[compiler] Improve more error messages

This PR uses the new diagnostic type for most of the error messages produced in our explicit validation passes (`Validation/` directory). One of the validations produced multiple errors as a hack to showing multiple related locations, which we can now consolidate into a single diagnostic.

.eslintrc.js

@@ -608,7 +608,6 @@ module.exports = {
     symbol: 'readonly',
     SyntheticEvent: 'readonly',
     SyntheticMouseEvent: 'readonly',
-    SyntheticPointerEvent: 'readonly',
     Thenable: 'readonly',
     TimeoutID: 'readonly',
     WheelEventHandler: 'readonly',

CHANGELOG.md

@@ -1,8 +1,3 @@
-## 19.1.1 (July 28, 2025)
-
-### React
-* Fixed Owner Stacks to work with ES2015 function.name semantics ([#33680](https://github.com/facebook/react/pull/33680) by @hoxyq)
-
 ## 19.1.0 (March 28, 2025)
 
 ### Owner Stack

compiler/apps/playground/__tests__/e2e/__snapshots__/page.spec.ts/compilationMode-all-output.txt

@@ -1,5 +1,5 @@
 import { c as _c } from "react/compiler-runtime"; // 
-@compilationMode:"all"
+        @compilationMode:"all"
 function nonReactFn() {
   const $ = _c(1);
   let t0;

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

@@ -11,7 +11,6 @@ import * as t from '@babel/types';
 import BabelPluginReactCompiler, {
   CompilerError,
   CompilerErrorDetail,
-  CompilerDiagnostic,
   Effect,
   ErrorSeverity,
   parseConfigPragmaForTests,
@@ -142,13 +141,10 @@ const COMMON_HOOKS: Array<[string, Hook]> = [
   ],
 ];
 
-function compile(
-  source: string,
-  mode: 'compiler' | 'linter',
-): [CompilerOutput, 'flow' | 'typescript'] {
+function compile(source: string): [CompilerOutput, 'flow' | 'typescript'] {
   const results = new Map<string, Array<PrintedCompilerPipelineValue>>();
   const error = new CompilerError();
-  const otherErrors: Array<CompilerErrorDetail | CompilerDiagnostic> = [];
+  const otherErrors: Array<CompilerErrorDetail> = [];
   const upsert: (result: PrintedCompilerPipelineValue) => void = result => {
     const entry = results.get(result.name);
     if (Array.isArray(entry)) {
@@ -207,23 +203,6 @@ function compile(
     };
     const parsedOptions = parseConfigPragmaForTests(pragma, {
       compilationMode: 'infer',
-      environment:
-        mode === 'linter'
-          ? {
-              // enabled in compiler
-              validateRefAccessDuringRender: false,
-              // enabled in linter
-              validateNoSetStateInRender: true,
-              validateNoSetStateInEffects: true,
-              validateNoJSXInTryStatements: true,
-              validateNoImpureFunctionsInRender: true,
-              validateStaticComponents: true,
-              validateNoFreezingKnownMutableFunctions: true,
-              validateNoVoidUseMemo: true,
-            }
-          : {
-              /* use defaults for compiler mode */
-            },
     });
     const opts: PluginOptions = parsePluginOptions({
       ...parsedOptions,
@@ -235,7 +214,7 @@ function compile(
         debugLogIRs: logIR,
         logEvent: (_filename: string | null, event: LoggerEvent) => {
           if (event.kind === 'CompileError') {
-            otherErrors.push(event.detail);
+            otherErrors.push(new CompilerErrorDetail(event.detail));
           }
         },
       },
@@ -247,7 +226,7 @@ function compile(
      * (i.e. object shape that is not CompilerError)
      */
     if (err instanceof CompilerError && err.details.length > 0) {
-      error.merge(err);
+      error.details.push(...err.details);
     } else {
       /**
        * Handle unexpected failures by logging (to get a stack trace)
@@ -266,15 +245,12 @@ function compile(
   }
   // Only include logger errors if there weren't other errors
   if (!error.hasErrors() && otherErrors.length !== 0) {
-    otherErrors.forEach(e => error.details.push(e));
+    otherErrors.forEach(e => error.push(e));
   }
   if (error.hasErrors()) {
-    return [{kind: 'err', results, error}, language];
+    return [{kind: 'err', results, error: error}, language];
   }
-  return [
-    {kind: 'ok', results, transformOutput, errors: error.details},
-    language,
-  ];
+  return [{kind: 'ok', results, transformOutput}, language];
 }
 
 export default function Editor(): JSX.Element {
@@ -283,11 +259,7 @@ export default function Editor(): JSX.Element {
   const dispatchStore = useStoreDispatch();
   const {enqueueSnackbar} = useSnackbar();
   const [compilerOutput, language] = useMemo(
-    () => compile(deferredStore.source, 'compiler'),
-    [deferredStore.source],
-  );
-  const [linterOutput] = useMemo(
-    () => compile(deferredStore.source, 'linter'),
+    () => compile(deferredStore.source),
     [deferredStore.source],
   );
 
@@ -313,26 +285,19 @@ export default function Editor(): JSX.Element {
     });
   });
 
-  let mergedOutput: CompilerOutput;
-  let errors: Array<CompilerErrorDetail | CompilerDiagnostic>;
-  if (compilerOutput.kind === 'ok') {
-    errors = linterOutput.kind === 'ok' ? [] : linterOutput.error.details;
-    mergedOutput = {
-      ...compilerOutput,
-      errors,
-    };
-  } else {
-    mergedOutput = compilerOutput;
-    errors = compilerOutput.error.details;
-  }
   return (
     <>
       <div className="relative flex basis top-14">
         <div className={clsx('relative sm:basis-1/4')}>
-          <Input language={language} errors={errors} />
+          <Input
+            language={language}
+            errors={
+              compilerOutput.kind === 'err' ? compilerOutput.error.details : []
+            }
+          />
         </div>
         <div className={clsx('flex sm:flex flex-wrap')}>
-          <Output store={deferredStore} compilerOutput={mergedOutput} />
+          <Output store={deferredStore} compilerOutput={compilerOutput} />
         </div>
       </div>
     </>

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

@@ -36,18 +36,13 @@ export default function Input({errors, language}: Props): JSX.Element {
     const uri = monaco.Uri.parse(`file:///index.js`);
     const model = monaco.editor.getModel(uri);
     invariant(model, 'Model must exist for the selected input file.');
-    renderReactCompilerMarkers({
-      monaco,
-      model,
-      details: errors,
-      source: store.source,
-    });
+    renderReactCompilerMarkers({monaco, model, details: errors});
     /**
      * N.B. that `tabSize` is a model property, not an editor property.
      * So, the tab size has to be set per model.
      */
     model.updateOptions({tabSize: 2});
-  }, [monaco, errors, store.source]);
+  }, [monaco, errors]);
 
   useEffect(() => {
     /**

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

@@ -11,11 +11,7 @@ import {
   InformationCircleIcon,
 } from '@heroicons/react/outline';
 import MonacoEditor, {DiffEditor} from '@monaco-editor/react';
-import {
-  CompilerErrorDetail,
-  CompilerDiagnostic,
-  type CompilerError,
-} from 'babel-plugin-react-compiler';
+import {type CompilerError} from 'babel-plugin-react-compiler';
 import parserBabel from 'prettier/plugins/babel';
 import * as prettierPluginEstree from 'prettier/plugins/estree';
 import * as prettier from 'prettier/standalone';
@@ -48,7 +44,6 @@ export type CompilerOutput =
       kind: 'ok';
       transformOutput: CompilerTransformOutput;
       results: Map<string, Array<PrintedCompilerPipelineValue>>;
-      errors: Array<CompilerErrorDetail | CompilerDiagnostic>;
     }
   | {
       kind: 'err';
@@ -128,36 +123,10 @@ async function tabify(
       parser: transformOutput.language === 'flow' ? 'babel-flow' : 'babel-ts',
       plugins: [parserBabel, prettierPluginEstree],
     });
-
-    let output: string;
-    let language: string;
-    if (compilerOutput.errors.length === 0) {
-      output = code;
-      language = 'javascript';
-    } else {
-      language = 'markdown';
-      output = `
-# Summary
-
-React Compiler compiled this function successfully, but there are lint errors that indicate potential issues with the original code.
-
-## ${compilerOutput.errors.length} Lint Errors
-
-${compilerOutput.errors.map(e => e.printErrorMessage(source, {eslint: false})).join('\n\n')}
-
-## Output
-
-\`\`\`js
-${code}
-\`\`\`
-`.trim();
-    }
-
     reorderedTabs.set(
-      'Output',
+      'JS',
       <TextTabContent
-        output={output}
-        language={language}
+        output={code}
         diff={null}
         showInfoPanel={false}></TextTabContent>,
     );
@@ -173,18 +142,6 @@ ${code}
         </>,
       );
     }
-  } else if (compilerOutput.kind === 'err') {
-    const errors = compilerOutput.error.printErrorMessage(source, {
-      eslint: false,
-    });
-    reorderedTabs.set(
-      'Output',
-      <TextTabContent
-        output={errors}
-        language="markdown"
-        diff={null}
-        showInfoPanel={false}></TextTabContent>,
-    );
   }
   tabs.forEach((tab, name) => {
     reorderedTabs.set(name, tab);
@@ -205,32 +162,17 @@ function getSourceMapUrl(code: string, map: string): string | null {
 }
 
 function Output({store, compilerOutput}: Props): JSX.Element {
-  const [tabsOpen, setTabsOpen] = useState<Set<string>>(
-    () => new Set(['Output']),
-  );
+  const [tabsOpen, setTabsOpen] = useState<Set<string>>(() => new Set(['JS']));
   const [tabs, setTabs] = useState<Map<string, React.ReactNode>>(
     () => new Map(),
   );
-
-  /*
-   * Update the active tab back to the output or errors tab when the compilation state
-   * changes between success/failure.
-   */
-  const [previousOutputKind, setPreviousOutputKind] = useState(
-    compilerOutput.kind,
-  );
-  if (compilerOutput.kind !== previousOutputKind) {
-    setPreviousOutputKind(compilerOutput.kind);
-    setTabsOpen(new Set(['Output']));
-  }
-
   useEffect(() => {
     tabify(store.source, compilerOutput).then(tabs => {
       setTabs(tabs);
     });
   }, [store.source, compilerOutput]);
 
-  const changedPasses: Set<string> = new Set(['Output', 'HIR']); // Initial and final passes should always be bold
+  const changedPasses: Set<string> = new Set(['JS', 'HIR']); // Initial and final passes should always be bold
   let lastResult: string = '';
   for (const [passName, results] of compilerOutput.results) {
     for (const result of results) {
@@ -254,6 +196,20 @@ function Output({store, compilerOutput}: Props): JSX.Element {
         tabs={tabs}
         changedPasses={changedPasses}
       />
+      {compilerOutput.kind === 'err' ? (
+        <div
+          className="flex flex-wrap absolute bottom-0 bg-white grow border-y border-grey-200 transition-all ease-in"
+          style={{width: 'calc(100vw - 650px)'}}>
+          <div className="w-full p-4 basis-full border-b">
+            <h2>COMPILER ERRORS</h2>
+          </div>
+          <pre
+            className="p-4 basis-full text-red-600 overflow-y-scroll whitespace-pre-wrap"
+            style={{width: 'calc(100vw - 650px)', height: '150px'}}>
+            <code>{compilerOutput.error.toString()}</code>
+          </pre>
+        </div>
+      ) : null}
     </>
   );
 }
@@ -262,12 +218,10 @@ function TextTabContent({
   output,
   diff,
   showInfoPanel,
-  language,
 }: {
   output: string;
   diff: string | null;
   showInfoPanel: boolean;
-  language: string;
 }): JSX.Element {
   const [diffMode, setDiffMode] = useState(false);
   return (
@@ -318,7 +272,7 @@ function TextTabContent({
         />
       ) : (
         <MonacoEditor
-          language={language ?? 'javascript'}
+          defaultLanguage="javascript"
           value={output}
           options={{
             ...monacoOptions,

compiler/apps/playground/components/Editor/monacoOptions.ts

@@ -28,5 +28,5 @@ export const monacoOptions: Partial<EditorProps['options']> = {
 
   automaticLayout: true,
   wordWrap: 'on',
-  wrappingIndent: 'same',
+  wrappingIndent: 'deepIndent',
 };

compiler/apps/playground/lib/reactCompilerMonacoDiagnostics.ts

@@ -6,11 +6,7 @@
  */
 
 import {Monaco} from '@monaco-editor/react';
-import {
-  CompilerDiagnostic,
-  CompilerErrorDetail,
-  ErrorSeverity,
-} from 'babel-plugin-react-compiler';
+import {CompilerErrorDetail, ErrorSeverity} from 'babel-plugin-react-compiler';
 import {MarkerSeverity, type editor} from 'monaco-editor';
 
 function mapReactCompilerSeverityToMonaco(
@@ -26,46 +22,38 @@ function mapReactCompilerSeverityToMonaco(
 }
 
 function mapReactCompilerDiagnosticToMonacoMarker(
-  detail: CompilerErrorDetail | CompilerDiagnostic,
+  detail: CompilerErrorDetail,
   monaco: Monaco,
-  source: string,
 ): editor.IMarkerData | null {
-  const loc = detail.primaryLocation();
-  if (loc == null || typeof loc === 'symbol') {
+  if (detail.loc == null || typeof detail.loc === 'symbol') {
     return null;
   }
   const severity = mapReactCompilerSeverityToMonaco(detail.severity, monaco);
-  let message = detail.printErrorMessage(source, {eslint: true});
+  let message = detail.printErrorMessage();
   return {
     severity,
     message,
-    startLineNumber: loc.start.line,
-    startColumn: loc.start.column + 1,
-    endLineNumber: loc.end.line,
-    endColumn: loc.end.column + 1,
+    startLineNumber: detail.loc.start.line,
+    startColumn: detail.loc.start.column + 1,
+    endLineNumber: detail.loc.end.line,
+    endColumn: detail.loc.end.column + 1,
   };
 }
 
 type ReactCompilerMarkerConfig = {
   monaco: Monaco;
   model: editor.ITextModel;
-  details: Array<CompilerErrorDetail | CompilerDiagnostic>;
-  source: string;
+  details: Array<CompilerErrorDetail>;
 };
 let decorations: Array<string> = [];
 export function renderReactCompilerMarkers({
   monaco,
   model,
   details,
-  source,
 }: ReactCompilerMarkerConfig): void {
   const markers: Array<editor.IMarkerData> = [];
   for (const detail of details) {
-    const marker = mapReactCompilerDiagnosticToMonacoMarker(
-      detail,
-      monaco,
-      source,
-    );
+    const marker = mapReactCompilerDiagnosticToMonacoMarker(detail, monaco);
     if (marker == null) {
       continue;
     }

compiler/packages/babel-plugin-react-compiler/src/Babel/BabelPlugin.ts

@@ -84,7 +84,7 @@ export default function BabelPluginReactCompiler(
             }
           } catch (e) {
             if (e instanceof CompilerError) {
-              throw e.withPrintedMessage(pass.file.code, {eslint: false});
+              throw new Error(e.printErrorMessage(pass.file.code));
             }
             throw e;
           }

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

@@ -5,7 +5,6 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import * as t from '@babel/types';
 import {codeFrameColumns} from '@babel/code-frame';
 import type {SourceLocation} from './HIR';
 import {Err, Ok, Result} from './Utils/Result';
@@ -94,14 +93,6 @@ export type CompilerErrorDetailOptions = {
   suggestions?: Array<CompilerSuggestion> | null | undefined;
 };
 
-export type PrintErrorMessageOptions = {
-  /**
-   * ESLint uses 1-indexed columns and prints one error at a time
-   * So it doesn't require the "Found # error(s)" text
-   */
-  eslint: boolean;
-};
-
 export class CompilerDiagnostic {
   options: CompilerDiagnosticOptions;
 
@@ -137,7 +128,7 @@ export class CompilerDiagnostic {
     return this.options.details.filter(d => d.kind === 'error')[0]?.loc ?? null;
   }
 
-  printErrorMessage(source: string, options: PrintErrorMessageOptions): string {
+  printErrorMessage(source: string): string {
     const buffer = [
       printErrorSummary(this.severity, this.category),
       '\n\n',
@@ -152,18 +143,28 @@ export class CompilerDiagnostic {
           }
           let codeFrame: string;
           try {
-            codeFrame = printCodeFrame(source, loc, detail.message);
+            codeFrame = codeFrameColumns(
+              source,
+              {
+                start: {
+                  line: loc.start.line,
+                  column: loc.start.column + 1,
+                },
+                end: {
+                  line: loc.end.line,
+                  column: loc.end.column + 1,
+                },
+              },
+              {
+                message: detail.message,
+              },
+            );
           } catch (e) {
             codeFrame = detail.message;
           }
-          buffer.push('\n\n');
-          if (loc.filename != null) {
-            const line = loc.start.line;
-            const column = options.eslint
-              ? loc.start.column + 1
-              : loc.start.column;
-            buffer.push(`${loc.filename}:${line}:${column}\n`);
-          }
+          buffer.push(
+            `\n\n${loc.filename}:${loc.start.line}:${loc.start.column}\n`,
+          );
           buffer.push(codeFrame);
           break;
         }
@@ -222,7 +223,7 @@ export class CompilerErrorDetail {
     return this.loc;
   }
 
-  printErrorMessage(source: string, options: PrintErrorMessageOptions): string {
+  printErrorMessage(source: string): string {
     const buffer = [printErrorSummary(this.severity, this.reason)];
     if (this.description != null) {
       buffer.push(`\n\n${this.description}.`);
@@ -231,16 +232,28 @@ export class CompilerErrorDetail {
     if (loc != null && typeof loc !== 'symbol') {
       let codeFrame: string;
       try {
-        codeFrame = printCodeFrame(source, loc, this.reason);
+        codeFrame = codeFrameColumns(
+          source,
+          {
+            start: {
+              line: loc.start.line,
+              column: loc.start.column + 1,
+            },
+            end: {
+              line: loc.end.line,
+              column: loc.end.column + 1,
+            },
+          },
+          {
+            message: this.reason,
+          },
+        );
       } catch (e) {
         codeFrame = '';
       }
-      buffer.push(`\n\n`);
-      if (loc.filename != null) {
-        const line = loc.start.line;
-        const column = options.eslint ? loc.start.column + 1 : loc.start.column;
-        buffer.push(`${loc.filename}:${line}:${column}\n`);
-      }
+      buffer.push(
+        `\n\n${loc.filename}:${loc.start.line}:${loc.start.column}\n`,
+      );
       buffer.push(codeFrame);
       buffer.push('\n\n');
     }
@@ -262,7 +275,6 @@ export class CompilerErrorDetail {
 
 export class CompilerError extends Error {
   details: Array<CompilerErrorDetail | CompilerDiagnostic> = [];
-  printedMessage: string | null = null;
 
   static invariant(
     condition: unknown,
@@ -348,38 +360,22 @@ export class CompilerError extends Error {
   }
 
   override get message(): string {
-    return this.printedMessage ?? this.toString();
+    return this.toString();
   }
 
   override set message(_message: string) {}
 
   override toString(): string {
-    if (this.printedMessage) {
-      return this.printedMessage;
-    }
     if (Array.isArray(this.details)) {
       return this.details.map(detail => detail.toString()).join('\n\n');
     }
     return this.name;
   }
 
-  withPrintedMessage(
-    source: string,
-    options: PrintErrorMessageOptions,
-  ): CompilerError {
-    this.printedMessage = this.printErrorMessage(source, options);
-    return this;
-  }
-
-  printErrorMessage(source: string, options: PrintErrorMessageOptions): string {
-    if (options.eslint && this.details.length === 1) {
-      return this.details[0].printErrorMessage(source, options);
-    }
+  printErrorMessage(source: string): string {
     return (
-      `Found ${this.details.length} error${this.details.length === 1 ? '' : 's'}:\n\n` +
-      this.details
-        .map(detail => detail.printErrorMessage(source, options).trim())
-        .join('\n\n')
+      `Found ${this.details.length} error${this.details.length === 1 ? '' : 's'}:\n` +
+      this.details.map(detail => detail.printErrorMessage(source)).join('\n')
     );
   }
 
@@ -442,29 +438,6 @@ export class CompilerError extends Error {
   }
 }
 
-function printCodeFrame(
-  source: string,
-  loc: t.SourceLocation,
-  message: string,
-): string {
-  return codeFrameColumns(
-    source,
-    {
-      start: {
-        line: loc.start.line,
-        column: loc.start.column + 1,
-      },
-      end: {
-        line: loc.end.line,
-        column: loc.end.column + 1,
-      },
-    },
-    {
-      message,
-    },
-  );
-}
-
 function printErrorSummary(severity: ErrorSeverity, message: string): string {
   let severityCategory: string;
   switch (severity) {

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

@@ -174,7 +174,7 @@ function runWithEnvironment(
     !env.config.disableMemoizationForDebugging &&
     !env.config.enableChangeDetectionForDebugging
   ) {
-    dropManualMemoization(hir).unwrap();
+    dropManualMemoization(hir);
     log({kind: 'hir', name: 'DropManualMemoization', value: hir});
   }
 

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

@@ -8,8 +8,8 @@
 import {NodePath} from '@babel/core';
 import * as t from '@babel/types';
 import {
-  CompilerDiagnostic,
   CompilerError,
+  CompilerErrorDetail,
   CompilerSuggestionOperation,
   ErrorSeverity,
 } from '../CompilerError';
@@ -181,11 +181,12 @@ export function suppressionsToCompilerError(
           'Unhandled suppression source',
         );
     }
-    error.pushDiagnostic(
-      CompilerDiagnostic.create({
-        category: 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 \`${suppressionRange.disableComment.value.trim()}\``,
+    error.pushErrorDetail(
+      new CompilerErrorDetail({
+        reason: `${reason}. React Compiler only works when your components follow all the rules of React, disabling them may result in unexpected or incorrect behavior`,
+        description: suppressionRange.disableComment.value.trim(),
         severity: ErrorSeverity.InvalidReact,
+        loc: suppressionRange.disableComment.loc ?? null,
         suggestions: [
           {
             description: suggestion,
@@ -196,10 +197,6 @@ export function suppressionsToCompilerError(
             op: CompilerSuggestionOperation.Remove,
           },
         ],
-      }).withDetail({
-        kind: 'error',
-        loc: suppressionRange.disableComment.loc ?? null,
-        message: 'Found React rule suppression',
       }),
     );
   }

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

@@ -107,9 +107,10 @@ export function lower(
       if (binding.kind !== 'Identifier') {
         builder.errors.pushDiagnostic(
           CompilerDiagnostic.create({
-            severity: ErrorSeverity.Invariant,
             category: 'Could not find binding',
-            description: `[BuildHIR] Could not find binding for param \`${param.node.name}\`.`,
+            description: `[BuildHIR] Could not find binding for param \`${param.node.name}\``,
+            severity: ErrorSeverity.Invariant,
+            suggestions: null,
           }).withDetail({
             kind: 'error',
             loc: param.node.loc ?? null,
@@ -171,9 +172,10 @@ export function lower(
     } else {
       builder.errors.pushDiagnostic(
         CompilerDiagnostic.create({
-          severity: ErrorSeverity.Todo,
           category: `Handle ${param.node.type} parameters`,
-          description: `[BuildHIR] Add support for ${param.node.type} parameters.`,
+          description: `[BuildHIR] Add support for ${param.node.type} parameters`,
+          severity: ErrorSeverity.Todo,
+          suggestions: null,
         }).withDetail({
           kind: 'error',
           loc: param.node.loc ?? null,
@@ -189,7 +191,6 @@ export function lower(
     const fallthrough = builder.reserve('block');
     const terminal: ReturnTerminal = {
       kind: 'return',
-      returnVariant: 'Implicit',
       loc: GeneratedSource,
       value: lowerExpressionToTemporary(builder, body),
       id: makeInstructionId(0),
@@ -204,7 +205,8 @@ export function lower(
       CompilerDiagnostic.create({
         severity: ErrorSeverity.InvalidJS,
         category: `Unexpected function body kind`,
-        description: `Expected function body to be an expression or a block statement, got \`${body.type}\`.`,
+        description: `Expected function body to be an expression or a block statement, got \`${body.type}\``,
+        suggestions: null,
       }).withDetail({
         kind: 'error',
         loc: body.node.loc ?? null,
@@ -220,7 +222,6 @@ export function lower(
   builder.terminate(
     {
       kind: 'return',
-      returnVariant: 'Void',
       loc: GeneratedSource,
       value: lowerValueToTemporary(builder, {
         kind: 'Primitive',
@@ -304,7 +305,6 @@ function lowerStatement(
       }
       const terminal: ReturnTerminal = {
         kind: 'return',
-        returnVariant: 'Explicit',
         loc: stmt.node.loc ?? GeneratedSource,
         value,
         id: makeInstructionId(0),

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

@@ -608,7 +608,7 @@ export const EnvironmentConfigSchema = z.object({
    *
    * Here the variables `ref` and `myRef` will be typed as Refs.
    */
-  enableTreatRefLikeIdentifiersAsRefs: z.boolean().default(true),
+  enableTreatRefLikeIdentifiersAsRefs: z.boolean().default(false),
 
   /*
    * If specified a value, the compiler lowers any calls to `useContext` to use
@@ -631,17 +631,6 @@ export const EnvironmentConfigSchema = z.object({
    * ```
    */
   lowerContextAccess: ExternalFunctionSchema.nullable().default(null),
-
-  /**
-   * If enabled, will validate useMemos that don't return any values:
-   *
-   * Valid:
-   *   useMemo(() => foo, [foo]);
-   *   useMemo(() => { return foo }, [foo]);
-   * Invalid:
-   *   useMemo(() => { ... }, [...]);
-   */
-  validateNoVoidUseMemo: z.boolean().default(false),
 });
 
 export type EnvironmentConfig = z.infer<typeof EnvironmentConfigSchema>;

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

@@ -446,20 +446,8 @@ export type ThrowTerminal = {
 };
 export type Case = {test: Place | null; block: BlockId};
 
-export type ReturnVariant = 'Void' | 'Implicit' | 'Explicit';
 export type ReturnTerminal = {
   kind: 'return';
-  /**
-   * Void:
-   *   () => { ... }
-   *   function() { ... }
-   * Implicit (ArrowFunctionExpression only):
-   *   () => foo
-   * Explicit:
-   *   () => { return ... }
-   *   function () { return ... }
-   */
-  returnVariant: ReturnVariant;
   loc: SourceLocation;
   value: Place;
   id: InstructionId;

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

@@ -1211,8 +1211,6 @@ addObject(BUILTIN_SHAPES, BuiltInRefValueId, [
   ['*', {kind: 'Object', shapeId: BuiltInRefValueId}],
 ]);
 
-addObject(BUILTIN_SHAPES, ReanimatedSharedValueId, []);
-
 addFunction(
   BUILTIN_SHAPES,
   [],

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

@@ -215,7 +215,7 @@ export function printTerminal(terminal: Terminal): Array<string> | string {
       break;
     }
     case 'return': {
-      value = `[${terminal.id}] Return ${terminal.returnVariant}${
+      value = `[${terminal.id}] Return${
         terminal.value != null ? ' ' + printPlace(terminal.value) : ''
       }`;
       if (terminal.effects != null) {
@@ -943,10 +943,7 @@ export function printAliasingEffect(effect: AliasingEffect): string {
       return `Assign ${printPlaceForAliasEffect(effect.into)} = ${printPlaceForAliasEffect(effect.from)}`;
     }
     case 'Alias': {
-      return `Alias ${printPlaceForAliasEffect(effect.into)} <- ${printPlaceForAliasEffect(effect.from)}`;
-    }
-    case 'MaybeAlias': {
-      return `MaybeAlias ${printPlaceForAliasEffect(effect.into)} <- ${printPlaceForAliasEffect(effect.from)}`;
+      return `Alias ${printPlaceForAliasEffect(effect.into)} = ${printPlaceForAliasEffect(effect.from)}`;
     }
     case 'Capture': {
       return `Capture ${printPlaceForAliasEffect(effect.into)} <- ${printPlaceForAliasEffect(effect.from)}`;
@@ -998,13 +995,13 @@ export function printAliasingEffect(effect: AliasingEffect): string {
       return `${effect.kind} ${printPlaceForAliasEffect(effect.value)}`;
     }
     case 'MutateFrozen': {
-      return `MutateFrozen ${printPlaceForAliasEffect(effect.place)} reason=${JSON.stringify(effect.error.category)}`;
+      return `MutateFrozen ${printPlaceForAliasEffect(effect.place)} reason=${JSON.stringify(effect.error.reason)}`;
     }
     case 'MutateGlobal': {
-      return `MutateGlobal ${printPlaceForAliasEffect(effect.place)} reason=${JSON.stringify(effect.error.category)}`;
+      return `MutateGlobal ${printPlaceForAliasEffect(effect.place)} reason=${JSON.stringify(effect.error.reason)}`;
     }
     case 'Impure': {
-      return `Impure ${printPlaceForAliasEffect(effect.place)} reason=${JSON.stringify(effect.error.category)}`;
+      return `Impure ${printPlaceForAliasEffect(effect.place)} reason=${JSON.stringify(effect.error.reason)}`;
     }
     case 'Render': {
       return `Render ${printPlaceForAliasEffect(effect.place)}`;

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

@@ -777,7 +777,6 @@ export function mapTerminalSuccessors(
     case 'return': {
       return {
         kind: 'return',
-        returnVariant: terminal.returnVariant,
         loc: terminal.loc,
         value: terminal.value,
         id: makeInstructionId(0),

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

@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {CompilerDiagnostic} from '../CompilerError';
+import {CompilerErrorDetailOptions} from '../CompilerError';
 import {
   FunctionExpression,
   GeneratedSource,
@@ -90,23 +90,6 @@ export type AliasingEffect =
    * c could be mutating a.
    */
   | {kind: 'Alias'; from: Place; into: Place}
-
-  /**
-   * Indicates the potential for information flow from `from` to `into`. This is used for a specific
-   * case: functions with unknown signatures. If the compiler sees a call such as `foo(x)`, it has to
-   * consider several possibilities (which may depend on the arguments):
-   * - foo(x) returns a new mutable value that does not capture any information from x.
-   * - foo(x) returns a new mutable value that *does* capture information from x.
-   * - foo(x) returns x itself, ie foo is the identity function
-   *
-   * The same is true of functions that take multiple arguments: `cond(a, b, c)` could conditionally
-   * return b or c depending on the value of a.
-   *
-   * To represent this case, MaybeAlias represents the fact that an aliasing relationship could exist.
-   * Any mutations that flow through this relationship automatically become conditional.
-   */
-  | {kind: 'MaybeAlias'; from: Place; into: Place}
-
   /**
    * Records direct assignment: `into = from`.
    */
@@ -150,19 +133,19 @@ export type AliasingEffect =
   /**
    * Mutation of a value known to be immutable
    */
-  | {kind: 'MutateFrozen'; place: Place; error: CompilerDiagnostic}
+  | {kind: 'MutateFrozen'; place: Place; error: CompilerErrorDetailOptions}
   /**
    * Mutation of a global
    */
   | {
       kind: 'MutateGlobal';
       place: Place;
-      error: CompilerDiagnostic;
+      error: CompilerErrorDetailOptions;
     }
   /**
    * Indicates a side-effect that is not safe during render
    */
-  | {kind: 'Impure'; place: Place; error: CompilerDiagnostic}
+  | {kind: 'Impure'; place: Place; error: CompilerErrorDetailOptions}
   /**
    * Indicates that a given place is accessed during render. Used to distingush
    * hook arguments that are known to be called immediately vs those used for
@@ -200,8 +183,7 @@ export function hashEffect(effect: AliasingEffect): string {
     case 'ImmutableCapture':
     case 'Assign':
     case 'Alias':
-    case 'Capture':
-    case 'MaybeAlias': {
+    case 'Capture': {
       return [
         effect.kind,
         effect.from.identifier.id,
@@ -229,9 +211,9 @@ export function hashEffect(effect: AliasingEffect): string {
         effect.kind,
         effect.place.identifier.id,
         effect.error.severity,
-        effect.error.category,
+        effect.error.reason,
         effect.error.description,
-        printSourceLocation(effect.error.primaryLocation() ?? GeneratedSource),
+        printSourceLocation(effect.error.loc ?? GeneratedSource),
       ].join(':');
     }
     case 'Mutate':

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

@@ -85,8 +85,7 @@ function lowerWithMutationAliasing(fn: HIRFunction): void {
       case 'Assign':
       case 'Alias':
       case 'Capture':
-      case 'CreateFrom':
-      case 'MaybeAlias': {
+      case 'CreateFrom': {
         capturedOrMutated.add(effect.from.identifier.id);
         break;
       }

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

@@ -5,12 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {
-  CompilerDiagnostic,
-  CompilerError,
-  ErrorSeverity,
-  SourceLocation,
-} from '..';
+import {CompilerError, SourceLocation} from '..';
 import {
   CallExpression,
   Effect,
@@ -35,7 +30,6 @@ import {
   makeInstructionId,
 } from '../HIR';
 import {createTemporaryPlace, markInstructionIds} from '../HIR/HIRBuilder';
-import {Result} from '../Utils/Result';
 
 type ManualMemoCallee = {
   kind: 'useMemo' | 'useCallback';
@@ -289,43 +283,26 @@ function extractManualMemoizationArgs(
   instr: TInstruction<CallExpression> | TInstruction<MethodCall>,
   kind: 'useCallback' | 'useMemo',
   sidemap: IdentifierSidemap,
-  errors: CompilerError,
 ): {
-  fnPlace: Place | null;
+  fnPlace: Place;
   depsList: Array<ManualMemoDependency> | null;
 } {
   const [fnPlace, depsListPlace] = instr.value.args as Array<
     Place | SpreadPattern | undefined
   >;
   if (fnPlace == null) {
-    errors.pushDiagnostic(
-      CompilerDiagnostic.create({
-        severity: ErrorSeverity.InvalidReact,
-        category: `Expected a callback function to be passed to ${kind}`,
-        description: `Expected a callback function to be passed to ${kind}`,
-        suggestions: null,
-      }).withDetail({
-        kind: 'error',
-        loc: instr.value.loc,
-        message: `Expected a callback function to be passed to ${kind}`,
-      }),
-    );
-    return {fnPlace: null, depsList: null};
+    CompilerError.throwInvalidReact({
+      reason: `Expected a callback function to be passed to ${kind}`,
+      loc: instr.value.loc,
+      suggestions: null,
+    });
   }
   if (fnPlace.kind === 'Spread' || depsListPlace?.kind === 'Spread') {
-    errors.pushDiagnostic(
-      CompilerDiagnostic.create({
-        severity: ErrorSeverity.InvalidReact,
-        category: `Unexpected spread argument to ${kind}`,
-        description: `Unexpected spread argument to ${kind}`,
-        suggestions: null,
-      }).withDetail({
-        kind: 'error',
-        loc: instr.value.loc,
-        message: `Unexpected spread argument to ${kind}`,
-      }),
-    );
-    return {fnPlace: null, depsList: null};
+    CompilerError.throwInvalidReact({
+      reason: `Unexpected spread argument to ${kind}`,
+      loc: instr.value.loc,
+      suggestions: null,
+    });
   }
   let depsList: Array<ManualMemoDependency> | null = null;
   if (depsListPlace != null) {
@@ -333,40 +310,23 @@ function extractManualMemoizationArgs(
       depsListPlace.identifier.id,
     );
     if (maybeDepsList == null) {
-      errors.pushDiagnostic(
-        CompilerDiagnostic.create({
-          severity: ErrorSeverity.InvalidReact,
-          category: `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({
-          kind: 'error',
-          loc: depsListPlace.loc,
-          message: `Expected the dependency list for ${kind} to be an array literal`,
-        }),
-      );
-      return {fnPlace, depsList: null};
+      CompilerError.throwInvalidReact({
+        reason: `Expected the dependency list for ${kind} to be an array literal`,
+        suggestions: null,
+        loc: depsListPlace.loc,
+      });
     }
-    depsList = [];
-    for (const dep of maybeDepsList) {
+    depsList = maybeDepsList.map(dep => {
       const maybeDep = sidemap.maybeDeps.get(dep.identifier.id);
       if (maybeDep == null) {
-        errors.pushDiagnostic(
-          CompilerDiagnostic.create({
-            severity: ErrorSeverity.InvalidReact,
-            category: `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({
-            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\`)`,
-          }),
-        );
-      } else {
-        depsList.push(maybeDep);
+        CompilerError.throwInvalidReact({
+          reason: `Expected the dependency list to be an array of simple expressions (e.g. \`x\`, \`x.y.z\`, \`x?.y?.z\`)`,
+          suggestions: null,
+          loc: dep.loc,
+        });
       }
-    }
+      return maybeDep;
+    });
   }
   return {
     fnPlace,
@@ -381,14 +341,8 @@ function extractManualMemoizationArgs(
  * rely on type inference to find useMemo/useCallback invocations, and instead does basic tracking
  * of globals and property loads to find both direct calls as well as usage via the React namespace,
  * eg `React.useMemo()`.
- *
- * This pass also validates that useMemo callbacks return a value (not void), ensuring that useMemo
- * is only used for memoizing values and not for running arbitrary side effects.
  */
-export function dropManualMemoization(
-  func: HIRFunction,
-): Result<void, CompilerError> {
-  const errors = new CompilerError();
+export function dropManualMemoization(func: HIRFunction): void {
   const isValidationEnabled =
     func.env.config.validatePreserveExistingMemoizationGuarantees ||
     func.env.config.validateNoSetStateInRender ||
@@ -435,47 +389,7 @@ export function dropManualMemoization(
             instr as TInstruction<CallExpression> | TInstruction<MethodCall>,
             manualMemo.kind,
             sidemap,
-            errors,
           );
-
-          if (fnPlace == null) {
-            continue;
-          }
-
-          /**
-           * Bailout on void return useMemos. This is an anti-pattern where code might be using
-           * useMemo like useEffect: running arbirtary side-effects synced to changes in specific
-           * values.
-           */
-          if (
-            func.env.config.validateNoVoidUseMemo &&
-            manualMemo.kind === 'useMemo'
-          ) {
-            const funcToCheck = sidemap.functions.get(
-              fnPlace.identifier.id,
-            )?.value;
-            if (funcToCheck !== undefined && funcToCheck.loweredFunc.func) {
-              if (!hasNonVoidReturn(funcToCheck.loweredFunc.func)) {
-                errors.pushDiagnostic(
-                  CompilerDiagnostic.create({
-                    severity: ErrorSeverity.InvalidReact,
-                    category: '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({
-                    kind: 'error',
-                    loc: instr.value.loc,
-                    message: 'useMemo() callbacks must return a value',
-                  }),
-                );
-              }
-            }
-          }
-
           instr.value = getManualMemoizationReplacement(
             fnPlace,
             instr.value.loc,
@@ -496,19 +410,11 @@ export function dropManualMemoization(
              * is rare and likely sketchy.
              */
             if (!sidemap.functions.has(fnPlace.identifier.id)) {
-              errors.pushDiagnostic(
-                CompilerDiagnostic.create({
-                  severity: ErrorSeverity.InvalidReact,
-                  category: `Expected the first argument to be an inline function expression`,
-                  description: `Expected the first argument to be an inline function expression`,
-                  suggestions: [],
-                }).withDetail({
-                  kind: 'error',
-                  loc: fnPlace.loc,
-                  message: `Expected the first argument to be an inline function expression`,
-                }),
-              );
-              continue;
+              CompilerError.throwInvalidReact({
+                reason: `Expected the first argument to be an inline function expression`,
+                suggestions: [],
+                loc: fnPlace.loc,
+              });
             }
             const memoDecl: Place =
               manualMemo.kind === 'useMemo'
@@ -580,8 +486,6 @@ export function dropManualMemoization(
       markInstructionIds(func.body);
     }
   }
-
-  return errors.asResult();
 }
 
 function findOptionalPlaces(fn: HIRFunction): Set<IdentifierId> {
@@ -626,17 +530,3 @@ function findOptionalPlaces(fn: HIRFunction): Set<IdentifierId> {
   }
   return optionals;
 }
-
-function hasNonVoidReturn(func: HIRFunction): boolean {
-  for (const [, block] of func.body.blocks) {
-    if (block.terminal.kind === 'return') {
-      if (
-        block.terminal.returnVariant === 'Explicit' ||
-        block.terminal.returnVariant === 'Implicit'
-      ) {
-        return true;
-      }
-    }
-  }
-  return false;
-}

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

@@ -326,26 +326,26 @@ function isEffectSafeOutsideRender(effect: FunctionEffect): boolean {
 
 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';
+    return 'Writing to 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';
+    return 'Updating a value used previously in JSX is not allowed. Consider moving the mutation before the JSX';
   } else if (abstractValue.reason.has(ValueReason.Context)) {
-    return `Modifying a value returned from 'useContext()' is not allowed.`;
+    return `Mutating a value returned from 'useContext()', which should not be mutated`;
   } else if (abstractValue.reason.has(ValueReason.KnownReturnSignature)) {
-    return 'Modifying a value returned from a function whose return value should not be mutated';
+    return 'Mutating 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';
+    return 'Mutating 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";
+    return "Mutating a value returned from 'useState()', which should not be mutated. 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";
+    return "Mutating a value returned from 'useReducer()', which should not be mutated. 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()';
+    return 'Updating a value used previously in an effect function or as an effect dependency is not allowed. Consider moving the mutation 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';
+    return 'Updating a value previously passed as an argument to a hook is not allowed. Consider moving the mutation 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';
+    return 'Updating a value returned from a hook is not allowed. Consider moving the mutation into the hook where the value is constructed';
   } else {
-    return 'This modifies a variable that React considers immutable';
+    return 'This mutates a variable that React considers immutable';
   }
 }

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

@@ -6,7 +6,6 @@
  */
 
 import {
-  CompilerDiagnostic,
   CompilerError,
   Effect,
   ErrorSeverity,
@@ -447,23 +446,20 @@ function applySignature(
               reason: value.reason,
               context: new Set(),
             });
-            const variable =
-              effect.value.identifier.name !== null &&
-              effect.value.identifier.name.kind === 'named'
-                ? `\`${effect.value.identifier.name.value}\``
-                : 'value';
             effects.push({
               kind: 'MutateFrozen',
               place: effect.value,
-              error: CompilerDiagnostic.create({
+              error: {
                 severity: ErrorSeverity.InvalidReact,
-                category: 'This value cannot be modified',
-                description: `${reason}.`,
-              }).withDetail({
-                kind: 'error',
+                reason,
+                description:
+                  effect.value.identifier.name !== null &&
+                  effect.value.identifier.name.kind === 'named'
+                    ? `Found mutation of \`${effect.value.identifier.name.value}\``
+                    : null,
                 loc: effect.value.loc,
-                message: `${variable} cannot be modified`,
-              }),
+                suggestions: null,
+              },
             });
           }
         }
@@ -691,7 +687,6 @@ function applyEffect(
       }
       break;
     }
-    case 'MaybeAlias':
     case 'Alias':
     case 'Capture': {
       CompilerError.invariant(
@@ -956,7 +951,7 @@ function applyEffect(
             context,
             state,
             // OK: recording information flow
-            {kind: 'MaybeAlias', from: operand, into: effect.into},
+            {kind: 'Alias', from: operand, into: effect.into},
             initialized,
             effects,
           );
@@ -1018,31 +1013,33 @@ function applyEffect(
             effect.value.identifier.declarationId,
           )
         ) {
-          const variable =
+          const description =
             effect.value.identifier.name !== null &&
             effect.value.identifier.name.kind === 'named'
-              ? `\`${effect.value.identifier.name.value}\``
+              ? `Variable \`${effect.value.identifier.name.value}\` is accessed before it is declared`
               : null;
           const hoistedAccess = context.hoistedContextDeclarations.get(
             effect.value.identifier.declarationId,
           );
-          const diagnostic = CompilerDiagnostic.create({
-            severity: ErrorSeverity.InvalidReact,
-            category: 'Cannot access variable before it is declared',
-            description: `${variable ?? 'This variable'} is accessed before it is declared, which prevents the earlier access from updating when this value changes over time.`,
-          });
           if (hoistedAccess != null && hoistedAccess.loc != effect.value.loc) {
-            diagnostic.withDetail({
-              kind: 'error',
-              loc: hoistedAccess.loc,
-              message: `${variable ?? 'variable'} accessed before it is declared`,
-            });
+            applyEffect(
+              context,
+              state,
+              {
+                kind: 'MutateFrozen',
+                place: effect.value,
+                error: {
+                  severity: ErrorSeverity.InvalidReact,
+                  reason: `This variable is accessed before it is declared, which may prevent it from updating as the assigned value changes over time`,
+                  description,
+                  loc: hoistedAccess.loc,
+                  suggestions: null,
+                },
+              },
+              initialized,
+              effects,
+            );
           }
-          diagnostic.withDetail({
-            kind: 'error',
-            loc: effect.value.loc,
-            message: `${variable ?? 'variable'} is declared here`,
-          });
 
           applyEffect(
             context,
@@ -1050,7 +1047,13 @@ function applyEffect(
             {
               kind: 'MutateFrozen',
               place: effect.value,
-              error: diagnostic,
+              error: {
+                severity: ErrorSeverity.InvalidReact,
+                reason: `This variable is accessed before it is declared, which prevents the earlier access from updating when this value changes over time`,
+                description,
+                loc: effect.value.loc,
+                suggestions: null,
+              },
             },
             initialized,
             effects,
@@ -1061,11 +1064,11 @@ function applyEffect(
             reason: value.reason,
             context: new Set(),
           });
-          const variable =
+          const description =
             effect.value.identifier.name !== null &&
             effect.value.identifier.name.kind === 'named'
-              ? `\`${effect.value.identifier.name.value}\``
-              : 'value';
+              ? `Found mutation of \`${effect.value.identifier.name.value}\``
+              : null;
           applyEffect(
             context,
             state,
@@ -1075,15 +1078,13 @@ function applyEffect(
                   ? 'MutateFrozen'
                   : 'MutateGlobal',
               place: effect.value,
-              error: CompilerDiagnostic.create({
+              error: {
                 severity: ErrorSeverity.InvalidReact,
-                category: 'This value cannot be modified',
-                description: `${reason}.`,
-              }).withDetail({
-                kind: 'error',
+                reason,
+                description,
                 loc: effect.value.loc,
-                message: `${variable} cannot be modified`,
-              }),
+                suggestions: null,
+              },
             },
             initialized,
             effects,
@@ -1324,7 +1325,7 @@ class InferenceState {
             return 'mutate-global';
           }
           case ValueKind.MaybeFrozen: {
-            return 'mutate-frozen';
+            return 'none';
           }
           default: {
             assertExhaustive(kind, `Unexpected kind ${kind}`);
@@ -2002,20 +2003,16 @@ function computeSignatureForInstruction(
       break;
     }
     case 'StoreGlobal': {
-      const variable = `\`${value.name}\``;
       effects.push({
         kind: 'MutateGlobal',
         place: value.value,
-        error: CompilerDiagnostic.create({
-          severity: ErrorSeverity.InvalidReact,
-          category:
-            'Cannot reassign variables declared outside of the component/hook',
-          description: `Variable ${variable} is declared outside of the component/hook. Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)`,
-        }).withDetail({
-          kind: 'error',
+        error: {
+          reason:
+            'Unexpected reassignment of a variable which was defined outside of the component. Components and hooks should be pure and side-effect free, but variable reassignment is a form of side-effect. If this variable is used in rendering, use useState instead. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)',
           loc: instr.loc,
-          message: `${variable} cannot be reassigned`,
-        }),
+          suggestions: null,
+          severity: ErrorSeverity.InvalidReact,
+        },
       });
       effects.push({kind: 'Assign', from: value.value, into: lvalue});
       break;
@@ -2105,19 +2102,17 @@ function computeEffectsForLegacySignature(
     effects.push({
       kind: 'Impure',
       place: receiver,
-      error: CompilerDiagnostic.create({
-        severity: ErrorSeverity.InvalidReact,
-        category: 'Cannot call impure function during render',
+      error: {
+        reason:
+          'Calling an impure function can produce unstable results. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#components-and-hooks-must-be-idempotent)',
         description:
-          (signature.canonicalName != null
-            ? `\`${signature.canonicalName}\` is an impure function. `
-            : '') +
-          'Calling an impure function can produce unstable results that update unpredictably when the component happens to re-render. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#components-and-hooks-must-be-idempotent)',
-      }).withDetail({
-        kind: 'error',
+          signature.canonicalName != null
+            ? `\`${signature.canonicalName}\` is an impure function whose results may change on every call`
+            : null,
+        severity: ErrorSeverity.InvalidReact,
         loc,
-        message: 'Cannot call impure function',
-      }),
+        suggestions: null,
+      },
     });
   }
   const stores: Array<Place> = [];
@@ -2377,7 +2372,6 @@ function computeEffectsForSignature(
   // Apply substitutions
   for (const effect of signature.effects) {
     switch (effect.kind) {
-      case 'MaybeAlias':
       case 'Assign':
       case 'ImmutableCapture':
       case 'Alias':

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

@@ -160,8 +160,6 @@ export function inferMutationAliasingRanges(
           state.assign(index++, effect.from, effect.into);
         } else if (effect.kind === 'Alias') {
           state.assign(index++, effect.from, effect.into);
-        } else if (effect.kind === 'MaybeAlias') {
-          state.maybeAlias(index++, effect.from, effect.into);
         } else if (effect.kind === 'Capture') {
           state.capture(index++, effect.from, effect.into);
         } else if (
@@ -197,7 +195,7 @@ export function inferMutationAliasingRanges(
           effect.kind === 'MutateGlobal' ||
           effect.kind === 'Impure'
         ) {
-          errors.pushDiagnostic(effect.error);
+          errors.push(effect.error);
           functionEffects.push(effect);
         } else if (effect.kind === 'Render') {
           renders.push({index: index++, place: effect.place});
@@ -249,7 +247,6 @@ export function inferMutationAliasingRanges(
   }
   for (const param of [...fn.context, ...fn.params]) {
     const place = param.kind === 'Identifier' ? param : param.place;
-
     const node = state.nodes.get(place.identifier);
     if (node == null) {
       continue;
@@ -349,8 +346,7 @@ export function inferMutationAliasingRanges(
           case 'Assign':
           case 'Alias':
           case 'Capture':
-          case 'CreateFrom':
-          case 'MaybeAlias': {
+          case 'CreateFrom': {
             const isMutatedOrReassigned =
               effect.into.identifier.mutableRange.end > instr.id;
             if (isMutatedOrReassigned) {
@@ -553,7 +549,7 @@ function appendFunctionErrors(errors: CompilerError, fn: HIRFunction): void {
       case 'Impure':
       case 'MutateFrozen':
       case 'MutateGlobal': {
-        errors.pushDiagnostic(effect.error);
+        errors.push(effect.error);
         break;
       }
     }
@@ -571,12 +567,7 @@ type Node = {
   createdFrom: Map<Identifier, number>;
   captures: Map<Identifier, number>;
   aliases: Map<Identifier, number>;
-  maybeAliases: Map<Identifier, number>;
-  edges: Array<{
-    index: number;
-    node: Identifier;
-    kind: 'capture' | 'alias' | 'maybeAlias';
-  }>;
+  edges: Array<{index: number; node: Identifier; kind: 'capture' | 'alias'}>;
   transitive: {kind: MutationKind; loc: SourceLocation} | null;
   local: {kind: MutationKind; loc: SourceLocation} | null;
   lastMutated: number;
@@ -594,7 +585,6 @@ class AliasingState {
       createdFrom: new Map(),
       captures: new Map(),
       aliases: new Map(),
-      maybeAliases: new Map(),
       edges: [],
       transitive: null,
       local: null,
@@ -640,18 +630,6 @@ class AliasingState {
     }
   }
 
-  maybeAlias(index: number, from: Place, into: Place): void {
-    const fromNode = this.nodes.get(from.identifier);
-    const toNode = this.nodes.get(into.identifier);
-    if (fromNode == null || toNode == null) {
-      return;
-    }
-    fromNode.edges.push({index, node: into.identifier, kind: 'maybeAlias'});
-    if (!toNode.maybeAliases.has(from.identifier)) {
-      toNode.maybeAliases.set(from.identifier, index);
-    }
-  }
-
   render(index: number, start: Identifier, errors: CompilerError): void {
     const seen = new Set<Identifier>();
     const queue: Array<Identifier> = [start];
@@ -695,24 +673,22 @@ class AliasingState {
     // Null is used for simulated mutations
     end: InstructionId | null,
     transitive: boolean,
-    startKind: MutationKind,
+    kind: MutationKind,
     loc: SourceLocation,
     errors: CompilerError,
   ): void {
-    const seen = new Map<Identifier, MutationKind>();
+    const seen = new Set<Identifier>();
     const queue: Array<{
       place: Identifier;
       transitive: boolean;
       direction: 'backwards' | 'forwards';
-      kind: MutationKind;
-    }> = [{place: start, transitive, direction: 'backwards', kind: startKind}];
+    }> = [{place: start, transitive, direction: 'backwards'}];
     while (queue.length !== 0) {
-      const {place: current, transitive, direction, kind} = queue.pop()!;
-      const previousKind = seen.get(current);
-      if (previousKind != null && previousKind >= kind) {
+      const {place: current, transitive, direction} = queue.pop()!;
+      if (seen.has(current)) {
         continue;
       }
-      seen.set(current, kind);
+      seen.add(current);
       const node = this.nodes.get(current);
       if (node == null) {
         continue;
@@ -748,18 +724,13 @@ class AliasingState {
         if (edge.index >= index) {
           break;
         }
-        queue.push({place: edge.node, transitive, direction: 'forwards', kind});
+        queue.push({place: edge.node, transitive, direction: 'forwards'});
       }
       for (const [alias, when] of node.createdFrom) {
         if (when >= index) {
           continue;
         }
-        queue.push({
-          place: alias,
-          transitive: true,
-          direction: 'backwards',
-          kind,
-        });
+        queue.push({place: alias, transitive: true, direction: 'backwards'});
       }
       if (direction === 'backwards' || node.value.kind !== 'Phi') {
         /**
@@ -776,25 +747,7 @@ class AliasingState {
           if (when >= index) {
             continue;
           }
-          queue.push({place: alias, transitive, direction: 'backwards', kind});
-        }
-        /**
-         * MaybeAlias indicates potential data flow from unknown function calls,
-         * so we downgrade mutations through these aliases to consider them
-         * conditional. This means we'll consider them for mutation *range*
-         * purposes but not report validation errors for mutations, since
-         * we aren't sure that the `from` value could actually be aliased.
-         */
-        for (const [alias, when] of node.maybeAliases) {
-          if (when >= index) {
-            continue;
-          }
-          queue.push({
-            place: alias,
-            transitive,
-            direction: 'backwards',
-            kind: MutationKind.Conditional,
-          });
+          queue.push({place: alias, transitive, direction: 'backwards'});
         }
       }
       /**
@@ -805,12 +758,7 @@ class AliasingState {
           if (when >= index) {
             continue;
           }
-          queue.push({
-            place: capture,
-            transitive,
-            direction: 'backwards',
-            kind,
-          });
+          queue.push({place: capture, transitive, direction: 'backwards'});
         }
       }
     }

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

@@ -21,6 +21,7 @@ import {
   isStableType,
   isStableTypeContainer,
   isUseOperator,
+  isUseRefType,
 } from '../HIR';
 import {PostDominator} from '../HIR/Dominator';
 import {
@@ -69,6 +70,13 @@ class StableSidemap {
               isStable: false,
             });
           }
+        } else if (
+          this.env.config.enableTreatRefLikeIdentifiersAsRefs &&
+          isUseRefType(lvalue.identifier)
+        ) {
+          this.map.set(lvalue.identifier.id, {
+            isStable: true,
+          });
         }
         break;
       }

compiler/packages/babel-plugin-react-compiler/src/Inference/MUTABILITY_ALIASING_MODEL.md

@@ -153,10 +153,6 @@ This is somewhat the inverse of `Capture`. The `CreateFrom` effect describes tha
 
 Describes immutable data flow from one value to another. This is not currently used for anything, but is intended to eventually power a more sophisticated escape analysis.
 
-### MaybeAlias
-
-Describes potential data flow that the compiler knows may occur behind a function call, but cannot be sure about. For example, `foo(x)` _may_ be the identity function and return `x`, or `cond(a, b, c)` may conditionally return `b` or `c` depending on the value of `a`, but those functions could just as easily return new mutable values and not capture any information from their arguments. MaybeAlias represents that we have to consider the potential for data flow when deciding mutable ranges, but should be conservative about reporting errors. For example, `foo(someFrozenValue).property = true` should not error since we don't know for certain that foo returns its input.
-
 ### State-Changing Effects
 
 The following effects describe state changes to specific values, not data flow. In many cases, JavaScript semantics will involve a combination of both data-flow effects *and* state-change effects. For example, `object.property = value` has data flow (`Capture object <- value`) and mutation (`Mutate object`).
@@ -351,17 +347,6 @@ a.b = b; // capture
 mutate(a); // can transitively mutate b
 ```
 
-### MaybeAlias makes mutation conditional
-
-Because we don't know for certain that the aliasing occurs, we consider the mutation conditional against the source.
-
-```
-MaybeAlias a <- b
-Mutate a
-=>
-MutateConditional b
-```
-
 ### Freeze Does Not Freeze the Value
 
 Freeze does not freeze the value itself:

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

@@ -237,7 +237,6 @@ function emitSelectorFn(env: Environment, keys: Array<string>): Instruction {
     terminal: {
       id: makeInstructionId(0),
       kind: 'return',
-      returnVariant: 'Explicit',
       loc: GeneratedSource,
       value: arrayInstr.lvalue,
       effects: null,

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

@@ -352,7 +352,6 @@ function emitOutlinedFn(
     terminal: {
       id: makeInstructionId(0),
       kind: 'return',
-      returnVariant: 'Explicit',
       loc: GeneratedSource,
       value: instructions.at(-1)!.lvalue,
       effects: null,

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

@@ -14,7 +14,6 @@ import {
   Identifier,
   IdentifierId,
   Instruction,
-  InstructionKind,
   makePropertyLiteral,
   makeType,
   PropType,
@@ -195,29 +194,12 @@ function* generateInstructionTypes(
       break;
     }
 
-    // We intentionally do not infer types for most context variables
+    // We intentionally do not infer types for context variables
     case 'DeclareContext':
+    case 'StoreContext':
     case 'LoadContext': {
       break;
     }
-    case 'StoreContext': {
-      /**
-       * The caveat is StoreContext const, where we know the value is
-       * assigned once such that everywhere the value is accessed, it
-       * must have the same type from the rvalue.
-       *
-       * A concrete example where this is useful is `const ref = useRef()`
-       * where the ref is referenced before its declaration in a function
-       * expression, causing it to be converted to a const context variable.
-       */
-      if (value.lvalue.kind === InstructionKind.Const) {
-        yield equation(
-          value.lvalue.place.identifier.type,
-          value.value.identifier.type,
-        );
-      }
-      break;
-    }
 
     case 'StoreLocal': {
       if (env.config.enableUseTypeAnnotations) {
@@ -451,18 +433,6 @@ function* generateInstructionTypes(
 
     case 'JsxExpression':
     case 'JsxFragment': {
-      if (env.config.enableTreatRefLikeIdentifiersAsRefs) {
-        if (value.kind === 'JsxExpression') {
-          for (const prop of value.props) {
-            if (prop.kind === 'JsxAttribute' && prop.name === 'ref') {
-              yield equation(prop.place.identifier.type, {
-                kind: 'Object',
-                shapeId: BuiltInUseRefId,
-              });
-            }
-          }
-        }
-      }
       yield equation(left, {kind: 'Object', shapeId: BuiltInJsxId});
       break;
     }
@@ -478,36 +448,7 @@ function* generateInstructionTypes(
       yield equation(left, returnType);
       break;
     }
-    case 'PropertyStore': {
-      /**
-       * Infer types based on assignments to known object properties
-       * This is important for refs, where assignment to `<maybeRef>.current`
-       * can help us infer that an object itself is a ref
-       */
-      yield equation(
-        /**
-         * Our property type declarations are best-effort and we haven't tested
-         * using them to drive inference of rvalues from lvalues. We want to emit
-         * a Property type in order to infer refs from `.current` accesses, but
-         * stay conservative by not otherwise inferring anything about rvalues.
-         * So we use a dummy type here.
-         *
-         * TODO: consider using the rvalue type here
-         */
-        makeType(),
-        // unify() only handles properties in the second position
-        {
-          kind: 'Property',
-          objectType: value.object.identifier.type,
-          objectName: getName(names, value.object.identifier.id),
-          propertyName: {
-            kind: 'literal',
-            value: value.property,
-          },
-        },
-      );
-      break;
-    }
+    case 'PropertyStore':
     case 'DeclareLocal':
     case 'RegExpLiteral':
     case 'MetaProperty':

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

@@ -113,13 +113,8 @@ function* splitPragma(
  */
 function parseConfigPragmaEnvironmentForTest(
   pragma: string,
-  defaultConfig: PartialEnvironmentConfig,
 ): EnvironmentConfig {
-  // throw early if the defaults are invalid
-  EnvironmentConfigSchema.parse(defaultConfig);
-
-  const maybeConfig: Partial<Record<keyof EnvironmentConfig, unknown>> =
-    defaultConfig;
+  const maybeConfig: Partial<Record<keyof EnvironmentConfig, unknown>> = {};
 
   for (const {key, value: val} of splitPragma(pragma)) {
     if (!hasOwnProperty(EnvironmentConfigSchema.shape, key)) {
@@ -179,13 +174,9 @@ export function parseConfigPragmaForTests(
   pragma: string,
   defaults: {
     compilationMode: CompilationMode;
-    environment?: PartialEnvironmentConfig;
   },
 ): PluginOptions {
-  const environment = parseConfigPragmaEnvironmentForTest(
-    pragma,
-    defaults.environment ?? {},
-  );
+  const environment = parseConfigPragmaEnvironmentForTest(pragma);
   const options: Record<keyof PluginOptions, unknown> = {
     ...defaultOptions,
     panicThreshold: 'all_errors',

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

@@ -29,20 +29,15 @@ export function validateLocalsNotReassignedAfterRender(fn: HIRFunction): void {
   );
   if (reassignment !== null) {
     const errors = new CompilerError();
-    const variable =
-      reassignment.identifier.name != null &&
-      reassignment.identifier.name.kind === 'named'
-        ? `\`${reassignment.identifier.name.value}\``
-        : 'variable';
     errors.pushDiagnostic(
       CompilerDiagnostic.create({
         severity: ErrorSeverity.InvalidReact,
-        category: 'Cannot reassign variable after render completes',
-        description: `Reassigning ${variable} after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead.`,
+        category: 'Cannot reassign a variable after render completes',
+        description: `Reassigning ${reassignment.identifier.name != null && reassignment.identifier.name.kind === 'named' ? `variable \`${reassignment.identifier.name.value}\`` : 'a variable'} after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead`,
       }).withDetail({
         kind: 'error',
         loc: reassignment.loc,
-        message: `Cannot reassign ${variable} after render completes`,
+        message: 'Cannot reassign variable after render completes',
       }),
     );
     throw errors;
@@ -83,25 +78,16 @@ function getContextReassignment(
           // if the function or its depends reassign, propagate that fact on the lvalue
           if (reassignment !== null) {
             if (isAsync || value.loweredFunc.func.async) {
-              const errors = new CompilerError();
-              const variable =
-                reassignment.identifier.name !== null &&
-                reassignment.identifier.name.kind === 'named'
-                  ? `\`${reassignment.identifier.name.value}\``
-                  : 'variable';
-              errors.pushDiagnostic(
-                CompilerDiagnostic.create({
-                  severity: ErrorSeverity.InvalidReact,
-                  category: '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({
-                  kind: 'error',
-                  loc: reassignment.loc,
-                  message: `Cannot reassign ${variable}`,
-                }),
-              );
-              throw errors;
+              CompilerError.throwInvalidReact({
+                reason:
+                  'Reassigning a variable in an async function can cause inconsistent behavior on subsequent renders. Consider using state instead',
+                description:
+                  reassignment.identifier.name !== null &&
+                  reassignment.identifier.name.kind === 'named'
+                    ? `Variable \`${reassignment.identifier.name.value}\` cannot be reassigned after render`
+                    : '',
+                loc: reassignment.loc,
+              });
             }
             reassigningFunctions.set(lvalue.identifier.id, reassignment);
           }

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

@@ -57,28 +57,22 @@ export function validateNoFreezingKnownMutableFunctions(
     if (operand.effect === Effect.Freeze) {
       const effect = contextMutationEffects.get(operand.identifier.id);
       if (effect != null) {
-        const place = [...effect.places][0];
-        const variable =
-          place != null &&
-          place.identifier.name != null &&
-          place.identifier.name.kind === 'named'
-            ? `\`${place.identifier.name.value}\``
-            : 'a local variable';
         errors.pushDiagnostic(
           CompilerDiagnostic.create({
             severity: ErrorSeverity.InvalidReact,
             category: '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.`,
+            description: `This argument is a function which may reassign or mutate local variables after render, which can cause inconsistent behavior on subsequent renders. Consider using state instead`,
           })
             .withDetail({
               kind: 'error',
               loc: operand.loc,
-              message: `This function may (indirectly) reassign or modify ${variable} after render`,
+              message:
+                'This function may (indirectly) reassign or modify local variables after render',
             })
             .withDetail({
               kind: 'error',
               loc: effect.loc,
-              message: `This modifies ${variable}`,
+              message: 'This modifies a local variable',
             }),
         );
       }

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

@@ -5,11 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {
-  CompilerDiagnostic,
-  CompilerError,
-  ErrorSeverity,
-} from '../CompilerError';
+import {CompilerError, ErrorSeverity} from '../CompilerError';
 import {
   BlockId,
   HIRFunction,
@@ -27,7 +23,6 @@ import {
   eachTerminalOperand,
 } from '../HIR/visitors';
 import {Err, Ok, Result} from '../Utils/Result';
-import {retainWhere} from '../Utils/utils';
 
 /**
  * Validates that a function does not access a ref value during render. This includes a partial check
@@ -80,18 +75,8 @@ type RefAccessRefType =
 
 type RefFnType = {readRefEffect: boolean; returnType: RefAccessType};
 
-class Env {
+class Env extends Map<IdentifierId, RefAccessType> {
   #changed = false;
-  #data: Map<IdentifierId, RefAccessType> = new Map();
-  #temporaries: Map<IdentifierId, Place> = new Map();
-
-  lookup(place: Place): Place {
-    return this.#temporaries.get(place.identifier.id) ?? place;
-  }
-
-  define(place: Place, value: Place): void {
-    this.#temporaries.set(place.identifier.id, value);
-  }
 
   resetChanged(): void {
     this.#changed = false;
@@ -101,14 +86,8 @@ class Env {
     return this.#changed;
   }
 
-  get(key: IdentifierId): RefAccessType | undefined {
-    const operandId = this.#temporaries.get(key)?.identifier.id ?? key;
-    return this.#data.get(operandId);
-  }
-
-  set(key: IdentifierId, value: RefAccessType): this {
-    const operandId = this.#temporaries.get(key)?.identifier.id ?? key;
-    const cur = this.#data.get(operandId);
+  override set(key: IdentifierId, value: RefAccessType): this {
+    const cur = this.get(key);
     const widenedValue = joinRefAccessTypes(value, cur ?? {kind: 'None'});
     if (
       !(cur == null && widenedValue.kind === 'None') &&
@@ -116,8 +95,7 @@ class Env {
     ) {
       this.#changed = true;
     }
-    this.#data.set(operandId, widenedValue);
-    return this;
+    return super.set(key, widenedValue);
   }
 }
 
@@ -125,48 +103,9 @@ export function validateNoRefAccessInRender(
   fn: HIRFunction,
 ): Result<void, CompilerError> {
   const env = new Env();
-  collectTemporariesSidemap(fn, env);
   return validateNoRefAccessInRenderImpl(fn, env).map(_ => undefined);
 }
 
-function collectTemporariesSidemap(fn: HIRFunction, env: Env): void {
-  for (const block of fn.body.blocks.values()) {
-    for (const instr of block.instructions) {
-      const {lvalue, value} = instr;
-      switch (value.kind) {
-        case 'LoadLocal': {
-          const temp = env.lookup(value.place);
-          if (temp != null) {
-            env.define(lvalue, temp);
-          }
-          break;
-        }
-        case 'StoreLocal': {
-          const temp = env.lookup(value.value);
-          if (temp != null) {
-            env.define(lvalue, temp);
-            env.define(value.lvalue.place, temp);
-          }
-          break;
-        }
-        case 'PropertyLoad': {
-          if (
-            isUseRefType(value.object.identifier) &&
-            value.property === 'current'
-          ) {
-            continue;
-          }
-          const temp = env.lookup(value.object);
-          if (temp != null) {
-            env.define(lvalue, temp);
-          }
-          break;
-        }
-      }
-    }
-  }
-}
-
 function refTypeOfType(place: Place): RefAccessType {
   if (isRefValueType(place.identifier)) {
     return {kind: 'RefValue'};
@@ -319,27 +258,12 @@ function validateNoRefAccessInRenderImpl(
     env.set(place.identifier.id, type);
   }
 
-  const interpolatedAsJsx = new Set<IdentifierId>();
-  for (const block of fn.body.blocks.values()) {
-    for (const instr of block.instructions) {
-      const {value} = instr;
-      if (value.kind === 'JsxExpression' || value.kind === 'JsxFragment') {
-        if (value.children != null) {
-          for (const child of value.children) {
-            interpolatedAsJsx.add(child.identifier.id);
-          }
-        }
-      }
-    }
-  }
-
   for (let i = 0; (i == 0 || env.hasChanged()) && i < 10; i++) {
     env.resetChanged();
     returnValues = [];
-    const safeBlocks: Array<{block: BlockId; ref: RefId}> = [];
+    const safeBlocks = new Map<BlockId, RefId>();
     const errors = new CompilerError();
     for (const [, block] of fn.body.blocks) {
-      retainWhere(safeBlocks, entry => entry.block !== block.id);
       for (const phi of block.phis) {
         env.set(
           phi.place.identifier.id,
@@ -461,79 +385,28 @@ function validateNoRefAccessInRenderImpl(
             const hookKind = getHookKindForType(fn.env, callee.identifier.type);
             let returnType: RefAccessType = {kind: 'None'};
             const fnType = env.get(callee.identifier.id);
-            let didError = false;
             if (fnType?.kind === 'Structure' && fnType.fn !== null) {
               returnType = fnType.fn.returnType;
               if (fnType.fn.readRefEffect) {
-                didError = true;
-                errors.pushDiagnostic(
-                  CompilerDiagnostic.create({
-                    severity: ErrorSeverity.InvalidReact,
-                    category: 'Cannot access refs during render',
-                    description: ERROR_DESCRIPTION,
-                  }).withDetail({
-                    kind: 'error',
-                    loc: callee.loc,
-                    message: `This function accesses a ref value`,
-                  }),
-                );
+                errors.push({
+                  severity: ErrorSeverity.InvalidReact,
+                  reason:
+                    'This function accesses a ref value (the `current` property), which may not be accessed during render. (https://react.dev/reference/react/useRef)',
+                  loc: callee.loc,
+                  description:
+                    callee.identifier.name !== null &&
+                    callee.identifier.name.kind === 'named'
+                      ? `Function \`${callee.identifier.name.value}\` accesses a ref`
+                      : null,
+                  suggestions: null,
+                });
               }
             }
-            /*
-             * If we already reported an error on this instruction, don't report
-             * duplicate errors
-             */
-            if (!didError) {
-              const isRefLValue = isUseRefType(instr.lvalue.identifier);
-              for (const operand of eachInstructionValueOperand(instr.value)) {
-                /**
-                 * By default we check that function call operands are not refs,
-                 * ref values, or functions that can access refs.
-                 */
-                if (
-                  isRefLValue ||
-                  (hookKind != null &&
-                    hookKind !== 'useState' &&
-                    hookKind !== 'useReducer')
-                ) {
-                  /**
-                   * Special cases:
-                   *
-                   * 1. the lvalue is a ref
-                   * In general passing a ref to a function may access that ref
-                   * value during render, so we disallow it.
-                   *
-                   * The main exception is the "mergeRefs" pattern, ie a function
-                   * that accepts multiple refs as arguments (or an array of refs)
-                   * and returns a new, aggregated ref. If the lvalue is a ref,
-                   * we assume that the user is doing this pattern and allow passing
-                   * refs.
-                   *
-                   * Eg `const mergedRef = mergeRefs(ref1, ref2)`
-                   *
-                   * 2. calling hooks
-                   *
-                   * Hooks are independently checked to ensure they don't access refs
-                   * during render.
-                   */
-                  validateNoDirectRefValueAccess(errors, operand, env);
-                } else if (interpolatedAsJsx.has(instr.lvalue.identifier.id)) {
-                  /**
-                   * Special case: the lvalue is passed as a jsx child
-                   *
-                   * For example `<Foo>{renderHelper(ref)}</Foo>`. Here we have more
-                   * context and infer that the ref is being passed to a component-like
-                   * render function which attempts to obey the rules.
-                   */
-                  validateNoRefValueAccess(errors, env, operand);
-                } else {
-                  validateNoRefPassedToFunction(
-                    errors,
-                    env,
-                    operand,
-                    operand.loc,
-                  );
-                }
+            for (const operand of eachInstructionValueOperand(instr.value)) {
+              if (hookKind != null) {
+                validateNoDirectRefValueAccess(errors, operand, env);
+              } else {
+                validateNoRefAccess(errors, env, operand, operand.loc);
               }
             }
             env.set(instr.lvalue.identifier.id, returnType);
@@ -566,39 +439,23 @@ function validateNoRefAccessInRenderImpl(
           case 'PropertyStore':
           case 'ComputedDelete':
           case 'ComputedStore': {
+            const safe = safeBlocks.get(block.id);
             const target = env.get(instr.value.object.identifier.id);
-            let safe: (typeof safeBlocks)['0'] | null | undefined = null;
             if (
               instr.value.kind === 'PropertyStore' &&
-              target != null &&
-              target.kind === 'Ref'
+              safe != null &&
+              target?.kind === 'Ref' &&
+              target.refId === safe
             ) {
-              safe = safeBlocks.find(entry => entry.ref === target.refId);
-            }
-            if (safe != null) {
-              retainWhere(safeBlocks, entry => entry !== safe);
+              safeBlocks.delete(block.id);
             } else {
-              validateNoRefUpdate(errors, env, instr.value.object, instr.loc);
+              validateNoRefAccess(errors, env, instr.value.object, instr.loc);
             }
-            if (
-              instr.value.kind === 'ComputedDelete' ||
-              instr.value.kind === 'ComputedStore'
-            ) {
-              validateNoRefValueAccess(errors, env, instr.value.property);
-            }
-            if (
-              instr.value.kind === 'ComputedStore' ||
-              instr.value.kind === 'PropertyStore'
-            ) {
-              validateNoDirectRefValueAccess(errors, instr.value.value, env);
-              const type = env.get(instr.value.value.identifier.id);
-              if (type != null && type.kind === 'Structure') {
-                let objectType: RefAccessType = type;
-                if (target != null) {
-                  objectType = joinRefAccessTypes(objectType, target);
-                }
-                env.set(instr.value.object.identifier.id, objectType);
+            for (const operand of eachInstructionValueOperand(instr.value)) {
+              if (operand === instr.value.object) {
+                continue;
               }
+              validateNoRefValueAccess(errors, env, operand);
             }
             break;
           }
@@ -678,11 +535,8 @@ function validateNoRefAccessInRenderImpl(
 
       if (block.terminal.kind === 'if') {
         const test = env.get(block.terminal.test.identifier.id);
-        if (
-          test?.kind === 'Guard' &&
-          safeBlocks.find(entry => entry.ref === test.refId) == null
-        ) {
-          safeBlocks.push({block: block.terminal.fallthrough, ref: test.refId});
+        if (test?.kind === 'Guard') {
+          safeBlocks.set(block.terminal.consequent, test.refId);
         }
       }
 
@@ -729,17 +583,18 @@ function destructure(
 
 function guardCheck(errors: CompilerError, operand: Place, env: Env): void {
   if (env.get(operand.identifier.id)?.kind === 'Guard') {
-    errors.pushDiagnostic(
-      CompilerDiagnostic.create({
-        severity: ErrorSeverity.InvalidReact,
-        category: 'Cannot access refs during render',
-        description: ERROR_DESCRIPTION,
-      }).withDetail({
-        kind: 'error',
-        loc: operand.loc,
-        message: `Cannot access ref value during render`,
-      }),
-    );
+    errors.push({
+      severity: ErrorSeverity.InvalidReact,
+      reason:
+        'Ref values (the `current` property) may not be accessed during render. (https://react.dev/reference/react/useRef)',
+      loc: operand.loc,
+      description:
+        operand.identifier.name !== null &&
+        operand.identifier.name.kind === 'named'
+          ? `Cannot access ref value \`${operand.identifier.name.value}\``
+          : null,
+      suggestions: null,
+    });
   }
 }
 
@@ -753,21 +608,22 @@ function validateNoRefValueAccess(
     type?.kind === 'RefValue' ||
     (type?.kind === 'Structure' && type.fn?.readRefEffect)
   ) {
-    errors.pushDiagnostic(
-      CompilerDiagnostic.create({
-        severity: ErrorSeverity.InvalidReact,
-        category: '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`,
-      }),
-    );
+    errors.push({
+      severity: ErrorSeverity.InvalidReact,
+      reason:
+        'Ref values (the `current` property) may not be accessed during render. (https://react.dev/reference/react/useRef)',
+      loc: (type.kind === 'RefValue' && type.loc) || operand.loc,
+      description:
+        operand.identifier.name !== null &&
+        operand.identifier.name.kind === 'named'
+          ? `Cannot access ref value \`${operand.identifier.name.value}\``
+          : null,
+      suggestions: null,
+    });
   }
 }
 
-function validateNoRefPassedToFunction(
+function validateNoRefAccess(
   errors: CompilerError,
   env: Env,
   operand: Place,
@@ -779,39 +635,18 @@ function validateNoRefPassedToFunction(
     type?.kind === 'RefValue' ||
     (type?.kind === 'Structure' && type.fn?.readRefEffect)
   ) {
-    errors.pushDiagnostic(
-      CompilerDiagnostic.create({
-        severity: ErrorSeverity.InvalidReact,
-        category: '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`,
-      }),
-    );
-  }
-}
-
-function validateNoRefUpdate(
-  errors: CompilerError,
-  env: Env,
-  operand: Place,
-  loc: SourceLocation,
-): void {
-  const type = destructure(env.get(operand.identifier.id));
-  if (type?.kind === 'Ref' || type?.kind === 'RefValue') {
-    errors.pushDiagnostic(
-      CompilerDiagnostic.create({
-        severity: ErrorSeverity.InvalidReact,
-        category: 'Cannot access refs during render',
-        description: ERROR_DESCRIPTION,
-      }).withDetail({
-        kind: 'error',
-        loc: (type.kind === 'RefValue' && type.loc) || loc,
-        message: `Cannot update ref during render`,
-      }),
-    );
+    errors.push({
+      severity: ErrorSeverity.InvalidReact,
+      reason:
+        'Ref values (the `current` property) may not be accessed during render. (https://react.dev/reference/react/useRef)',
+      loc: (type.kind === 'RefValue' && type.loc) || loc,
+      description:
+        operand.identifier.name !== null &&
+        operand.identifier.name.kind === 'named'
+          ? `Cannot access ref value \`${operand.identifier.name.value}\``
+          : null,
+      suggestions: null,
+    });
   }
 }
 
@@ -822,22 +657,17 @@ function validateNoDirectRefValueAccess(
 ): void {
   const type = destructure(env.get(operand.identifier.id));
   if (type?.kind === 'RefValue') {
-    errors.pushDiagnostic(
-      CompilerDiagnostic.create({
-        severity: ErrorSeverity.InvalidReact,
-        category: 'Cannot access refs during render',
-        description: ERROR_DESCRIPTION,
-      }).withDetail({
-        kind: 'error',
-        loc: type.loc ?? operand.loc,
-        message: `Cannot access ref value during render`,
-      }),
-    );
+    errors.push({
+      severity: ErrorSeverity.InvalidReact,
+      reason:
+        'Ref values (the `current` property) may not be accessed during render. (https://react.dev/reference/react/useRef)',
+      loc: type.loc ?? operand.loc,
+      description:
+        operand.identifier.name !== null &&
+        operand.identifier.name.kind === 'named'
+          ? `Cannot access ref value \`${operand.identifier.name.value}\``
+          : null,
+      suggestions: null,
+    });
   }
 }
-
-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

@@ -97,21 +97,16 @@ export function validateNoSetStateInEffects(
                 errors.pushDiagnostic(
                   CompilerDiagnostic.create({
                     category:
-                      'Calling setState synchronously within an effect can trigger cascading renders',
+                      'Calling setState 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)',
+                      'Calling setState directly within a useEffect causes cascading renders that can hurt performance, and is not recommended. Consider alternatives to useEffect. (https://react.dev/learn/you-might-not-need-an-effect)',
                     severity: ErrorSeverity.InvalidReact,
                     suggestions: null,
                   }).withDetail({
                     kind: 'error',
                     loc: setState.loc,
                     message:
-                      'Avoid calling setState() directly within an effect',
+                      'Avoid calling setState() in the top-level of an effect',
                   }),
                 );
               }

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

@@ -5,11 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {
-  CompilerDiagnostic,
-  CompilerError,
-  ErrorSeverity,
-} from '../CompilerError';
+import {CompilerError, ErrorSeverity} from '../CompilerError';
 import {
   DeclarationId,
   Effect,
@@ -279,37 +275,27 @@ function validateInferredDep(
       errorDiagnostic = merge(errorDiagnostic ?? compareResult, compareResult);
     }
   }
-  errorState.pushDiagnostic(
-    CompilerDiagnostic.create({
-      severity: ErrorSeverity.CannotPreserveMemoization,
-      category:
-        '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. ',
-        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')
-          ? `The inferred dependency was \`${prettyPrintScopeDependency(
-              dep,
-            )}\`, but the source dependencies were [${validDepsInMemoBlock
-              .map(dep => printManualMemoDependency(dep, true))
-              .join(', ')}]. ${
-              errorDiagnostic
-                ? getCompareDependencyResultDescription(errorDiagnostic)
-                : 'Inferred dependency not present in source'
-            }.`
-          : '',
-      ]
-        .join('')
-        .trim(),
-      suggestions: null,
-    }).withDetail({
-      kind: 'error',
-      loc: memoLocation,
-      message: 'Could not preserve existing manual memoization',
-    }),
-  );
+  errorState.push({
+    severity: ErrorSeverity.CannotPreserveMemoization,
+    reason:
+      'React Compiler has skipped optimizing this component because the existing manual memoization could not be preserved. The inferred dependencies did not match the manually specified dependencies, which could cause the value to change more or less frequently than expected',
+    description:
+      DEBUG ||
+      // If the dependency is a named variable then we can report it. Otherwise only print in debug mode
+      (dep.identifier.name != null && dep.identifier.name.kind === 'named')
+        ? `The inferred dependency was \`${prettyPrintScopeDependency(
+            dep,
+          )}\`, but the source dependencies were [${validDepsInMemoBlock
+            .map(dep => printManualMemoDependency(dep, true))
+            .join(', ')}]. ${
+            errorDiagnostic
+              ? getCompareDependencyResultDescription(errorDiagnostic)
+              : 'Inferred dependency not present in source'
+          }`
+        : null,
+    loc: memoLocation,
+    suggestions: null,
+  });
 }
 
 class Visitor extends ReactiveFunctionVisitor<VisitorState> {
@@ -533,21 +519,14 @@ class Visitor extends ReactiveFunctionVisitor<VisitorState> {
           !this.scopes.has(identifier.scope.id) &&
           !this.prunedScopes.has(identifier.scope.id)
         ) {
-          state.errors.pushDiagnostic(
-            CompilerDiagnostic.create({
-              severity: ErrorSeverity.CannotPreserveMemoization,
-              category:
-                '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({
-              kind: 'error',
-              loc,
-              message: 'This dependency may be modified later',
-            }),
-          );
+          state.errors.push({
+            reason:
+              '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',
+            description: null,
+            severity: ErrorSeverity.CannotPreserveMemoization,
+            loc,
+            suggestions: null,
+          });
         }
       }
     }
@@ -581,25 +560,16 @@ class Visitor extends ReactiveFunctionVisitor<VisitorState> {
 
           for (const identifier of decls) {
             if (isUnmemoized(identifier, this.scopes)) {
-              state.errors.pushDiagnostic(
-                CompilerDiagnostic.create({
-                  severity: ErrorSeverity.CannotPreserveMemoization,
-                  category:
-                    '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
-                      ? `${printIdentifier(identifier)} was not memoized.`
-                      : '',
-                  ]
-                    .join('')
-                    .trim(),
-                }).withDetail({
-                  kind: 'error',
-                  loc,
-                  message: 'Could not preserve existing memoization',
-                }),
-              );
+              state.errors.push({
+                reason:
+                  'React Compiler has skipped optimizing this component because the existing manual memoization could not be preserved. This value was memoized in source but not in compilation output.',
+                description: DEBUG
+                  ? `${printIdentifier(identifier)} was not memoized`
+                  : null,
+                severity: ErrorSeverity.CannotPreserveMemoization,
+                loc,
+                suggestions: null,
+              });
             }
           }
         }

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

@@ -5,11 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {
-  CompilerDiagnostic,
-  CompilerError,
-  ErrorSeverity,
-} from '../CompilerError';
+import {CompilerError, ErrorSeverity} from '../CompilerError';
 import {HIRFunction, IdentifierId, SourceLocation} from '../HIR';
 import {Result} from '../Utils/Result';
 
@@ -63,23 +59,20 @@ export function validateStaticComponents(
               value.tag.identifier.id,
             );
             if (location != null) {
-              error.pushDiagnostic(
-                CompilerDiagnostic.create({
-                  severity: ErrorSeverity.InvalidReact,
-                  category: 'Cannot create components during render',
-                  description: `Components created during render will reset their state each time they are created. Declare components outside of render. `,
-                })
-                  .withDetail({
-                    kind: 'error',
-                    loc: value.tag.loc,
-                    message: 'This component is created during render',
-                  })
-                  .withDetail({
-                    kind: 'error',
-                    loc: location,
-                    message: 'The component is created during render here',
-                  }),
-              );
+              error.push({
+                reason: `Components created during render will reset their state each time they are created. Declare components outside of render. `,
+                severity: ErrorSeverity.InvalidReact,
+                loc: value.tag.loc,
+                description: null,
+                suggestions: null,
+              });
+              error.push({
+                reason: `The component may be created during render`,
+                severity: ErrorSeverity.InvalidReact,
+                loc: location,
+                description: null,
+                suggestions: null,
+              });
             }
           }
         }

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

@@ -82,7 +82,7 @@ export function validateUseMemo(fn: HIRFunction): Result<void, CompilerError> {
               }).withDetail({
                 kind: 'error',
                 loc,
-                message: 'Callbacks with parameters are not supported',
+                message: '',
               }),
             );
           }
@@ -92,9 +92,9 @@ export function validateUseMemo(fn: HIRFunction): Result<void, CompilerError> {
               CompilerDiagnostic.create({
                 severity: ErrorSeverity.InvalidReact,
                 category:
-                  'useMemo() callbacks may not be async or generator functions',
+                  'useMemo callbacks may not be async or generator functions',
                 description:
-                  'useMemo() callbacks are called once and must synchronously return a value.',
+                  'useMemo() callbacks are called once and must synchronously return a value',
                 suggestions: null,
               }).withDetail({
                 kind: 'error',

compiler/packages/babel-plugin-react-compiler/src/__tests__/Logger-test.ts

@@ -58,8 +58,7 @@ it('logs failed compilation', () => {
 
   expect(event.detail.severity).toEqual('InvalidReact');
   //@ts-ignore
-  const {start, end, identifierName} =
-    event.detail.primaryLocation() as t.SourceLocation;
+  const {start, end, identifierName} = event.detail.loc as t.SourceLocation;
   expect(start).toEqual({column: 28, index: 28, line: 1});
   expect(end).toEqual({column: 33, index: 33, line: 1});
   expect(identifierName).toEqual('props');

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/allow-assigning-ref-accessing-function-to-object-property-if-not-mutated.expect.md

@@ -1,52 +0,0 @@
-
-## Input
-
-```javascript
-import {useRef} from 'react';
-import {Stringify} from 'shared-runtime';
-
-function Component(props) {
-  const ref = useRef(props.value);
-  const object = {};
-  object.foo = () => ref.current;
-  return <Stringify object={object} shouldInvokeFns={true} />;
-}
-
-export const FIXTURE_ENTRYPOINT = {
-  fn: Component,
-  params: [{value: 42}],
-};
-
-```
-
-## Code
-
-```javascript
-import { c as _c } from "react/compiler-runtime";
-import { useRef } from "react";
-import { Stringify } from "shared-runtime";
-
-function Component(props) {
-  const $ = _c(1);
-  const ref = useRef(props.value);
-  let t0;
-  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
-    const object = {};
-    object.foo = () => ref.current;
-    t0 = <Stringify object={object} shouldInvokeFns={true} />;
-    $[0] = t0;
-  } else {
-    t0 = $[0];
-  }
-  return t0;
-}
-
-export const FIXTURE_ENTRYPOINT = {
-  fn: Component,
-  params: [{ value: 42 }],
-};
-
-```
-      
-### Eval output
-(kind: ok) <div>{"object":{"foo":{"kind":"Function","result":42}},"shouldInvokeFns":true}</div>

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/allow-assigning-ref-accessing-function-to-object-property-if-not-mutated.js

@@ -1,14 +0,0 @@
-import {useRef} from 'react';
-import {Stringify} from 'shared-runtime';
-
-function Component(props) {
-  const ref = useRef(props.value);
-  const object = {};
-  object.foo = () => ref.current;
-  return <Stringify object={object} shouldInvokeFns={true} />;
-}
-
-export const FIXTURE_ENTRYPOINT = {
-  fn: Component,
-  params: [{value: 42}],
-};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/allow-merge-refs-pattern.expect.md

@@ -1,44 +0,0 @@
-
-## Input
-
-```javascript
-// @enableTreatRefLikeIdentifiersAsRefs @validateRefAccessDuringRender
-
-import {useRef} from 'react';
-
-function Component() {
-  const ref = useRef(null);
-  const ref2 = useRef(null);
-  const mergedRef = mergeRefs([ref], ref2);
-
-  return <Stringify ref={mergedRef} />;
-}
-
-```
-
-## Code
-
-```javascript
-import { c as _c } from "react/compiler-runtime"; // @enableTreatRefLikeIdentifiersAsRefs @validateRefAccessDuringRender
-
-import { useRef } from "react";
-
-function Component() {
-  const $ = _c(1);
-  const ref = useRef(null);
-  const ref2 = useRef(null);
-  const mergedRef = mergeRefs([ref], ref2);
-  let t0;
-  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
-    t0 = <Stringify ref={mergedRef} />;
-    $[0] = t0;
-  } else {
-    t0 = $[0];
-  }
-  return t0;
-}
-
-```
-      
-### Eval output
-(kind: exception) Fixture not implemented

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/allow-merge-refs-pattern.js

@@ -1,11 +0,0 @@
-// @enableTreatRefLikeIdentifiersAsRefs @validateRefAccessDuringRender
-
-import {useRef} from 'react';
-
-function Component() {
-  const ref = useRef(null);
-  const ref2 = useRef(null);
-  const mergedRef = mergeRefs([ref], ref2);
-
-  return <Stringify ref={mergedRef} />;
-}

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/allow-passing-ref-to-render-helper-props-object.expect.md

@@ -1,45 +0,0 @@
-
-## Input
-
-```javascript
-// @enableTreatRefLikeIdentifiersAsRefs @validateRefAccessDuringRender
-
-import {useRef} from 'react';
-
-function Component(props) {
-  const ref = useRef(null);
-
-  return <Foo>{props.render({ref})}</Foo>;
-}
-
-```
-
-## Code
-
-```javascript
-import { c as _c } from "react/compiler-runtime"; // @enableTreatRefLikeIdentifiersAsRefs @validateRefAccessDuringRender
-
-import { useRef } from "react";
-
-function Component(props) {
-  const $ = _c(3);
-  const ref = useRef(null);
-
-  const T0 = Foo;
-  const t0 = props.render({ ref });
-  let t1;
-  if ($[0] !== T0 || $[1] !== t0) {
-    t1 = <T0>{t0}</T0>;
-    $[0] = T0;
-    $[1] = t0;
-    $[2] = t1;
-  } else {
-    t1 = $[2];
-  }
-  return t1;
-}
-
-```
-      
-### Eval output
-(kind: exception) Fixture not implemented

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/allow-passing-ref-to-render-helper-props-object.js

@@ -1,9 +0,0 @@
-// @enableTreatRefLikeIdentifiersAsRefs @validateRefAccessDuringRender
-
-import {useRef} from 'react';
-
-function Component(props) {
-  const ref = useRef(null);
-
-  return <Foo>{props.render({ref})}</Foo>;
-}

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/allow-passing-ref-to-render-helper.expect.md

@@ -1,49 +0,0 @@
-
-## Input
-
-```javascript
-// @enableTreatRefLikeIdentifiersAsRefs @validateRefAccessDuringRender
-
-import {useRef} from 'react';
-
-function Component(props) {
-  const ref = useRef(null);
-
-  return <Foo>{props.render(ref)}</Foo>;
-}
-
-```
-
-## Code
-
-```javascript
-import { c as _c } from "react/compiler-runtime"; // @enableTreatRefLikeIdentifiersAsRefs @validateRefAccessDuringRender
-
-import { useRef } from "react";
-
-function Component(props) {
-  const $ = _c(4);
-  const ref = useRef(null);
-  let t0;
-  if ($[0] !== props.render) {
-    t0 = props.render(ref);
-    $[0] = props.render;
-    $[1] = t0;
-  } else {
-    t0 = $[1];
-  }
-  let t1;
-  if ($[2] !== t0) {
-    t1 = <Foo>{t0}</Foo>;
-    $[2] = t0;
-    $[3] = t1;
-  } else {
-    t1 = $[3];
-  }
-  return t1;
-}
-
-```
-      
-### Eval output
-(kind: exception) Fixture not implemented

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/allow-passing-ref-to-render-helper.js

@@ -1,9 +0,0 @@
-// @enableTreatRefLikeIdentifiersAsRefs @validateRefAccessDuringRender
-
-import {useRef} from 'react';
-
-function Component(props) {
-  const ref = useRef(null);
-
-  return <Foo>{props.render(ref)}</Foo>;
-}

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/allow-ref-access-in-effect-indirect.expect.md

@@ -27,7 +27,6 @@ function Component() {
 }
 
 function Child({ref}) {
-  'use no memo';
   // This violates the rules of React, so we access the ref in a child
   // component
   return ref.current;
@@ -101,10 +100,8 @@ function Component() {
   return t6;
 }
 
-function Child({ ref }) {
-  "use no memo";
-  // This violates the rules of React, so we access the ref in a child
-  // component
+function Child(t0) {
+  const { ref } = t0;
   return ref.current;
 }
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/allow-ref-access-in-effect-indirect.js

@@ -23,7 +23,6 @@ function Component() {
 }
 
 function Child({ref}) {
-  'use no memo';
   // This violates the rules of React, so we access the ref in a child
   // component
   return ref.current;

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/allow-ref-access-in-effect.expect.md

@@ -23,7 +23,6 @@ function Component() {
 }
 
 function Child({ref}) {
-  'use no memo';
   // This violates the rules of React, so we access the ref in a child
   // component
   return ref.current;
@@ -87,10 +86,8 @@ function Component() {
   return t5;
 }
 
-function Child({ ref }) {
-  "use no memo";
-  // This violates the rules of React, so we access the ref in a child
-  // component
+function Child(t0) {
+  const { ref } = t0;
   return ref.current;
 }
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/allow-ref-access-in-effect.js

@@ -19,7 +19,6 @@ function Component() {
 }
 
 function Child({ref}) {
-  'use no memo';
   // This violates the rules of React, so we access the ref in a child
   // component
   return ref.current;

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/allow-ref-access-in-unused-callback-nested.expect.md

@@ -25,7 +25,6 @@ function Component() {
 }
 
 function Child({ref}) {
-  'use no memo';
   // This violates the rules of React, so we access the ref in a child
   // component
   return ref.current;
@@ -84,10 +83,8 @@ function Component() {
 }
 function _temp() {}
 
-function Child({ ref }) {
-  "use no memo";
-  // This violates the rules of React, so we access the ref in a child
-  // component
+function Child(t0) {
+  const { ref } = t0;
   return ref.current;
 }
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/allow-ref-access-in-unused-callback-nested.js

@@ -21,7 +21,6 @@ function Component() {
 }
 
 function Child({ref}) {
-  'use no memo';
   // This violates the rules of React, so we access the ref in a child
   // component
   return ref.current;

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/allow-ref-lazy-initialization-with-logical.expect.md

@@ -1,68 +0,0 @@
-
-## Input
-
-```javascript
-// @validateRefAccessDuringRender
-
-import {useRef} from 'react';
-
-function Component(props) {
-  const ref = useRef(null);
-  if (ref.current == null) {
-    // the logical means the ref write is in a different block
-    // from the if consequent. this tests that the "safe" blocks
-    // extend up to the if's fallthrough
-    ref.current = props.unknownKey ?? props.value;
-  }
-  return <Child ref={ref} />;
-}
-
-function Child({ref}) {
-  'use no memo';
-  return ref.current;
-}
-
-export const FIXTURE_ENTRYPOINT = {
-  fn: Component,
-  params: [{value: 42}],
-};
-
-```
-
-## Code
-
-```javascript
-import { c as _c } from "react/compiler-runtime"; // @validateRefAccessDuringRender
-
-import { useRef } from "react";
-
-function Component(props) {
-  const $ = _c(1);
-  const ref = useRef(null);
-  if (ref.current == null) {
-    ref.current = props.unknownKey ?? props.value;
-  }
-  let t0;
-  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
-    t0 = <Child ref={ref} />;
-    $[0] = t0;
-  } else {
-    t0 = $[0];
-  }
-  return t0;
-}
-
-function Child({ ref }) {
-  "use no memo";
-  return ref.current;
-}
-
-export const FIXTURE_ENTRYPOINT = {
-  fn: Component,
-  params: [{ value: 42 }],
-};
-
-```
-      
-### Eval output
-(kind: ok) 42

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/allow-ref-lazy-initialization-with-logical.js

@@ -1,24 +0,0 @@
-// @validateRefAccessDuringRender
-
-import {useRef} from 'react';
-
-function Component(props) {
-  const ref = useRef(null);
-  if (ref.current == null) {
-    // the logical means the ref write is in a different block
-    // from the if consequent. this tests that the "safe" blocks
-    // extend up to the if's fallthrough
-    ref.current = props.unknownKey ?? props.value;
-  }
-  return <Child ref={ref} />;
-}
-
-function Child({ref}) {
-  'use no memo';
-  return ref.current;
-}
-
-export const FIXTURE_ENTRYPOINT = {
-  fn: Component,
-  params: [{value: 42}],
-};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error._todo.computed-lval-in-destructure.expect.md

@@ -16,7 +16,6 @@ function Component(props) {
 
 ```
 Found 1 error:
-
 Todo: (BuildHIR::lowerAssignment) Handle computed properties in ObjectPattern
 
 error._todo.computed-lval-in-destructure.ts:3:9
@@ -27,6 +26,8 @@ error._todo.computed-lval-in-destructure.ts:3:9
   4 |
   5 |   return x;
   6 | }
+
+
 ```
           
       

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

@@ -16,19 +16,18 @@ function Component() {
 
 ```
 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)
+Error: Unexpected reassignment of a variable which was defined outside of the component. Components and hooks should be pure and side-effect free, but variable reassignment is a form of side-effect. If this variable is used in rendering, use useState instead. (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
+    |     ^^^^^^^^^^ Unexpected reassignment of a variable which was defined outside of the component. Components and hooks should be pure and side-effect free, but variable reassignment is a form of side-effect. If this variable is used in rendering, use useState instead. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)
   4 |   };
   5 |   return <Foo />;
   6 | }
+
+
 ```
           
       

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

@@ -19,19 +19,18 @@ function Component() {
 
 ```
 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)
+Error: Unexpected reassignment of a variable which was defined outside of the component. Components and hooks should be pure and side-effect free, but variable reassignment is a form of side-effect. If this variable is used in rendering, use useState instead. (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
+    |     ^^^^^^^^^^ Unexpected reassignment of a variable which was defined outside of the component. Components and hooks should be pure and side-effect free, but variable reassignment is a form of side-effect. If this variable is used in rendering, use useState instead. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)
   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

@@ -17,7 +17,6 @@ function Component() {
 
 ```
 Found 1 error:
-
 Error: Unexpected reassignment of a variable which was defined outside of the component. Components and hooks should be pure and side-effect free, but variable reassignment is a form of side-effect. If this variable is used in rendering, use useState instead. (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
@@ -28,6 +27,8 @@ error.assign-global-in-jsx-spread-attribute.ts:4:4
   5 |   };
   6 |   return <div {...foo} />;
   7 | }
+
+
 ```
           
       

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

@@ -17,19 +17,20 @@ function Foo(props) {
 
 ```
 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
 
-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 `$FlowFixMe[react-rule-hook]`
+$FlowFixMe[react-rule-hook].
 
 error.bailout-on-flow-suppression.ts:4:2
   2 |
   3 | function Foo(props) {
 > 4 |   // $FlowFixMe[react-rule-hook]
-    |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Found React rule suppression
+    |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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
   5 |   useX();
   6 |   return null;
   7 | }
+
+
 ```
           
       

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

@@ -20,32 +20,34 @@ function lowercasecomponent() {
 
 ```
 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
 
-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`
+eslint-disable my-app/react-rule.
 
 error.bailout-on-suppression-of-custom-rule.ts:3:0
   1 | // @eslintSuppressionRules:["my-app","react-rule"]
   2 |
 > 3 | /* eslint-disable my-app/react-rule */
-    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Found React rule suppression
+    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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
   4 | function lowercasecomponent() {
   5 |   'use forget';
   6 |   const x = [];
 
-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`
+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
+
+eslint-disable-next-line my-app/react-rule.
 
 error.bailout-on-suppression-of-custom-rule.ts:7:2
    5 |   'use forget';
    6 |   const x = [];
 >  7 |   // eslint-disable-next-line my-app/react-rule
-     |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Found React rule suppression
+     |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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
    8 |   return <div>{x}</div>;
    9 | }
   10 | /* eslint-enable my-app/react-rule */
+
+
 ```
           
       

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

@@ -37,10 +37,9 @@ function Component() {
 
 ```
 Found 1 error:
-
 Error: Cannot modify local variables after render completes
 
-This argument is a function which may reassign or mutate a local variable after render, which can cause inconsistent behavior on subsequent renders. Consider using state instead.
+This argument is a function which may reassign or mutate local variables 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 |   );
@@ -54,7 +53,7 @@ error.bug-old-inference-false-positive-ref-validation-in-use-effect.ts:20:12
 > 23 |     }
      | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 > 24 |   }, [update]);
-     | ^^^^ This function may (indirectly) reassign or modify a local variable after render
+     | ^^^^ This function may (indirectly) reassign or modify local variables after render
   25 |
   26 |   return 'ok';
   27 | }

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.call-args-destructuring-asignment-complex.expect.md

@@ -15,7 +15,6 @@ function Component(props) {
 
 ```
 Found 1 error:
-
 Invariant: Const declaration cannot be referenced as an expression
 
 error.call-args-destructuring-asignment-complex.ts:3:9
@@ -26,6 +25,8 @@ error.call-args-destructuring-asignment-complex.ts:3:9
   4 |   return x;
   5 | }
   6 |
+
+
 ```
           
       

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

@@ -15,7 +15,6 @@ function Foo() {
 
 ```
 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..
@@ -27,6 +26,8 @@ error.capitalized-function-call-aliased.ts:4:2
     |   ^^^ 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
   5 | }
   6 |
+
+
 ```
           
       

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

@@ -16,7 +16,6 @@ function Component() {
 
 ```
 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..
@@ -29,6 +28,8 @@ error.capitalized-function-call.ts:3:12
   4 |
   5 |   return x;
   6 | }
+
+
 ```
           
       

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

@@ -16,7 +16,6 @@ function Component() {
 
 ```
 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..
@@ -29,6 +28,8 @@ error.capitalized-method-call.ts:3:12
   4 |
   5 |   return x;
   6 | }
+
+
 ```
           
       

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

@@ -32,33 +32,55 @@ export const FIXTURE_ENTRYPOINT = {
 ## Error
 
 ```
-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)
+Found 4 errors:
+Error: This function accesses a ref value (the `current` property), which may not be accessed during render. (https://react.dev/reference/react/useRef)
 
 error.capture-ref-for-mutation.ts:12:13
   10 |   };
   11 |   const moveLeft = {
 > 12 |     handler: handleKey('left')(),
-     |              ^^^^^^^^^^^^^^^^^ This function accesses a ref value
+     |              ^^^^^^^^^^^^^^^^^ This function accesses a ref value (the `current` property), which may not be accessed during render. (https://react.dev/reference/react/useRef)
   13 |   };
   14 |   const moveRight = {
   15 |     handler: handleKey('right')(),
 
-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)
+Error: Ref values (the `current` property) may not be accessed during render. (https://react.dev/reference/react/useRef)
+
+error.capture-ref-for-mutation.ts:12:13
+  10 |   };
+  11 |   const moveLeft = {
+> 12 |     handler: handleKey('left')(),
+     |              ^^^^^^^^^^^^^^^^^ Ref values (the `current` property) may not be accessed during render. (https://react.dev/reference/react/useRef)
+  13 |   };
+  14 |   const moveRight = {
+  15 |     handler: handleKey('right')(),
+
+
+Error: This function accesses a ref value (the `current` property), which may not be accessed during render. (https://react.dev/reference/react/useRef)
 
 error.capture-ref-for-mutation.ts:15:13
   13 |   };
   14 |   const moveRight = {
 > 15 |     handler: handleKey('right')(),
-     |              ^^^^^^^^^^^^^^^^^^ This function accesses a ref value
+     |              ^^^^^^^^^^^^^^^^^^ This function accesses a ref value (the `current` property), which may not be accessed during render. (https://react.dev/reference/react/useRef)
   16 |   };
   17 |   return [moveLeft, moveRight];
   18 | }
+
+
+Error: Ref values (the `current` property) may not be accessed during render. (https://react.dev/reference/react/useRef)
+
+error.capture-ref-for-mutation.ts:15:13
+  13 |   };
+  14 |   const moveRight = {
+> 15 |     handler: handleKey('right')(),
+     |              ^^^^^^^^^^^^^^^^^^ Ref values (the `current` property) may not be accessed during render. (https://react.dev/reference/react/useRef)
+  16 |   };
+  17 |   return [moveLeft, moveRight];
+  18 | }
+
+
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.conditional-hook-unknown-hook-react-namespace.expect.md

@@ -17,7 +17,6 @@ function Component(props) {
 
 ```
 Found 1 error:
-
 Error: 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)
 
 error.conditional-hook-unknown-hook-react-namespace.ts:4:8
@@ -28,6 +27,8 @@ error.conditional-hook-unknown-hook-react-namespace.ts:4:8
   5 |   }
   6 |   return x;
   7 | }
+
+
 ```
           
       

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

@@ -17,7 +17,6 @@ function Component(props) {
 
 ```
 Found 1 error:
-
 Error: 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)
 
 error.conditional-hooks-as-method-call.ts:4:8
@@ -28,6 +27,8 @@ error.conditional-hooks-as-method-call.ts:4:8
   5 |   }
   6 |   return x;
   7 | }
+
+
 ```
           
       

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

@@ -29,16 +29,15 @@ export const FIXTURE_ENTRYPOINT = {
 
 ```
 Found 1 error:
+Error: Cannot reassign a variable after render completes
 
-Error: Cannot reassign variable after render completes
-
-Reassigning `x` after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead.
+Reassigning variable `x` 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 |   };
    9 |   const fn2 = () => {
 > 10 |     const copy2 = (x = 4);
-     |                    ^ Cannot reassign `x` after render completes
+     |                    ^ Cannot reassign variable after render completes
   11 |     return [invoke(fn1), copy2, identity(copy2)];
   12 |   };
   13 |   return invoke(fn2);

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

@@ -18,16 +18,15 @@ function Component() {
 
 ```
 Found 1 error:
+Error: Cannot reassign a variable after render completes
 
-Error: Cannot reassign variable after render completes
-
-Reassigning `x` after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead.
+Reassigning variable `x` 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;
   3 |   function foo() {
 > 4 |     x = 9;
-    |     ^ Cannot reassign `x` after render completes
+    |     ^ Cannot reassign variable after render completes
   5 |   }
   6 |   const y = bar(foo);
   7 |   return <Child y={y} />;

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.default-param-accesses-local.expect.md

@@ -23,7 +23,6 @@ export const FIXTURE_ENTRYPOINT = {
 
 ```
 Found 1 error:
-
 Todo: (BuildHIR::node.lowerReorderableExpression) Expression type `ArrowFunctionExpression` cannot be safely reordered
 
 error.default-param-accesses-local.ts:3:6
@@ -38,6 +37,8 @@ error.default-param-accesses-local.ts:3:6
   6 | ) {
   7 |   return y();
   8 | }
+
+
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.dont-hoist-inline-reference.expect.md

@@ -20,7 +20,6 @@ export const FIXTURE_ENTRYPOINT = {
 
 ```
 Found 1 error:
-
 Todo: [hoisting] EnterSSA: Expected identifier to be defined before being used
 
 Identifier x$1 is undefined.
@@ -33,6 +32,8 @@ error.dont-hoist-inline-reference.ts:3:2
   4 |   return x;
   5 | }
   6 |
+
+
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.emit-freeze-conflicting-global.expect.md

@@ -16,7 +16,6 @@ function useFoo(props) {
 
 ```
 Found 1 error:
-
 Todo: Encountered conflicting global in generated program
 
 Conflict from local binding __DEV__.
@@ -29,6 +28,8 @@ error.emit-freeze-conflicting-global.ts:3:8
   4 |   console.log(__DEV__);
   5 |   return foo(props.x);
   6 | }
+
+
 ```
           
       

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

@@ -16,16 +16,15 @@ function Component() {
 
 ```
 Found 1 error:
+Error: Cannot reassign a variable after render completes
 
-Error: Cannot reassign variable after render completes
-
-Reassigning `callback` after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead.
+Reassigning variable `callback` 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() {
   2 |   let callback = () => {
 > 3 |     callback = null;
-    |     ^^^^^^^^ Cannot reassign `callback` after render completes
+    |     ^^^^^^^^ Cannot reassign variable after render completes
   4 |   };
   5 |   return <div onClick={callback} />;
   6 | }

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.hoist-optional-member-expression-with-conditional-optional.expect.md

@@ -25,10 +25,9 @@ function Component(props) {
 
 ```
 Found 1 error:
+Memoization: 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
 
-Memoization: Compilation skipped because existing memoization could not be preserved
-
-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. The inferred dependency was `props.items`, but the source dependencies were [props?.items, props.cond]. Inferred different dependency than source.
+The inferred dependency was `props.items`, but the source dependencies were [props?.items, props.cond]. Inferred different dependency than source.
 
 error.hoist-optional-member-expression-with-conditional-optional.ts:4:23
    2 | import {ValidateMemoization} from 'shared-runtime';
@@ -48,10 +47,12 @@ error.hoist-optional-member-expression-with-conditional-optional.ts:4:23
 > 10 |     return x;
      | ^^^^^^^^^^^^^^^^^
 > 11 |   }, [props?.items, props.cond]);
-     | ^^^^ Could not preserve existing manual memoization
+     | ^^^^ 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
   12 |   return (
   13 |     <ValidateMemoization inputs={[props?.items, props.cond]} output={data} />
   14 |   );
+
+
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.hoist-optional-member-expression-with-conditional.expect.md

@@ -25,10 +25,9 @@ function Component(props) {
 
 ```
 Found 1 error:
+Memoization: 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
 
-Memoization: Compilation skipped because existing memoization could not be preserved
-
-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. The inferred dependency was `props.items`, but the source dependencies were [props?.items, props.cond]. Inferred different dependency than source.
+The inferred dependency was `props.items`, but the source dependencies were [props?.items, props.cond]. Inferred different dependency than source.
 
 error.hoist-optional-member-expression-with-conditional.ts:4:23
    2 | import {ValidateMemoization} from 'shared-runtime';
@@ -48,10 +47,12 @@ error.hoist-optional-member-expression-with-conditional.ts:4:23
 > 10 |     return x;
      | ^^^^^^^^^^^^^^^^^
 > 11 |   }, [props?.items, props.cond]);
-     | ^^^^ Could not preserve existing manual memoization
+     | ^^^^ 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
   12 |   return (
   13 |     <ValidateMemoization inputs={[props?.items, props.cond]} output={data} />
   14 |   );
+
+
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.hoisting-simple-function-declaration.expect.md

@@ -25,7 +25,6 @@ export const FIXTURE_ENTRYPOINT = {
 
 ```
 Found 1 error:
-
 Todo: Support functions with unreachable code that may contain hoisted declarations
 
 error.hoisting-simple-function-declaration.ts:6:2
@@ -40,6 +39,8 @@ error.hoisting-simple-function-declaration.ts:6:2
    9 | }
   10 |
   11 | export const FIXTURE_ENTRYPOINT = {
+
+
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.hook-call-freezes-captured-identifier.expect.md

@@ -30,19 +30,18 @@ export const FIXTURE_ENTRYPOINT = {
 
 ```
 Found 1 error:
-
-Error: This value cannot be modified
-
-Modifying a value previously passed as an argument to a hook is not allowed. Consider moving the modification before calling the hook.
+Error: Updating a value previously passed as an argument to a hook is not allowed. Consider moving the mutation before calling the hook
 
 error.hook-call-freezes-captured-identifier.ts:13:2
   11 |   });
   12 |
 > 13 |   x.value += count;
-     |   ^ value cannot be modified
+     |   ^ Updating a value previously passed as an argument to a hook is not allowed. Consider moving the mutation before calling the hook
   14 |   return <Stringify x={x} cb={cb} />;
   15 | }
   16 |
+
+
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.hook-call-freezes-captured-memberexpr.expect.md

@@ -30,19 +30,18 @@ export const FIXTURE_ENTRYPOINT = {
 
 ```
 Found 1 error:
-
-Error: This value cannot be modified
-
-Modifying a value previously passed as an argument to a hook is not allowed. Consider moving the modification before calling the hook.
+Error: Updating a value previously passed as an argument to a hook is not allowed. Consider moving the mutation before calling the hook
 
 error.hook-call-freezes-captured-memberexpr.ts:13:2
   11 |   });
   12 |
 > 13 |   x.value += count;
-     |   ^ value cannot be modified
+     |   ^ Updating a value previously passed as an argument to a hook is not allowed. Consider moving the mutation before calling the hook
   14 |   return <Stringify x={x} cb={cb} />;
   15 | }
   16 |
+
+
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.hook-property-load-local-hook.expect.md

@@ -24,7 +24,6 @@ export const FIXTURE_ENTRYPOINT = {
 
 ```
 Found 2 errors:
-
 Error: 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
 
 error.hook-property-load-local-hook.ts:7:12
@@ -36,6 +35,7 @@ error.hook-property-load-local-hook.ts:7:12
    9 | }
   10 |
 
+
 Error: 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
 
 error.hook-property-load-local-hook.ts:8:9
@@ -46,6 +46,8 @@ error.hook-property-load-local-hook.ts:8:9
    9 | }
   10 |
   11 | export const FIXTURE_ENTRYPOINT = {
+
+
 ```
           
       

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

@@ -21,32 +21,30 @@ export const FIXTURE_ENTRYPOINT = {
 
 ```
 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)
+Error: Ref values (the `current` property) may not be accessed during render. (https://react.dev/reference/react/useRef)
 
 error.hook-ref-value.ts:5:23
   3 | function Component(props) {
   4 |   const ref = useRef();
 > 5 |   useEffect(() => {}, [ref.current]);
-    |                        ^^^^^^^^^^^ Cannot access ref value during render
+    |                        ^^^^^^^^^^^ Ref values (the `current` property) may not be accessed during render. (https://react.dev/reference/react/useRef)
   6 | }
   7 |
   8 | export const FIXTURE_ENTRYPOINT = {
 
-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)
+Error: Ref values (the `current` property) may not be accessed during render. (https://react.dev/reference/react/useRef)
 
 error.hook-ref-value.ts:5:23
   3 | function Component(props) {
   4 |   const ref = useRef();
 > 5 |   useEffect(() => {}, [ref.current]);
-    |                        ^^^^^^^^^^^ Cannot access ref value during render
+    |                        ^^^^^^^^^^^ Ref values (the `current` property) may not be accessed during render. (https://react.dev/reference/react/useRef)
   6 | }
   7 |
   8 | export const FIXTURE_ENTRYPOINT = {
+
+
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-ReactUseMemo-async-callback.expect.md

@@ -16,10 +16,9 @@ function component(a, b) {
 
 ```
 Found 1 error:
+Error: useMemo callbacks may not be async or generator functions
 
-Error: useMemo() callbacks may not be async or generator functions
-
-useMemo() callbacks are called once and must synchronously return a value.
+useMemo() callbacks are called once and must synchronously return a value
 
 error.invalid-ReactUseMemo-async-callback.ts:2:24
   1 | function component(a, b) {

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

@@ -16,19 +16,18 @@ function Component(props) {
 
 ```
 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)
+Error: Ref values (the `current` property) may not be accessed during render. (https://react.dev/reference/react/useRef)
 
 error.invalid-access-ref-during-render.ts:4:16
   2 | function Component(props) {
   3 |   const ref = useRef(null);
 > 4 |   const value = ref.current;
-    |                 ^^^^^^^^^^^ Cannot access ref value during render
+    |                 ^^^^^^^^^^^ Ref values (the `current` property) may not be accessed during render. (https://react.dev/reference/react/useRef)
   5 |   return value;
   6 | }
   7 |
+
+
 ```
           
       

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

@@ -1,45 +0,0 @@
-
-## Input
-
-```javascript
-import {useReducer, useRef} from 'react';
-
-function Component(props) {
-  const ref = useRef(props.value);
-  const [state] = useReducer(
-    (state, action) => state + action,
-    0,
-    init => ref.current
-  );
-
-  return <Stringify state={state} />;
-}
-
-export const FIXTURE_ENTRYPOINT = {
-  fn: Component,
-  params: [{value: 42}],
-};
-
-```
-
-
-## Error
-
-```
-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)
-
-error.invalid-access-ref-in-reducer-init.ts:8:4
-   6 |     (state, action) => state + action,
-   7 |     0,
->  8 |     init => ref.current
-     |     ^^^^^^^^^^^^^^^^^^^ Passing a ref to a function may read its value during render
-   9 |   );
-  10 |
-  11 |   return <Stringify state={state} />;
-```
-          
-      

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

@@ -1,17 +0,0 @@
-import {useReducer, useRef} from 'react';
-
-function Component(props) {
-  const ref = useRef(props.value);
-  const [state] = useReducer(
-    (state, action) => state + action,
-    0,
-    init => ref.current
-  );
-
-  return <Stringify state={state} />;
-}
-
-export const FIXTURE_ENTRYPOINT = {
-  fn: Component,
-  params: [{value: 42}],
-};

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

@@ -1,41 +0,0 @@
-
-## Input
-
-```javascript
-import {useReducer, useRef} from 'react';
-
-function Component(props) {
-  const ref = useRef(props.value);
-  const [state] = useReducer(() => ref.current, null);
-
-  return <Stringify state={state} />;
-}
-
-export const FIXTURE_ENTRYPOINT = {
-  fn: Component,
-  params: [{value: 42}],
-};
-
-```
-
-
-## Error
-
-```
-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)
-
-error.invalid-access-ref-in-reducer.ts:5:29
-  3 | function Component(props) {
-  4 |   const ref = useRef(props.value);
-> 5 |   const [state] = useReducer(() => ref.current, null);
-    |                              ^^^^^^^^^^^^^^^^^ Passing a ref to a function may read its value during render
-  6 |
-  7 |   return <Stringify state={state} />;
-  8 | }
-```
-          
-      

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

@@ -1,13 +0,0 @@
-import {useReducer, useRef} from 'react';
-
-function Component(props) {
-  const ref = useRef(props.value);
-  const [state] = useReducer(() => ref.current, null);
-
-  return <Stringify state={state} />;
-}
-
-export const FIXTURE_ENTRYPOINT = {
-  fn: Component,
-  params: [{value: 42}],
-};

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

@@ -1,37 +0,0 @@
-
-## Input
-
-```javascript
-import {useRef} from 'react';
-
-function Component() {
-  const ref = useRef(null);
-  const object = {};
-  object.foo = () => ref.current;
-  const refValue = object.foo();
-  return <div>{refValue}</div>;
-}
-
-```
-
-
-## Error
-
-```
-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)
-
-error.invalid-access-ref-in-render-mutate-object-with-ref-function.ts:7:19
-   5 |   const object = {};
-   6 |   object.foo = () => ref.current;
->  7 |   const refValue = object.foo();
-     |                    ^^^^^^^^^^ This function accesses a ref value
-   8 |   return <div>{refValue}</div>;
-   9 | }
-  10 |
-```
-          
-      

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

@@ -1,9 +0,0 @@
-import {useRef} from 'react';
-
-function Component() {
-  const ref = useRef(null);
-  const object = {};
-  object.foo = () => ref.current;
-  const refValue = object.foo();
-  return <div>{refValue}</div>;
-}

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

@@ -1,41 +0,0 @@
-
-## Input
-
-```javascript
-import {useRef, useState} from 'react';
-
-function Component(props) {
-  const ref = useRef(props.value);
-  const [state] = useState(() => ref.current);
-
-  return <Stringify state={state} />;
-}
-
-export const FIXTURE_ENTRYPOINT = {
-  fn: Component,
-  params: [{value: 42}],
-};
-
-```
-
-
-## Error
-
-```
-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)
-
-error.invalid-access-ref-in-state-initializer.ts:5:27
-  3 | function Component(props) {
-  4 |   const ref = useRef(props.value);
-> 5 |   const [state] = useState(() => ref.current);
-    |                            ^^^^^^^^^^^^^^^^^ Passing a ref to a function may read its value during render
-  6 |
-  7 |   return <Stringify state={state} />;
-  8 | }
-```
-          
-      

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

@@ -1,13 +0,0 @@
-import {useRef, useState} from 'react';
-
-function Component(props) {
-  const ref = useRef(props.value);
-  const [state] = useState(() => ref.current);
-
-  return <Stringify state={state} />;
-}
-
-export const FIXTURE_ENTRYPOINT = {
-  fn: Component,
-  params: [{value: 42}],
-};

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

@@ -20,18 +20,17 @@ function Component(props) {
 
 ```
 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)
+Error: Ref values (the `current` property) may not be accessed during render. (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} />;
    8 |   };
 >  9 |   return <Items>{props.items.map(item => renderItem(item))}</Items>;
-     |                                  ^^^^^^^^^^^^^^^^^^^^^^^^ Cannot access ref value during render
+     |                                  ^^^^^^^^^^^^^^^^^^^^^^^^ Ref values (the `current` property) may not be accessed during render. (https://react.dev/reference/react/useRef)
   10 | }
   11 |
+
+
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-array-push-frozen.expect.md

@@ -16,19 +16,18 @@ function Component(props) {
 
 ```
 Found 1 error:
-
-Error: This value cannot be modified
-
-Modifying a value used previously in JSX is not allowed. Consider moving the modification before the JSX.
+Error: Updating a value used previously in JSX is not allowed. Consider moving the mutation before the JSX
 
 error.invalid-array-push-frozen.ts:4:2
   2 |   const x = [];
   3 |   <div>{x}</div>;
 > 4 |   x.push(props.value);
-    |   ^ value cannot be modified
+    |   ^ Updating a value used previously in JSX is not allowed. Consider moving the mutation before the JSX
   5 |   return x;
   6 | }
   7 |
+
+
 ```
           
       

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

@@ -1,36 +0,0 @@
-
-## Input
-
-```javascript
-// @flow @enableTreatRefLikeIdentifiersAsRefs @validateRefAccessDuringRender
-import {makeObject_Primitives} from 'shared-runtime';
-
-component Example() {
-  const fooRef = makeObject_Primitives();
-  fooRef.current = true;
-
-  return <Stringify foo={fooRef} />;
-}
-
-```
-
-
-## Error
-
-```
-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)
-
-  4 | component Example() {
-  5 |   const fooRef = makeObject_Primitives();
-> 6 |   fooRef.current = true;
-    |   ^^^^^^^^^^^^^^ Cannot update ref during render
-  7 |
-  8 |   return <Stringify foo={fooRef} />;
-  9 | }
-```
-          
-      

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

@@ -1,9 +0,0 @@
-// @flow @enableTreatRefLikeIdentifiersAsRefs @validateRefAccessDuringRender
-import {makeObject_Primitives} from 'shared-runtime';
-
-component Example() {
-  const fooRef = makeObject_Primitives();
-  fooRef.current = true;
-
-  return <Stringify foo={fooRef} />;
-}

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-assign-hook-to-local.expect.md

@@ -15,7 +15,6 @@ function Component(props) {
 
 ```
 Found 1 error:
-
 Error: 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
 
 error.invalid-assign-hook-to-local.ts:2:12
@@ -25,6 +24,8 @@ error.invalid-assign-hook-to-local.ts:2:12
   3 |   const state = x(null);
   4 |   return state[0];
   5 | }
+
+
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-computed-store-to-frozen-value.expect.md

@@ -17,19 +17,18 @@ function Component(props) {
 
 ```
 Found 1 error:
-
-Error: This value cannot be modified
-
-Modifying a value used previously in JSX is not allowed. Consider moving the modification before the JSX.
+Error: Updating a value used previously in JSX is not allowed. Consider moving the mutation before the JSX
 
 error.invalid-computed-store-to-frozen-value.ts:5:2
   3 |   // freeze
   4 |   <div>{x}</div>;
 > 5 |   x[0] = true;
-    |   ^ value cannot be modified
+    |   ^ Updating a value used previously in JSX is not allowed. Consider moving the mutation before the JSX
   6 |   return x;
   7 | }
   8 |
+
+
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-conditional-call-aliased-hook-import.expect.md

@@ -19,7 +19,6 @@ function Component(props) {
 
 ```
 Found 1 error:
-
 Error: 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)
 
 error.invalid-conditional-call-aliased-hook-import.ts:6:11
@@ -30,6 +29,8 @@ error.invalid-conditional-call-aliased-hook-import.ts:6:11
   7 |   }
   8 |   return data;
   9 | }
+
+
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-conditional-call-aliased-react-hook.expect.md

@@ -19,7 +19,6 @@ function Component(props) {
 
 ```
 Found 1 error:
-
 Error: 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)
 
 error.invalid-conditional-call-aliased-react-hook.ts:6:10
@@ -30,6 +29,8 @@ error.invalid-conditional-call-aliased-react-hook.ts:6:10
   7 |   }
   8 |   return s;
   9 | }
+
+
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-conditional-call-non-hook-imported-as-hook.expect.md

@@ -19,7 +19,6 @@ function Component(props) {
 
 ```
 Found 1 error:
-
 Error: 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)
 
 error.invalid-conditional-call-non-hook-imported-as-hook.ts:6:11
@@ -30,6 +29,8 @@ error.invalid-conditional-call-non-hook-imported-as-hook.ts:6:11
   7 |   }
   8 |   return data;
   9 | }
+
+
 ```