.`,
               loc: value.loc,
-              suggestions: null,
             });
           }
           break;
@@ -80,13 +75,9 @@ export function validateNoCapitalizedCalls(
           const propertyIdentifier = value.property.identifier.id;
           const propertyName = capitalizedProperties.get(propertyIdentifier);
           if (propertyName != null) {
-            errors.push({
-              category: ErrorCategory.CapitalizedCalls,
-              severity: ErrorSeverity.InvalidReact,
-              reason,
+            errors.pushErrorCode(ErrorCode.CAPITALIZED_CALLS, {
               description: `${propertyName} may be a component.`,
               loc: value.loc,
-              suggestions: null,
             });
           }
           break;

compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateNoDerivedComputationsInEffects.ts

@@ -5,8 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {CompilerError, ErrorSeverity, SourceLocation} from '..';
-import {ErrorCategory} from '../CompilerError';
+import {CompilerError, SourceLocation} from '..';
 import {
   ArrayExpression,
   BlockId,
@@ -20,6 +19,8 @@ import {
   eachInstructionValueOperand,
   eachTerminalOperand,
 } from '../HIR/visitors';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
+import {Result} from '../Utils/Result';
 
 /**
  * Validates that useEffect is not used for derived computations which could/should
@@ -44,7 +45,9 @@ import {
  * const fullName = firstName + ' ' + lastName;
  * ```
  */
-export function validateNoDerivedComputationsInEffects(fn: HIRFunction): void {
+export function validateNoDerivedComputationsInEffects(
+  fn: HIRFunction,
+): Result<void, CompilerError> {
   const candidateDependencies: Map<IdentifierId, ArrayExpression> = new Map();
   const functions: Map<IdentifierId, FunctionExpression> = new Map();
   const locals: Map<IdentifierId, IdentifierId> = new Map();
@@ -97,9 +100,7 @@ export function validateNoDerivedComputationsInEffects(fn: HIRFunction): void {
       }
     }
   }
-  if (errors.hasErrors()) {
-    throw errors;
-  }
+  return errors.asResult();
 }
 
 function validateEffect(
@@ -219,14 +220,6 @@ function validateEffect(
   }
 
   for (const loc of setStateLocations) {
-    errors.push({
-      category: ErrorCategory.EffectDerivationsOfState,
-      reason:
-        'Values derived from props and state should be calculated during render, not in an effect. (https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state)',
-      description: null,
-      severity: ErrorSeverity.InvalidReact,
-      loc,
-      suggestions: null,
-    });
+    errors.pushErrorCode(ErrorCode.NO_DERIVED_COMPUTATIONS_IN_EFFECTS, {loc});
   }
 }

compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateNoFreezingKnownMutableFunctions.ts

@@ -5,11 +5,13 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {CompilerDiagnostic, CompilerError, Effect, ErrorSeverity} from '..';
-import {ErrorCategory} from '../CompilerError';
+import {CompilerDiagnostic, CompilerError, Effect} from '..';
+import {ErrorCode} from '../CompilerError';
 import {
+  FunctionEffect,
   HIRFunction,
   IdentifierId,
+  isMutableEffect,
   isRefOrRefLikeMutableType,
   Place,
 } from '../HIR';
@@ -17,8 +19,8 @@ import {
   eachInstructionValueOperand,
   eachTerminalOperand,
 } from '../HIR/visitors';
-import {AliasingEffect} from '../Inference/AliasingEffects';
 import {Result} from '../Utils/Result';
+import {Iterable_some} from '../Utils/utils';
 
 /**
  * Validates that functions with known mutations (ie due to types) cannot be passed
@@ -49,14 +51,14 @@ export function validateNoFreezingKnownMutableFunctions(
   const errors = new CompilerError();
   const contextMutationEffects: Map<
     IdentifierId,
-    Extract<AliasingEffect, {kind: 'Mutate'} | {kind: 'MutateTransitive'}>
+    Extract<FunctionEffect, {kind: 'ContextMutation'}>
   > = new Map();
 
   function visitOperand(operand: Place): void {
     if (operand.effect === Effect.Freeze) {
       const effect = contextMutationEffects.get(operand.identifier.id);
       if (effect != null) {
-        const place = effect.value;
+        const place = [...effect.places][0];
         const variable =
           place != null &&
           place.identifier.name != null &&
@@ -64,12 +66,7 @@ export function validateNoFreezingKnownMutableFunctions(
             ? `\`${place.identifier.name.value}\``
             : 'a local variable';
         errors.pushDiagnostic(
-          CompilerDiagnostic.create({
-            category: ErrorCategory.Immutability,
-            severity: ErrorSeverity.InvalidReact,
-            reason: 'Cannot modify local variables after render completes',
-            description: `This argument is a function which may reassign or mutate ${variable} after render, which can cause inconsistent behavior on subsequent renders. Consider using state instead.`,
-          })
+          CompilerDiagnostic.fromCode(ErrorCode.WRITE_AFTER_RENDER)
             .withDetail({
               kind: 'error',
               loc: operand.loc,
@@ -77,7 +74,7 @@ export function validateNoFreezingKnownMutableFunctions(
             })
             .withDetail({
               kind: 'error',
-              loc: effect.value.loc,
+              loc: effect.loc,
               message: `This modifies ${variable}`,
             }),
         );
@@ -108,7 +105,27 @@ export function validateNoFreezingKnownMutableFunctions(
           break;
         }
         case 'FunctionExpression': {
-          if (value.loweredFunc.func.aliasingEffects != null) {
+          const knownMutation = (value.loweredFunc.func.effects ?? []).find(
+            effect => {
+              return (
+                effect.kind === 'ContextMutation' &&
+                (effect.effect === Effect.Store ||
+                  effect.effect === Effect.Mutate) &&
+                Iterable_some(effect.places, place => {
+                  return (
+                    isMutableEffect(place.effect, place.loc) &&
+                    !isRefOrRefLikeMutableType(place.identifier.type)
+                  );
+                })
+              );
+            },
+          );
+          if (knownMutation && knownMutation.kind === 'ContextMutation') {
+            contextMutationEffects.set(lvalue.identifier.id, knownMutation);
+          } else if (
+            fn.env.config.enableNewMutationAliasingModel &&
+            value.loweredFunc.func.aliasingEffects != null
+          ) {
             const context = new Set(
               value.loweredFunc.func.context.map(p => p.identifier.id),
             );
@@ -129,7 +146,12 @@ export function validateNoFreezingKnownMutableFunctions(
                     context.has(effect.value.identifier.id) &&
                     !isRefOrRefLikeMutableType(effect.value.identifier.type)
                   ) {
-                    contextMutationEffects.set(lvalue.identifier.id, effect);
+                    contextMutationEffects.set(lvalue.identifier.id, {
+                      kind: 'ContextMutation',
+                      effect: Effect.Mutate,
+                      loc: effect.value.loc,
+                      places: new Set([effect.value]),
+                    });
                     break effects;
                   }
                   break;

compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateNoImpureFunctionsInRender.ts

@@ -5,10 +5,10 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {CompilerDiagnostic, CompilerError, ErrorSeverity} from '..';
-import {ErrorCategory} from '../CompilerError';
+import {CompilerDiagnostic, CompilerError} from '..';
 import {HIRFunction} from '../HIR';
-import {getFunctionCallSignature} from '../Inference/InferMutationAliasingEffects';
+import {getFunctionCallSignature} from '../Inference/InferReferenceEffects';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 import {Result} from '../Utils/Result';
 
 /**
@@ -36,20 +36,13 @@ export function validateNoImpureFunctionsInRender(
         );
         if (signature != null && signature.impure === true) {
           errors.pushDiagnostic(
-            CompilerDiagnostic.create({
-              category: ErrorCategory.Purity,
-              reason: 'Cannot call impure function during render',
-              description:
-                (signature.canonicalName != null
-                  ? `\`${signature.canonicalName}\` is an impure function. `
-                  : '') +
-                'Calling an impure function can produce unstable results that update unpredictably when the component happens to re-render. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#components-and-hooks-must-be-idempotent)',
-              severity: ErrorSeverity.InvalidReact,
-              suggestions: null,
-            }).withDetail({
+            CompilerDiagnostic.fromCode(ErrorCode.IMPURE_FUNCTIONS).withDetail({
               kind: 'error',
               loc: callee.loc,
-              message: 'Cannot call impure function',
+              message:
+                signature.canonicalName != null
+                  ? `\`${signature.canonicalName}\` is an impure function. `
+                  : 'This is an impure function.',
             }),
           );
         }

compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateNoJSXInTryStatement.ts

@@ -5,9 +5,9 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {CompilerDiagnostic, CompilerError, ErrorSeverity} from '..';
-import {ErrorCategory} from '../CompilerError';
+import {CompilerDiagnostic, CompilerError} from '..';
 import {BlockId, HIRFunction} from '../HIR';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 import {Result} from '../Utils/Result';
 import {retainWhere} from '../Utils/utils';
 
@@ -36,12 +36,7 @@ export function validateNoJSXInTryStatement(
           case 'JsxExpression':
           case 'JsxFragment': {
             errors.pushDiagnostic(
-              CompilerDiagnostic.create({
-                category: ErrorCategory.ErrorBoundaries,
-                severity: ErrorSeverity.InvalidReact,
-                reason: 'Avoid constructing JSX within try/catch',
-                description: `React does not immediately render components when JSX is rendered, so any errors from this component will not be caught by the try/catch. To catch errors in rendering a given component, wrap that component in an error boundary. (https://react.dev/reference/react/Component#catching-rendering-errors-with-an-error-boundary)`,
-              }).withDetail({
+              CompilerDiagnostic.fromCode(ErrorCode.JSX_IN_TRY).withDetail({
                 kind: 'error',
                 loc: value.loc,
                 message: 'Avoid constructing JSX within try/catch',

compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateNoRefAccessInRender.ts

@@ -5,12 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {
-  CompilerDiagnostic,
-  CompilerError,
-  ErrorCategory,
-  ErrorSeverity,
-} from '../CompilerError';
+import {CompilerDiagnostic, CompilerError} from '../CompilerError';
 import {
   BlockId,
   HIRFunction,
@@ -27,6 +22,7 @@ import {
   eachPatternOperand,
   eachTerminalOperand,
 } from '../HIR/visitors';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 import {Err, Ok, Result} from '../Utils/Result';
 import {retainWhere} from '../Utils/utils';
 
@@ -468,12 +464,9 @@ function validateNoRefAccessInRenderImpl(
               if (fnType.fn.readRefEffect) {
                 didError = true;
                 errors.pushDiagnostic(
-                  CompilerDiagnostic.create({
-                    category: ErrorCategory.Refs,
-                    severity: ErrorSeverity.InvalidReact,
-                    reason: 'Cannot access refs during render',
-                    description: ERROR_DESCRIPTION,
-                  }).withDetail({
+                  CompilerDiagnostic.fromCode(
+                    ErrorCode.NO_REF_ACCESS_IN_RENDER,
+                  ).withDetail({
                     kind: 'error',
                     loc: callee.loc,
                     message: `This function accesses a ref value`,
@@ -732,16 +725,13 @@ function destructure(
 function guardCheck(errors: CompilerError, operand: Place, env: Env): void {
   if (env.get(operand.identifier.id)?.kind === 'Guard') {
     errors.pushDiagnostic(
-      CompilerDiagnostic.create({
-        category: ErrorCategory.Refs,
-        severity: ErrorSeverity.InvalidReact,
-        reason: 'Cannot access refs during render',
-        description: ERROR_DESCRIPTION,
-      }).withDetail({
-        kind: 'error',
-        loc: operand.loc,
-        message: `Cannot access ref value during render`,
-      }),
+      CompilerDiagnostic.fromCode(ErrorCode.NO_REF_ACCESS_IN_RENDER).withDetail(
+        {
+          kind: 'error',
+          loc: operand.loc,
+          message: `Cannot access ref value during render`,
+        },
+      ),
     );
   }
 }
@@ -757,16 +747,13 @@ function validateNoRefValueAccess(
     (type?.kind === 'Structure' && type.fn?.readRefEffect)
   ) {
     errors.pushDiagnostic(
-      CompilerDiagnostic.create({
-        category: ErrorCategory.Refs,
-        severity: ErrorSeverity.InvalidReact,
-        reason: 'Cannot access refs during render',
-        description: ERROR_DESCRIPTION,
-      }).withDetail({
-        kind: 'error',
-        loc: (type.kind === 'RefValue' && type.loc) || operand.loc,
-        message: `Cannot access ref value during render`,
-      }),
+      CompilerDiagnostic.fromCode(ErrorCode.NO_REF_ACCESS_IN_RENDER).withDetail(
+        {
+          kind: 'error',
+          loc: (type.kind === 'RefValue' && type.loc) || operand.loc,
+          message: `Cannot access ref value during render`,
+        },
+      ),
     );
   }
 }
@@ -784,16 +771,13 @@ function validateNoRefPassedToFunction(
     (type?.kind === 'Structure' && type.fn?.readRefEffect)
   ) {
     errors.pushDiagnostic(
-      CompilerDiagnostic.create({
-        category: ErrorCategory.Refs,
-        severity: ErrorSeverity.InvalidReact,
-        reason: 'Cannot access refs during render',
-        description: ERROR_DESCRIPTION,
-      }).withDetail({
-        kind: 'error',
-        loc: (type.kind === 'RefValue' && type.loc) || loc,
-        message: `Passing a ref to a function may read its value during render`,
-      }),
+      CompilerDiagnostic.fromCode(ErrorCode.NO_REF_ACCESS_IN_RENDER).withDetail(
+        {
+          kind: 'error',
+          loc: (type.kind === 'RefValue' && type.loc) || loc,
+          message: `Passing a ref to a function may read its value during render`,
+        },
+      ),
     );
   }
 }
@@ -807,16 +791,13 @@ function validateNoRefUpdate(
   const type = destructure(env.get(operand.identifier.id));
   if (type?.kind === 'Ref' || type?.kind === 'RefValue') {
     errors.pushDiagnostic(
-      CompilerDiagnostic.create({
-        category: ErrorCategory.Refs,
-        severity: ErrorSeverity.InvalidReact,
-        reason: 'Cannot access refs during render',
-        description: ERROR_DESCRIPTION,
-      }).withDetail({
-        kind: 'error',
-        loc: (type.kind === 'RefValue' && type.loc) || loc,
-        message: `Cannot update ref during render`,
-      }),
+      CompilerDiagnostic.fromCode(ErrorCode.NO_REF_ACCESS_IN_RENDER).withDetail(
+        {
+          kind: 'error',
+          loc: (type.kind === 'RefValue' && type.loc) || loc,
+          message: `Cannot update ref during render`,
+        },
+      ),
     );
   }
 }
@@ -829,22 +810,13 @@ function validateNoDirectRefValueAccess(
   const type = destructure(env.get(operand.identifier.id));
   if (type?.kind === 'RefValue') {
     errors.pushDiagnostic(
-      CompilerDiagnostic.create({
-        category: ErrorCategory.Refs,
-        severity: ErrorSeverity.InvalidReact,
-        reason: 'Cannot access refs during render',
-        description: ERROR_DESCRIPTION,
-      }).withDetail({
-        kind: 'error',
-        loc: type.loc ?? operand.loc,
-        message: `Cannot access ref value during render`,
-      }),
+      CompilerDiagnostic.fromCode(ErrorCode.NO_REF_ACCESS_IN_RENDER).withDetail(
+        {
+          kind: 'error',
+          loc: type.loc ?? operand.loc,
+          message: `Cannot access ref value during render`,
+        },
+      ),
     );
   }
 }
-
-const ERROR_DESCRIPTION =
-  'React refs are values that are not needed for rendering. Refs should only be accessed ' +
-  'outside of render, such as in event handlers or effects. ' +
-  'Accessing a ref value (the `current` property) during render can cause your component ' +
-  'not to update as expected (https://react.dev/reference/react/useRef)';

compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateNoSetStateInEffects.ts

@@ -5,12 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {
-  CompilerDiagnostic,
-  CompilerError,
-  ErrorCategory,
-  ErrorSeverity,
-} from '../CompilerError';
+import {CompilerDiagnostic, CompilerError} from '../CompilerError';
 import {
   HIRFunction,
   IdentifierId,
@@ -21,6 +16,7 @@ import {
   Place,
 } from '../HIR';
 import {eachInstructionValueOperand} from '../HIR/visitors';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 import {Result} from '../Utils/Result';
 
 /**
@@ -96,20 +92,9 @@ export function validateNoSetStateInEffects(
               const setState = setStateFunctions.get(arg.identifier.id);
               if (setState !== undefined) {
                 errors.pushDiagnostic(
-                  CompilerDiagnostic.create({
-                    category: ErrorCategory.EffectSetState,
-                    reason:
-                      'Calling setState synchronously within an effect can trigger cascading renders',
-                    description:
-                      'Effects are intended to synchronize state between React and external systems such as manually updating the DOM, state management libraries, or other platform APIs. ' +
-                      'In general, the body of an effect should do one or both of the following:\n' +
-                      '* Update external systems with the latest state from React.\n' +
-                      '* Subscribe for updates from some external system, calling setState in a callback function when external state changes.\n\n' +
-                      'Calling setState synchronously within an effect body causes cascading renders that can hurt performance, and is not recommended. ' +
-                      '(https://react.dev/learn/you-might-not-need-an-effect)',
-                    severity: ErrorSeverity.InvalidReact,
-                    suggestions: null,
-                  }).withDetail({
+                  CompilerDiagnostic.fromCode(
+                    ErrorCode.INVALID_SET_STATE_IN_EFFECTS,
+                  ).withDetail({
                     kind: 'error',
                     loc: setState.loc,
                     message:

compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateNoSetStateInRender.ts

@@ -5,15 +5,11 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {
-  CompilerDiagnostic,
-  CompilerError,
-  ErrorCategory,
-  ErrorSeverity,
-} from '../CompilerError';
+import {CompilerDiagnostic, CompilerError} from '../CompilerError';
 import {HIRFunction, IdentifierId, isSetStateType} from '../HIR';
 import {computeUnconditionalBlocks} from '../HIR/ComputeUnconditionalBlocks';
 import {eachInstructionValueOperand} from '../HIR/visitors';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 import {Result} from '../Utils/Result';
 
 /**
@@ -128,15 +124,9 @@ function validateNoSetStateInRenderImpl(
           ) {
             if (activeManualMemoId !== null) {
               errors.pushDiagnostic(
-                CompilerDiagnostic.create({
-                  category: ErrorCategory.RenderSetState,
-                  reason:
-                    'Calling setState from useMemo may trigger an infinite loop',
-                  description:
-                    'Each time the memo callback is evaluated it will change state. This can cause a memoization dependency to change, running the memo function again and causing an infinite loop. Instead of setting state in useMemo(), prefer deriving the value during render. (https://react.dev/reference/react/useState)',
-                  severity: ErrorSeverity.InvalidReact,
-                  suggestions: null,
-                }).withDetail({
+                CompilerDiagnostic.fromCode(
+                  ErrorCode.INVALID_SET_STATE_IN_MEMO,
+                ).withDetail({
                   kind: 'error',
                   loc: callee.loc,
                   message: 'Found setState() within useMemo()',
@@ -144,18 +134,12 @@ function validateNoSetStateInRenderImpl(
               );
             } else if (unconditionalBlocks.has(block.id)) {
               errors.pushDiagnostic(
-                CompilerDiagnostic.create({
-                  category: ErrorCategory.RenderSetState,
-                  reason:
-                    'Calling setState during render may trigger an infinite loop',
-                  description:
-                    'Calling setState during render will trigger another render, and can lead to infinite loops. (https://react.dev/reference/react/useState)',
-                  severity: ErrorSeverity.InvalidReact,
-                  suggestions: null,
-                }).withDetail({
+                CompilerDiagnostic.fromCode(
+                  ErrorCode.INVALID_SET_STATE_IN_RENDER,
+                ).withDetail({
                   kind: 'error',
                   loc: callee.loc,
-                  message: 'Found setState() in render',
+                  message: 'Found setState() call here',
                 }),
               );
             }

compiler/packages/babel-plugin-react-compiler/src/Validation/ValidatePreservedManualMemoization.ts

@@ -5,12 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {
-  CompilerDiagnostic,
-  CompilerError,
-  ErrorCategory,
-  ErrorSeverity,
-} from '../CompilerError';
+import {CompilerDiagnostic, CompilerError, ErrorCode} from '../CompilerError';
 import {
   DeclarationId,
   Effect,
@@ -281,14 +276,8 @@ function validateInferredDep(
     }
   }
   errorState.pushDiagnostic(
-    CompilerDiagnostic.create({
-      category: ErrorCategory.PreserveManualMemo,
-      severity: ErrorSeverity.CannotPreserveMemoization,
-      reason:
-        'Compilation skipped because existing memoization could not be preserved',
-      description: [
-        'React Compiler has skipped optimizing this component because the existing manual memoization could not be preserved. ',
-        'The inferred dependencies did not match the manually specified dependencies, which could cause the value to change more or less frequently than expected. ',
+    CompilerDiagnostic.fromCode(ErrorCode.MANUAL_MEMO_DEPENDENCIES_CONFLICT, {
+      description:
         DEBUG ||
         // If the dependency is a named variable then we can report it. Otherwise only print in debug mode
         (dep.identifier.name != null && dep.identifier.name.kind === 'named')
@@ -300,11 +289,8 @@ function validateInferredDep(
               errorDiagnostic
                 ? getCompareDependencyResultDescription(errorDiagnostic)
                 : 'Inferred dependency not present in source'
-            }.`
+            }`
           : '',
-      ]
-        .join('')
-        .trim(),
       suggestions: null,
     }).withDetail({
       kind: 'error',
@@ -536,16 +522,9 @@ class Visitor extends ReactiveFunctionVisitor<VisitorState> {
           !this.prunedScopes.has(identifier.scope.id)
         ) {
           state.errors.pushDiagnostic(
-            CompilerDiagnostic.create({
-              category: ErrorCategory.PreserveManualMemo,
-              severity: ErrorSeverity.CannotPreserveMemoization,
-              reason:
-                'Compilation skipped because existing memoization could not be preserved',
-              description: [
-                'React Compiler has skipped optimizing this component because the existing manual memoization could not be preserved. ',
-                'This dependency may be mutated later, which could cause the value to change unexpectedly.',
-              ].join(''),
-            }).withDetail({
+            CompilerDiagnostic.fromCode(
+              ErrorCode.MANUAL_MEMO_MUTATED_LATER,
+            ).withDetail({
               kind: 'error',
               loc,
               message: 'This dependency may be modified later',
@@ -585,19 +564,10 @@ class Visitor extends ReactiveFunctionVisitor<VisitorState> {
           for (const identifier of decls) {
             if (isUnmemoized(identifier, this.scopes)) {
               state.errors.pushDiagnostic(
-                CompilerDiagnostic.create({
-                  category: ErrorCategory.PreserveManualMemo,
-                  severity: ErrorSeverity.CannotPreserveMemoization,
-                  reason:
-                    'Compilation skipped because existing memoization could not be preserved',
-                  description: [
-                    'React Compiler has skipped optimizing this component because the existing manual memoization could not be preserved. This value was memoized in source but not in compilation output. ',
-                    DEBUG
-                      ? `${printIdentifier(identifier)} was not memoized.`
-                      : '',
-                  ]
-                    .join('')
-                    .trim(),
+                CompilerDiagnostic.fromCode(ErrorCode.MANUAL_MEMO_REMOVED, {
+                  description: DEBUG
+                    ? `${printIdentifier(identifier)} was not memoized`
+                    : '',
                 }).withDetail({
                   kind: 'error',
                   loc,

compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateStaticComponents.ts

@@ -5,13 +5,9 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {
-  CompilerDiagnostic,
-  CompilerError,
-  ErrorCategory,
-  ErrorSeverity,
-} from '../CompilerError';
+import {CompilerDiagnostic, CompilerError} from '../CompilerError';
 import {HIRFunction, IdentifierId, SourceLocation} from '../HIR';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 import {Result} from '../Utils/Result';
 
 /**
@@ -65,10 +61,7 @@ export function validateStaticComponents(
             );
             if (location != null) {
               error.pushDiagnostic(
-                CompilerDiagnostic.create({
-                  category: ErrorCategory.StaticComponents,
-                  severity: ErrorSeverity.InvalidReact,
-                  reason: 'Cannot create components during render',
+                CompilerDiagnostic.fromCode(ErrorCode.STATIC_COMPONENTS, {
                   description: `Components created during render will reset their state each time they are created. Declare components outside of render. `,
                 })
                   .withDetail({

compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateUseMemo.ts

@@ -5,13 +5,9 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {
-  CompilerDiagnostic,
-  CompilerError,
-  ErrorCategory,
-  ErrorSeverity,
-} from '../CompilerError';
+import {CompilerDiagnostic, CompilerError} from '../CompilerError';
 import {FunctionExpression, HIRFunction, IdentifierId} from '../HIR';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 import {Result} from '../Utils/Result';
 
 export function validateUseMemo(fn: HIRFunction): Result<void, CompilerError> {
@@ -74,14 +70,9 @@ export function validateUseMemo(fn: HIRFunction): Result<void, CompilerError> {
                 ? firstParam.loc
                 : firstParam.place.loc;
             errors.pushDiagnostic(
-              CompilerDiagnostic.create({
-                category: ErrorCategory.UseMemo,
-                severity: ErrorSeverity.InvalidReact,
-                reason: 'useMemo() callbacks may not accept parameters',
-                description:
-                  'useMemo() callbacks are called by React to cache calculations across re-renders. They should not take parameters. Instead, directly reference the props, state, or local variables needed for the computation.',
-                suggestions: null,
-              }).withDetail({
+              CompilerDiagnostic.fromCode(
+                ErrorCode.INVALID_USE_MEMO_CALLBACK_PARAMETERS,
+              ).withDetail({
                 kind: 'error',
                 loc,
                 message: 'Callbacks with parameters are not supported',
@@ -91,15 +82,9 @@ export function validateUseMemo(fn: HIRFunction): Result<void, CompilerError> {
 
           if (body.loweredFunc.func.async || body.loweredFunc.func.generator) {
             errors.pushDiagnostic(
-              CompilerDiagnostic.create({
-                category: ErrorCategory.UseMemo,
-                severity: ErrorSeverity.InvalidReact,
-                reason:
-                  'useMemo() callbacks may not be async or generator functions',
-                description:
-                  'useMemo() callbacks are called once and must synchronously return a value.',
-                suggestions: null,
-              }).withDetail({
+              CompilerDiagnostic.fromCode(
+                ErrorCode.INVALID_USE_MEMO_CALLBACK_ASYNC,
+              ).withDetail({
                 kind: 'error',
                 loc: body.loc,
                 message: 'Async and generator functions are not supported',

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/allow-assigning-to-global-in-function-spread-as-jsx.expect.md

@@ -1,39 +0,0 @@
-
-## Input
-
-```javascript
-// @enableNewMutationAliasingModel:false
-function Component() {
-  const foo = () => {
-    someGlobal = true;
-  };
-  // spreading a function is weird, but it doesn't call the function so this is allowed
-  return <div {...foo} />;
-}
-
-```
-
-## Code
-
-```javascript
-import { c as _c } from "react/compiler-runtime"; // @enableNewMutationAliasingModel:false
-function Component() {
-  const $ = _c(1);
-  const foo = _temp;
-  let t0;
-  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
-    t0 = <div {...foo} />;
-    $[0] = t0;
-  } else {
-    t0 = $[0];
-  }
-  return t0;
-}
-function _temp() {
-  someGlobal = true;
-}
-
-```
-      
-### Eval output
-(kind: exception) Fixture not implemented

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/bug-aliased-capture-aliased-mutate.expect.md

@@ -0,0 +1,107 @@
+
+## Input
+
+```javascript
+// @flow @enableTransitivelyFreezeFunctionExpressions:false @enableNewMutationAliasingModel:false
+import {arrayPush, setPropertyByKey, Stringify} from 'shared-runtime';
+
+/**
+ * 1. `InferMutableRanges` derives the mutable range of identifiers and their
+ *     aliases from `LoadLocal`, `PropertyLoad`, etc
+ *   - After this pass, y's mutable range only extends to `arrayPush(x, y)`
+ *   - We avoid assigning mutable ranges to loads after y's mutable range, as
+ *     these are working with an immutable value. As a result, `LoadLocal y` and
+ *     `PropertyLoad y` do not get mutable ranges
+ * 2. `InferReactiveScopeVariables` extends mutable ranges and creates scopes,
+ *    as according to the 'co-mutation' of different values
+ *   - Here, we infer that
+ *     - `arrayPush(y, x)` might alias `x` and `y` to each other
+ *     - `setPropertyKey(x, ...)` may mutate both `x` and `y`
+ *   - This pass correctly extends the mutable range of `y`
+ *   - Since we didn't run `InferMutableRange` logic again, the LoadLocal /
+ *     PropertyLoads still don't have a mutable range
+ *
+ * Note that the this bug is an edge case. Compiler output is only invalid for:
+ *  - function expressions with
+ *    `enableTransitivelyFreezeFunctionExpressions:false`
+ *  - functions that throw and get retried without clearing the memocache
+ *
+ * Found differences in evaluator results
+ * Non-forget (expected):
+ *   (kind: ok)
+ *   <div>{"cb":{"kind":"Function","result":10},"shouldInvokeFns":true}</div>
+ *   <div>{"cb":{"kind":"Function","result":11},"shouldInvokeFns":true}</div>
+ * Forget:
+ *   (kind: ok)
+ *   <div>{"cb":{"kind":"Function","result":10},"shouldInvokeFns":true}</div>
+ *   <div>{"cb":{"kind":"Function","result":10},"shouldInvokeFns":true}</div>
+ */
+function useFoo({a, b}: {a: number, b: number}) {
+  const x = [];
+  const y = {value: a};
+
+  arrayPush(x, y); // x and y co-mutate
+  const y_alias = y;
+  const cb = () => y_alias.value;
+  setPropertyByKey(x[0], 'value', b); // might overwrite y.value
+  return <Stringify cb={cb} shouldInvokeFns={true} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useFoo,
+  params: [{a: 2, b: 10}],
+  sequentialRenders: [
+    {a: 2, b: 10},
+    {a: 2, b: 11},
+  ],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime";
+import { arrayPush, setPropertyByKey, Stringify } from "shared-runtime";
+
+function useFoo(t0) {
+  const $ = _c(5);
+  const { a, b } = t0;
+  let t1;
+  if ($[0] !== a || $[1] !== b) {
+    const x = [];
+    const y = { value: a };
+
+    arrayPush(x, y);
+    const y_alias = y;
+    let t2;
+    if ($[3] !== y_alias.value) {
+      t2 = () => y_alias.value;
+      $[3] = y_alias.value;
+      $[4] = t2;
+    } else {
+      t2 = $[4];
+    }
+    const cb = t2;
+    setPropertyByKey(x[0], "value", b);
+    t1 = <Stringify cb={cb} shouldInvokeFns={true} />;
+    $[0] = a;
+    $[1] = b;
+    $[2] = t1;
+  } else {
+    t1 = $[2];
+  }
+  return t1;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useFoo,
+  params: [{ a: 2, b: 10 }],
+  sequentialRenders: [
+    { a: 2, b: 10 },
+    { a: 2, b: 11 },
+  ],
+};
+
+```
+      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/bug-aliased-capture-aliased-mutate.js

@@ -0,0 +1,53 @@
+// @flow @enableTransitivelyFreezeFunctionExpressions:false @enableNewMutationAliasingModel:false
+import {arrayPush, setPropertyByKey, Stringify} from 'shared-runtime';
+
+/**
+ * 1. `InferMutableRanges` derives the mutable range of identifiers and their
+ *     aliases from `LoadLocal`, `PropertyLoad`, etc
+ *   - After this pass, y's mutable range only extends to `arrayPush(x, y)`
+ *   - We avoid assigning mutable ranges to loads after y's mutable range, as
+ *     these are working with an immutable value. As a result, `LoadLocal y` and
+ *     `PropertyLoad y` do not get mutable ranges
+ * 2. `InferReactiveScopeVariables` extends mutable ranges and creates scopes,
+ *    as according to the 'co-mutation' of different values
+ *   - Here, we infer that
+ *     - `arrayPush(y, x)` might alias `x` and `y` to each other
+ *     - `setPropertyKey(x, ...)` may mutate both `x` and `y`
+ *   - This pass correctly extends the mutable range of `y`
+ *   - Since we didn't run `InferMutableRange` logic again, the LoadLocal /
+ *     PropertyLoads still don't have a mutable range
+ *
+ * Note that the this bug is an edge case. Compiler output is only invalid for:
+ *  - function expressions with
+ *    `enableTransitivelyFreezeFunctionExpressions:false`
+ *  - functions that throw and get retried without clearing the memocache
+ *
+ * Found differences in evaluator results
+ * Non-forget (expected):
+ *   (kind: ok)
+ *   <div>{"cb":{"kind":"Function","result":10},"shouldInvokeFns":true}</div>
+ *   <div>{"cb":{"kind":"Function","result":11},"shouldInvokeFns":true}</div>
+ * Forget:
+ *   (kind: ok)
+ *   <div>{"cb":{"kind":"Function","result":10},"shouldInvokeFns":true}</div>
+ *   <div>{"cb":{"kind":"Function","result":10},"shouldInvokeFns":true}</div>
+ */
+function useFoo({a, b}: {a: number, b: number}) {
+  const x = [];
+  const y = {value: a};
+
+  arrayPush(x, y); // x and y co-mutate
+  const y_alias = y;
+  const cb = () => y_alias.value;
+  setPropertyByKey(x[0], 'value', b); // might overwrite y.value
+  return <Stringify cb={cb} shouldInvokeFns={true} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useFoo,
+  params: [{a: 2, b: 10}],
+  sequentialRenders: [
+    {a: 2, b: 10},
+    {a: 2, b: 11},
+  ],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/bug-aliased-capture-mutate.expect.md

@@ -0,0 +1,87 @@
+
+## Input
+
+```javascript
+// @flow @enableTransitivelyFreezeFunctionExpressions:false @enableNewMutationAliasingModel:false
+import {setPropertyByKey, Stringify} from 'shared-runtime';
+
+/**
+ * Variation of bug in `bug-aliased-capture-aliased-mutate`
+ * Found differences in evaluator results
+ * Non-forget (expected):
+ *   (kind: ok)
+ *   <div>{"cb":{"kind":"Function","result":2},"shouldInvokeFns":true}</div>
+ *   <div>{"cb":{"kind":"Function","result":3},"shouldInvokeFns":true}</div>
+ * Forget:
+ *   (kind: ok)
+ *   <div>{"cb":{"kind":"Function","result":2},"shouldInvokeFns":true}</div>
+ *   <div>{"cb":{"kind":"Function","result":2},"shouldInvokeFns":true}</div>
+ */
+
+function useFoo({a}: {a: number, b: number}) {
+  const arr = [];
+  const obj = {value: a};
+
+  setPropertyByKey(obj, 'arr', arr);
+  const obj_alias = obj;
+  const cb = () => obj_alias.arr.length;
+  for (let i = 0; i < a; i++) {
+    arr.push(i);
+  }
+  return <Stringify cb={cb} shouldInvokeFns={true} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useFoo,
+  params: [{a: 2}],
+  sequentialRenders: [{a: 2}, {a: 3}],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime";
+import { setPropertyByKey, Stringify } from "shared-runtime";
+
+function useFoo(t0) {
+  const $ = _c(4);
+  const { a } = t0;
+  let t1;
+  if ($[0] !== a) {
+    const arr = [];
+    const obj = { value: a };
+
+    setPropertyByKey(obj, "arr", arr);
+    const obj_alias = obj;
+    let t2;
+    if ($[2] !== obj_alias.arr.length) {
+      t2 = () => obj_alias.arr.length;
+      $[2] = obj_alias.arr.length;
+      $[3] = t2;
+    } else {
+      t2 = $[3];
+    }
+    const cb = t2;
+    for (let i = 0; i < a; i++) {
+      arr.push(i);
+    }
+
+    t1 = <Stringify cb={cb} shouldInvokeFns={true} />;
+    $[0] = a;
+    $[1] = t1;
+  } else {
+    t1 = $[1];
+  }
+  return t1;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useFoo,
+  params: [{ a: 2 }],
+  sequentialRenders: [{ a: 2 }, { a: 3 }],
+};
+
+```
+      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/bug-aliased-capture-mutate.js

@@ -0,0 +1,34 @@
+// @flow @enableTransitivelyFreezeFunctionExpressions:false @enableNewMutationAliasingModel:false
+import {setPropertyByKey, Stringify} from 'shared-runtime';
+
+/**
+ * Variation of bug in `bug-aliased-capture-aliased-mutate`
+ * Found differences in evaluator results
+ * Non-forget (expected):
+ *   (kind: ok)
+ *   <div>{"cb":{"kind":"Function","result":2},"shouldInvokeFns":true}</div>
+ *   <div>{"cb":{"kind":"Function","result":3},"shouldInvokeFns":true}</div>
+ * Forget:
+ *   (kind: ok)
+ *   <div>{"cb":{"kind":"Function","result":2},"shouldInvokeFns":true}</div>
+ *   <div>{"cb":{"kind":"Function","result":2},"shouldInvokeFns":true}</div>
+ */
+
+function useFoo({a}: {a: number, b: number}) {
+  const arr = [];
+  const obj = {value: a};
+
+  setPropertyByKey(obj, 'arr', arr);
+  const obj_alias = obj;
+  const cb = () => obj_alias.arr.length;
+  for (let i = 0; i < a; i++) {
+    arr.push(i);
+  }
+  return <Stringify cb={cb} shouldInvokeFns={true} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useFoo,
+  params: [{a: 2}],
+  sequentialRenders: [{a: 2}, {a: 3}],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/bug-capturing-func-maybealias-captured-mutate.expect.md

@@ -85,11 +85,19 @@ import { makeArray, mutate } from "shared-runtime";
  * used when we analyze CallExpressions.
  */
 function Component(t0) {
-  const $ = _c(3);
+  const $ = _c(5);
   const { foo, bar } = t0;
+  let t1;
+  if ($[0] !== foo) {
+    t1 = { foo };
+    $[0] = foo;
+    $[1] = t1;
+  } else {
+    t1 = $[1];
+  }
+  const x = t1;
   let y;
-  if ($[0] !== bar || $[1] !== foo) {
-    const x = { foo };
+  if ($[2] !== bar || $[3] !== x) {
     y = { bar };
     const f0 = function () {
       const a = makeArray(y);
@@ -100,11 +108,11 @@ function Component(t0) {
 
     f0();
     mutate(y.x);
-    $[0] = bar;
-    $[1] = foo;
-    $[2] = y;
+    $[2] = bar;
+    $[3] = x;
+    $[4] = y;
   } else {
-    y = $[2];
+    y = $[4];
   }
   return y;
 }

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/bug-invalid-phi-as-dependency.expect.md

@@ -0,0 +1,92 @@
+
+## Input
+
+```javascript
+// @enableNewMutationAliasingModel:false
+import {CONST_TRUE, Stringify, mutate, useIdentity} from 'shared-runtime';
+
+/**
+ * Fixture showing an edge case for ReactiveScope variable propagation.
+ *
+ * Found differences in evaluator results
+ *   Non-forget (expected):
+ *   <div>{"obj":{"inner":{"value":"hello"},"wat0":"joe"},"inner":["[[ cyclic ref *2 ]]"]}</div>
+ *   <div>{"obj":{"inner":{"value":"hello"},"wat0":"joe"},"inner":["[[ cyclic ref *2 ]]"]}</div>
+ *   Forget:
+ *   <div>{"obj":{"inner":{"value":"hello"},"wat0":"joe"},"inner":["[[ cyclic ref *2 ]]"]}</div>
+ *   [[ (exception in render) Error: invariant broken ]]
+ *
+ */
+function Component() {
+  const obj = CONST_TRUE ? {inner: {value: 'hello'}} : null;
+  const boxedInner = [obj?.inner];
+  useIdentity(null);
+  mutate(obj);
+  if (boxedInner[0] !== obj?.inner) {
+    throw new Error('invariant broken');
+  }
+  return <Stringify obj={obj} inner={boxedInner} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{arg: 0}],
+  sequentialRenders: [{arg: 0}, {arg: 1}],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @enableNewMutationAliasingModel:false
+import { CONST_TRUE, Stringify, mutate, useIdentity } from "shared-runtime";
+
+/**
+ * Fixture showing an edge case for ReactiveScope variable propagation.
+ *
+ * Found differences in evaluator results
+ *   Non-forget (expected):
+ *   <div>{"obj":{"inner":{"value":"hello"},"wat0":"joe"},"inner":["[[ cyclic ref *2 ]]"]}</div>
+ *   <div>{"obj":{"inner":{"value":"hello"},"wat0":"joe"},"inner":["[[ cyclic ref *2 ]]"]}</div>
+ *   Forget:
+ *   <div>{"obj":{"inner":{"value":"hello"},"wat0":"joe"},"inner":["[[ cyclic ref *2 ]]"]}</div>
+ *   [[ (exception in render) Error: invariant broken ]]
+ *
+ */
+function Component() {
+  const $ = _c(4);
+  const obj = CONST_TRUE ? { inner: { value: "hello" } } : null;
+  let t0;
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+    t0 = [obj?.inner];
+    $[0] = t0;
+  } else {
+    t0 = $[0];
+  }
+  const boxedInner = t0;
+  useIdentity(null);
+  mutate(obj);
+  if (boxedInner[0] !== obj?.inner) {
+    throw new Error("invariant broken");
+  }
+  let t1;
+  if ($[1] !== boxedInner || $[2] !== obj) {
+    t1 = <Stringify obj={obj} inner={boxedInner} />;
+    $[1] = boxedInner;
+    $[2] = obj;
+    $[3] = t1;
+  } else {
+    t1 = $[3];
+  }
+  return t1;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{ arg: 0 }],
+  sequentialRenders: [{ arg: 0 }, { arg: 1 }],
+};
+
+```
+      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/bug-invalid-phi-as-dependency.tsx

@@ -0,0 +1,31 @@
+// @enableNewMutationAliasingModel:false
+import {CONST_TRUE, Stringify, mutate, useIdentity} from 'shared-runtime';
+
+/**
+ * Fixture showing an edge case for ReactiveScope variable propagation.
+ *
+ * Found differences in evaluator results
+ *   Non-forget (expected):
+ *   <div>{"obj":{"inner":{"value":"hello"},"wat0":"joe"},"inner":["[[ cyclic ref *2 ]]"]}</div>
+ *   <div>{"obj":{"inner":{"value":"hello"},"wat0":"joe"},"inner":["[[ cyclic ref *2 ]]"]}</div>
+ *   Forget:
+ *   <div>{"obj":{"inner":{"value":"hello"},"wat0":"joe"},"inner":["[[ cyclic ref *2 ]]"]}</div>
+ *   [[ (exception in render) Error: invariant broken ]]
+ *
+ */
+function Component() {
+  const obj = CONST_TRUE ? {inner: {value: 'hello'}} : null;
+  const boxedInner = [obj?.inner];
+  useIdentity(null);
+  mutate(obj);
+  if (boxedInner[0] !== obj?.inner) {
+    throw new Error('invariant broken');
+  }
+  return <Stringify obj={obj} inner={boxedInner} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{arg: 0}],
+  sequentialRenders: [{arg: 0}, {arg: 1}],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/bug-object-expression-computed-key-modified-during-after-construction-hoisted-sequence-expr.expect.md

@@ -0,0 +1,110 @@
+
+## Input
+
+```javascript
+// @enableNewMutationAliasingModel:false
+import {identity, mutate} from 'shared-runtime';
+
+/**
+ * Bug: copy of error.todo-object-expression-computed-key-modified-during-after-construction-sequence-expr
+ * with the mutation hoisted to a named variable instead of being directly
+ * inlined into the Object key.
+ *
+ * Found differences in evaluator results
+ *   Non-forget (expected):
+ *   (kind: ok) [{"[object Object]":[42]},{"wat0":"joe","wat1":"joe"}]
+ *   [{"[object Object]":[42]},{"wat0":"joe","wat1":"joe"}]
+ *   Forget:
+ *   (kind: ok) [{"[object Object]":[42]},{"wat0":"joe","wat1":"joe"}]
+ *   [{"[object Object]":[42]},{"wat0":"joe","wat1":"joe","wat2":"joe"}]
+ */
+function Component(props) {
+  const key = {};
+  const tmp = (mutate(key), key);
+  const context = {
+    // Here, `tmp` is frozen (as it's inferred to be a primitive/string)
+    [tmp]: identity([props.value]),
+  };
+  mutate(key);
+  return [context, key];
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{value: 42}],
+  sequentialRenders: [{value: 42}, {value: 42}],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @enableNewMutationAliasingModel:false
+import { identity, mutate } from "shared-runtime";
+
+/**
+ * Bug: copy of error.todo-object-expression-computed-key-modified-during-after-construction-sequence-expr
+ * with the mutation hoisted to a named variable instead of being directly
+ * inlined into the Object key.
+ *
+ * Found differences in evaluator results
+ *   Non-forget (expected):
+ *   (kind: ok) [{"[object Object]":[42]},{"wat0":"joe","wat1":"joe"}]
+ *   [{"[object Object]":[42]},{"wat0":"joe","wat1":"joe"}]
+ *   Forget:
+ *   (kind: ok) [{"[object Object]":[42]},{"wat0":"joe","wat1":"joe"}]
+ *   [{"[object Object]":[42]},{"wat0":"joe","wat1":"joe","wat2":"joe"}]
+ */
+function Component(props) {
+  const $ = _c(8);
+  let key;
+  let t0;
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+    key = {};
+    t0 = (mutate(key), key);
+    $[0] = key;
+    $[1] = t0;
+  } else {
+    key = $[0];
+    t0 = $[1];
+  }
+  const tmp = t0;
+  let t1;
+  if ($[2] !== props.value) {
+    t1 = identity([props.value]);
+    $[2] = props.value;
+    $[3] = t1;
+  } else {
+    t1 = $[3];
+  }
+  let t2;
+  if ($[4] !== t1) {
+    t2 = { [tmp]: t1 };
+    $[4] = t1;
+    $[5] = t2;
+  } else {
+    t2 = $[5];
+  }
+  const context = t2;
+
+  mutate(key);
+  let t3;
+  if ($[6] !== context) {
+    t3 = [context, key];
+    $[6] = context;
+    $[7] = t3;
+  } else {
+    t3 = $[7];
+  }
+  return t3;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{ value: 42 }],
+  sequentialRenders: [{ value: 42 }, { value: 42 }],
+};
+
+```
+      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/bug-object-expression-computed-key-modified-during-after-construction-hoisted-sequence-expr.js

@@ -0,0 +1,32 @@
+// @enableNewMutationAliasingModel:false
+import {identity, mutate} from 'shared-runtime';
+
+/**
+ * Bug: copy of error.todo-object-expression-computed-key-modified-during-after-construction-sequence-expr
+ * with the mutation hoisted to a named variable instead of being directly
+ * inlined into the Object key.
+ *
+ * Found differences in evaluator results
+ *   Non-forget (expected):
+ *   (kind: ok) [{"[object Object]":[42]},{"wat0":"joe","wat1":"joe"}]
+ *   [{"[object Object]":[42]},{"wat0":"joe","wat1":"joe"}]
+ *   Forget:
+ *   (kind: ok) [{"[object Object]":[42]},{"wat0":"joe","wat1":"joe"}]
+ *   [{"[object Object]":[42]},{"wat0":"joe","wat1":"joe","wat2":"joe"}]
+ */
+function Component(props) {
+  const key = {};
+  const tmp = (mutate(key), key);
+  const context = {
+    // Here, `tmp` is frozen (as it's inferred to be a primitive/string)
+    [tmp]: identity([props.value]),
+  };
+  mutate(key);
+  return [context, key];
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{value: 42}],
+  sequentialRenders: [{value: 42}, {value: 42}],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/ecma/error.reserved-words.expect.md

@@ -24,18 +24,9 @@ function useThing(fn) {
 ```
 Found 1 error:
 
-Error: `this` is not supported syntax
+Error: Expected a non-reserved identifier name
 
-React Compiler does not support compiling functions that use `this`
-
-error.reserved-words.ts:8:28
-   6 |
-   7 |   if (ref.current === null) {
->  8 |     ref.current = function (this: unknown, ...args) {
-     |                             ^^^^^^^^^^^^^ `this` was used here
-   9 |       return fnRef.current.call(this, ...args);
-  10 |     };
-  11 |   }
+`this` is a reserved word in JavaScript and cannot be used as an identifier name.
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.assign-global-in-component-tag-function.expect.md

@@ -19,13 +19,13 @@ Found 1 error:
 
 Error: Cannot reassign variables declared outside of the component/hook
 
-Variable `someGlobal` is declared outside of the component/hook. Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)
+Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render).
 
 error.assign-global-in-component-tag-function.ts:3:4
   1 | function Component() {
   2 |   const Foo = () => {
 > 3 |     someGlobal = true;
-    |     ^^^^^^^^^^ `someGlobal` cannot be reassigned
+    |     ^^^^^^^^^^ `someGlobal` should not be reassigned
   4 |   };
   5 |   return <Foo />;
   6 | }

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.assign-global-in-jsx-children.expect.md

@@ -22,13 +22,13 @@ Found 1 error:
 
 Error: Cannot reassign variables declared outside of the component/hook
 
-Variable `someGlobal` is declared outside of the component/hook. Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)
+Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render).
 
 error.assign-global-in-jsx-children.ts:3:4
   1 | function Component() {
   2 |   const foo = () => {
 > 3 |     someGlobal = true;
-    |     ^^^^^^^^^^ `someGlobal` cannot be reassigned
+    |     ^^^^^^^^^^ `someGlobal` should not be reassigned
   4 |   };
   5 |   // Children are generally access/called during render, so
   6 |   // modifying a global in a children function is almost

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.assign-global-in-jsx-spread-attribute.expect.md

@@ -0,0 +1,35 @@
+
+## Input
+
+```javascript
+// @enableNewMutationAliasingModel:false
+function Component() {
+  const foo = () => {
+    someGlobal = true;
+  };
+  return <div {...foo} />;
+}
+
+```
+
+
+## Error
+
+```
+Found 1 error:
+
+Error: Cannot reassign variables declared outside of the component/hook
+
+Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render).
+
+error.assign-global-in-jsx-spread-attribute.ts:4:4
+  2 | function Component() {
+  3 |   const foo = () => {
+> 4 |     someGlobal = true;
+    |     ^^^^^^^^^^ Cannot reassign variables declared outside of the component/hook
+  5 |   };
+  6 |   return <div {...foo} />;
+  7 | }
+```
+          
+      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.assign-global-in-jsx-spread-attribute.js

@@ -3,6 +3,5 @@ function Component() {
   const foo = () => {
     someGlobal = true;
   };
-  // spreading a function is weird, but it doesn't call the function so this is allowed
   return <div {...foo} />;
 }

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.assign-ref-in-effect-hint.expect.md

@@ -1,37 +0,0 @@
-
-## Input
-
-```javascript
-// Fixture to test that we show a hint to name as `ref` or `-Ref` when attempting
-// to assign .current inside an effect
-function Component({foo}) {
-  useEffect(() => {
-    foo.current = true;
-  }, [foo]);
-}
-
-```
-
-
-## Error
-
-```
-Found 1 error:
-
-Error: This value cannot be modified
-
-Modifying component props or hook arguments is not allowed. Consider using a local variable instead.
-
-error.assign-ref-in-effect-hint.ts:5:4
-  3 | function Component({foo}) {
-  4 |   useEffect(() => {
-> 5 |     foo.current = true;
-    |     ^^^ `foo` cannot be modified
-  6 |   }, [foo]);
-  7 | }
-  8 |
-
-Hint: If this value is a Ref (value returned by `useRef()`), rename the variable to end in "Ref".
-```
-          
-      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.assign-ref-in-effect-hint.js

@@ -1,7 +0,0 @@
-// Fixture to test that we show a hint to name as `ref` or `-Ref` when attempting
-// to assign .current inside an effect
-function Component({foo}) {
-  useEffect(() => {
-    foo.current = true;
-  }, [foo]);
-}

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.bailout-on-flow-suppression.expect.md

@@ -20,7 +20,7 @@ Found 1 error:
 
 Error: React Compiler has skipped optimizing this component because one or more React rule violations were reported by Flow
 
-React Compiler only works when your components follow all the rules of React, disabling them may result in unexpected or incorrect behavior. Found suppression `$FlowFixMe[react-rule-hook]`
+React Compiler only works when your components follow all the rules of React, disabling them may result in unexpected or incorrect behavior. Found suppression `$FlowFixMe[react-rule-hook]`.
 
 error.bailout-on-flow-suppression.ts:4:2
   2 |

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.bailout-on-suppression-of-custom-rule.expect.md

@@ -23,7 +23,7 @@ Found 2 errors:
 
 Error: React Compiler has skipped optimizing this component because one or more React ESLint rules were disabled
 
-React Compiler only works when your components follow all the rules of React, disabling them may result in unexpected or incorrect behavior. Found suppression `eslint-disable my-app/react-rule`
+React Compiler only works when your components follow all the rules of React, disabling them may result in unexpected or incorrect behavior. Found suppression `eslint-disable my-app/react-rule`.
 
 error.bailout-on-suppression-of-custom-rule.ts:3:0
   1 | // @eslintSuppressionRules:["my-app","react-rule"]
@@ -36,7 +36,7 @@ error.bailout-on-suppression-of-custom-rule.ts:3:0
 
 Error: React Compiler has skipped optimizing this component because one or more React ESLint rules were disabled
 
-React Compiler only works when your components follow all the rules of React, disabling them may result in unexpected or incorrect behavior. Found suppression `eslint-disable-next-line my-app/react-rule`
+React Compiler only works when your components follow all the rules of React, disabling them may result in unexpected or incorrect behavior. Found suppression `eslint-disable-next-line my-app/react-rule`.
 
 error.bailout-on-suppression-of-custom-rule.ts:7:2
    5 |   'use forget';

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.bug-old-inference-false-positive-ref-validation-in-use-effect.expect.md

@@ -0,0 +1,72 @@
+
+## Input
+
+```javascript
+// @validateNoFreezingKnownMutableFunctions @enableNewMutationAliasingModel:false
+
+import {useCallback, useEffect, useRef} from 'react';
+import {useHook} from 'shared-runtime';
+
+function Component() {
+  const params = useHook();
+  const update = useCallback(
+    partialParams => {
+      const nextParams = {
+        ...params,
+        ...partialParams,
+      };
+      nextParams.param = 'value';
+      console.log(nextParams);
+    },
+    [params]
+  );
+  const ref = useRef(null);
+  useEffect(() => {
+    if (ref.current === null) {
+      update();
+    }
+  }, [update]);
+
+  return 'ok';
+}
+
+```
+
+
+## Error
+
+```
+Found 1 error:
+
+Error: Cannot modify local variables after render completes
+
+This argument is a function which may reassign or mutate a variable after render, which can cause inconsistent behavior on subsequent renders. Consider using state instead.
+
+error.bug-old-inference-false-positive-ref-validation-in-use-effect.ts:20:12
+  18 |   );
+  19 |   const ref = useRef(null);
+> 20 |   useEffect(() => {
+     |             ^^^^^^^
+> 21 |     if (ref.current === null) {
+     | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+> 22 |       update();
+     | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+> 23 |     }
+     | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+> 24 |   }, [update]);
+     | ^^^^ This function may (indirectly) reassign or modify a local variable after render
+  25 |
+  26 |   return 'ok';
+  27 | }
+
+error.bug-old-inference-false-positive-ref-validation-in-use-effect.ts:14:6
+  12 |         ...partialParams,
+  13 |       };
+> 14 |       nextParams.param = 'value';
+     |       ^^^^^^^^^^ This modifies a local variable
+  15 |       console.log(nextParams);
+  16 |     },
+  17 |     [params]
+```
+          
+      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.bug-old-inference-false-positive-ref-validation-in-use-effect.js

@@ -0,0 +1,27 @@
+// @validateNoFreezingKnownMutableFunctions @enableNewMutationAliasingModel:false
+
+import {useCallback, useEffect, useRef} from 'react';
+import {useHook} from 'shared-runtime';
+
+function Component() {
+  const params = useHook();
+  const update = useCallback(
+    partialParams => {
+      const nextParams = {
+        ...params,
+        ...partialParams,
+      };
+      nextParams.param = 'value';
+      console.log(nextParams);
+    },
+    [params]
+  );
+  const ref = useRef(null);
+  useEffect(() => {
+    if (ref.current === null) {
+      update();
+    }
+  }, [update]);
+
+  return 'ok';
+}

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.capitalized-function-call-aliased.expect.md

@@ -18,7 +18,7 @@ Found 1 error:
 
 Error: Capitalized functions are reserved for components, which must be invoked with JSX. If this is a component, render it with JSX. Otherwise, ensure that it has no hook calls and rename it to begin with a lowercase letter. Alternatively, if you know for a fact that this function is not a component, you can allowlist it via the compiler config
 
-Bar may be a component..
+Bar may be a component.
 
 error.capitalized-function-call-aliased.ts:4:2
   2 | function Foo() {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.capitalized-function-call.expect.md

@@ -19,7 +19,7 @@ Found 1 error:
 
 Error: Capitalized functions are reserved for components, which must be invoked with JSX. If this is a component, render it with JSX. Otherwise, ensure that it has no hook calls and rename it to begin with a lowercase letter. Alternatively, if you know for a fact that this function is not a component, you can allowlist it via the compiler config
 
-SomeFunc may be a component..
+SomeFunc may be a component.
 
 error.capitalized-function-call.ts:3:12
   1 | // @validateNoCapitalizedCalls

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.capitalized-method-call.expect.md

@@ -19,7 +19,7 @@ Found 1 error:
 
 Error: Capitalized functions are reserved for components, which must be invoked with JSX. If this is a component, render it with JSX. Otherwise, ensure that it has no hook calls and rename it to begin with a lowercase letter. Alternatively, if you know for a fact that this function is not a component, you can allowlist it via the compiler config
 
-SomeFunc may be a component..
+SomeFunc may be a component.
 
 error.capitalized-method-call.ts:3:12
   1 | // @validateNoCapitalizedCalls

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.capture-ref-for-mutation.expect.md

@@ -36,7 +36,7 @@ Found 2 errors:
 
 Error: Cannot access refs during render
 
-React refs are values that are not needed for rendering. Refs should only be accessed outside of render, such as in event handlers or effects. Accessing a ref value (the `current` property) during render can cause your component not to update as expected (https://react.dev/reference/react/useRef)
+React refs are values that are not needed for rendering. Refs should only be accessed outside of render, such as in event handlers or effects. Accessing a ref value (the `current` property) during render can cause your component not to update as expected (https://react.dev/reference/react/useRef).
 
 error.capture-ref-for-mutation.ts:12:13
   10 |   };
@@ -49,7 +49,7 @@ error.capture-ref-for-mutation.ts:12:13
 
 Error: Cannot access refs during render
 
-React refs are values that are not needed for rendering. Refs should only be accessed outside of render, such as in event handlers or effects. Accessing a ref value (the `current` property) during render can cause your component not to update as expected (https://react.dev/reference/react/useRef)
+React refs are values that are not needed for rendering. Refs should only be accessed outside of render, such as in event handlers or effects. Accessing a ref value (the `current` property) during render can cause your component not to update as expected (https://react.dev/reference/react/useRef).
 
 error.capture-ref-for-mutation.ts:15:13
   13 |   };

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.context-variable-only-chained-assign.expect.md

@@ -30,9 +30,9 @@ export const FIXTURE_ENTRYPOINT = {
 ```
 Found 1 error:
 
-Error: Cannot reassign variable after render completes
+Error: Cannot reassign local variables after render completes
 
-Reassigning `x` after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead.
+Reassigning local variables after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead.
 
 error.context-variable-only-chained-assign.ts:10:19
    8 |   };

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.declare-reassign-variable-in-function-declaration.expect.md

@@ -19,9 +19,9 @@ function Component() {
 ```
 Found 1 error:
 
-Error: Cannot reassign variable after render completes
+Error: Cannot reassign local variables after render completes
 
-Reassigning `x` after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead.
+Reassigning local variables after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead.
 
 error.declare-reassign-variable-in-function-declaration.ts:4:4
   2 |   let x = null;

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.function-expression-references-variable-its-assigned-to.expect.md

@@ -17,9 +17,9 @@ function Component() {
 ```
 Found 1 error:
 
-Error: Cannot reassign variable after render completes
+Error: Cannot reassign local variables after render completes
 
-Reassigning `callback` after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead.
+Reassigning local variables after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead.
 
 error.function-expression-references-variable-its-assigned-to.ts:3:4
   1 | function Component() {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.hook-ref-value.expect.md

@@ -24,7 +24,7 @@ Found 2 errors:
 
 Error: Cannot access refs during render
 
-React refs are values that are not needed for rendering. Refs should only be accessed outside of render, such as in event handlers or effects. Accessing a ref value (the `current` property) during render can cause your component not to update as expected (https://react.dev/reference/react/useRef)
+React refs are values that are not needed for rendering. Refs should only be accessed outside of render, such as in event handlers or effects. Accessing a ref value (the `current` property) during render can cause your component not to update as expected (https://react.dev/reference/react/useRef).
 
 error.hook-ref-value.ts:5:23
   3 | function Component(props) {
@@ -37,7 +37,7 @@ error.hook-ref-value.ts:5:23
 
 Error: Cannot access refs during render
 
-React refs are values that are not needed for rendering. Refs should only be accessed outside of render, such as in event handlers or effects. Accessing a ref value (the `current` property) during render can cause your component not to update as expected (https://react.dev/reference/react/useRef)
+React refs are values that are not needed for rendering. Refs should only be accessed outside of render, such as in event handlers or effects. Accessing a ref value (the `current` property) during render can cause your component not to update as expected (https://react.dev/reference/react/useRef).
 
 error.hook-ref-value.ts:5:23
   3 | function Component(props) {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-access-ref-during-render.expect.md

@@ -19,7 +19,7 @@ Found 1 error:
 
 Error: Cannot access refs during render
 
-React refs are values that are not needed for rendering. Refs should only be accessed outside of render, such as in event handlers or effects. Accessing a ref value (the `current` property) during render can cause your component not to update as expected (https://react.dev/reference/react/useRef)
+React refs are values that are not needed for rendering. Refs should only be accessed outside of render, such as in event handlers or effects. Accessing a ref value (the `current` property) during render can cause your component not to update as expected (https://react.dev/reference/react/useRef).
 
 error.invalid-access-ref-during-render.ts:4:16
   2 | function Component(props) {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-access-ref-in-reducer-init.expect.md

@@ -30,7 +30,7 @@ Found 1 error:
 
 Error: Cannot access refs during render
 
-React refs are values that are not needed for rendering. Refs should only be accessed outside of render, such as in event handlers or effects. Accessing a ref value (the `current` property) during render can cause your component not to update as expected (https://react.dev/reference/react/useRef)
+React refs are values that are not needed for rendering. Refs should only be accessed outside of render, such as in event handlers or effects. Accessing a ref value (the `current` property) during render can cause your component not to update as expected (https://react.dev/reference/react/useRef).
 
 error.invalid-access-ref-in-reducer-init.ts:8:4
    6 |     (state, action) => state + action,

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-access-ref-in-reducer.expect.md

@@ -26,7 +26,7 @@ Found 1 error:
 
 Error: Cannot access refs during render
 
-React refs are values that are not needed for rendering. Refs should only be accessed outside of render, such as in event handlers or effects. Accessing a ref value (the `current` property) during render can cause your component not to update as expected (https://react.dev/reference/react/useRef)
+React refs are values that are not needed for rendering. Refs should only be accessed outside of render, such as in event handlers or effects. Accessing a ref value (the `current` property) during render can cause your component not to update as expected (https://react.dev/reference/react/useRef).
 
 error.invalid-access-ref-in-reducer.ts:5:29
   3 | function Component(props) {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-access-ref-in-render-mutate-object-with-ref-function.expect.md

@@ -22,7 +22,7 @@ Found 1 error:
 
 Error: Cannot access refs during render
 
-React refs are values that are not needed for rendering. Refs should only be accessed outside of render, such as in event handlers or effects. Accessing a ref value (the `current` property) during render can cause your component not to update as expected (https://react.dev/reference/react/useRef)
+React refs are values that are not needed for rendering. Refs should only be accessed outside of render, such as in event handlers or effects. Accessing a ref value (the `current` property) during render can cause your component not to update as expected (https://react.dev/reference/react/useRef).
 
 error.invalid-access-ref-in-render-mutate-object-with-ref-function.ts:7:19
    5 |   const object = {};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-access-ref-in-state-initializer.expect.md

@@ -26,7 +26,7 @@ Found 1 error:
 
 Error: Cannot access refs during render
 
-React refs are values that are not needed for rendering. Refs should only be accessed outside of render, such as in event handlers or effects. Accessing a ref value (the `current` property) during render can cause your component not to update as expected (https://react.dev/reference/react/useRef)
+React refs are values that are not needed for rendering. Refs should only be accessed outside of render, such as in event handlers or effects. Accessing a ref value (the `current` property) during render can cause your component not to update as expected (https://react.dev/reference/react/useRef).
 
 error.invalid-access-ref-in-state-initializer.ts:5:27
   3 | function Component(props) {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-aliased-ref-in-callback-invoked-during-render-.expect.md

@@ -23,7 +23,7 @@ Found 1 error:
 
 Error: Cannot access refs during render
 
-React refs are values that are not needed for rendering. Refs should only be accessed outside of render, such as in event handlers or effects. Accessing a ref value (the `current` property) during render can cause your component not to update as expected (https://react.dev/reference/react/useRef)
+React refs are values that are not needed for rendering. Refs should only be accessed outside of render, such as in event handlers or effects. Accessing a ref value (the `current` property) during render can cause your component not to update as expected (https://react.dev/reference/react/useRef).
 
 error.invalid-aliased-ref-in-callback-invoked-during-render-.ts:9:33
    7 |     return <Foo item={item} current={current} />;

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-assign-current-inferred-ref-during-render.expect.md

@@ -22,7 +22,7 @@ Found 1 error:
 
 Error: Cannot access refs during render
 
-React refs are values that are not needed for rendering. Refs should only be accessed outside of render, such as in event handlers or effects. Accessing a ref value (the `current` property) during render can cause your component not to update as expected (https://react.dev/reference/react/useRef)
+React refs are values that are not needed for rendering. Refs should only be accessed outside of render, such as in event handlers or effects. Accessing a ref value (the `current` property) during render can cause your component not to update as expected (https://react.dev/reference/react/useRef).
 
   4 | component Example() {
   5 |   const fooRef = makeObject_Primitives();

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-assign-global-in-function-factory.js

@@ -1,7 +0,0 @@
-function Component() {
-  const f = () => () => {
-    global.property = true;
-  };
-  f()();
-  return <div>Ooops</div>;
-}