[compiler] Aggregate error reporting, separate eslint rules

All error messages that are not invariants, todos, or config validation errors are now moved to a registry.  This helps us check that error messages and linked documentation is uniform and up to date. This also lets us link error codes to linter reporting categories and break the single `react-compiler` rule up into many smaller rules.


Changes to error reporting in React Compiler:
- instead of writing raw error message, add a new ErrorCode to `CompilerErrorCodes`
- create errors by constructing a `CompilerErrorDetailOptions` with the correct error code, or calling `CompilerErrorDetail.fromCode()` / `CompilerDiagnostic.fromCode()`.

Changes to linter:
- `react-compiler` lint rule is now broken up into many smaller lint rules, each with their own test cases.
- linting no longer fails early when a non-fatal error is find. Instead, we now log and move on to lint for more errors!

Todos:
- Codebases previously using the eslint plugin may already have `react-compiler` eslint suppressions. Since this PR removes this rule, these codebases may get new eslint warnings on already-suppressed ranges. Some options I can think of:
  - Force everyone to add the new suppressions
  - Release a script to rewrite previous suppressions to the new suppressions. Codebases that had incomplete suppressions / waited to update may benefit here, as this still surfaces errors on previously-unseen suppressions
  - Hard code logic in our eslint plugin to avoid reporting if we see a `eslint-disable-next-line react-compiler`. This doesn't feel ideal
- Align on eslint plugin rule names and error code mappings
  - I aggregated a few error codes here. For example, reassigning and modifying local variables after render now have the same error code + message. See changes fixtures for more examples
- More test cases for linter rules. Will add these once lint rules are more finalized

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

@@ -10,48 +10,22 @@ import {codeFrameColumns} from '@babel/code-frame';
 import type {SourceLocation} from './HIR';
 import {Err, Ok, Result} from './Utils/Result';
 import {assertExhaustive} from './Utils/utils';
-
-export enum ErrorSeverity {
-  /**
-   * Invalid JS syntax, or valid syntax that is semantically invalid which may indicate some
-   * misunderstanding on the user’s part.
-   */
-  InvalidJS = 'InvalidJS',
-  /**
-   * JS syntax that is not supported and which we do not plan to support. Developers should
-   * rewrite to use supported forms.
-   */
-  UnsupportedJS = 'UnsupportedJS',
-  /**
-   * Code that breaks the rules of React.
-   */
-  InvalidReact = 'InvalidReact',
-  /**
-   * Incorrect configuration of the compiler.
-   */
-  InvalidConfig = 'InvalidConfig',
-  /**
-   * Code that can reasonably occur and that doesn't break any rules, but is unsafe to preserve
-   * memoization.
-   */
-  CannotPreserveMemoization = 'CannotPreserveMemoization',
-  /**
-   * Unhandled syntax that we don't support yet.
-   */
-  Todo = 'Todo',
-  /**
-   * An unexpected internal error in the compiler that indicates critical issues that can panic
-   * the compiler.
-   */
-  Invariant = 'Invariant',
-}
+import {ErrorSeverity} from './Utils/CompilerErrorSeverity';
+import {
+  ErrorCode,
+  ErrorCodeDetails,
+  LinterCategory,
+} from './Utils/CompilerErrorCodes';
+export {ErrorSeverity};
+export {ErrorCode, ErrorCodeDetails, LinterCategory};
 
 export type CompilerDiagnosticOptions = {
   severity: ErrorSeverity;
   category: string;
-  description: string;
+  description?: string | null | undefined;
   details: Array<CompilerDiagnosticDetail>;
   suggestions?: Array<CompilerSuggestion> | null | undefined;
+  linterCategory?: LinterCategory | null | undefined;
 };
 
 export type CompilerDiagnosticDetail =
@@ -86,13 +60,28 @@ export type CompilerSuggestion =
       description: string;
     };
 
-export type CompilerErrorDetailOptions = {
+export type PlainCompilerErrorDetailOptions = {
+  errorCode?: void;
   reason: string;
   description?: string | null | undefined;
-  severity: ErrorSeverity;
+  severity:
+    | ErrorSeverity.Invariant
+    | ErrorSeverity.Todo
+    | ErrorSeverity.InvalidConfig;
   loc: SourceLocation | null;
   suggestions?: Array<CompilerSuggestion> | null | undefined;
 };
+export type CodedCompilerErrorDetailOptions = {
+  errorCode: ErrorCode;
+  description?: string | null | undefined;
+  loc: SourceLocation | null;
+  suggestions?: Array<CompilerSuggestion> | null | undefined;
+  linterCategory?: LinterCategory | null | undefined;
+};
+
+export type CompilerErrorDetailOptions =
+  | PlainCompilerErrorDetailOptions
+  | CodedCompilerErrorDetailOptions;
 
 export type PrintErrorMessageOptions = {
   /**
@@ -102,19 +91,72 @@ export type PrintErrorMessageOptions = {
   eslint: boolean;
 };
 
+export function makeCompilerDiagnostic(
+  code: ErrorCode,
+  options?: {
+    description?: string;
+    suggestions?: Array<CompilerSuggestion> | null | undefined;
+  },
+): CompilerDiagnostic {
+  return makeCompilerDiagnostic(code, options);
+}
+
 export class CompilerDiagnostic {
   options: CompilerDiagnosticOptions;
 
-  constructor(options: CompilerDiagnosticOptions) {
+  /**
+   * Constructor is private to enforce that we either only create invariant diagnostics
+   * or use ErrorCodes
+   */
+  private constructor(options: CompilerDiagnosticOptions) {
     this.options = options;
   }
 
-  static create(
-    options: Omit<CompilerDiagnosticOptions, 'details'>,
-  ): CompilerDiagnostic {
+  static create<
+    T extends CompilerDiagnosticOptions & {severity: ErrorSeverity.Invariant},
+  >(options: Omit<T, 'details'>): CompilerDiagnostic {
     return new CompilerDiagnostic({...options, details: []});
   }
 
+  static fromCode(
+    code: ErrorCode,
+    options?: {
+      description?: string;
+      suggestions?: Array<CompilerSuggestion> | null | undefined;
+      details?: Array<CompilerDiagnosticDetail> | null | undefined;
+    },
+  ): CompilerDiagnostic {
+    const errorEntry = ErrorCodeDetails[code];
+    let description = undefined;
+    if (errorEntry.description != null) {
+      description = errorEntry.description;
+    }
+    if (options?.description != null && options.description.length > 0) {
+      if (description != null && description.length > 0) {
+        description += ' ';
+      } else {
+        description = '';
+      }
+      description += options.description;
+    }
+
+    const diagnosticOptions: CompilerDiagnosticOptions = {
+      severity: errorEntry.severity,
+      category: errorEntry.reason,
+      description,
+      linterCategory: errorEntry.linterCategory,
+      suggestions: options?.suggestions,
+      details: options?.details ?? [],
+    };
+
+    return new CompilerDiagnostic(diagnosticOptions);
+  }
+
+  // TODO: remove after converting test fixtures to use printErrorMessage
+  serialize(): unknown {
+    return {options: {...this.options, linterCategory: undefined}};
+  }
+
   get category(): CompilerDiagnosticOptions['category'] {
     return this.options.category;
   }
@@ -127,6 +169,9 @@ export class CompilerDiagnostic {
   get suggestions(): CompilerDiagnosticOptions['suggestions'] {
     return this.options.suggestions;
   }
+  get linterCategory(): CompilerDiagnosticOptions['linterCategory'] {
+    return this.options.linterCategory;
+  }
 
   withDetail(detail: CompilerDiagnosticDetail): CompilerDiagnostic {
     this.options.details.push(detail);
@@ -138,11 +183,10 @@ export class CompilerDiagnostic {
   }
 
   printErrorMessage(source: string, options: PrintErrorMessageOptions): string {
-    const buffer = [
-      printErrorSummary(this.severity, this.category),
-      '\n\n',
-      this.description,
-    ];
+    const buffer = [printErrorSummary(this.severity, this.category)];
+    if (this.description != null) {
+      buffer.push(`\n\n${this.description}`);
+    }
     for (const detail of this.options.details) {
       switch (detail.kind) {
         case 'error': {
@@ -202,13 +246,65 @@ export class CompilerErrorDetail {
     this.options = options;
   }
 
-  get reason(): CompilerErrorDetailOptions['reason'] {
-    return this.options.reason;
+  static fromCode(
+    code: ErrorCode,
+    details?: {
+      description?: string | null;
+      loc?: SourceLocation | null;
+      suggestions?: Array<CompilerSuggestion> | null | undefined;
+    },
+  ): CompilerErrorDetail {
+    return new CompilerErrorDetail({
+      ...details,
+      errorCode: code,
+    } as CodedCompilerErrorDetailOptions);
   }
-  get description(): CompilerErrorDetailOptions['description'] {
+
+  // TODO: remove after converting test fixtures to use printErrorMessage
+  serialize(): unknown {
+    return {
+      options: {
+        reason: this.reason,
+        description: this.description,
+        severity: this.severity,
+        loc: this.loc,
+        suggestions: this.suggestions,
+      },
+    };
+  }
+
+  get reason(): string {
+    if (this.options.errorCode != null) {
+      return ErrorCodeDetails[this.options.errorCode].reason;
+    } else {
+      return this.options.reason;
+    }
+  }
+  get description(): string | null | undefined {
+    if (this.options.errorCode != null) {
+      let description = undefined;
+      if (ErrorCodeDetails[this.options.errorCode].description != null) {
+        description = ErrorCodeDetails[this.options.errorCode].description;
+      }
+      if (
+        this.options.description != null &&
+        this.options.description.length > 0
+      ) {
+        if (description != null && description.length > 0) {
+          description += '. ';
+        } else {
+          description = '';
+        }
+        description += this.options.description;
+      }
+      return description;
+    }
     return this.options.description;
   }
-  get severity(): CompilerErrorDetailOptions['severity'] {
+  get severity(): ErrorSeverity {
+    if (this.options.errorCode != null) {
+      return ErrorCodeDetails[this.options.errorCode].severity;
+    }
     return this.options.severity;
   }
   get loc(): CompilerErrorDetailOptions['loc'] {
@@ -217,6 +313,12 @@ export class CompilerErrorDetail {
   get suggestions(): CompilerErrorDetailOptions['suggestions'] {
     return this.options.suggestions;
   }
+  get linterCategory(): LinterCategory | null | undefined {
+    if (this.options.errorCode != null) {
+      return ErrorCodeDetails[this.options.errorCode].linterCategory;
+    }
+    return undefined;
+  }
 
   primaryLocation(): SourceLocation | null {
     return this.loc;
@@ -266,7 +368,7 @@ export class CompilerError extends Error {
 
   static invariant(
     condition: unknown,
-    options: Omit<CompilerErrorDetailOptions, 'severity'>,
+    options: Omit<PlainCompilerErrorDetailOptions, 'severity'>,
   ): asserts condition {
     if (!condition) {
       const errors = new CompilerError();
@@ -280,14 +382,14 @@ export class CompilerError extends Error {
     }
   }
 
-  static throwDiagnostic(options: CompilerDiagnosticOptions): never {
+  static throwDiagnostic(diagnostic: CompilerDiagnostic): never {
     const errors = new CompilerError();
-    errors.pushDiagnostic(new CompilerDiagnostic(options));
+    errors.pushDiagnostic(diagnostic);
     throw errors;
   }
 
   static throwTodo(
-    options: Omit<CompilerErrorDetailOptions, 'severity'>,
+    options: Omit<PlainCompilerErrorDetailOptions, 'severity'>,
   ): never {
     const errors = new CompilerError();
     errors.pushErrorDetail(
@@ -296,34 +398,21 @@ export class CompilerError extends Error {
     throw errors;
   }
 
-  static throwInvalidJS(
-    options: Omit<CompilerErrorDetailOptions, 'severity'>,
+  static throwFromCode(
+    code: ErrorCode,
+    options?: {
+      description?: string | null;
+      loc?: SourceLocation | null;
+      suggestions?: Array<CompilerSuggestion> | null | undefined;
+    },
   ): never {
     const errors = new CompilerError();
-    errors.pushErrorDetail(
-      new CompilerErrorDetail({
-        ...options,
-        severity: ErrorSeverity.InvalidJS,
-      }),
-    );
-    throw errors;
-  }
-
-  static throwInvalidReact(
-    options: Omit<CompilerErrorDetailOptions, 'severity'>,
-  ): never {
-    const errors = new CompilerError();
-    errors.pushErrorDetail(
-      new CompilerErrorDetail({
-        ...options,
-        severity: ErrorSeverity.InvalidReact,
-      }),
-    );
+    errors.pushErrorDetail(CompilerErrorDetail.fromCode(code, options));
     throw errors;
   }
 
   static throwInvalidConfig(
-    options: Omit<CompilerErrorDetailOptions, 'severity'>,
+    options: Omit<PlainCompilerErrorDetailOptions, 'severity'>,
   ): never {
     const errors = new CompilerError();
     errors.pushErrorDetail(
@@ -392,13 +481,10 @@ export class CompilerError extends Error {
   }
 
   push(options: CompilerErrorDetailOptions): CompilerErrorDetail {
-    const detail = new CompilerErrorDetail({
-      reason: options.reason,
-      description: options.description ?? null,
-      severity: options.severity,
-      suggestions: options.suggestions,
-      loc: typeof options.loc === 'symbol' ? null : options.loc,
-    });
+    if (options instanceof CompilerErrorDetail) {
+      return this.pushErrorDetail(options);
+    }
+    const detail = new CompilerErrorDetail(options);
     return this.pushErrorDetail(detail);
   }
 
@@ -407,6 +493,19 @@ export class CompilerError extends Error {
     return detail;
   }
 
+  pushErrorCode(
+    code: ErrorCode,
+    details?: {
+      description?: string | null;
+      loc?: SourceLocation | null;
+      suggestions?: Array<CompilerSuggestion> | null | undefined;
+    },
+  ): CompilerErrorDetail {
+    const detail = CompilerErrorDetail.fromCode(code, details);
+    this.details.push(detail);
+    return detail;
+  }
+
   hasErrors(): boolean {
     return this.details.length > 0;
   }

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

@@ -38,10 +38,10 @@ export function validateRestrictedImports(
     ImportDeclaration(importDeclPath) {
       if (restrictedImports.has(importDeclPath.node.source.value)) {
         error.push({
-          severity: ErrorSeverity.Todo,
           reason: 'Bailing out due to blocklisted import',
           description: `Import from module ${importDeclPath.node.source.value}`,
           loc: importDeclPath.node.loc ?? null,
+          severity: ErrorSeverity.Todo,
         });
       }
     },
@@ -205,10 +205,10 @@ export class ProgramContext {
     }
     const error = new CompilerError();
     error.push({
-      severity: ErrorSeverity.Todo,
       reason: 'Encountered conflicting global in generated program',
       description: `Conflict from local binding ${name}`,
       loc: scope.getBinding(name)?.path.node.loc ?? null,
+      severity: ErrorSeverity.Todo,
       suggestions: null,
     });
     return Err(error);

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

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

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

@@ -100,7 +100,6 @@ import {outlineJSX} from '../Optimization/OutlineJsx';
 import {optimizePropsMethodCalls} from '../Optimization/OptimizePropsMethodCalls';
 import {transformFire} from '../Transform';
 import {validateNoImpureFunctionsInRender} from '../Validation/ValidateNoImpureFunctionsInRender';
-import {CompilerError} from '..';
 import {validateStaticComponents} from '../Validation/ValidateStaticComponents';
 import {validateNoFreezingKnownMutableFunctions} from '../Validation/ValidateNoFreezingKnownMutableFunctions';
 import {inferMutationAliasingEffects} from '../Inference/InferMutationAliasingEffects';
@@ -174,7 +173,7 @@ function runWithEnvironment(
     !env.config.disableMemoizationForDebugging &&
     !env.config.enableChangeDetectionForDebugging
   ) {
-    dropManualMemoization(hir).unwrap();
+    env.logOrThrowErrors(dropManualMemoization(hir));
     log({kind: 'hir', name: 'DropManualMemoization', value: hir});
   }
 
@@ -207,10 +206,10 @@ function runWithEnvironment(
 
   if (env.isInferredMemoEnabled) {
     if (env.config.validateHooksUsage) {
-      validateHooksUsage(hir).unwrap();
+      env.logOrThrowErrors(validateHooksUsage(hir));
     }
-    if (env.config.validateNoCapitalizedCalls) {
-      validateNoCapitalizedCalls(hir).unwrap();
+    if (env.config.validateNoCapitalizedCalls != null) {
+      env.logOrThrowErrors(validateNoCapitalizedCalls(hir));
     }
   }
 
@@ -230,20 +229,17 @@ function runWithEnvironment(
   log({kind: 'hir', name: 'AnalyseFunctions', value: hir});
 
   if (!env.config.enableNewMutationAliasingModel) {
-    const fnEffectErrors = inferReferenceEffects(hir);
+    const fnEffectResult = inferReferenceEffects(hir);
+
     if (env.isInferredMemoEnabled) {
-      if (fnEffectErrors.length > 0) {
-        CompilerError.throw(fnEffectErrors[0]);
-      }
+      env.logOrThrowErrors(fnEffectResult);
     }
     log({kind: 'hir', name: 'InferReferenceEffects', value: hir});
   } else {
     const mutabilityAliasingErrors = inferMutationAliasingEffects(hir);
     log({kind: 'hir', name: 'InferMutationAliasingEffects', value: hir});
     if (env.isInferredMemoEnabled) {
-      if (mutabilityAliasingErrors.isErr()) {
-        throw mutabilityAliasingErrors.unwrapErr();
-      }
+      env.logOrThrowErrors(mutabilityAliasingErrors);
     }
   }
 
@@ -272,10 +268,8 @@ function runWithEnvironment(
     });
     log({kind: 'hir', name: 'InferMutationAliasingRanges', value: hir});
     if (env.isInferredMemoEnabled) {
-      if (mutabilityAliasingErrors.isErr()) {
-        throw mutabilityAliasingErrors.unwrapErr();
-      }
-      validateLocalsNotReassignedAfterRender(hir);
+      env.logOrThrowErrors(mutabilityAliasingErrors.map(() => undefined));
+      env.logOrThrowErrors(validateLocalsNotReassignedAfterRender(hir));
     }
   }
 
@@ -285,15 +279,15 @@ function runWithEnvironment(
     }
 
     if (env.config.validateRefAccessDuringRender) {
-      validateNoRefAccessInRender(hir).unwrap();
+      env.logOrThrowErrors(validateNoRefAccessInRender(hir));
     }
 
     if (env.config.validateNoSetStateInRender) {
-      validateNoSetStateInRender(hir).unwrap();
+      env.logOrThrowErrors(validateNoSetStateInRender(hir));
     }
 
     if (env.config.validateNoDerivedComputationsInEffects) {
-      validateNoDerivedComputationsInEffects(hir);
+      env.logOrThrowErrors(validateNoDerivedComputationsInEffects(hir));
     }
 
     if (env.config.validateNoSetStateInEffects) {
@@ -303,16 +297,18 @@ function runWithEnvironment(
     if (env.config.validateNoJSXInTryStatements) {
       env.logErrors(validateNoJSXInTryStatement(hir));
     }
-
-    if (env.config.validateNoImpureFunctionsInRender) {
-      validateNoImpureFunctionsInRender(hir).unwrap();
+    if (
+      env.config.validateNoImpureFunctionsInRender &&
+      !env.config.enableNewMutationAliasingModel
+    ) {
+      env.logOrThrowErrors(validateNoImpureFunctionsInRender(hir));
     }
 
     if (
       env.config.validateNoFreezingKnownMutableFunctions ||
       env.config.enableNewMutationAliasingModel
     ) {
-      validateNoFreezingKnownMutableFunctions(hir).unwrap();
+      env.logOrThrowErrors(validateNoFreezingKnownMutableFunctions(hir));
     }
   }
 

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

@@ -7,11 +7,7 @@
 
 import {NodePath} from '@babel/core';
 import * as t from '@babel/types';
-import {
-  CompilerError,
-  CompilerErrorDetail,
-  ErrorSeverity,
-} from '../CompilerError';
+import {CompilerError, ErrorSeverity} from '../CompilerError';
 import {ExternalFunction, ReactFunctionType} from '../HIR/Environment';
 import {CodegenFunction} from '../ReactiveScopes';
 import {isComponentDeclaration} from '../Utils/ComponentDeclaration';
@@ -32,6 +28,7 @@ import {
 } from './Suppression';
 import {GeneratedSource} from '../HIR';
 import {Err, Ok, Result} from '../Utils/Result';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 
 export type CompilerPass = {
   opts: PluginOptions;
@@ -101,12 +98,9 @@ function findDirectivesDynamicGating(
       if (t.isValidIdentifier(maybeMatch[1])) {
         result.push({directive, match: maybeMatch[1]});
       } else {
-        errors.push({
-          reason: `Dynamic gating directive is not a valid JavaScript identifier`,
+        errors.pushErrorCode(ErrorCode.DYNAMIC_GATING_IS_NOT_IDENTIFIER, {
           description: `Found '${directive.value.value}'`,
-          severity: ErrorSeverity.InvalidReact,
           loc: directive.loc ?? null,
-          suggestions: null,
         });
       }
     }
@@ -115,14 +109,11 @@ function findDirectivesDynamicGating(
     return Err(errors);
   } else if (result.length > 1) {
     const error = new CompilerError();
-    error.push({
-      reason: `Multiple dynamic gating directives found`,
+    error.pushErrorCode(ErrorCode.DYNAMIC_GATING_MULTIPLE_DIRECTIVES, {
       description: `Expected a single directive but found [${result
         .map(r => r.directive.value.value)
         .join(', ')}]`,
-      severity: ErrorSeverity.InvalidReact,
       loc: result[0].directive.loc ?? null,
-      suggestions: null,
     });
     return Err(error);
   } else if (result.length === 1) {
@@ -451,14 +442,12 @@ export function compileProgram(
   if (programContext.hasModuleScopeOptOut) {
     if (compiledFns.length > 0) {
       const error = new CompilerError();
-      error.pushErrorDetail(
-        new CompilerErrorDetail({
-          reason:
-            'Unexpected compiled functions when module scope opt-out is present',
-          severity: ErrorSeverity.Invariant,
-          loc: null,
-        }),
-      );
+      error.push({
+        reason:
+          'Unexpected compiled functions when module scope opt-out is present',
+        severity: ErrorSeverity.Invariant,
+        loc: null,
+      });
       handleError(error, programContext, null);
     }
     return null;
@@ -591,9 +580,7 @@ function processFn(
   let compiledFn: CodegenFunction;
   const compileResult = tryCompileFunction(fn, fnType, programContext);
   if (compileResult.kind === 'error') {
-    if (directives.optOut != null) {
-      logError(compileResult.error, programContext, fn.node.loc ?? null);
-    } else {
+    if (directives.optOut == null) {
       handleError(compileResult.error, programContext, fn.node.loc ?? null);
     }
     const retryResult = retryCompileFunction(fn, fnType, programContext);
@@ -692,7 +679,7 @@ function tryCompileFunction(
         fn,
         programContext.opts.environment,
         fnType,
-        'all_features',
+        programContext.opts.noEmit ? 'lint_only' : 'all_features',
         programContext,
         programContext.opts.logger,
         programContext.filename,
@@ -805,15 +792,7 @@ function shouldSkipCompilation(
   if (pass.opts.sources) {
     if (pass.filename === null) {
       const error = new CompilerError();
-      error.pushErrorDetail(
-        new CompilerErrorDetail({
-          reason: `Expected a filename but found none.`,
-          description:
-            "When the 'sources' config options is specified, the React compiler will only compile files with a name",
-          severity: ErrorSeverity.InvalidConfig,
-          loc: null,
-        }),
-      );
+      error.pushErrorCode(ErrorCode.FILENAME_NOT_SET);
       handleError(error, pass, null);
       return true;
     }

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

@@ -11,7 +11,7 @@ import {
   CompilerDiagnostic,
   CompilerError,
   CompilerSuggestionOperation,
-  ErrorSeverity,
+  ErrorCode,
 } from '../CompilerError';
 import {assertExhaustive} from '../Utils/utils';
 import {GeneratedSource} from '../HIR';
@@ -165,14 +165,12 @@ export function suppressionsToCompilerError(
     let reason, suggestion;
     switch (suppressionRange.source) {
       case 'Eslint':
-        reason =
-          'React Compiler has skipped optimizing this component because one or more React ESLint rules were disabled';
+        reason = ErrorCode.BAILOUT_ESLINT_SUPPRESSION;
         suggestion =
           'Remove the ESLint suppression and address the React error';
         break;
       case 'Flow':
-        reason =
-          'React Compiler has skipped optimizing this component because one or more React rule violations were reported by Flow';
+        reason = ErrorCode.BAILOUT_FLOW_SUPPRESSION;
         suggestion = 'Remove the Flow suppression and address the React error';
         break;
       default:
@@ -182,10 +180,8 @@ export function suppressionsToCompilerError(
         );
     }
     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 \`${suppressionRange.disableComment.value.trim()}\``,
-        severity: ErrorSeverity.InvalidReact,
+      CompilerDiagnostic.fromCode(reason, {
+        description: `Found suppression \`${suppressionRange.disableComment.value.trim()}\``,
         suggestions: [
           {
             description: suggestion,

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

@@ -8,27 +8,24 @@
 import {NodePath} from '@babel/core';
 import * as t from '@babel/types';
 
-import {CompilerError, EnvironmentConfig, ErrorSeverity, Logger} from '..';
+import {CompilerError, EnvironmentConfig, Logger} from '..';
 import {getOrInsertWith} from '../Utils/utils';
 import {Environment, GeneratedSource} from '../HIR';
 import {DEFAULT_EXPORT} from '../HIR/Environment';
 import {CompileProgramMetadata} from './Program';
-import {CompilerDiagnostic, CompilerDiagnosticOptions} from '../CompilerError';
+import {CompilerDiagnostic} from '../CompilerError';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 
-function throwInvalidReact(
-  options: Omit<CompilerDiagnosticOptions, 'severity'>,
+function logAndThrowDiagnostic(
+  diagnostic: CompilerDiagnostic,
   {logger, filename}: TraversalState,
 ): never {
-  const detail: CompilerDiagnosticOptions = {
-    severity: ErrorSeverity.InvalidReact,
-    ...options,
-  };
   logger?.logEvent(filename, {
     kind: 'CompileError',
     fnLoc: null,
-    detail: new CompilerDiagnostic(detail),
+    detail: diagnostic,
   });
-  CompilerError.throwDiagnostic(detail);
+  CompilerError.throwDiagnostic(diagnostic);
 }
 
 function isAutodepsSigil(
@@ -90,10 +87,8 @@ function assertValidEffectImportReference(
          * as it may have already been transformed by the compiler (and not
          * memoized).
          */
-        throwInvalidReact(
-          {
-            category:
-              'Cannot infer dependencies of this effect. This will break your build!',
+        logAndThrowDiagnostic(
+          CompilerDiagnostic.fromCode(ErrorCode.DID_NOT_INFER_DEPS, {
             description:
               'To resolve, either pass a dependency array or fix reported compiler bailout diagnostics.' +
               (maybeErrorDiagnostic ? ` ${maybeErrorDiagnostic}` : ''),
@@ -104,7 +99,7 @@ function assertValidEffectImportReference(
                 loc: parent.node.loc ?? GeneratedSource,
               },
             ],
-          },
+          }),
           context,
         );
       }
@@ -121,10 +116,8 @@ function assertValidFireImportReference(
       paths[0],
       context.transformErrors,
     );
-    throwInvalidReact(
-      {
-        category:
-          '[Fire] Untransformed reference to compiler-required feature.',
+    logAndThrowDiagnostic(
+      CompilerDiagnostic.fromCode(ErrorCode.CANNOT_COMPILE_FIRE, {
         description:
           'Either remove this `fire` call or ensure it is successfully transformed by the compiler' +
           maybeErrorDiagnostic
@@ -137,7 +130,7 @@ function assertValidFireImportReference(
             loc: paths[0].node.loc ?? GeneratedSource,
           },
         ],
-      },
+      }),
       context,
     );
   }

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

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

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

@@ -12,6 +12,7 @@ import {
   CompilerDiagnostic,
   CompilerError,
   CompilerSuggestionOperation,
+  ErrorCode,
   ErrorSeverity,
 } from '../CompilerError';
 import {Err, Ok, Result} from '../Utils/Result';
@@ -170,14 +171,12 @@ export function lower(
       );
     } else {
       builder.errors.pushDiagnostic(
-        CompilerDiagnostic.create({
-          severity: ErrorSeverity.Todo,
-          category: `Handle ${param.node.type} parameters`,
+        CompilerDiagnostic.fromCode(ErrorCode.UNKNOWN_FUNCTION_PARAMETERS, {
           description: `[BuildHIR] Add support for ${param.node.type} parameters.`,
         }).withDetail({
           kind: 'error',
           loc: param.node.loc ?? null,
-          message: 'Unsupported parameter type',
+          message: `Unsupported parameter type: ${param.node.type}`,
         }),
       );
     }
@@ -201,14 +200,12 @@ export function lower(
     directives = body.get('directives').map(d => d.node.value.value);
   } else {
     builder.errors.pushDiagnostic(
-      CompilerDiagnostic.create({
-        severity: ErrorSeverity.InvalidJS,
-        category: `Unexpected function body kind`,
+      CompilerDiagnostic.fromCode(ErrorCode.INVALID_JAVASCRIPT_AST, {
         description: `Expected function body to be an expression or a block statement, got \`${body.type}\`.`,
       }).withDetail({
         kind: 'error',
         loc: body.node.loc ?? null,
-        message: 'Expected a block statement or expression',
+        message: 'Change this to a block statement or expression',
       }),
     );
   }
@@ -769,12 +766,12 @@ function lowerStatement(
         const testExpr = case_.get('test');
         if (testExpr.node == null) {
           if (hasDefault) {
-            builder.errors.push({
-              reason: `Expected at most one \`default\` branch in a switch statement, this code should have failed to parse`,
-              severity: ErrorSeverity.InvalidJS,
-              loc: case_.node.loc ?? null,
-              suggestions: null,
-            });
+            builder.errors.pushErrorCode(
+              ErrorCode.INVALID_SYNTAX_MULTIPLE_DEFAULTS,
+              {
+                loc: case_.node.loc ?? null,
+              },
+            );
             break;
           }
           hasDefault = true;
@@ -886,19 +883,20 @@ function lowerStatement(
             if (builder.isContextIdentifier(id)) {
               if (kind === InstructionKind.Const) {
                 const declRangeStart = declaration.parentPath.node.start!;
-                builder.errors.push({
-                  reason: `Expect \`const\` declaration not to be reassigned`,
-                  severity: ErrorSeverity.InvalidJS,
-                  loc: id.node.loc ?? null,
-                  suggestions: [
-                    {
-                      description: 'Change to a `let` declaration',
-                      op: CompilerSuggestionOperation.Replace,
-                      range: [declRangeStart, declRangeStart + 5], // "const".length
-                      text: 'let',
-                    },
-                  ],
-                });
+                builder.errors.pushErrorCode(
+                  ErrorCode.INVALID_SYNTAX_REASSIGNED_CONST,
+                  {
+                    loc: id.node.loc ?? null,
+                    suggestions: [
+                      {
+                        description: 'Change to a `let` declaration',
+                        op: CompilerSuggestionOperation.Replace,
+                        range: [declRangeStart, declRangeStart + 5], // "const".length
+                        text: 'let',
+                      },
+                    ],
+                  },
+                );
               }
               lowerValueToTemporary(builder, {
                 kind: 'DeclareContext',
@@ -932,13 +930,13 @@ function lowerStatement(
             }
           }
         } else {
-          builder.errors.push({
-            reason: `Expected variable declaration to be an identifier if no initializer was provided`,
-            description: `Got a \`${id.type}\``,
-            severity: ErrorSeverity.InvalidJS,
-            loc: stmt.node.loc ?? null,
-            suggestions: null,
-          });
+          builder.errors.pushErrorCode(
+            ErrorCode.INVALID_SYNTAX_BAD_VARIABLE_DECL,
+            {
+              description: `Got a \`${id.type}\``,
+              loc: stmt.node.loc ?? null,
+            },
+          );
         }
       }
       return;
@@ -1374,12 +1372,8 @@ function lowerStatement(
       return;
     }
     case 'WithStatement': {
-      builder.errors.push({
-        reason: `JavaScript 'with' syntax is not supported`,
-        description: `'with' syntax is considered deprecated and removed from JavaScript standards, consider alternatives`,
-        severity: ErrorSeverity.UnsupportedJS,
+      builder.errors.pushErrorCode(ErrorCode.UNSUPPORTED_WITH, {
         loc: stmtPath.node.loc ?? null,
-        suggestions: null,
       });
       lowerValueToTemporary(builder, {
         kind: 'UnsupportedNode',
@@ -1394,12 +1388,8 @@ function lowerStatement(
        * and complex enough to support that we don't anticipate supporting anytime soon. Developers
        * are encouraged to lift classes out of component/hook declarations.
        */
-      builder.errors.push({
-        reason: 'Inline `class` declarations are not supported',
-        description: `Move class declarations outside of components/hooks`,
-        severity: ErrorSeverity.UnsupportedJS,
+      builder.errors.pushErrorCode(ErrorCode.UNSUPPORTED_INNER_CLASS, {
         loc: stmtPath.node.loc ?? null,
-        suggestions: null,
       });
       lowerValueToTemporary(builder, {
         kind: 'UnsupportedNode',
@@ -1423,12 +1413,8 @@ function lowerStatement(
     case 'ImportDeclaration':
     case 'TSExportAssignment':
     case 'TSImportEqualsDeclaration': {
-      builder.errors.push({
-        reason:
-          'JavaScript `import` and `export` statements may only appear at the top level of a module',
-        severity: ErrorSeverity.InvalidJS,
+      builder.errors.pushErrorCode(ErrorCode.INVALID_IMPORT_EXPORT, {
         loc: stmtPath.node.loc ?? null,
-        suggestions: null,
       });
       lowerValueToTemporary(builder, {
         kind: 'UnsupportedNode',
@@ -1438,12 +1424,8 @@ function lowerStatement(
       return;
     }
     case 'TSNamespaceExportDeclaration': {
-      builder.errors.push({
-        reason:
-          'TypeScript `namespace` statements may only appear at the top level of a module',
-        severity: ErrorSeverity.InvalidJS,
+      builder.errors.pushErrorCode(ErrorCode.INVALID_TS_NAMESPACE, {
         loc: stmtPath.node.loc ?? null,
-        suggestions: null,
       });
       lowerValueToTemporary(builder, {
         kind: 'UnsupportedNode',
@@ -1698,12 +1680,8 @@ function lowerExpression(
       const expr = exprPath as NodePath<t.NewExpression>;
       const calleePath = expr.get('callee');
       if (!calleePath.isExpression()) {
-        builder.errors.push({
-          reason: `Expected an expression as the \`new\` expression receiver (v8 intrinsics are not supported)`,
-          description: `Got a \`${calleePath.node.type}\``,
-          severity: ErrorSeverity.InvalidJS,
+        builder.errors.pushErrorCode(ErrorCode.UNSUPPORTED_NEW_EXPRESSION, {
           loc: calleePath.node.loc ?? null,
-          suggestions: null,
         });
         return {kind: 'UnsupportedNode', node: exprNode, loc: exprLoc};
       }
@@ -1800,12 +1778,12 @@ function lowerExpression(
           last = lowerExpressionToTemporary(builder, item);
         }
         if (last === null) {
-          builder.errors.push({
-            reason: `Expected sequence expression to have at least one expression`,
-            severity: ErrorSeverity.InvalidJS,
-            loc: expr.node.loc ?? null,
-            suggestions: null,
-          });
+          builder.errors.pushErrorCode(
+            ErrorCode.UNSUPPORTED_EMPTY_SEQUENCE_EXPRESSION,
+            {
+              loc: expr.node.loc ?? null,
+            },
+          );
         } else {
           lowerValueToTemporary(builder, {
             kind: 'StoreLocal',
@@ -2289,18 +2267,18 @@ function lowerExpression(
         });
         for (const [name, locations] of Object.entries(fbtLocations)) {
           if (locations.length > 1) {
-            CompilerError.throwDiagnostic({
-              severity: ErrorSeverity.Todo,
-              category: 'Support duplicate fbt tags',
-              description: `Support \`<${tagName}>\` tags with multiple \`<${tagName}:${name}>\` values`,
-              details: locations.map(loc => {
-                return {
-                  kind: 'error',
-                  message: `Multiple \`<${tagName}:${name}>\` tags found`,
-                  loc,
-                };
+            CompilerError.throwDiagnostic(
+              CompilerDiagnostic.fromCode(ErrorCode.TODO_DUPLICATE_FBT_TAGS, {
+                description: `Support \`<${tagName}>\` tags with multiple \`<${tagName}:${name}>\` values`,
+                details: locations.map(loc => {
+                  return {
+                    kind: 'error',
+                    message: `Multiple \`<${tagName}:${name}>\` tags found`,
+                    loc,
+                  };
+                }),
               }),
-            });
+            );
           }
         }
       }
@@ -2389,11 +2367,8 @@ function lowerExpression(
       const quasis = expr.get('quasis');
 
       if (subexprs.length !== quasis.length - 1) {
-        builder.errors.push({
-          reason: `Unexpected quasi and subexpression lengths in template literal`,
-          severity: ErrorSeverity.InvalidJS,
+        builder.errors.pushErrorCode(ErrorCode.INVALID_QUASI_LENGTHS, {
           loc: exprPath.node.loc ?? null,
-          suggestions: null,
         });
         return {kind: 'UnsupportedNode', node: exprNode, loc: exprLoc};
       }
@@ -2441,24 +2416,23 @@ function lowerExpression(
             };
           }
         } else {
-          builder.errors.push({
-            reason: `Only object properties can be deleted`,
-            severity: ErrorSeverity.InvalidJS,
-            loc: expr.node.loc ?? null,
-            suggestions: [
-              {
-                description: 'Remove this line',
-                range: [expr.node.start!, expr.node.end!],
-                op: CompilerSuggestionOperation.Remove,
-              },
-            ],
-          });
+          builder.errors.pushErrorCode(
+            ErrorCode.INVALID_SYNTAX_DELETE_EXPRESSION,
+            {
+              loc: expr.node.loc ?? null,
+              suggestions: [
+                {
+                  description: 'Remove this line',
+                  range: [expr.node.start!, expr.node.end!],
+                  op: CompilerSuggestionOperation.Remove,
+                },
+              ],
+            },
+          );
           return {kind: 'UnsupportedNode', node: expr.node, loc: exprLoc};
         }
       } else if (expr.node.operator === 'throw') {
-        builder.errors.push({
-          reason: `Throw expressions are not supported`,
-          severity: ErrorSeverity.InvalidJS,
+        builder.errors.pushErrorCode(ErrorCode.UNSUPPORTED_THROW_EXPRESSION, {
           loc: expr.node.loc ?? null,
           suggestions: [
             {
@@ -3285,10 +3259,8 @@ function lowerJsxElementName(
     const name = exprPath.node.name.name;
     const tag = `${namespace}:${name}`;
     if (namespace.indexOf(':') !== -1 || name.indexOf(':') !== -1) {
-      builder.errors.push({
-        reason: `Expected JSXNamespacedName to have no colons in the namespace or name`,
+      builder.errors.pushErrorCode(ErrorCode.INVALID_JSX_NAMESPACED_NAME, {
         description: `Got \`${namespace}\` : \`${name}\``,
-        severity: ErrorSeverity.InvalidJS,
         loc: exprPath.node.loc ?? null,
         suggestions: null,
       });
@@ -3583,11 +3555,7 @@ function lowerIdentifier(
     }
     default: {
       if (binding.kind === 'Global' && binding.name === 'eval') {
-        builder.errors.push({
-          reason: `The 'eval' function is not supported`,
-          description:
-            'Eval is an anti-pattern in JavaScript, and the code executed cannot be evaluated by React Compiler',
-          severity: ErrorSeverity.UnsupportedJS,
+        builder.errors.pushErrorCode(ErrorCode.UNSUPPORTED_EVAL, {
           loc: exprPath.node.loc ?? null,
           suggestions: null,
         });
@@ -3653,9 +3621,7 @@ function lowerIdentifierForAssignment(
     binding.bindingKind === 'const' &&
     kind === InstructionKind.Reassign
   ) {
-    builder.errors.push({
-      reason: `Cannot reassign a \`const\` variable`,
-      severity: ErrorSeverity.InvalidJS,
+    builder.errors.pushErrorCode(ErrorCode.INVALID_SYNTAX_REASSIGNED_CONST, {
       loc: path.node.loc ?? null,
       description:
         binding.identifier.name != null
@@ -3710,12 +3676,13 @@ function lowerAssignment(
       let temporary;
       if (builder.isContextIdentifier(lvalue)) {
         if (kind === InstructionKind.Const && !isHoistedIdentifier) {
-          builder.errors.push({
-            reason: `Expected \`const\` declaration not to be reassigned`,
-            severity: ErrorSeverity.InvalidJS,
-            loc: lvalue.node.loc ?? null,
-            suggestions: null,
-          });
+          builder.errors.pushErrorCode(
+            ErrorCode.INVALID_SYNTAX_REASSIGNED_CONST,
+            {
+              loc: lvalue.node.loc ?? null,
+              suggestions: null,
+            },
+          );
         }
 
         if (
@@ -3726,7 +3693,8 @@ function lowerAssignment(
         ) {
           builder.errors.push({
             reason: `Unexpected context variable kind`,
-            severity: ErrorSeverity.InvalidJS,
+            description: `Expected one of Const, Reassign, Let, Function, got ${kind}`,
+            severity: ErrorSeverity.Invariant,
             loc: lvalue.node.loc ?? null,
             suggestions: null,
           });

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

@@ -93,7 +93,7 @@ export const MacroSchema = z.union([
   z.tuple([z.string(), z.array(MacroMethodSchema)]),
 ]);
 
-export type CompilerMode = 'all_features' | 'no_inferred_memo';
+export type CompilerMode = 'all_features' | 'no_inferred_memo' | 'lint_only';
 
 export type Macro = z.infer<typeof MacroSchema>;
 export type MacroMethod = z.infer<typeof MacroMethodSchema>;
@@ -829,6 +829,14 @@ export class Environment {
     }
   }
 
+  logOrThrowErrors(errors: Result<void, CompilerError>): void {
+    if (this.compilerMode === 'lint_only') {
+      this.logErrors(errors);
+    } else {
+      errors.unwrap();
+    }
+  }
+
   isContextIdentifier(node: t.Identifier): boolean {
     return this.#contextIdentifiers.has(node);
   }

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

@@ -15,6 +15,7 @@ import {Type, makeType} from './Types';
 import {z} from 'zod';
 import type {AliasingEffect} from '../Inference/AliasingEffects';
 import {isReservedWord} from '../Utils/Keyword';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 
 /*
  * *******************************************************************************************
@@ -1322,18 +1323,18 @@ export function forkTemporaryIdentifier(
  */
 export function makeIdentifierName(name: string): ValidatedIdentifier {
   if (isReservedWord(name)) {
-    CompilerError.throwInvalidJS({
-      reason: 'Expected a non-reserved identifier name',
-      loc: GeneratedSource,
-      description: `\`${name}\` is a reserved word in JavaScript and cannot be used as an identifier name`,
-      suggestions: null,
-    });
+    CompilerError.throwFromCode(
+      ErrorCode.INVALID_SYNTAX_RESERVED_VARIABLE_NAME,
+      {
+        loc: GeneratedSource,
+        description: `\`${name}\` is a reserved word in JavaScript and cannot be used as an identifier name`,
+      },
+    );
   } else {
     CompilerError.invariant(t.isValidIdentifier(name), {
       reason: `Expected a valid identifier name`,
       loc: GeneratedSource,
       description: `\`${name}\` is not a valid JavaScript identifier`,
-      suggestions: null,
     });
   }
   return {

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

@@ -7,7 +7,7 @@
 
 import {Binding, NodePath} from '@babel/traverse';
 import * as t from '@babel/types';
-import {CompilerError, ErrorSeverity} from '../CompilerError';
+import {CompilerDiagnostic, CompilerError} from '../CompilerError';
 import {Environment} from './Environment';
 import {
   BasicBlock,
@@ -37,6 +37,7 @@ import {
   mapTerminalSuccessors,
   terminalFallthrough,
 } from './visitors';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 
 /*
  * *******************************************************************************************
@@ -308,19 +309,17 @@ export default class HIRBuilder {
 
   resolveBinding(node: t.Identifier): Identifier {
     if (node.name === 'fbt') {
-      CompilerError.throwDiagnostic({
-        severity: ErrorSeverity.Todo,
-        category: 'Support local variables named `fbt`',
-        description:
-          'Local variables named `fbt` may conflict with the fbt plugin and are not yet supported',
-        details: [
-          {
-            kind: 'error',
-            message: 'Rename to avoid conflict with fbt plugin',
-            loc: node.loc ?? GeneratedSource,
-          },
-        ],
-      });
+      CompilerError.throwDiagnostic(
+        CompilerDiagnostic.fromCode(ErrorCode.TODO_CONFLICTING_FBT_IDENTIFIER, {
+          details: [
+            {
+              kind: 'error',
+              message: 'Rename to avoid conflict with fbt plugin',
+              loc: node.loc ?? GeneratedSource,
+            },
+          ],
+        }),
+      );
     }
     const originalName = node.name;
     let name = originalName;

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

@@ -5,12 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {
-  CompilerDiagnostic,
-  CompilerError,
-  ErrorSeverity,
-  SourceLocation,
-} from '..';
+import {CompilerDiagnostic, CompilerError, SourceLocation} from '..';
 import {
   CallExpression,
   Effect,
@@ -35,6 +30,7 @@ import {
   makeInstructionId,
 } from '../HIR';
 import {createTemporaryPlace, markInstructionIds} from '../HIR/HIRBuilder';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 import {Result} from '../Utils/Result';
 
 type ManualMemoCallee = {
@@ -299,12 +295,11 @@ function extractManualMemoizationArgs(
   >;
   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({
+      CompilerDiagnostic.fromCode(
+        kind === 'useMemo'
+          ? ErrorCode.INVALID_USE_MEMO_NO_ARG0
+          : ErrorCode.INVALID_USE_CALLBACK_NO_ARG0,
+      ).withDetail({
         kind: 'error',
         loc: instr.value.loc,
         message: `Expected a callback function to be passed to ${kind}`,
@@ -314,12 +309,11 @@ function extractManualMemoizationArgs(
   }
   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({
+      CompilerDiagnostic.fromCode(
+        fnPlace.kind === 'Spread'
+          ? ErrorCode.DYNAMIC_USE_MEMO_SPREAD_ARGUMENT
+          : ErrorCode.DYNAMIC_USE_CALLBACK_SPREAD_ARGUMENT,
+      ).withDetail({
         kind: 'error',
         loc: instr.value.loc,
         message: `Unexpected spread argument to ${kind}`,
@@ -334,12 +328,9 @@ function extractManualMemoizationArgs(
     );
     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({
+        CompilerDiagnostic.fromCode(
+          ErrorCode.DYNAMIC_MANUAL_MEMO_DEPENDENCY_LIST,
+        ).withDetail({
           kind: 'error',
           loc: depsListPlace.loc,
           message: `Expected the dependency list for ${kind} to be an array literal`,
@@ -352,12 +343,9 @@ function extractManualMemoizationArgs(
       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({
+          CompilerDiagnostic.fromCode(
+            ErrorCode.COMPLEX_MANUAL_MEMO_DEPENDENCY_LIST_ENTRY,
+          ).withDetail({
             kind: 'error',
             loc: dep.loc,
             message: `Expected the dependency list to be an array of simple expressions (e.g. \`x\`, \`x.y.z\`, \`x?.y?.z\`)`,
@@ -457,16 +445,16 @@ export function dropManualMemoization(
             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({
+                  CompilerDiagnostic.fromCode(
+                    ErrorCode.INVALID_USE_MEMO_CALLBACK_RETURN,
+                    {
+                      description: `This ${
+                        manualMemo.loadInstr.value.kind === 'PropertyLoad'
+                          ? 'React.useMemo'
+                          : 'useMemo'
+                      } callback doesn't return a value. useMemo is for computing and caching values, not for arbitrary side effects.`,
+                    },
+                  ).withDetail({
                     kind: 'error',
                     loc: instr.value.loc,
                     message: 'useMemo() callbacks must return a value',
@@ -497,12 +485,9 @@ export function dropManualMemoization(
              */
             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({
+                CompilerDiagnostic.fromCode(
+                  ErrorCode.DYNAMIC_MANUAL_MEMO_CALLBACK,
+                ).withDetail({
                   kind: 'error',
                   loc: fnPlace.loc,
                   message: `Expected the first argument to be an inline function expression`,

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

@@ -25,6 +25,7 @@ import {
   isRefOrRefValue,
 } from '../HIR';
 import {eachInstructionOperand, eachTerminalOperand} from '../HIR/visitors';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 import {assertExhaustive} from '../Utils/utils';
 
 interface State {
@@ -62,22 +63,20 @@ function inferOperandEffect(state: State, place: Place): null | FunctionEffect {
         // We ignore mutations of primitives since this is not a React-specific problem
         value.kind !== ValueKind.Primitive
       ) {
-        let reason = getWriteErrorReason(value);
+        let errorCode = getWriteErrorReason(value);
         return {
           kind:
             value.reason.size === 1 && value.reason.has(ValueReason.Global)
               ? 'GlobalMutation'
               : 'ReactMutation',
           error: {
-            reason,
+            errorCode,
             description:
               place.identifier.name !== null &&
               place.identifier.name.kind === 'named'
                 ? `Found mutation of \`${place.identifier.name.value}\``
                 : null,
             loc: place.loc,
-            suggestions: null,
-            severity: ErrorSeverity.InvalidReact,
           },
         };
       }
@@ -266,11 +265,8 @@ export function inferInstructionFunctionEffects(
       functionEffects.push({
         kind: 'GlobalMutation',
         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)',
+          errorCode: ErrorCode.INVALID_WRITE_GLOBAL,
           loc: instr.loc,
-          suggestions: null,
-          severity: ErrorSeverity.InvalidReact,
         },
       });
       break;
@@ -324,28 +320,28 @@ function isEffectSafeOutsideRender(effect: FunctionEffect): boolean {
   return effect.kind === 'GlobalMutation';
 }
 
-export function getWriteErrorReason(abstractValue: AbstractValue): string {
+export function getWriteErrorReason(abstractValue: AbstractValue): ErrorCode {
   if (abstractValue.reason.has(ValueReason.Global)) {
-    return 'Modifying a variable defined outside a component or hook is not allowed. Consider using an effect';
+    return ErrorCode.INVALID_WRITE_GLOBAL;
   } 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 ErrorCode.INVALID_WRITE_FROZEN_VALUE_JSX;
   } else if (abstractValue.reason.has(ValueReason.Context)) {
-    return `Modifying a value returned from 'useContext()' is not allowed.`;
+    return ErrorCode.INVALID_WRITE_IMMUTABLE_VALUE_USE_CONTEXT;
   } else if (abstractValue.reason.has(ValueReason.KnownReturnSignature)) {
-    return 'Modifying a value returned from a function whose return value should not be mutated';
+    return ErrorCode.INVALID_WRITE_IMMUTABLE_VALUE_KNOWN_SIGNATURE;
   } else if (abstractValue.reason.has(ValueReason.ReactiveFunctionArgument)) {
-    return 'Modifying component props or hook arguments is not allowed. Consider using a local variable instead';
+    return ErrorCode.INVALID_WRITE_IMMUTABLE_ARGS;
   } 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 ErrorCode.INVALID_WRITE_STATE;
   } 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 ErrorCode.INVALID_WRITE_REDUCER_STATE;
   } 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 ErrorCode.INVALID_WRITE_EFFECT_DEPENDENCY;
   } 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 ErrorCode.INVALID_WRITE_HOOK_CAPTURED;
   } 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 ErrorCode.INVALID_WRITE_HOOK_RETURN;
   } else {
-    return 'This modifies a variable that React considers immutable';
+    return ErrorCode.INVALID_WRITE_GENERIC;
   }
 }

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

@@ -9,7 +9,6 @@ import {
   CompilerDiagnostic,
   CompilerError,
   Effect,
-  ErrorSeverity,
   SourceLocation,
   ValueKind,
 } from '..';
@@ -69,6 +68,7 @@ import {getWriteErrorReason} from './InferFunctionEffects';
 import prettyFormat from 'pretty-format';
 import {createTemporaryPlace} from '../HIR/HIRBuilder';
 import {AliasingEffect, AliasingSignature, hashEffect} from './AliasingEffects';
+import {ErrorCode, ErrorCodeDetails} from '../Utils/CompilerErrorCodes';
 
 const DEBUG = false;
 
@@ -442,7 +442,7 @@ function applySignature(
         const value = state.kind(effect.value);
         switch (value.kind) {
           case ValueKind.Frozen: {
-            const reason = getWriteErrorReason({
+            const errorCode = getWriteErrorReason({
               kind: value.kind,
               reason: value.reason,
               context: new Set(),
@@ -455,10 +455,9 @@ function applySignature(
             effects.push({
               kind: 'MutateFrozen',
               place: effect.value,
-              error: CompilerDiagnostic.create({
-                severity: ErrorSeverity.InvalidReact,
-                category: 'This value cannot be modified',
-                description: `${reason}.`,
+              // TODO: remove ERROR_CODE.INVALID_WRITE and update test fixtures
+              error: CompilerDiagnostic.fromCode(ErrorCode.INVALID_WRITE, {
+                description: ErrorCodeDetails[errorCode].reason + '.',
               }).withDetail({
                 kind: 'error',
                 loc: effect.value.loc,
@@ -1026,22 +1025,20 @@ function applyEffect(
           const hoistedAccess = context.hoistedContextDeclarations.get(
             effect.value.identifier.declarationId,
           );
-          const diagnostic = CompilerDiagnostic.create({
-            severity: ErrorSeverity.InvalidReact,
-            category: 'Cannot access variable before it is declared',
-            description: `${variable ?? 'This variable'} is accessed before it is declared, which prevents the earlier access from updating when this value changes over time.`,
-          });
+          const diagnostic = CompilerDiagnostic.fromCode(
+            ErrorCode.INVALID_ACCESS_BEFORE_INIT,
+          );
           if (hoistedAccess != null && hoistedAccess.loc != effect.value.loc) {
             diagnostic.withDetail({
               kind: 'error',
               loc: hoistedAccess.loc,
-              message: `${variable ?? 'variable'} accessed before it is declared`,
+              message: `${variable ?? 'This variable'} is accessed before it is declared`,
             });
           }
           diagnostic.withDetail({
             kind: 'error',
             loc: effect.value.loc,
-            message: `${variable ?? 'variable'} is declared here`,
+            message: `${variable ?? 'This variable'} is declared here`,
           });
 
           applyEffect(
@@ -1056,7 +1053,7 @@ function applyEffect(
             effects,
           );
         } else {
-          const reason = getWriteErrorReason({
+          const errorCode = getWriteErrorReason({
             kind: value.kind,
             reason: value.reason,
             context: new Set(),
@@ -1075,10 +1072,9 @@ function applyEffect(
                   ? 'MutateFrozen'
                   : 'MutateGlobal',
               place: effect.value,
-              error: CompilerDiagnostic.create({
-                severity: ErrorSeverity.InvalidReact,
-                category: 'This value cannot be modified',
-                description: `${reason}.`,
+              // TODO: remove ERROR_CODE.INVALID_WRITE and update test fixtures
+              error: CompilerDiagnostic.fromCode(ErrorCode.INVALID_WRITE, {
+                description: ErrorCodeDetails[errorCode].reason + '.',
               }).withDetail({
                 kind: 'error',
                 loc: effect.value.loc,
@@ -2006,15 +2002,12 @@ function computeSignatureForInstruction(
       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 ${variable} is declared outside of the component/hook. Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)`,
-        }).withDetail({
+        error: CompilerDiagnostic.fromCode(
+          ErrorCode.INVALID_WRITE_GLOBAL,
+        ).withDetail({
           kind: 'error',
           loc: instr.loc,
-          message: `${variable} cannot be reassigned`,
+          message: `${variable} should not be reassigned`,
         }),
       });
       effects.push({kind: 'Assign', from: value.value, into: lvalue});
@@ -2105,19 +2098,16 @@ function computeEffectsForLegacySignature(
     effects.push({
       kind: 'Impure',
       place: receiver,
-      error: CompilerDiagnostic.create({
-        severity: ErrorSeverity.InvalidReact,
-        category: 'Cannot call impure function during render',
-        description:
-          (signature.canonicalName != null
-            ? `\`${signature.canonicalName}\` is an impure function. `
-            : '') +
-          'Calling an impure function can produce unstable results that update unpredictably when the component happens to re-render. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#components-and-hooks-must-be-idempotent)',
-      }).withDetail({
-        kind: 'error',
-        loc,
-        message: 'Cannot call impure function',
-      }),
+      error: CompilerDiagnostic.fromCode(ErrorCode.IMPURE_FUNCTIONS).withDetail(
+        {
+          kind: 'error',
+          loc,
+          message:
+            signature.canonicalName != null
+              ? `\`${signature.canonicalName}\` is an impure function. `
+              : 'This is an impure function.',
+        },
+      ),
     });
   }
   const stores: Array<Place> = [];

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

@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {CompilerError, CompilerErrorDetailOptions} from '../CompilerError';
+import {CompilerError} from '../CompilerError';
 import {Environment} from '../HIR';
 import {
   AbstractValue,
@@ -48,6 +48,7 @@ import {
   eachTerminalOperand,
   eachTerminalSuccessor,
 } from '../HIR/visitors';
+import {Err, Ok, Result} from '../Utils/Result';
 import {assertExhaustive, Set_isSuperset} from '../Utils/utils';
 import {
   inferTerminalFunctionEffects,
@@ -106,7 +107,7 @@ const UndefinedValue: InstructionValue = {
 export default function inferReferenceEffects(
   fn: HIRFunction,
   options: {isFunctionExpression: boolean} = {isFunctionExpression: false},
-): Array<CompilerErrorDetailOptions> {
+): Result<void, CompilerError> {
   /*
    * Initial state contains function params
    * TODO: include module declarations here as well
@@ -247,10 +248,17 @@ export default function inferReferenceEffects(
 
   if (options.isFunctionExpression) {
     fn.effects = functionEffects;
-    return [];
   } else {
-    return transformFunctionEffectErrors(functionEffects);
+    const errors = transformFunctionEffectErrors(functionEffects);
+    if (errors.length > 0) {
+      const compilerError = new CompilerError();
+      for (const detail of errors) {
+        compilerError.push(detail);
+      }
+      return Err(compilerError);
+    }
   }
+  return Ok(void 0);
 }
 
 type FreezeAction = {values: Set<InstructionValue>; reason: Set<ValueReason>};

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

@@ -42,6 +42,7 @@ import {
 import {eachInstructionOperand} from '../HIR/visitors';
 import {printSourceLocationLine} from '../HIR/PrintHIR';
 import {USE_FIRE_FUNCTION_NAME} from '../HIR/Environment';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 
 /*
  * TODO(jmbrown):
@@ -50,8 +51,6 @@ import {USE_FIRE_FUNCTION_NAME} from '../HIR/Environment';
  *   - React.useEffect calls
  */
 
-const CANNOT_COMPILE_FIRE = 'Cannot compile `fire`';
-
 export function transformFire(fn: HIRFunction): void {
   const context = new Context(fn.env);
   replaceFireFunctions(fn, context);
@@ -178,9 +177,7 @@ function replaceFireFunctions(fn: HIRFunction, context: Context): void {
                 loc: value.args[1].loc,
                 description:
                   'You must use an array literal for an effect dependency array when that effect uses `fire()`',
-                severity: ErrorSeverity.Invariant,
-                reason: CANNOT_COMPILE_FIRE,
-                suggestions: null,
+                errorCode: ErrorCode.CANNOT_COMPILE_FIRE,
               });
             }
           } else if (value.args.length > 1 && value.args[1].kind === 'Spread') {
@@ -188,9 +185,7 @@ function replaceFireFunctions(fn: HIRFunction, context: Context): void {
               loc: value.args[1].place.loc,
               description:
                 'You must use an array literal for an effect dependency array when that effect uses `fire()`',
-              severity: ErrorSeverity.Invariant,
-              reason: CANNOT_COMPILE_FIRE,
-              suggestions: null,
+              errorCode: ErrorCode.CANNOT_COMPILE_FIRE,
             });
           }
         }
@@ -243,11 +238,9 @@ function replaceFireFunctions(fn: HIRFunction, context: Context): void {
           } else {
             context.pushError({
               loc: value.loc,
+              errorCode: ErrorCode.CANNOT_COMPILE_FIRE,
               description:
                 '`fire()` can only receive a function call such as `fire(fn(a,b)). Method calls and other expressions are not allowed',
-              severity: ErrorSeverity.InvalidReact,
-              reason: CANNOT_COMPILE_FIRE,
-              suggestions: null,
             });
           }
         } else {
@@ -262,10 +255,8 @@ function replaceFireFunctions(fn: HIRFunction, context: Context): void {
           }
           context.pushError({
             loc: value.loc,
+            errorCode: ErrorCode.CANNOT_COMPILE_FIRE,
             description,
-            severity: ErrorSeverity.InvalidReact,
-            reason: CANNOT_COMPILE_FIRE,
-            suggestions: null,
           });
         }
       } else if (value.kind === 'CallExpression') {
@@ -394,9 +385,7 @@ function ensureNoRemainingCalleeCaptures(
         description: `All uses of ${calleeName} must be either used with a fire() call in \
 this effect or not used with a fire() call at all. ${calleeName} was used with fire() on line \
 ${printSourceLocationLine(calleeInfo.fireLoc)} in this effect`,
-        severity: ErrorSeverity.InvalidReact,
-        reason: CANNOT_COMPILE_FIRE,
-        suggestions: null,
+        errorCode: ErrorCode.CANNOT_COMPILE_FIRE,
       });
     }
   }
@@ -411,9 +400,7 @@ function ensureNoMoreFireUses(fn: HIRFunction, context: Context): void {
       context.pushError({
         loc: place.identifier.loc,
         description: 'Cannot use `fire` outside of a useEffect function',
-        severity: ErrorSeverity.Invariant,
-        reason: CANNOT_COMPILE_FIRE,
-        suggestions: null,
+        errorCode: ErrorCode.CANNOT_COMPILE_FIRE,
       });
     }
   }

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

@@ -0,0 +1,622 @@
+import {ErrorSeverity} from './CompilerErrorSeverity';
+
+export enum LinterCategory {
+  RULES_OF_HOOKS = 'rules-of-hooks',
+  IMPURE_FUNCTIONS = 'impure-functions',
+  JSX_IN_TRY = 'jsx-in-try',
+  NO_REF_ACCESS_IN_RENDER = 'no-ref-access-in-render',
+  VALIDATE_MANUAL_MEMO = 'validate-manual-memo',
+  DYNAMIC_MANUAL_MEMO = 'dynamic-manual-memo',
+
+  EXHAUSTIVE_DEPS = 'exhaustive-deps',
+  MEMOIZED_DEPENDENCIES = 'memoized-dependencies', // not real!
+  INVALID_WRITE = 'invalid-write',
+  CAPITALIZED_CALLS = 'capitalized-calls',
+  STATIC_COMPONENTS = 'static-components',
+  NO_SET_STATE_IN_RENDER = 'no-set-state-in-render',
+  NO_SET_STATE_IN_EFFECTS = 'no-set-state-in-effects',
+  UNNECESSARY_EFFECTS = 'unnecessary-effects',
+
+  UNSUPPORTED_SYNTAX = 'unsupported-syntax',
+
+  TODO_SYNTAX = 'todo-syntax',
+
+  COMPILER_CONFIG = 'compiler-config',
+}
+
+export enum ErrorCode {
+  HOOK_CALL_STATIC,
+  HOOK_INVALID_REFERENCE,
+  HOOK_CALL_REACTIVE,
+  HOOK_CALL_NOT_TOP_LEVEL,
+  IMPURE_FUNCTIONS,
+  JSX_IN_TRY,
+  NO_REF_ACCESS_IN_RENDER,
+  WRITE_AFTER_RENDER,
+  REASSIGN_AFTER_RENDER,
+  REASSIGN_IN_ASYNC,
+  INVALID_WRITE,
+  CAPITALIZED_CALLS,
+  STATIC_COMPONENTS,
+  INVALID_USE_MEMO_CALLBACK_RETURN,
+  INVALID_USE_MEMO_CALLBACK_PARAMETERS,
+  INVALID_USE_MEMO_CALLBACK_ASYNC,
+  INVALID_USE_MEMO_NO_ARG0,
+  INVALID_USE_CALLBACK_NO_ARG0,
+  DYNAMIC_MANUAL_MEMO_CALLBACK,
+  DYNAMIC_USE_MEMO_SPREAD_ARGUMENT,
+  DYNAMIC_USE_CALLBACK_SPREAD_ARGUMENT,
+  DYNAMIC_MANUAL_MEMO_DEPENDENCY_LIST,
+  COMPLEX_MANUAL_MEMO_DEPENDENCY_LIST_ENTRY,
+
+  INVALID_SET_STATE_IN_RENDER,
+  INVALID_SET_STATE_IN_MEMO,
+  INVALID_SET_STATE_IN_EFFECTS,
+
+  NO_DERIVED_COMPUTATIONS_IN_EFFECTS,
+
+  DYNAMIC_GATING_IS_NOT_IDENTIFIER,
+  DYNAMIC_GATING_MULTIPLE_DIRECTIVES,
+  FILENAME_NOT_SET,
+
+  INVALID_WRITE_GLOBAL,
+  INVALID_WRITE_FROZEN_VALUE_JSX,
+  INVALID_WRITE_IMMUTABLE_VALUE_USE_CONTEXT,
+  INVALID_WRITE_IMMUTABLE_VALUE_KNOWN_SIGNATURE,
+  INVALID_WRITE_IMMUTABLE_ARGS,
+  INVALID_WRITE_STATE,
+  INVALID_WRITE_REDUCER_STATE,
+  INVALID_WRITE_EFFECT_DEPENDENCY,
+  INVALID_WRITE_HOOK_CAPTURED,
+  INVALID_WRITE_HOOK_RETURN,
+  INVALID_ACCESS_BEFORE_INIT,
+  INVALID_WRITE_GENERIC,
+
+  MEMOIZED_EFFECT_DEPENDENCIES,
+
+  INVALID_SYNTAX_MULTIPLE_DEFAULTS,
+  INVALID_SYNTAX_REASSIGNED_CONST,
+  INVALID_SYNTAX_BAD_VARIABLE_DECL,
+  UNSUPPORTED_WITH,
+  UNSUPPORTED_INNER_CLASS,
+  INVALID_IMPORT_EXPORT,
+  INVALID_TS_NAMESPACE,
+  UNSUPPORTED_NEW_EXPRESSION,
+  UNSUPPORTED_EMPTY_SEQUENCE_EXPRESSION,
+  INVALID_QUASI_LENGTHS,
+  INVALID_SYNTAX_DELETE_EXPRESSION,
+  UNSUPPORTED_THROW_EXPRESSION,
+  INVALID_JSX_NAMESPACED_NAME,
+  UNSUPPORTED_EVAL,
+  INVALID_SYNTAX_RESERVED_VARIABLE_NAME,
+  INVALID_JAVASCRIPT_AST,
+  BAILOUT_ESLINT_SUPPRESSION,
+  BAILOUT_FLOW_SUPPRESSION,
+  MANUAL_MEMO_MUTATED_LATER,
+  MANUAL_MEMO_REMOVED,
+  MANUAL_MEMO_DEPENDENCIES_CONFLICT,
+
+  CANNOT_COMPILE_FIRE,
+  DID_NOT_INFER_DEPS,
+
+  /** Todo syntax */
+  TODO_CONFLICTING_FBT_IDENTIFIER,
+  TODO_DUPLICATE_FBT_TAGS,
+  UNKNOWN_FUNCTION_PARAMETERS,
+}
+
+type ErrorCodeType = {
+  code: ErrorCode;
+  description?: string;
+  severity: ErrorSeverity;
+  reason: string;
+  linterCategory: LinterCategory | null;
+};
+
+export const ErrorCodeDetails: Record<ErrorCode, ErrorCodeType> = {
+  [ErrorCode.HOOK_CALL_STATIC]: {
+    code: ErrorCode.HOOK_CALL_STATIC,
+    severity: ErrorSeverity.InvalidReact,
+    reason:
+      'Hooks must always be called in a consistent order, and may not be called conditionally. See the Rules of Hooks (https://react.dev/warnings/invalid-hook-call-warning)',
+    linterCategory: LinterCategory.RULES_OF_HOOKS,
+  },
+  [ErrorCode.HOOK_INVALID_REFERENCE]: {
+    code: ErrorCode.HOOK_INVALID_REFERENCE,
+    severity: ErrorSeverity.InvalidReact,
+    reason:
+      'Hooks may not be referenced as normal values, they must be called. See https://react.dev/reference/rules/react-calls-components-and-hooks#never-pass-around-hooks-as-regular-values',
+    linterCategory: LinterCategory.RULES_OF_HOOKS,
+  },
+  [ErrorCode.HOOK_CALL_REACTIVE]: {
+    code: ErrorCode.HOOK_CALL_REACTIVE,
+    severity: ErrorSeverity.InvalidReact,
+    reason:
+      'Hooks must be the same function on every render, but this value may change over time to a different function. See https://react.dev/reference/rules/react-calls-components-and-hooks#dont-dynamically-use-hooks',
+    linterCategory: LinterCategory.RULES_OF_HOOKS,
+  },
+  [ErrorCode.HOOK_CALL_NOT_TOP_LEVEL]: {
+    code: ErrorCode.HOOK_CALL_NOT_TOP_LEVEL,
+    severity: ErrorSeverity.InvalidReact,
+    reason:
+      'Hooks must be called at the top level in the body of a function component or custom hook, and may not be called within function expressions. See the Rules of Hooks (https://react.dev/warnings/invalid-hook-call-warning)',
+    linterCategory: LinterCategory.RULES_OF_HOOKS,
+  },
+  [ErrorCode.IMPURE_FUNCTIONS]: {
+    code: ErrorCode.IMPURE_FUNCTIONS,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'Cannot call impure functions during render',
+    description:
+      'Calling an impure function can produce unstable results that update unpredictably when the component happens to re-render. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#components-and-hooks-must-be-idempotent).',
+    linterCategory: LinterCategory.IMPURE_FUNCTIONS,
+  },
+  [ErrorCode.JSX_IN_TRY]: {
+    code: ErrorCode.JSX_IN_TRY,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'Avoid constructing JSX within try/catch',
+    description: `React does not immediately render components when JSX is rendered, so any errors from this component will not be caught by the try/catch. To catch errors in rendering a given component, wrap that component in an error boundary. (https://react.dev/reference/react/Component#catching-rendering-errors-with-an-error-boundary)`,
+    linterCategory: LinterCategory.JSX_IN_TRY,
+  },
+  [ErrorCode.NO_REF_ACCESS_IN_RENDER]: {
+    code: ErrorCode.NO_REF_ACCESS_IN_RENDER,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'Cannot access refs during render',
+    description:
+      'React refs are values that are not needed for rendering. Refs should only be accessed ' +
+      'outside of render, such as in event handlers or effects. ' +
+      'Accessing a ref value (the `current` property) during render can cause your component ' +
+      'not to update as expected (https://react.dev/reference/react/useRef)',
+    linterCategory: LinterCategory.NO_REF_ACCESS_IN_RENDER,
+  },
+  [ErrorCode.INVALID_SET_STATE_IN_EFFECTS]: {
+    code: ErrorCode.INVALID_SET_STATE_IN_EFFECTS,
+    severity: ErrorSeverity.InvalidReact,
+    reason:
+      'Calling setState synchronously within an effect can trigger cascading renders',
+    description:
+      'Effects are intended to synchronize state between React and external systems such as manually updating the DOM, state management libraries, or other platform APIs. ' +
+      'In general, the body of an effect should do one or both of the following:\n' +
+      '* Update external systems with the latest state from React.\n' +
+      '* Subscribe for updates from some external system, calling setState in a callback function when external state changes.\n\n' +
+      'Calling setState synchronously within an effect body causes cascading renders that can hurt performance, and is not recommended. ' +
+      '(https://react.dev/learn/you-might-not-need-an-effect)',
+    linterCategory: LinterCategory.NO_SET_STATE_IN_EFFECTS,
+  },
+  [ErrorCode.WRITE_AFTER_RENDER]: {
+    code: ErrorCode.WRITE_AFTER_RENDER,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'Cannot modify local variables after render completes',
+    description: `This argument is a function which may reassign or mutate a variable after render, which can cause inconsistent behavior on subsequent renders. Consider using state instead.`,
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+  [ErrorCode.REASSIGN_AFTER_RENDER]: {
+    code: ErrorCode.REASSIGN_AFTER_RENDER,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'Cannot reassign local variables after render completes',
+    description: `Reassigning local variables after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead.`,
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+  [ErrorCode.REASSIGN_IN_ASYNC]: {
+    code: ErrorCode.REASSIGN_IN_ASYNC,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'Cannot reassign variable in async function',
+    description:
+      'Reassigning a variable in an async function can cause inconsistent behavior on subsequent renders. Consider using state instead',
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+  [ErrorCode.INVALID_WRITE]: {
+    code: ErrorCode.INVALID_WRITE,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'This value cannot be modified',
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+  [ErrorCode.CAPITALIZED_CALLS]: {
+    code: ErrorCode.CAPITALIZED_CALLS,
+    severity: ErrorSeverity.InvalidReact,
+    reason:
+      'Capitalized functions are reserved for components, which must be invoked with JSX. If this is a component, render it with JSX. Otherwise, ensure that it has no hook calls and rename it to begin with a lowercase letter. Alternatively, if you know for a fact that this function is not a component, you can allowlist it via the compiler config',
+    linterCategory: LinterCategory.CAPITALIZED_CALLS,
+  },
+  [ErrorCode.STATIC_COMPONENTS]: {
+    code: ErrorCode.STATIC_COMPONENTS,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'Cannot create components during render',
+    linterCategory: LinterCategory.STATIC_COMPONENTS,
+  },
+  [ErrorCode.INVALID_USE_MEMO_NO_ARG0]: {
+    code: ErrorCode.INVALID_USE_MEMO_NO_ARG0,
+    severity: ErrorSeverity.InvalidReact,
+    reason: `Expected a callback function to be passed to useMemo`,
+    linterCategory: LinterCategory.VALIDATE_MANUAL_MEMO,
+  },
+  [ErrorCode.INVALID_USE_CALLBACK_NO_ARG0]: {
+    code: ErrorCode.INVALID_USE_CALLBACK_NO_ARG0,
+    severity: ErrorSeverity.InvalidReact,
+    reason: `Expected a callback function to be passed to useCallback`,
+    linterCategory: LinterCategory.VALIDATE_MANUAL_MEMO,
+  },
+  [ErrorCode.DYNAMIC_USE_MEMO_SPREAD_ARGUMENT]: {
+    code: ErrorCode.DYNAMIC_USE_MEMO_SPREAD_ARGUMENT,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'Unexpected spread argument to useMemo',
+    linterCategory: LinterCategory.DYNAMIC_MANUAL_MEMO,
+  },
+
+  [ErrorCode.DYNAMIC_USE_CALLBACK_SPREAD_ARGUMENT]: {
+    code: ErrorCode.DYNAMIC_USE_CALLBACK_SPREAD_ARGUMENT,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'Unexpected spread argument to useCallback',
+    linterCategory: LinterCategory.DYNAMIC_MANUAL_MEMO,
+  },
+  [ErrorCode.INVALID_USE_MEMO_CALLBACK_PARAMETERS]: {
+    code: ErrorCode.INVALID_USE_MEMO_CALLBACK_PARAMETERS,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'useMemo() callbacks may not accept parameters',
+    description:
+      'useMemo() callbacks are called by React to cache calculations across re-renders. They should not take parameters. Instead, directly reference the props, state, or local variables needed for the computation.',
+    linterCategory: LinterCategory.VALIDATE_MANUAL_MEMO,
+  },
+  [ErrorCode.INVALID_USE_MEMO_CALLBACK_ASYNC]: {
+    code: ErrorCode.INVALID_USE_MEMO_CALLBACK_ASYNC,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'useMemo() callbacks may not be async or generator functions',
+    description:
+      'useMemo() callbacks are called once and must synchronously return a value.',
+    linterCategory: LinterCategory.VALIDATE_MANUAL_MEMO,
+  },
+  [ErrorCode.INVALID_USE_MEMO_CALLBACK_RETURN]: {
+    code: ErrorCode.INVALID_USE_MEMO_CALLBACK_RETURN,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'useMemo() callbacks must return a value',
+    linterCategory: LinterCategory.VALIDATE_MANUAL_MEMO,
+  },
+  [ErrorCode.DYNAMIC_MANUAL_MEMO_CALLBACK]: {
+    code: ErrorCode.DYNAMIC_MANUAL_MEMO_CALLBACK,
+    severity: ErrorSeverity.InvalidReact,
+    reason: `Expected the first argument to be an inline function expression`,
+    linterCategory: LinterCategory.DYNAMIC_MANUAL_MEMO,
+  },
+  [ErrorCode.DYNAMIC_MANUAL_MEMO_DEPENDENCY_LIST]: {
+    code: ErrorCode.DYNAMIC_MANUAL_MEMO_DEPENDENCY_LIST,
+    severity: ErrorSeverity.InvalidReact,
+    reason: `Expected the dependency list of useMemo or useCallback to be an array literal`,
+    linterCategory: LinterCategory.DYNAMIC_MANUAL_MEMO,
+  },
+  [ErrorCode.COMPLEX_MANUAL_MEMO_DEPENDENCY_LIST_ENTRY]: {
+    code: ErrorCode.COMPLEX_MANUAL_MEMO_DEPENDENCY_LIST_ENTRY,
+    severity: ErrorSeverity.InvalidReact,
+    reason: `Expected the dependency list to be an array of simple expressions (e.g. \`x\`, \`x.y.z\`, \`x?.y?.z\`)`,
+    linterCategory: LinterCategory.DYNAMIC_MANUAL_MEMO,
+  },
+  [ErrorCode.INVALID_SET_STATE_IN_RENDER]: {
+    code: ErrorCode.INVALID_SET_STATE_IN_RENDER,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'Calling setState during render may trigger an infinite loop',
+    description:
+      'Calling setState during render will trigger another render, and can lead to infinite loops. (https://react.dev/reference/react/useState)',
+    linterCategory: LinterCategory.NO_SET_STATE_IN_RENDER,
+  },
+  [ErrorCode.INVALID_SET_STATE_IN_MEMO]: {
+    code: ErrorCode.INVALID_SET_STATE_IN_MEMO,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'Calling setState from useMemo may trigger an infinite loop',
+    description:
+      'Each time the memo callback is evaluated it will change state. This can cause a memoization dependency to change, running the memo function again and causing an infinite loop. Instead of setting state in useMemo(), prefer deriving the value during render. (https://react.dev/reference/react/useState)',
+    linterCategory: LinterCategory.NO_SET_STATE_IN_RENDER,
+  },
+  [ErrorCode.NO_DERIVED_COMPUTATIONS_IN_EFFECTS]: {
+    code: ErrorCode.NO_DERIVED_COMPUTATIONS_IN_EFFECTS,
+    severity: ErrorSeverity.InvalidReact,
+    reason:
+      'Values derived from props and state should be calculated during render, not in an effect. (https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state)',
+    linterCategory: LinterCategory.UNNECESSARY_EFFECTS,
+  },
+
+  /** Invalid writes */
+  [ErrorCode.INVALID_WRITE_GLOBAL]: {
+    code: ErrorCode.INVALID_WRITE_GLOBAL,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'Cannot reassign variables declared outside of the component/hook',
+    description:
+      'Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)',
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+  [ErrorCode.INVALID_WRITE_FROZEN_VALUE_JSX]: {
+    code: ErrorCode.INVALID_WRITE_FROZEN_VALUE_JSX,
+    severity: ErrorSeverity.InvalidReact,
+    reason:
+      'Modifying a value used previously in JSX is not allowed. Consider moving the modification before the JSX',
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+  [ErrorCode.INVALID_WRITE_IMMUTABLE_VALUE_USE_CONTEXT]: {
+    code: ErrorCode.INVALID_WRITE_IMMUTABLE_VALUE_USE_CONTEXT,
+    severity: ErrorSeverity.InvalidReact,
+    reason: `Modifying a value returned from 'useContext()' is not allowed.`,
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+  [ErrorCode.INVALID_WRITE_IMMUTABLE_VALUE_KNOWN_SIGNATURE]: {
+    code: ErrorCode.INVALID_WRITE_IMMUTABLE_VALUE_KNOWN_SIGNATURE,
+    severity: ErrorSeverity.InvalidReact,
+    reason:
+      'Modifying a value returned from a function whose return value should not be mutated',
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+  [ErrorCode.INVALID_WRITE_IMMUTABLE_ARGS]: {
+    code: ErrorCode.INVALID_WRITE_IMMUTABLE_ARGS,
+    severity: ErrorSeverity.InvalidReact,
+    reason:
+      'Modifying component props or hook arguments is not allowed. Consider using a local variable instead',
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+  [ErrorCode.INVALID_WRITE_STATE]: {
+    code: ErrorCode.INVALID_WRITE_STATE,
+    severity: ErrorSeverity.InvalidReact,
+    reason:
+      "Modifying a value returned from 'useState()', which should not be modified directly. Use the setter function to update instead",
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+  [ErrorCode.INVALID_WRITE_REDUCER_STATE]: {
+    code: ErrorCode.INVALID_WRITE_REDUCER_STATE,
+    severity: ErrorSeverity.InvalidReact,
+    reason:
+      "Modifying a value returned from 'useReducer()', which should not be modified directly. Use the dispatch function to update instead",
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+  [ErrorCode.INVALID_WRITE_EFFECT_DEPENDENCY]: {
+    code: ErrorCode.INVALID_WRITE_EFFECT_DEPENDENCY,
+    severity: ErrorSeverity.InvalidReact,
+    reason:
+      'Modifying a value used previously in an effect function or as an effect dependency is not allowed. Consider moving the modification before calling useEffect()',
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+  [ErrorCode.INVALID_WRITE_HOOK_CAPTURED]: {
+    code: ErrorCode.INVALID_WRITE_HOOK_CAPTURED,
+    severity: ErrorSeverity.InvalidReact,
+    reason:
+      'Modifying a value previously passed as an argument to a hook is not allowed. Consider moving the modification before calling the hook',
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+  [ErrorCode.INVALID_WRITE_HOOK_RETURN]: {
+    code: ErrorCode.INVALID_WRITE_HOOK_RETURN,
+    severity: ErrorSeverity.InvalidReact,
+    reason:
+      'Modifying a value returned from a hook is not allowed. Consider moving the modification into the hook where the value is constructed',
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+  [ErrorCode.INVALID_ACCESS_BEFORE_INIT]: {
+    code: ErrorCode.INVALID_ACCESS_BEFORE_INIT,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'Cannot access variable before it is declared',
+    description: `Reading a variable before it is initialized will prevent the earlier access from updating when this value changes over time. Instead, move the variable access to after it has been initialized`,
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+  [ErrorCode.INVALID_WRITE_GENERIC]: {
+    code: ErrorCode.INVALID_WRITE_GENERIC,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'This modifies a variable that React considers immutable',
+    linterCategory: LinterCategory.INVALID_WRITE,
+  },
+
+  /** Compiler Config */
+  [ErrorCode.DYNAMIC_GATING_IS_NOT_IDENTIFIER]: {
+    code: ErrorCode.DYNAMIC_GATING_IS_NOT_IDENTIFIER,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'Dynamic gating directive is not a valid JavaScript identifier',
+    linterCategory: LinterCategory.COMPILER_CONFIG,
+  },
+  [ErrorCode.DYNAMIC_GATING_MULTIPLE_DIRECTIVES]: {
+    code: ErrorCode.DYNAMIC_GATING_MULTIPLE_DIRECTIVES,
+    severity: ErrorSeverity.InvalidReact,
+    reason: 'Expected a single dynamic gating directive',
+    linterCategory: LinterCategory.COMPILER_CONFIG,
+  },
+  [ErrorCode.FILENAME_NOT_SET]: {
+    code: ErrorCode.FILENAME_NOT_SET,
+    severity: ErrorSeverity.InvalidConfig,
+    reason: `Expected a filename but found none.`,
+    description:
+      "When the 'sources' config options is specified, the React compiler will only compile files with a name",
+    linterCategory: LinterCategory.COMPILER_CONFIG,
+  },
+
+  /** Effect dependencies */
+  [ErrorCode.MEMOIZED_EFFECT_DEPENDENCIES]: {
+    code: ErrorCode.MEMOIZED_EFFECT_DEPENDENCIES,
+    reason:
+      'React Compiler has skipped optimizing this component because the effect dependencies could not be memoized. Unmemoized effect dependencies can trigger an infinite loop or other unexpected behavior',
+    severity: ErrorSeverity.CannotPreserveMemoization,
+    linterCategory: LinterCategory.MEMOIZED_DEPENDENCIES,
+  },
+
+  /** Invalid / unsupported syntax */
+  [ErrorCode.INVALID_SYNTAX_MULTIPLE_DEFAULTS]: {
+    code: ErrorCode.INVALID_SYNTAX_MULTIPLE_DEFAULTS,
+    reason: `Expected at most one \`default\` branch in a switch statement, this code should have failed to parse`,
+    severity: ErrorSeverity.InvalidJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.INVALID_SYNTAX_REASSIGNED_CONST]: {
+    code: ErrorCode.INVALID_SYNTAX_REASSIGNED_CONST,
+    reason: `Expect \`const\` declaration not to be reassigned`,
+    severity: ErrorSeverity.InvalidJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.INVALID_SYNTAX_BAD_VARIABLE_DECL]: {
+    code: ErrorCode.INVALID_SYNTAX_BAD_VARIABLE_DECL,
+    reason: `Expected variable declaration to be an identifier if no initializer was provided`,
+    severity: ErrorSeverity.InvalidJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.UNSUPPORTED_WITH]: {
+    code: ErrorCode.UNSUPPORTED_WITH,
+    reason: `JavaScript 'with' syntax is not supported`,
+    description: `'with' syntax is considered deprecated and removed from JavaScript standards, consider alternatives`,
+    severity: ErrorSeverity.UnsupportedJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.UNSUPPORTED_INNER_CLASS]: {
+    code: ErrorCode.UNSUPPORTED_INNER_CLASS,
+    reason: 'Inline `class` declarations are not supported',
+    description: `Move class declarations outside of components/hooks`,
+    severity: ErrorSeverity.UnsupportedJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.INVALID_IMPORT_EXPORT]: {
+    code: ErrorCode.INVALID_IMPORT_EXPORT,
+    reason:
+      'JavaScript `import` and `export` statements may only appear at the top level of a module',
+    severity: ErrorSeverity.InvalidJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.INVALID_TS_NAMESPACE]: {
+    code: ErrorCode.INVALID_TS_NAMESPACE,
+    reason:
+      'TypeScript `namespace` statements may only appear at the top level of a module',
+    severity: ErrorSeverity.InvalidJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.UNSUPPORTED_NEW_EXPRESSION]: {
+    code: ErrorCode.UNSUPPORTED_NEW_EXPRESSION,
+    reason: `Expected an expression as the \`new\` expression receiver (v8 intrinsics are not supported)`,
+    severity: ErrorSeverity.InvalidJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.UNSUPPORTED_EMPTY_SEQUENCE_EXPRESSION]: {
+    code: ErrorCode.UNSUPPORTED_EMPTY_SEQUENCE_EXPRESSION,
+    reason: `Expected sequence expression to have at least one expression`,
+    severity: ErrorSeverity.InvalidJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.INVALID_QUASI_LENGTHS]: {
+    code: ErrorCode.INVALID_QUASI_LENGTHS,
+    reason: `Unexpected quasi and subexpression lengths in template literal`,
+    severity: ErrorSeverity.InvalidJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.INVALID_SYNTAX_DELETE_EXPRESSION]: {
+    code: ErrorCode.INVALID_SYNTAX_DELETE_EXPRESSION,
+    reason: `Only object properties can be deleted`,
+    severity: ErrorSeverity.InvalidJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.UNSUPPORTED_THROW_EXPRESSION]: {
+    code: ErrorCode.UNSUPPORTED_THROW_EXPRESSION,
+    reason: `Throw expressions are not supported`,
+    severity: ErrorSeverity.InvalidJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.INVALID_JSX_NAMESPACED_NAME]: {
+    code: ErrorCode.INVALID_JSX_NAMESPACED_NAME,
+    reason: `Expected JSXNamespacedName to have no colons in the namespace or name`,
+    severity: ErrorSeverity.InvalidJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.UNSUPPORTED_EVAL]: {
+    code: ErrorCode.UNSUPPORTED_EVAL,
+    reason: `The 'eval' function is not supported`,
+    description:
+      'Eval is an anti-pattern in JavaScript, and the code executed cannot be evaluated by React Compiler',
+    severity: ErrorSeverity.UnsupportedJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.INVALID_SYNTAX_RESERVED_VARIABLE_NAME]: {
+    code: ErrorCode.INVALID_SYNTAX_RESERVED_VARIABLE_NAME,
+    reason: 'Expected a non-reserved identifier name',
+    severity: ErrorSeverity.InvalidJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.INVALID_JAVASCRIPT_AST]: {
+    code: ErrorCode.INVALID_JAVASCRIPT_AST,
+    reason: 'Encountered invalid JavaScript',
+    severity: ErrorSeverity.InvalidJS,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.BAILOUT_ESLINT_SUPPRESSION]: {
+    code: ErrorCode.BAILOUT_ESLINT_SUPPRESSION,
+    reason:
+      'React Compiler has skipped optimizing this component because one or more React ESLint rules were disabled',
+    description:
+      'React Compiler only works when your components follow all the rules of React, disabling them may result in unexpected or incorrect behavior',
+    severity: ErrorSeverity.InvalidReact,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.MANUAL_MEMO_REMOVED]: {
+    code: ErrorCode.MANUAL_MEMO_REMOVED,
+    reason:
+      'Compilation skipped because existing memoization could not be preserved',
+    description:
+      'React Compiler has skipped optimizing this component because the existing manual memoization could not be preserved. This value was memoized in source but not in compilation output.',
+    severity: ErrorSeverity.CannotPreserveMemoization,
+    linterCategory: LinterCategory.TODO_SYNTAX,
+  },
+
+  /**
+   * This is left vague as fire is very experimental
+   */
+  [ErrorCode.CANNOT_COMPILE_FIRE]: {
+    code: ErrorCode.CANNOT_COMPILE_FIRE,
+    reason: 'Cannot compile `fire`',
+    severity: ErrorSeverity.InvalidReact,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.DID_NOT_INFER_DEPS]: {
+    code: ErrorCode.DID_NOT_INFER_DEPS,
+    reason:
+      'Cannot infer dependencies of this effect. This will break your build!',
+    severity: ErrorSeverity.InvalidReact,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+
+  [ErrorCode.BAILOUT_FLOW_SUPPRESSION]: {
+    code: ErrorCode.BAILOUT_FLOW_SUPPRESSION,
+    reason:
+      'React Compiler has skipped optimizing this component because one or more React rule violations were reported by Flow',
+    description:
+      'React Compiler only works when your components follow all the rules of React, disabling them may result in unexpected or incorrect behavior',
+    severity: ErrorSeverity.InvalidReact,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+
+  /** Syntax React Compiler may eventually support */
+  [ErrorCode.TODO_CONFLICTING_FBT_IDENTIFIER]: {
+    code: ErrorCode.TODO_CONFLICTING_FBT_IDENTIFIER,
+    reason: 'Support local variables named `fbt`',
+    description:
+      'Local variables named `fbt` may conflict with the fbt plugin and are not yet supported',
+    severity: ErrorSeverity.Todo,
+    linterCategory: LinterCategory.TODO_SYNTAX,
+  },
+  [ErrorCode.TODO_DUPLICATE_FBT_TAGS]: {
+    code: ErrorCode.TODO_DUPLICATE_FBT_TAGS,
+    reason: 'Support duplicate fbt tags',
+    severity: ErrorSeverity.Todo,
+    linterCategory: LinterCategory.TODO_SYNTAX,
+  },
+  [ErrorCode.UNKNOWN_FUNCTION_PARAMETERS]: {
+    code: ErrorCode.UNKNOWN_FUNCTION_PARAMETERS,
+    severity: ErrorSeverity.Todo,
+    reason: 'Currently unsupported function parameter syntax',
+    linterCategory: LinterCategory.TODO_SYNTAX,
+  },
+  [ErrorCode.MANUAL_MEMO_MUTATED_LATER]: {
+    code: ErrorCode.MANUAL_MEMO_MUTATED_LATER,
+    reason:
+      'Compilation skipped because existing memoization could not be preserved',
+    description: [
+      'React Compiler has skipped optimizing this component because the existing manual memoization could not be preserved. ',
+      'This dependency may be mutated later, which could cause the value to change unexpectedly.',
+    ].join(''),
+    severity: ErrorSeverity.CannotPreserveMemoization,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+  [ErrorCode.MANUAL_MEMO_DEPENDENCIES_CONFLICT]: {
+    code: ErrorCode.MANUAL_MEMO_DEPENDENCIES_CONFLICT,
+    reason:
+      'Compilation skipped because existing memoization could not be preserved',
+    description:
+      'React Compiler has skipped optimizing this component because the existing manual memoization could not be preserved. ' +
+      'The inferred dependencies did not match the manually specified dependencies, which could cause the value to change more or less frequently than expected.',
+    severity: ErrorSeverity.CannotPreserveMemoization,
+    linterCategory: LinterCategory.UNSUPPORTED_SYNTAX,
+  },
+};

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

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

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

@@ -6,11 +6,7 @@
  */
 
 import * as t from '@babel/types';
-import {
-  CompilerError,
-  CompilerErrorDetail,
-  ErrorSeverity,
-} from '../CompilerError';
+import {CompilerError, CompilerErrorDetail} from '../CompilerError';
 import {computeUnconditionalBlocks} from '../HIR/ComputeUnconditionalBlocks';
 import {isHookName} from '../HIR/Environment';
 import {
@@ -27,6 +23,7 @@ import {
 } from '../HIR/visitors';
 import {assertExhaustive} from '../Utils/utils';
 import {Result} from '../Utils/Result';
+import {ErrorCode, ErrorCodeDetails} from '../Utils/CompilerErrorCodes';
 
 /**
  * Represents the possible kinds of value which may be stored at a given Place during
@@ -111,8 +108,6 @@ export function validateHooksUsage(
     // Once a particular hook has a conditional call error, don't report any further issues for this hook
     setKind(place, Kind.Error);
 
-    const reason =
-      'Hooks must always be called in a consistent order, and may not be called conditionally. See the Rules of Hooks (https://react.dev/warnings/invalid-hook-call-warning)';
     const previousError =
       typeof place.loc !== 'symbol' ? errorsByPlace.get(place.loc) : undefined;
 
@@ -120,15 +115,15 @@ export function validateHooksUsage(
      * In some circumstances such as optional calls, we may first encounter a "hook may not be referenced as normal values" error.
      * If that same place is also used as a conditional call, upgrade the error to a conditonal hook error
      */
-    if (previousError === undefined || previousError.reason !== reason) {
+    if (
+      previousError === undefined ||
+      previousError.reason !==
+        ErrorCodeDetails[ErrorCode.HOOK_CALL_STATIC].reason
+    ) {
       recordError(
         place.loc,
-        new CompilerErrorDetail({
-          description: null,
-          reason,
+        CompilerErrorDetail.fromCode(ErrorCode.HOOK_CALL_STATIC, {
           loc: place.loc,
-          severity: ErrorSeverity.InvalidReact,
-          suggestions: null,
         }),
       );
     }
@@ -139,13 +134,8 @@ export function validateHooksUsage(
     if (previousError === undefined) {
       recordError(
         place.loc,
-        new CompilerErrorDetail({
-          description: null,
-          reason:
-            'Hooks may not be referenced as normal values, they must be called. See https://react.dev/reference/rules/react-calls-components-and-hooks#never-pass-around-hooks-as-regular-values',
+        CompilerErrorDetail.fromCode(ErrorCode.HOOK_INVALID_REFERENCE, {
           loc: place.loc,
-          severity: ErrorSeverity.InvalidReact,
-          suggestions: null,
         }),
       );
     }
@@ -156,14 +146,12 @@ export function validateHooksUsage(
     if (previousError === undefined) {
       recordError(
         place.loc,
-        new CompilerErrorDetail({
-          description: null,
-          reason:
-            'Hooks must be the same function on every render, but this value may change over time to a different function. See https://react.dev/reference/rules/react-calls-components-and-hooks#dont-dynamically-use-hooks',
-          loc: place.loc,
-          severity: ErrorSeverity.InvalidReact,
-          suggestions: null,
-        }),
+        CompilerErrorDetail.fromCode(
+          ErrorCodeDetails[ErrorCode.HOOK_CALL_REACTIVE].code,
+          {
+            loc: place.loc,
+          },
+        ),
       );
     }
   }
@@ -424,7 +412,7 @@ export function validateHooksUsage(
   }
 
   for (const [, error] of errorsByPlace) {
-    errors.push(error);
+    errors.pushErrorDetail(error);
   }
   return errors.asResult();
 }
@@ -446,16 +434,10 @@ function visitFunctionExpression(errors: CompilerError, fn: HIRFunction): void {
               : instr.value.property;
           const hookKind = getHookKind(fn.env, callee.identifier);
           if (hookKind != null) {
-            errors.pushErrorDetail(
-              new CompilerErrorDetail({
-                severity: ErrorSeverity.InvalidReact,
-                reason:
-                  'Hooks must be called at the top level in the body of a function component or custom hook, and may not be called within function expressions. See the Rules of Hooks (https://react.dev/warnings/invalid-hook-call-warning)',
-                loc: callee.loc,
-                description: `Cannot call ${hookKind === 'Custom' ? 'hook' : hookKind} within a function expression`,
-                suggestions: null,
-              }),
-            );
+            errors.pushErrorCode(ErrorCode.HOOK_CALL_NOT_TOP_LEVEL, {
+              loc: callee.loc,
+              description: `Cannot call ${hookKind === 'Custom' ? 'hook' : hookKind} within a function expression`,
+            });
           }
           break;
         }

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

@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {CompilerDiagnostic, CompilerError, Effect, ErrorSeverity} from '..';
+import {CompilerDiagnostic, CompilerError, Effect} from '..';
 import {HIRFunction, IdentifierId, Place} from '../HIR';
 import {
   eachInstructionLValue,
@@ -13,13 +13,17 @@ import {
   eachTerminalOperand,
 } from '../HIR/visitors';
 import {getFunctionCallSignature} from '../Inference/InferReferenceEffects';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
+import {Ok, Result} from '../Utils/Result';
 
 /**
  * Validates that local variables cannot be reassigned after render.
  * This prevents a category of bugs in which a closure captures a
  * binding from one render but does not update
  */
-export function validateLocalsNotReassignedAfterRender(fn: HIRFunction): void {
+export function validateLocalsNotReassignedAfterRender(
+  fn: HIRFunction,
+): Result<void, CompilerError> {
   const contextVariables = new Set<IdentifierId>();
   const reassignment = getContextReassignment(
     fn,
@@ -35,18 +39,15 @@ export function validateLocalsNotReassignedAfterRender(fn: HIRFunction): void {
         ? `\`${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.`,
-      }).withDetail({
+      CompilerDiagnostic.fromCode(ErrorCode.REASSIGN_AFTER_RENDER).withDetail({
         kind: 'error',
         loc: reassignment.loc,
         message: `Cannot reassign ${variable} after render completes`,
       }),
     );
-    throw errors;
+    return errors.asResult();
   }
+  return Ok(undefined);
 }
 
 function getContextReassignment(
@@ -90,12 +91,9 @@ function getContextReassignment(
                   ? `\`${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({
+                CompilerDiagnostic.fromCode(
+                  ErrorCode.REASSIGN_IN_ASYNC,
+                ).withDetail({
                   kind: 'error',
                   loc: reassignment.loc,
                   message: `Cannot reassign ${variable}`,

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

@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {CompilerError, ErrorSeverity} from '..';
+import {CompilerError} from '..';
 import {
   Identifier,
   Instruction,
@@ -22,6 +22,7 @@ import {
   ReactiveFunctionVisitor,
   visitReactiveFunction,
 } from '../ReactiveScopes/visitors';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 import {Result} from '../Utils/Result';
 
 /**
@@ -108,12 +109,8 @@ class Visitor extends ReactiveFunctionVisitor<CompilerError> {
           isUnmemoized(deps.identifier, this.scopes))
       ) {
         state.push({
-          reason:
-            'React Compiler has skipped optimizing this component because the effect dependencies could not be memoized. Unmemoized effect dependencies can trigger an infinite loop or other unexpected behavior',
-          description: null,
-          severity: ErrorSeverity.CannotPreserveMemoization,
+          errorCode: ErrorCode.MEMOIZED_EFFECT_DEPENDENCIES,
           loc: typeof instruction.loc !== 'symbol' ? instruction.loc : null,
-          suggestions: null,
         });
       }
     }

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

@@ -5,9 +5,10 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {CompilerError, EnvironmentConfig, ErrorSeverity} from '..';
+import {CompilerError, EnvironmentConfig} from '..';
 import {HIRFunction, IdentifierId} from '../HIR';
 import {DEFAULT_GLOBALS} from '../HIR/Globals';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 import {Result} from '../Utils/Result';
 
 export function validateNoCapitalizedCalls(
@@ -33,8 +34,6 @@ export function validateNoCapitalizedCalls(
   const errors = new CompilerError();
   const capitalLoadGlobals = new Map<IdentifierId, string>();
   const capitalizedProperties = new Map<IdentifierId, string>();
-  const reason =
-    'Capitalized functions are reserved for components, which must be invoked with JSX. If this is a component, render it with JSX. Otherwise, ensure that it has no hook calls and rename it to begin with a lowercase letter. Alternatively, if you know for a fact that this function is not a component, you can allowlist it via the compiler config';
   for (const [, block] of fn.body.blocks) {
     for (const {lvalue, value} of block.instructions) {
       switch (value.kind) {
@@ -55,11 +54,9 @@ export function validateNoCapitalizedCalls(
           const calleeIdentifier = value.callee.identifier.id;
           const calleeName = capitalLoadGlobals.get(calleeIdentifier);
           if (calleeName != null) {
-            CompilerError.throwInvalidReact({
-              reason,
+            errors.pushErrorCode(ErrorCode.CAPITALIZED_CALLS, {
               description: `${calleeName} may be a component.`,
               loc: value.loc,
-              suggestions: null,
             });
           }
           break;
@@ -78,12 +75,9 @@ export function validateNoCapitalizedCalls(
           const propertyIdentifier = value.property.identifier.id;
           const propertyName = capitalizedProperties.get(propertyIdentifier);
           if (propertyName != null) {
-            errors.push({
-              severity: ErrorSeverity.InvalidReact,
-              reason,
+            errors.pushErrorCode(ErrorCode.CAPITALIZED_CALLS, {
               description: `${propertyName} may be a component.`,
               loc: value.loc,
-              suggestions: null,
             });
           }
           break;

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

@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {CompilerError, ErrorSeverity, SourceLocation} from '..';
+import {CompilerError, SourceLocation} from '..';
 import {
   ArrayExpression,
   BlockId,
@@ -19,6 +19,8 @@ import {
   eachInstructionValueOperand,
   eachTerminalOperand,
 } from '../HIR/visitors';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
+import {Result} from '../Utils/Result';
 
 /**
  * Validates that useEffect is not used for derived computations which could/should
@@ -43,7 +45,9 @@ import {
  * const fullName = firstName + ' ' + lastName;
  * ```
  */
-export function validateNoDerivedComputationsInEffects(fn: HIRFunction): void {
+export function validateNoDerivedComputationsInEffects(
+  fn: HIRFunction,
+): Result<void, CompilerError> {
   const candidateDependencies: Map<IdentifierId, ArrayExpression> = new Map();
   const functions: Map<IdentifierId, FunctionExpression> = new Map();
   const locals: Map<IdentifierId, IdentifierId> = new Map();
@@ -96,9 +100,7 @@ export function validateNoDerivedComputationsInEffects(fn: HIRFunction): void {
       }
     }
   }
-  if (errors.hasErrors()) {
-    throw errors;
-  }
+  return errors.asResult();
 }
 
 function validateEffect(
@@ -218,13 +220,6 @@ function validateEffect(
   }
 
   for (const loc of setStateLocations) {
-    errors.push({
-      reason:
-        'Values derived from props and state should be calculated during render, not in an effect. (https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state)',
-      description: null,
-      severity: ErrorSeverity.InvalidReact,
-      loc,
-      suggestions: null,
-    });
+    errors.pushErrorCode(ErrorCode.NO_DERIVED_COMPUTATIONS_IN_EFFECTS, {loc});
   }
 }

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

@@ -5,7 +5,8 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {CompilerDiagnostic, CompilerError, Effect, ErrorSeverity} from '..';
+import {CompilerDiagnostic, CompilerError, Effect} from '..';
+import {ErrorCode} from '../CompilerError';
 import {
   FunctionEffect,
   HIRFunction,
@@ -65,11 +66,7 @@ export function validateNoFreezingKnownMutableFunctions(
             ? `\`${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.`,
-          })
+          CompilerDiagnostic.fromCode(ErrorCode.WRITE_AFTER_RENDER)
             .withDetail({
               kind: 'error',
               loc: operand.loc,

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

@@ -5,9 +5,10 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {CompilerDiagnostic, CompilerError, ErrorSeverity} from '..';
+import {CompilerDiagnostic, CompilerError} from '..';
 import {HIRFunction} from '../HIR';
 import {getFunctionCallSignature} from '../Inference/InferReferenceEffects';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 import {Result} from '../Utils/Result';
 
 /**
@@ -35,19 +36,13 @@ export function validateNoImpureFunctionsInRender(
         );
         if (signature != null && signature.impure === true) {
           errors.pushDiagnostic(
-            CompilerDiagnostic.create({
-              category: 'Cannot call impure function during render',
-              description:
-                (signature.canonicalName != null
-                  ? `\`${signature.canonicalName}\` is an impure function. `
-                  : '') +
-                'Calling an impure function can produce unstable results that update unpredictably when the component happens to re-render. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#components-and-hooks-must-be-idempotent)',
-              severity: ErrorSeverity.InvalidReact,
-              suggestions: null,
-            }).withDetail({
+            CompilerDiagnostic.fromCode(ErrorCode.IMPURE_FUNCTIONS).withDetail({
               kind: 'error',
               loc: callee.loc,
-              message: 'Cannot call impure function',
+              message:
+                signature.canonicalName != null
+                  ? `\`${signature.canonicalName}\` is an impure function. `
+                  : 'This is an impure function.',
             }),
           );
         }

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

@@ -5,8 +5,9 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {CompilerDiagnostic, CompilerError, ErrorSeverity} from '..';
+import {CompilerDiagnostic, CompilerError} from '..';
 import {BlockId, HIRFunction} from '../HIR';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 import {Result} from '../Utils/Result';
 import {retainWhere} from '../Utils/utils';
 
@@ -35,11 +36,7 @@ export function validateNoJSXInTryStatement(
           case 'JsxExpression':
           case 'JsxFragment': {
             errors.pushDiagnostic(
-              CompilerDiagnostic.create({
-                severity: ErrorSeverity.InvalidReact,
-                category: 'Avoid constructing JSX within try/catch',
-                description: `React does not immediately render components when JSX is rendered, so any errors from this component will not be caught by the try/catch. To catch errors in rendering a given component, wrap that component in an error boundary. (https://react.dev/reference/react/Component#catching-rendering-errors-with-an-error-boundary)`,
-              }).withDetail({
+              CompilerDiagnostic.fromCode(ErrorCode.JSX_IN_TRY).withDetail({
                 kind: 'error',
                 loc: value.loc,
                 message: 'Avoid constructing JSX within try/catch',

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

@@ -5,11 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {
-  CompilerDiagnostic,
-  CompilerError,
-  ErrorSeverity,
-} from '../CompilerError';
+import {CompilerDiagnostic, CompilerError} from '../CompilerError';
 import {
   BlockId,
   HIRFunction,
@@ -26,6 +22,7 @@ import {
   eachPatternOperand,
   eachTerminalOperand,
 } from '../HIR/visitors';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 import {Err, Ok, Result} from '../Utils/Result';
 import {retainWhere} from '../Utils/utils';
 
@@ -467,11 +464,9 @@ function validateNoRefAccessInRenderImpl(
               if (fnType.fn.readRefEffect) {
                 didError = true;
                 errors.pushDiagnostic(
-                  CompilerDiagnostic.create({
-                    severity: ErrorSeverity.InvalidReact,
-                    category: 'Cannot access refs during render',
-                    description: ERROR_DESCRIPTION,
-                  }).withDetail({
+                  CompilerDiagnostic.fromCode(
+                    ErrorCode.NO_REF_ACCESS_IN_RENDER,
+                  ).withDetail({
                     kind: 'error',
                     loc: callee.loc,
                     message: `This function accesses a ref value`,
@@ -730,15 +725,13 @@ function destructure(
 function guardCheck(errors: CompilerError, operand: Place, env: Env): void {
   if (env.get(operand.identifier.id)?.kind === 'Guard') {
     errors.pushDiagnostic(
-      CompilerDiagnostic.create({
-        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`,
-      }),
+      CompilerDiagnostic.fromCode(ErrorCode.NO_REF_ACCESS_IN_RENDER).withDetail(
+        {
+          kind: 'error',
+          loc: operand.loc,
+          message: `Cannot access ref value during render`,
+        },
+      ),
     );
   }
 }
@@ -754,15 +747,13 @@ function validateNoRefValueAccess(
     (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`,
-      }),
+      CompilerDiagnostic.fromCode(ErrorCode.NO_REF_ACCESS_IN_RENDER).withDetail(
+        {
+          kind: 'error',
+          loc: (type.kind === 'RefValue' && type.loc) || operand.loc,
+          message: `Cannot access ref value during render`,
+        },
+      ),
     );
   }
 }
@@ -780,15 +771,13 @@ function validateNoRefPassedToFunction(
     (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`,
-      }),
+      CompilerDiagnostic.fromCode(ErrorCode.NO_REF_ACCESS_IN_RENDER).withDetail(
+        {
+          kind: 'error',
+          loc: (type.kind === 'RefValue' && type.loc) || loc,
+          message: `Passing a ref to a function may read its value during render`,
+        },
+      ),
     );
   }
 }
@@ -802,15 +791,13 @@ function validateNoRefUpdate(
   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`,
-      }),
+      CompilerDiagnostic.fromCode(ErrorCode.NO_REF_ACCESS_IN_RENDER).withDetail(
+        {
+          kind: 'error',
+          loc: (type.kind === 'RefValue' && type.loc) || loc,
+          message: `Cannot update ref during render`,
+        },
+      ),
     );
   }
 }
@@ -823,21 +810,13 @@ function validateNoDirectRefValueAccess(
   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`,
-      }),
+      CompilerDiagnostic.fromCode(ErrorCode.NO_REF_ACCESS_IN_RENDER).withDetail(
+        {
+          kind: 'error',
+          loc: type.loc ?? operand.loc,
+          message: `Cannot access ref value during render`,
+        },
+      ),
     );
   }
 }
-
-const ERROR_DESCRIPTION =
-  'React refs are values that are not needed for rendering. Refs should only be accessed ' +
-  'outside of render, such as in event handlers or effects. ' +
-  'Accessing a ref value (the `current` property) during render can cause your component ' +
-  'not to update as expected (https://react.dev/reference/react/useRef)';

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

@@ -5,11 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {
-  CompilerDiagnostic,
-  CompilerError,
-  ErrorSeverity,
-} from '../CompilerError';
+import {CompilerDiagnostic, CompilerError} from '../CompilerError';
 import {
   HIRFunction,
   IdentifierId,
@@ -20,6 +16,7 @@ import {
   Place,
 } from '../HIR';
 import {eachInstructionValueOperand} from '../HIR/visitors';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 import {Result} from '../Utils/Result';
 
 /**
@@ -95,19 +92,9 @@ export function validateNoSetStateInEffects(
               const setState = setStateFunctions.get(arg.identifier.id);
               if (setState !== undefined) {
                 errors.pushDiagnostic(
-                  CompilerDiagnostic.create({
-                    category:
-                      'Calling setState synchronously within an effect can trigger cascading renders',
-                    description:
-                      'Effects are intended to synchronize state between React and external systems such as manually updating the DOM, state management libraries, or other platform APIs. ' +
-                      'In general, the body of an effect should do one or both of the following:\n' +
-                      '* Update external systems with the latest state from React.\n' +
-                      '* Subscribe for updates from some external system, calling setState in a callback function when external state changes.\n\n' +
-                      'Calling setState synchronously within an effect body causes cascading renders that can hurt performance, and is not recommended. ' +
-                      '(https://react.dev/learn/you-might-not-need-an-effect)',
-                    severity: ErrorSeverity.InvalidReact,
-                    suggestions: null,
-                  }).withDetail({
+                  CompilerDiagnostic.fromCode(
+                    ErrorCode.INVALID_SET_STATE_IN_EFFECTS,
+                  ).withDetail({
                     kind: 'error',
                     loc: setState.loc,
                     message:

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

@@ -5,14 +5,11 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {
-  CompilerDiagnostic,
-  CompilerError,
-  ErrorSeverity,
-} from '../CompilerError';
+import {CompilerDiagnostic, CompilerError} from '../CompilerError';
 import {HIRFunction, IdentifierId, isSetStateType} from '../HIR';
 import {computeUnconditionalBlocks} from '../HIR/ComputeUnconditionalBlocks';
 import {eachInstructionValueOperand} from '../HIR/visitors';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 import {Result} from '../Utils/Result';
 
 /**
@@ -127,14 +124,9 @@ function validateNoSetStateInRenderImpl(
           ) {
             if (activeManualMemoId !== null) {
               errors.pushDiagnostic(
-                CompilerDiagnostic.create({
-                  category:
-                    'Calling setState from useMemo may trigger an infinite loop',
-                  description:
-                    'Each time the memo callback is evaluated it will change state. This can cause a memoization dependency to change, running the memo function again and causing an infinite loop. Instead of setting state in useMemo(), prefer deriving the value during render. (https://react.dev/reference/react/useState)',
-                  severity: ErrorSeverity.InvalidReact,
-                  suggestions: null,
-                }).withDetail({
+                CompilerDiagnostic.fromCode(
+                  ErrorCode.INVALID_SET_STATE_IN_MEMO,
+                ).withDetail({
                   kind: 'error',
                   loc: callee.loc,
                   message: 'Found setState() within useMemo()',
@@ -142,17 +134,12 @@ function validateNoSetStateInRenderImpl(
               );
             } else if (unconditionalBlocks.has(block.id)) {
               errors.pushDiagnostic(
-                CompilerDiagnostic.create({
-                  category:
-                    'Calling setState during render may trigger an infinite loop',
-                  description:
-                    'Calling setState during render will trigger another render, and can lead to infinite loops. (https://react.dev/reference/react/useState)',
-                  severity: ErrorSeverity.InvalidReact,
-                  suggestions: null,
-                }).withDetail({
+                CompilerDiagnostic.fromCode(
+                  ErrorCode.INVALID_SET_STATE_IN_RENDER,
+                ).withDetail({
                   kind: 'error',
                   loc: callee.loc,
-                  message: 'Found setState() within useMemo()',
+                  message: 'Found setState() call here',
                 }),
               );
             }

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 {CompilerDiagnostic, CompilerError, ErrorCode} from '../CompilerError';
 import {
   DeclarationId,
   Effect,
@@ -280,13 +276,8 @@ function validateInferredDep(
     }
   }
   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. ',
+    CompilerDiagnostic.fromCode(ErrorCode.MANUAL_MEMO_DEPENDENCIES_CONFLICT, {
+      description:
         DEBUG ||
         // If the dependency is a named variable then we can report it. Otherwise only print in debug mode
         (dep.identifier.name != null && dep.identifier.name.kind === 'named')
@@ -300,9 +291,6 @@ function validateInferredDep(
                 : 'Inferred dependency not present in source'
             }.`
           : '',
-      ]
-        .join('')
-        .trim(),
       suggestions: null,
     }).withDetail({
       kind: 'error',
@@ -534,15 +522,9 @@ class Visitor extends ReactiveFunctionVisitor<VisitorState> {
           !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({
+            CompilerDiagnostic.fromCode(
+              ErrorCode.MANUAL_MEMO_MUTATED_LATER,
+            ).withDetail({
               kind: 'error',
               loc,
               message: 'This dependency may be modified later',
@@ -582,18 +564,10 @@ 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
-                      ? `${printIdentifier(identifier)} was not memoized.`
-                      : '',
-                  ]
-                    .join('')
-                    .trim(),
+                CompilerDiagnostic.fromCode(ErrorCode.MANUAL_MEMO_REMOVED, {
+                  description: DEBUG
+                    ? `${printIdentifier(identifier)} was not memoized.`
+                    : '',
                 }).withDetail({
                   kind: 'error',
                   loc,

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

@@ -5,12 +5,9 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {
-  CompilerDiagnostic,
-  CompilerError,
-  ErrorSeverity,
-} from '../CompilerError';
+import {CompilerDiagnostic, CompilerError} from '../CompilerError';
 import {HIRFunction, IdentifierId, SourceLocation} from '../HIR';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 import {Result} from '../Utils/Result';
 
 /**
@@ -64,9 +61,7 @@ export function validateStaticComponents(
             );
             if (location != null) {
               error.pushDiagnostic(
-                CompilerDiagnostic.create({
-                  severity: ErrorSeverity.InvalidReact,
-                  category: 'Cannot create components during render',
+                CompilerDiagnostic.fromCode(ErrorCode.STATIC_COMPONENTS, {
                   description: `Components created during render will reset their state each time they are created. Declare components outside of render. `,
                 })
                   .withDetail({

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

@@ -5,12 +5,9 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {
-  CompilerDiagnostic,
-  CompilerError,
-  ErrorSeverity,
-} from '../CompilerError';
+import {CompilerDiagnostic, CompilerError} from '../CompilerError';
 import {FunctionExpression, HIRFunction, IdentifierId} from '../HIR';
+import {ErrorCode} from '../Utils/CompilerErrorCodes';
 import {Result} from '../Utils/Result';
 
 export function validateUseMemo(fn: HIRFunction): Result<void, CompilerError> {
@@ -73,13 +70,9 @@ export function validateUseMemo(fn: HIRFunction): Result<void, CompilerError> {
                 ? firstParam.loc
                 : firstParam.place.loc;
             errors.pushDiagnostic(
-              CompilerDiagnostic.create({
-                severity: ErrorSeverity.InvalidReact,
-                category: 'useMemo() callbacks may not accept parameters',
-                description:
-                  'useMemo() callbacks are called by React to cache calculations across re-renders. They should not take parameters. Instead, directly reference the props, state, or local variables needed for the computation.',
-                suggestions: null,
-              }).withDetail({
+              CompilerDiagnostic.fromCode(
+                ErrorCode.INVALID_USE_MEMO_CALLBACK_PARAMETERS,
+              ).withDetail({
                 kind: 'error',
                 loc,
                 message: 'Callbacks with parameters are not supported',
@@ -89,14 +82,9 @@ export function validateUseMemo(fn: HIRFunction): Result<void, CompilerError> {
 
           if (body.loweredFunc.func.async || body.loweredFunc.func.generator) {
             errors.pushDiagnostic(
-              CompilerDiagnostic.create({
-                severity: ErrorSeverity.InvalidReact,
-                category:
-                  'useMemo() callbacks may not be async or generator functions',
-                description:
-                  'useMemo() callbacks are called once and must synchronously return a value.',
-                suggestions: null,
-              }).withDetail({
+              CompilerDiagnostic.fromCode(
+                ErrorCode.INVALID_USE_MEMO_CALLBACK_ASYNC,
+              ).withDetail({
                 kind: 'error',
                 loc: body.loc,
                 message: 'Async and generator functions are not supported',

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

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

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

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

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

@@ -18,13 +18,15 @@ 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: Cannot reassign variables declared outside of the component/hook
+
+Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render).
 
 error.assign-global-in-jsx-spread-attribute.ts:4:4
   2 | function Component() {
   3 |   const foo = () => {
 > 4 |     someGlobal = true;
-    |     ^^^^^^^^^^ 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)
+    |     ^^^^^^^^^^ Cannot reassign variables declared outside of the component/hook
   5 |   };
   6 |   return <div {...foo} />;
   7 | }

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

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

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

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

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

@@ -40,7 +40,7 @@ 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 a variable after render, which can cause inconsistent behavior on subsequent renders. Consider using state instead.
 
 error.bug-old-inference-false-positive-ref-validation-in-use-effect.ts:20:12
   18 |   );

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

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

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

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

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

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

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-destructure-assignment-to-global.expect.md

@@ -17,12 +17,12 @@ Found 1 error:
 
 Error: Cannot reassign variables declared outside of the component/hook
 
-Variable `x` is declared outside of the component/hook. Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)
+Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)
 
 error.invalid-destructure-assignment-to-global.ts:2:3
   1 | function useFoo(props) {
 > 2 |   [x] = props;
-    |    ^ `x` cannot be reassigned
+    |    ^ `x` should not be reassigned
   3 |   return {x};
   4 | }
   5 |

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-destructure-to-local-global-variables.expect.md

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

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-global-reassignment-indirect.expect.md

@@ -39,13 +39,13 @@ Found 1 error:
 
 Error: Cannot reassign variables declared outside of the component/hook
 
-Variable `someGlobal` is declared outside of the component/hook. Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)
+Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)
 
 error.invalid-global-reassignment-indirect.ts:9:4
    7 |
    8 |   const setGlobal = () => {
 >  9 |     someGlobal = true;
-     |     ^^^^^^^^^^ `someGlobal` cannot be reassigned
+     |     ^^^^^^^^^^ `someGlobal` should not be reassigned
   10 |   };
   11 |   const indirectSetGlobal = () => {
   12 |     setGlobal();

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-hoisting-setstate.expect.md

@@ -42,13 +42,13 @@ Found 1 error:
 
 Error: Cannot access variable before it is declared
 
-`setState` is accessed before it is declared, which prevents the earlier access from updating when this value changes over time.
+Reading a variable before it is initialized will prevent the earlier access from updating when this value changes over time. Instead, move the variable access to after it has been initialized
 
 error.invalid-hoisting-setstate.ts:19:18
   17 |    * $2 = Function context=setState
   18 |    */
 > 19 |   useEffect(() => setState(2), []);
-     |                   ^^^^^^^^ `setState` accessed before it is declared
+     |                   ^^^^^^^^ `setState` is accessed before it is declared
   20 |
   21 |   const [state, setState] = useState(0);
   22 |   return <Stringify state={state} />;

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-hook-function-argument-mutates-local-variable.expect.md

@@ -21,7 +21,7 @@ Found 1 error:
 
 Error: Cannot modify local variables after render completes
 
-This argument is a function which may reassign or mutate `cache` after render, which can cause inconsistent behavior on subsequent renders. Consider using state instead.
+This argument is a function which may reassign or mutate a variable after render, which can cause inconsistent behavior on subsequent renders. Consider using state instead.
 
 error.invalid-hook-function-argument-mutates-local-variable.ts:5:10
   3 | function useFoo() {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-impure-functions-in-render.expect.md

@@ -19,41 +19,41 @@ function Component() {
 ```
 Found 3 errors:
 
-Error: Cannot call impure function during render
+Error: Cannot call impure functions during render
 
-`Date.now` 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)
+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).
 
 error.invalid-impure-functions-in-render.ts:4:15
   2 |
   3 | function Component() {
 > 4 |   const date = Date.now();
-    |                ^^^^^^^^^^ Cannot call impure function
+    |                ^^^^^^^^^^ `Date.now` is an impure function. 
   5 |   const now = performance.now();
   6 |   const rand = Math.random();
   7 |   return <Foo date={date} now={now} rand={rand} />;
 
-Error: Cannot call impure function during render
+Error: Cannot call impure functions during render
 
-`performance.now` 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)
+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).
 
 error.invalid-impure-functions-in-render.ts:5:14
   3 | function Component() {
   4 |   const date = Date.now();
 > 5 |   const now = performance.now();
-    |               ^^^^^^^^^^^^^^^^^ Cannot call impure function
+    |               ^^^^^^^^^^^^^^^^^ `performance.now` is an impure function. 
   6 |   const rand = Math.random();
   7 |   return <Foo date={date} now={now} rand={rand} />;
   8 | }
 
-Error: Cannot call impure function during render
+Error: Cannot call impure functions during render
 
-`Math.random` 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)
+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).
 
 error.invalid-impure-functions-in-render.ts:6:15
   4 |   const date = Date.now();
   5 |   const now = performance.now();
 > 6 |   const rand = Math.random();
-    |                ^^^^^^^^^^^^^ Cannot call impure function
+    |                ^^^^^^^^^^^^^ `Math.random` is an impure function. 
   7 |   return <Foo date={date} now={now} rand={rand} />;
   8 | }
   9 |

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-mutation-of-possible-props-phi-indirect.expect.md

@@ -23,7 +23,7 @@ Found 1 error:
 
 Error: This value cannot be modified
 
-Modifying a variable defined outside a component or hook is not allowed. Consider using an effect.
+Cannot reassign variables declared outside of the component/hook.
 
 error.invalid-mutation-of-possible-props-phi-indirect.ts:4:4
   2 |   let x = cond ? someGlobal : props.foo;

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-nested-function-reassign-local-variable-in-effect.expect.md

@@ -48,9 +48,9 @@ function Component() {
 ```
 Found 1 error:
 
-Error: Cannot reassign variable after render completes
+Error: Cannot reassign local variables after render completes
 
-Reassigning `local` after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead.
+Reassigning local variables after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead.
 
 error.invalid-nested-function-reassign-local-variable-in-effect.ts:7:6
    5 |     // Create the reassignment function inside another function, then return it

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-pass-mutable-function-as-prop.expect.md

@@ -21,7 +21,7 @@ Found 1 error:
 
 Error: Cannot modify local variables after render completes
 
-This argument is a function which may reassign or mutate `cache` after render, which can cause inconsistent behavior on subsequent renders. Consider using state instead.
+This argument is a function which may reassign or mutate a variable after render, which can cause inconsistent behavior on subsequent renders. Consider using state instead.
 
 error.invalid-pass-mutable-function-as-prop.ts:7:18
   5 |     cache.set('key', 'value');

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-reassign-const.expect.md

@@ -15,7 +15,7 @@ function Component() {
 ```
 Found 1 error:
 
-Error: Cannot reassign a `const` variable
+Error: Expect `const` declaration not to be reassigned
 
 `x` is declared as const.
 
@@ -23,7 +23,7 @@ error.invalid-reassign-const.ts:3:2
   1 | function Component() {
   2 |   const x = 0;
 > 3 |   x = 1;
-    |   ^ Cannot reassign a `const` variable
+    |   ^ Expect `const` declaration not to be reassigned
   4 | }
   5 |
 ```

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-reassign-local-in-hook-return-value.expect.md

@@ -17,9 +17,9 @@ function useFoo() {
 ```
 Found 1 error:
 
-Error: Cannot reassign variable after render completes
+Error: Cannot reassign local variables after render completes
 
-Reassigning `x` after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead.
+Reassigning local variables after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead.
 
 error.invalid-reassign-local-in-hook-return-value.ts:4:4
   2 |   let x = 0;

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-reassign-local-variable-in-effect.expect.md

@@ -49,9 +49,9 @@ function Component() {
 ```
 Found 1 error:
 
-Error: Cannot reassign variable after render completes
+Error: Cannot reassign local variables after render completes
 
-Reassigning `local` after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead.
+Reassigning local variables after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead.
 
 error.invalid-reassign-local-variable-in-effect.ts:7:4
    5 |

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-reassign-local-variable-in-hook-argument.expect.md

@@ -50,9 +50,9 @@ function Component() {
 ```
 Found 1 error:
 
-Error: Cannot reassign variable after render completes
+Error: Cannot reassign local variables after render completes
 
-Reassigning `local` after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead.
+Reassigning local variables after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead.
 
 error.invalid-reassign-local-variable-in-hook-argument.ts:8:4
    6 |

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-reassign-local-variable-in-jsx-callback.expect.md

@@ -43,9 +43,9 @@ function Component() {
 ```
 Found 1 error:
 
-Error: Cannot reassign variable after render completes
+Error: Cannot reassign local variables after render completes
 
-Reassigning `local` after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead.
+Reassigning local variables after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead.
 
 error.invalid-reassign-local-variable-in-jsx-callback.ts:5:4
   3 |

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-return-mutable-function-from-hook.expect.md

@@ -23,7 +23,7 @@ Found 1 error:
 
 Error: Cannot modify local variables after render completes
 
-This argument is a function which may reassign or mutate `cache` after render, which can cause inconsistent behavior on subsequent renders. Consider using state instead.
+This argument is a function which may reassign or mutate a variable after render, which can cause inconsistent behavior on subsequent renders. Consider using state instead.
 
 error.invalid-return-mutable-function-from-hook.ts:7:9
    5 |   useHook(); // for inference to kick in

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-sketchy-code-use-forget.expect.md

@@ -21,7 +21,7 @@ Found 2 errors:
 
 Error: React Compiler has skipped optimizing this component because one or more React ESLint rules were disabled
 
-React Compiler only works when your components follow all the rules of React, disabling them may result in unexpected or incorrect behavior. Found suppression `eslint-disable react-hooks/rules-of-hooks`
+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 react-hooks/rules-of-hooks`
 
 error.invalid-sketchy-code-use-forget.ts:1:0
 > 1 | /* eslint-disable react-hooks/rules-of-hooks */
@@ -32,7 +32,7 @@ error.invalid-sketchy-code-use-forget.ts:1:0
 
 Error: React Compiler has skipped optimizing this component because one or more React ESLint rules were disabled
 
-React Compiler only works when your components follow all the rules of React, disabling them may result in unexpected or incorrect behavior. Found suppression `eslint-disable-next-line react-hooks/rules-of-hooks`
+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 react-hooks/rules-of-hooks`
 
 error.invalid-sketchy-code-use-forget.ts:5:2
   3 |   'use forget';

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-uncalled-function-capturing-mutable-values-memoizes-with-captures-values.expect.md

@@ -51,7 +51,7 @@ Found 1 error:
 
 Error: Cannot modify local variables after render completes
 
-This argument is a function which may reassign or mutate `cache` after render, which can cause inconsistent behavior on subsequent renders. Consider using state instead.
+This argument is a function which may reassign or mutate a variable after render, which can cause inconsistent behavior on subsequent renders. Consider using state instead.
 
   19 |   map: TInput => TOutput
   20 | ): TInput => TOutput {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-unclosed-eslint-suppression.expect.md

@@ -40,7 +40,7 @@ Found 1 error:
 
 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 react-hooks/rules-of-hooks`
+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 react-hooks/rules-of-hooks`
 
 error.invalid-unclosed-eslint-suppression.ts:2:0
   1 | // Note: Everything below this is sketchy

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-unconditional-set-state-in-render.expect.md

@@ -29,7 +29,7 @@ error.invalid-unconditional-set-state-in-render.ts:6:2
   4 |   const aliased = setX;
   5 |
 > 6 |   setX(1);
-    |   ^^^^ Found setState() within useMemo()
+    |   ^^^^ Found setState() call here
   7 |   aliased(2);
   8 |
   9 |   return x;
@@ -42,7 +42,7 @@ error.invalid-unconditional-set-state-in-render.ts:7:2
    5 |
    6 |   setX(1);
 >  7 |   aliased(2);
-     |   ^^^^^^^ Found setState() within useMemo()
+     |   ^^^^^^^ Found setState() call here
    8 |
    9 |   return x;
   10 | }

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.mutable-range-shared-inner-outer-function.expect.md

@@ -34,9 +34,9 @@ export const FIXTURE_ENTRYPOINT = {
 ```
 Found 1 error:
 
-Error: Cannot reassign variable after render completes
+Error: Cannot reassign local variables after render completes
 
-Reassigning `a` after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead.
+Reassigning local variables after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead.
 
 error.mutable-range-shared-inner-outer-function.ts:8:6
    6 |   const f = () => {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.mutate-property-from-global.expect.md

@@ -19,7 +19,7 @@ Found 1 error:
 
 Error: This value cannot be modified
 
-Modifying a variable defined outside a component or hook is not allowed. Consider using an effect.
+Cannot reassign variables declared outside of the component/hook.
 
 error.mutate-property-from-global.ts:4:9
   2 |

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.not-useEffect-external-mutate.expect.md

@@ -21,7 +21,7 @@ Found 2 errors:
 
 Error: This value cannot be modified
 
-Modifying a variable defined outside a component or hook is not allowed. Consider using an effect.
+Cannot reassign variables declared outside of the component/hook.
 
 error.not-useEffect-external-mutate.ts:5:4
   3 | function Component(props) {
@@ -34,7 +34,7 @@ error.not-useEffect-external-mutate.ts:5:4
 
 Error: This value cannot be modified
 
-Modifying a variable defined outside a component or hook is not allowed. Consider using an effect.
+Cannot reassign variables declared outside of the component/hook.
 
 error.not-useEffect-external-mutate.ts:6:4
   4 |   foo(() => {

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

@@ -24,13 +24,15 @@ export const FIXTURE_ENTRYPOINT = {
 ```
 Found 1 error:
 
-Error: Modifying a variable defined outside a component or hook is not allowed. Consider using an effect
+Error: Cannot reassign variables declared outside of the component/hook
+
+Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render).
 
 error.object-capture-global-mutation.ts:4:4
   2 | function Foo() {
   3 |   const x = () => {
 > 4 |     window.href = 'foo';
-    |     ^^^^^^ Modifying a variable defined outside a component or hook is not allowed. Consider using an effect
+    |     ^^^^^^ Cannot reassign variables declared outside of the component/hook
   5 |   };
   6 |   const y = {x};
   7 |   return <Bar y={y} />;

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.reassign-global-fn-arg.expect.md

@@ -28,13 +28,13 @@ Found 1 error:
 
 Error: Cannot reassign variables declared outside of the component/hook
 
-Variable `b` is declared outside of the component/hook. Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)
+Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)
 
 error.reassign-global-fn-arg.ts:5:4
   3 | export default function MyApp() {
   4 |   const fn = () => {
 > 5 |     b = 2;
-    |     ^ `b` cannot be reassigned
+    |     ^ `b` should not be reassigned
   6 |   };
   7 |   return foo(fn);
   8 | }

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.reassignment-to-global-indirect.expect.md

@@ -21,26 +21,26 @@ Found 2 errors:
 
 Error: Cannot reassign variables declared outside of the component/hook
 
-Variable `someUnknownGlobal` is declared outside of the component/hook. Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)
+Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)
 
 error.reassignment-to-global-indirect.ts:4:4
   2 |   const foo = () => {
   3 |     // Cannot assign to globals
 > 4 |     someUnknownGlobal = true;
-    |     ^^^^^^^^^^^^^^^^^ `someUnknownGlobal` cannot be reassigned
+    |     ^^^^^^^^^^^^^^^^^ `someUnknownGlobal` should not be reassigned
   5 |     moduleLocal = true;
   6 |   };
   7 |   foo();
 
 Error: Cannot reassign variables declared outside of the component/hook
 
-Variable `moduleLocal` is declared outside of the component/hook. Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)
+Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)
 
 error.reassignment-to-global-indirect.ts:5:4
   3 |     // Cannot assign to globals
   4 |     someUnknownGlobal = true;
 > 5 |     moduleLocal = true;
-    |     ^^^^^^^^^^^ `moduleLocal` cannot be reassigned
+    |     ^^^^^^^^^^^ `moduleLocal` should not be reassigned
   6 |   };
   7 |   foo();
   8 | }

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.reassignment-to-global.expect.md

@@ -18,26 +18,26 @@ Found 2 errors:
 
 Error: Cannot reassign variables declared outside of the component/hook
 
-Variable `someUnknownGlobal` is declared outside of the component/hook. Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)
+Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)
 
 error.reassignment-to-global.ts:3:2
   1 | function Component() {
   2 |   // Cannot assign to globals
 > 3 |   someUnknownGlobal = true;
-    |   ^^^^^^^^^^^^^^^^^ `someUnknownGlobal` cannot be reassigned
+    |   ^^^^^^^^^^^^^^^^^ `someUnknownGlobal` should not be reassigned
   4 |   moduleLocal = true;
   5 | }
   6 |
 
 Error: Cannot reassign variables declared outside of the component/hook
 
-Variable `moduleLocal` is declared outside of the component/hook. Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)
+Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)
 
 error.reassignment-to-global.ts:4:2
   2 |   // Cannot assign to globals
   3 |   someUnknownGlobal = true;
 > 4 |   moduleLocal = true;
-    |   ^^^^^^^^^^^ `moduleLocal` cannot be reassigned
+    |   ^^^^^^^^^^^ `moduleLocal` should not be reassigned
   5 | }
   6 |
 ```

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.sketchy-code-exhaustive-deps.expect.md

@@ -24,7 +24,7 @@ Found 1 error:
 
 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 react-hooks/exhaustive-deps`
+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 react-hooks/exhaustive-deps`
 
 error.sketchy-code-exhaustive-deps.ts:6:7
   4 |     () => {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.sketchy-code-rules-of-hooks.expect.md

@@ -25,7 +25,7 @@ Found 1 error:
 
 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 react-hooks/rules-of-hooks`
+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 react-hooks/rules-of-hooks`
 
 error.sketchy-code-rules-of-hooks.ts:1:0
 > 1 | /* eslint-disable react-hooks/rules-of-hooks */

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.store-property-in-global.expect.md

@@ -19,7 +19,7 @@ Found 1 error:
 
 Error: This value cannot be modified
 
-Modifying a variable defined outside a component or hook is not allowed. Consider using an effect.
+Cannot reassign variables declared outside of the component/hook.
 
 error.store-property-in-global.ts:4:2
   2 |

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.todo-function-expression-references-later-variable-declaration.expect.md

@@ -19,9 +19,9 @@ function Component() {
 ```
 Found 1 error:
 
-Error: Cannot reassign variable after render completes
+Error: Cannot reassign local variables after render completes
 
-Reassigning `onClick` after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead.
+Reassigning local variables after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead.
 
 error.todo-function-expression-references-later-variable-declaration.ts:3:4
   1 | function Component() {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.unconditional-set-state-in-render-after-loop-break.expect.md

@@ -32,7 +32,7 @@ error.unconditional-set-state-in-render-after-loop-break.ts:11:2
    9 |     }
   10 |   }
 > 11 |   setState(true);
-     |   ^^^^^^^^ Found setState() within useMemo()
+     |   ^^^^^^^^ Found setState() call here
   12 |   return state;
   13 | }
   14 |

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.unconditional-set-state-in-render-after-loop.expect.md

@@ -27,7 +27,7 @@ error.unconditional-set-state-in-render-after-loop.ts:6:2
   4 |   for (const _ of props) {
   5 |   }
 > 6 |   setState(true);
-    |   ^^^^^^^^ Found setState() within useMemo()
+    |   ^^^^^^^^ Found setState() call here
   7 |   return state;
   8 | }
   9 |

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.unconditional-set-state-in-render-with-loop-throw.expect.md

@@ -32,7 +32,7 @@ error.unconditional-set-state-in-render-with-loop-throw.ts:11:2
    9 |     }
   10 |   }
 > 11 |   setState(true);
-     |   ^^^^^^^^ Found setState() within useMemo()
+     |   ^^^^^^^^ Found setState() call here
   12 |   return state;
   13 | }
   14 |

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.unconditional-set-state-lambda.expect.md

@@ -30,7 +30,7 @@ error.unconditional-set-state-lambda.ts:8:2
    6 |     setX(1);
    7 |   };
 >  8 |   foo();
-     |   ^^^ Found setState() within useMemo()
+     |   ^^^ Found setState() call here
    9 |
   10 |   return [x];
   11 | }

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.unconditional-set-state-nested-function-expressions.expect.md

@@ -38,7 +38,7 @@ error.unconditional-set-state-nested-function-expressions.ts:16:2
   14 |     bar();
   15 |   };
 > 16 |   baz();
-     |   ^^^ Found setState() within useMemo()
+     |   ^^^ Found setState() call here
   17 |
   18 |   return [x];
   19 | }

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.update-global-should-bailout.expect.md

@@ -23,13 +23,13 @@ Found 1 error:
 
 Error: Cannot reassign variables declared outside of the component/hook
 
-Variable `renderCount` is declared outside of the component/hook. Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)
+Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)
 
 error.update-global-should-bailout.ts:3:2
   1 | let renderCount = 0;
   2 | function useFoo() {
 > 3 |   renderCount += 1;
-    |   ^^^^^^^^^^^^^^^^ `renderCount` cannot be reassigned
+    |   ^^^^^^^^^^^^^^^^ `renderCount` should not be reassigned
   4 |   return renderCount;
   5 | }
   6 |

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.useMemo-non-literal-depslist.expect.md

@@ -30,9 +30,7 @@ export const FIXTURE_ENTRYPOINT = {
 ```
 Found 1 error:
 
-Error: Expected the dependency list for useMemo to be an array literal
-
-Expected the dependency list for useMemo to be an array literal
+Error: Expected the dependency list of useMemo or useCallback to be an array literal
 
 error.useMemo-non-literal-depslist.ts:10:4
    8 |       return text.toUpperCase();

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/gating/dynamic-gating-invalid-multiple.expect.md

@@ -38,7 +38,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Logs
 
 ```
-{"kind":"CompileError","fnLoc":{"start":{"line":3,"column":0,"index":86},"end":{"line":7,"column":1,"index":190},"filename":"dynamic-gating-invalid-multiple.ts"},"detail":{"options":{"reason":"Multiple dynamic gating directives found","description":"Expected a single directive but found [use memo if(getTrue), use memo if(getFalse)]","severity":"InvalidReact","suggestions":null,"loc":{"start":{"line":4,"column":2,"index":105},"end":{"line":4,"column":25,"index":128},"filename":"dynamic-gating-invalid-multiple.ts"}}}}
+{"kind":"CompileError","fnLoc":{"start":{"line":3,"column":0,"index":86},"end":{"line":7,"column":1,"index":190},"filename":"dynamic-gating-invalid-multiple.ts"},"detail":{"options":{"reason":"Expected a single dynamic gating directive","description":"Expected a single directive but found [use memo if(getTrue), use memo if(getFalse)]","severity":"InvalidReact","loc":{"start":{"line":4,"column":2,"index":105},"end":{"line":4,"column":25,"index":128},"filename":"dynamic-gating-invalid-multiple.ts"}}}}
 ```
       
 ### Eval output

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/infer-effect-dependencies/no-emit/retry-no-emit.expect.md

@@ -54,10 +54,11 @@ export const FIXTURE_ENTRYPOINT = {
 ## Logs
 
 ```
-{"kind":"CompileError","fnLoc":{"start":{"line":6,"column":0,"index":195},"end":{"line":14,"column":1,"index":409},"filename":"retry-no-emit.ts"},"detail":{"options":{"severity":"InvalidReact","category":"This value cannot be modified","description":"Modifying a value previously passed as an argument to a hook is not allowed. Consider moving the modification before calling the hook.","details":[{"kind":"error","loc":{"start":{"line":12,"column":2,"index":372},"end":{"line":12,"column":6,"index":376},"filename":"retry-no-emit.ts","identifierName":"arr2"},"message":"value cannot be modified"}]}}}
+{"kind":"CompileError","detail":{"options":{"severity":"InvalidReact","category":"This value cannot be modified","description":"Modifying a value previously passed as an argument to a hook is not allowed. Consider moving the modification before calling the hook.","details":[{"kind":"error","loc":{"start":{"line":12,"column":2,"index":372},"end":{"line":12,"column":6,"index":376},"filename":"retry-no-emit.ts","identifierName":"arr2"},"message":"value cannot be modified"}]}},"fnLoc":null}
+{"kind":"CompileError","detail":{"options":{"severity":"InvalidReact","category":"Cannot modify local variables after render completes","description":"This argument is a function which may reassign or mutate a variable after render, which can cause inconsistent behavior on subsequent renders. Consider using state instead.","details":[{"kind":"error","loc":{"start":{"line":11,"column":19,"index":333},"end":{"line":11,"column":43,"index":357},"filename":"retry-no-emit.ts"},"message":"This function may (indirectly) reassign or modify `arr2` after render"},{"kind":"error","loc":{"start":{"line":11,"column":25,"index":339},"end":{"line":11,"column":29,"index":343},"filename":"retry-no-emit.ts","identifierName":"arr2"},"message":"This modifies `arr2`"}]}},"fnLoc":null}
 {"kind":"AutoDepsDecorations","fnLoc":{"start":{"line":8,"column":2,"index":248},"end":{"line":8,"column":46,"index":292},"filename":"retry-no-emit.ts"},"decorations":[{"start":{"line":8,"column":31,"index":277},"end":{"line":8,"column":34,"index":280},"filename":"retry-no-emit.ts","identifierName":"arr"}]}
 {"kind":"AutoDepsDecorations","fnLoc":{"start":{"line":11,"column":2,"index":316},"end":{"line":11,"column":54,"index":368},"filename":"retry-no-emit.ts"},"decorations":[{"start":{"line":11,"column":25,"index":339},"end":{"line":11,"column":29,"index":343},"filename":"retry-no-emit.ts","identifierName":"arr2"},{"start":{"line":11,"column":25,"index":339},"end":{"line":11,"column":29,"index":343},"filename":"retry-no-emit.ts","identifierName":"arr2"},{"start":{"line":11,"column":35,"index":349},"end":{"line":11,"column":42,"index":356},"filename":"retry-no-emit.ts","identifierName":"propVal"}]}
-{"kind":"CompileSuccess","fnLoc":{"start":{"line":6,"column":0,"index":195},"end":{"line":14,"column":1,"index":409},"filename":"retry-no-emit.ts"},"fnName":"Foo","memoSlots":0,"memoBlocks":0,"memoValues":0,"prunedMemoBlocks":0,"prunedMemoValues":0}
+{"kind":"CompileSuccess","fnLoc":{"start":{"line":6,"column":0,"index":195},"end":{"line":14,"column":1,"index":409},"filename":"retry-no-emit.ts"},"fnName":"Foo","memoSlots":9,"memoBlocks":5,"memoValues":5,"prunedMemoBlocks":0,"prunedMemoValues":0}
 ```
       
 ### Eval output

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/invalid-setState-in-useEffect-transitive.expect.md

@@ -65,7 +65,7 @@ function _temp(s) {
 ## Logs
 
 ```
-{"kind":"CompileError","detail":{"options":{"category":"Calling setState synchronously within an effect can trigger cascading renders","description":"Effects are intended to synchronize state between React and external systems such as manually updating the DOM, state management libraries, or other platform APIs. In general, the body of an effect should do one or both of the following:\n* Update external systems with the latest state from React.\n* Subscribe for updates from some external system, calling setState in a callback function when external state changes.\n\nCalling setState synchronously within an effect body causes cascading renders that can hurt performance, and is not recommended. (https://react.dev/learn/you-might-not-need-an-effect)","severity":"InvalidReact","suggestions":null,"details":[{"kind":"error","loc":{"start":{"line":13,"column":4,"index":265},"end":{"line":13,"column":5,"index":266},"filename":"invalid-setState-in-useEffect-transitive.ts","identifierName":"g"},"message":"Avoid calling setState() directly within an effect"}]}},"fnLoc":null}
+{"kind":"CompileError","detail":{"options":{"severity":"InvalidReact","category":"Calling setState synchronously within an effect can trigger cascading renders","description":"Effects are intended to synchronize state between React and external systems such as manually updating the DOM, state management libraries, or other platform APIs. In general, the body of an effect should do one or both of the following:\n* Update external systems with the latest state from React.\n* Subscribe for updates from some external system, calling setState in a callback function when external state changes.\n\nCalling 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)","details":[{"kind":"error","loc":{"start":{"line":13,"column":4,"index":265},"end":{"line":13,"column":5,"index":266},"filename":"invalid-setState-in-useEffect-transitive.ts","identifierName":"g"},"message":"Avoid calling setState() directly within an effect"}]}},"fnLoc":null}
 {"kind":"CompileSuccess","fnLoc":{"start":{"line":4,"column":0,"index":92},"end":{"line":16,"column":1,"index":293},"filename":"invalid-setState-in-useEffect-transitive.ts"},"fnName":"Component","memoSlots":2,"memoBlocks":2,"memoValues":2,"prunedMemoBlocks":0,"prunedMemoValues":0}
 ```
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/invalid-setState-in-useEffect.expect.md

@@ -45,7 +45,7 @@ function _temp(s) {
 ## Logs
 
 ```
-{"kind":"CompileError","detail":{"options":{"category":"Calling setState synchronously within an effect can trigger cascading renders","description":"Effects are intended to synchronize state between React and external systems such as manually updating the DOM, state management libraries, or other platform APIs. In general, the body of an effect should do one or both of the following:\n* Update external systems with the latest state from React.\n* Subscribe for updates from some external system, calling setState in a callback function when external state changes.\n\nCalling setState synchronously within an effect body causes cascading renders that can hurt performance, and is not recommended. (https://react.dev/learn/you-might-not-need-an-effect)","severity":"InvalidReact","suggestions":null,"details":[{"kind":"error","loc":{"start":{"line":7,"column":4,"index":180},"end":{"line":7,"column":12,"index":188},"filename":"invalid-setState-in-useEffect.ts","identifierName":"setState"},"message":"Avoid calling setState() directly within an effect"}]}},"fnLoc":null}
+{"kind":"CompileError","detail":{"options":{"severity":"InvalidReact","category":"Calling setState synchronously within an effect can trigger cascading renders","description":"Effects are intended to synchronize state between React and external systems such as manually updating the DOM, state management libraries, or other platform APIs. In general, the body of an effect should do one or both of the following:\n* Update external systems with the latest state from React.\n* Subscribe for updates from some external system, calling setState in a callback function when external state changes.\n\nCalling 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)","details":[{"kind":"error","loc":{"start":{"line":7,"column":4,"index":180},"end":{"line":7,"column":12,"index":188},"filename":"invalid-setState-in-useEffect.ts","identifierName":"setState"},"message":"Avoid calling setState() directly within an effect"}]}},"fnLoc":null}
 {"kind":"CompileSuccess","fnLoc":{"start":{"line":4,"column":0,"index":92},"end":{"line":10,"column":1,"index":225},"filename":"invalid-setState-in-useEffect.ts"},"fnName":"Component","memoSlots":1,"memoBlocks":1,"memoValues":1,"prunedMemoBlocks":0,"prunedMemoValues":0}
 ```
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/error.invalid-impure-functions-in-render.expect.md

@@ -19,41 +19,41 @@ function Component() {
 ```
 Found 3 errors:
 
-Error: Cannot call impure function during render
+Error: Cannot call impure functions during render
 
-`Date.now` 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)
+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).
 
 error.invalid-impure-functions-in-render.ts:4:15
   2 |
   3 | function Component() {
 > 4 |   const date = Date.now();
-    |                ^^^^^^^^^^ Cannot call impure function
+    |                ^^^^^^^^^^ `Date.now` is an impure function. 
   5 |   const now = performance.now();
   6 |   const rand = Math.random();
   7 |   return <Foo date={date} now={now} rand={rand} />;
 
-Error: Cannot call impure function during render
+Error: Cannot call impure functions during render
 
-`performance.now` 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)
+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).
 
 error.invalid-impure-functions-in-render.ts:5:14
   3 | function Component() {
   4 |   const date = Date.now();
 > 5 |   const now = performance.now();
-    |               ^^^^^^^^^^^^^^^^^ Cannot call impure function
+    |               ^^^^^^^^^^^^^^^^^ `performance.now` is an impure function. 
   6 |   const rand = Math.random();
   7 |   return <Foo date={date} now={now} rand={rand} />;
   8 | }
 
-Error: Cannot call impure function during render
+Error: Cannot call impure functions during render
 
-`Math.random` 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)
+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).
 
 error.invalid-impure-functions-in-render.ts:6:15
   4 |   const date = Date.now();
   5 |   const now = performance.now();
 > 6 |   const rand = Math.random();
-    |                ^^^^^^^^^^^^^ Cannot call impure function
+    |                ^^^^^^^^^^^^^ `Math.random` is an impure function. 
   7 |   return <Foo date={date} now={now} rand={rand} />;
   8 | }
   9 |

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/error.invalid-reassign-local-variable-in-jsx-callback.expect.md

@@ -44,9 +44,9 @@ function Component() {
 ```
 Found 1 error:
 
-Error: Cannot reassign variable after render completes
+Error: Cannot reassign local variables after render completes
 
-Reassigning `local` after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead.
+Reassigning local variables after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead.
 
 error.invalid-reassign-local-variable-in-jsx-callback.ts:6:4
   4 |

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/error.invalid-referencing-frozen-hoisted-storecontext-const.expect.md

@@ -35,12 +35,12 @@ Found 1 error:
 
 Error: Cannot access variable before it is declared
 
-`data` is accessed before it is declared, which prevents the earlier access from updating when this value changes over time.
+Reading a variable before it is initialized will prevent the earlier access from updating when this value changes over time. Instead, move the variable access to after it has been initialized
 
    9 |   // TDZ violation!
   10 |   const onRefetch = useCallback(() => {
 > 11 |     refetch(data);
-     |             ^^^^ `data` accessed before it is declared
+     |             ^^^^ `data` is accessed before it is declared
   12 |   }, [refetch]);
   13 |
   14 |   // The context variable gets frozen here since it's passed to a hook

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/error.not-useEffect-external-mutate.expect.md

@@ -22,7 +22,7 @@ Found 2 errors:
 
 Error: This value cannot be modified
 
-Modifying a variable defined outside a component or hook is not allowed. Consider using an effect.
+Cannot reassign variables declared outside of the component/hook.
 
 error.not-useEffect-external-mutate.ts:6:4
   4 | function Component(props) {
@@ -35,7 +35,7 @@ error.not-useEffect-external-mutate.ts:6:4
 
 Error: This value cannot be modified
 
-Modifying a variable defined outside a component or hook is not allowed. Consider using an effect.
+Cannot reassign variables declared outside of the component/hook.
 
 error.not-useEffect-external-mutate.ts:7:4
    5 |   foo(() => {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/error.reassignment-to-global-indirect.expect.md

@@ -22,26 +22,26 @@ Found 2 errors:
 
 Error: Cannot reassign variables declared outside of the component/hook
 
-Variable `someUnknownGlobal` is declared outside of the component/hook. Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)
+Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)
 
 error.reassignment-to-global-indirect.ts:5:4
   3 |   const foo = () => {
   4 |     // Cannot assign to globals
 > 5 |     someUnknownGlobal = true;
-    |     ^^^^^^^^^^^^^^^^^ `someUnknownGlobal` cannot be reassigned
+    |     ^^^^^^^^^^^^^^^^^ `someUnknownGlobal` should not be reassigned
   6 |     moduleLocal = true;
   7 |   };
   8 |   foo();
 
 Error: Cannot reassign variables declared outside of the component/hook
 
-Variable `moduleLocal` is declared outside of the component/hook. Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)
+Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)
 
 error.reassignment-to-global-indirect.ts:6:4
   4 |     // Cannot assign to globals
   5 |     someUnknownGlobal = true;
 > 6 |     moduleLocal = true;
-    |     ^^^^^^^^^^^ `moduleLocal` cannot be reassigned
+    |     ^^^^^^^^^^^ `moduleLocal` should not be reassigned
   7 |   };
   8 |   foo();
   9 | }

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/error.reassignment-to-global.expect.md

@@ -19,26 +19,26 @@ Found 2 errors:
 
 Error: Cannot reassign variables declared outside of the component/hook
 
-Variable `someUnknownGlobal` is declared outside of the component/hook. Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)
+Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)
 
 error.reassignment-to-global.ts:4:2
   2 | function Component() {
   3 |   // Cannot assign to globals
 > 4 |   someUnknownGlobal = true;
-    |   ^^^^^^^^^^^^^^^^^ `someUnknownGlobal` cannot be reassigned
+    |   ^^^^^^^^^^^^^^^^^ `someUnknownGlobal` should not be reassigned
   5 |   moduleLocal = true;
   6 | }
   7 |
 
 Error: Cannot reassign variables declared outside of the component/hook
 
-Variable `moduleLocal` is declared outside of the component/hook. Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)
+Reassigning this value during render is a form of side effect, which can cause unpredictable behavior depending on when the component happens to re-render. If this variable is used in rendering, use useState instead. Otherwise, consider updating it in an effect. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#side-effects-must-run-outside-of-render)
 
 error.reassignment-to-global.ts:5:2
   3 |   // Cannot assign to globals
   4 |   someUnknownGlobal = true;
 > 5 |   moduleLocal = true;
-    |   ^^^^^^^^^^^ `moduleLocal` cannot be reassigned
+    |   ^^^^^^^^^^^ `moduleLocal` should not be reassigned
   6 | }
   7 |
 ```

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/retry-no-emit.expect.md

@@ -54,10 +54,11 @@ export const FIXTURE_ENTRYPOINT = {
 ## Logs
 
 ```
-{"kind":"CompileError","fnLoc":{"start":{"line":6,"column":0,"index":227},"end":{"line":14,"column":1,"index":441},"filename":"retry-no-emit.ts"},"detail":{"options":{"severity":"InvalidReact","category":"This value cannot be modified","description":"Modifying a value previously passed as an argument to a hook is not allowed. Consider moving the modification before calling the hook.","details":[{"kind":"error","loc":{"start":{"line":12,"column":2,"index":404},"end":{"line":12,"column":6,"index":408},"filename":"retry-no-emit.ts","identifierName":"arr2"},"message":"value cannot be modified"}]}}}
+{"kind":"CompileError","detail":{"options":{"severity":"InvalidReact","category":"This value cannot be modified","description":"Modifying a value previously passed as an argument to a hook is not allowed. Consider moving the modification before calling the hook.","details":[{"kind":"error","loc":{"start":{"line":12,"column":2,"index":404},"end":{"line":12,"column":6,"index":408},"filename":"retry-no-emit.ts","identifierName":"arr2"},"message":"value cannot be modified"}]}},"fnLoc":null}
+{"kind":"CompileError","detail":{"options":{"severity":"InvalidReact","category":"Cannot modify local variables after render completes","description":"This argument is a function which may reassign or mutate a variable after render, which can cause inconsistent behavior on subsequent renders. Consider using state instead.","details":[{"kind":"error","loc":{"start":{"line":11,"column":19,"index":365},"end":{"line":11,"column":43,"index":389},"filename":"retry-no-emit.ts"},"message":"This function may (indirectly) reassign or modify `arr2` after render"},{"kind":"error","loc":{"start":{"line":11,"column":25,"index":371},"end":{"line":11,"column":29,"index":375},"filename":"retry-no-emit.ts","identifierName":"arr2"},"message":"This modifies `arr2`"}]}},"fnLoc":null}
 {"kind":"AutoDepsDecorations","fnLoc":{"start":{"line":8,"column":2,"index":280},"end":{"line":8,"column":46,"index":324},"filename":"retry-no-emit.ts"},"decorations":[{"start":{"line":8,"column":31,"index":309},"end":{"line":8,"column":34,"index":312},"filename":"retry-no-emit.ts","identifierName":"arr"}]}
 {"kind":"AutoDepsDecorations","fnLoc":{"start":{"line":11,"column":2,"index":348},"end":{"line":11,"column":54,"index":400},"filename":"retry-no-emit.ts"},"decorations":[{"start":{"line":11,"column":25,"index":371},"end":{"line":11,"column":29,"index":375},"filename":"retry-no-emit.ts","identifierName":"arr2"},{"start":{"line":11,"column":25,"index":371},"end":{"line":11,"column":29,"index":375},"filename":"retry-no-emit.ts","identifierName":"arr2"},{"start":{"line":11,"column":35,"index":381},"end":{"line":11,"column":42,"index":388},"filename":"retry-no-emit.ts","identifierName":"propVal"}]}
-{"kind":"CompileSuccess","fnLoc":{"start":{"line":6,"column":0,"index":227},"end":{"line":14,"column":1,"index":441},"filename":"retry-no-emit.ts"},"fnName":"Foo","memoSlots":0,"memoBlocks":0,"memoValues":0,"prunedMemoBlocks":0,"prunedMemoValues":0}
+{"kind":"CompileSuccess","fnLoc":{"start":{"line":6,"column":0,"index":227},"end":{"line":14,"column":1,"index":441},"filename":"retry-no-emit.ts"},"fnName":"Foo","memoSlots":9,"memoBlocks":5,"memoValues":5,"prunedMemoBlocks":0,"prunedMemoValues":0}
 ```
       
 ### Eval output

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/preserve-memo-validation/error.validate-useMemo-named-function.expect.md

@@ -24,8 +24,6 @@ Found 1 error:
 
 Error: Expected the first argument to be an inline function expression
 
-Expected the first argument to be an inline function expression
-
 error.validate-useMemo-named-function.ts:9:20
    7 | // for now.
    8 | function Component(props) {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/transform-fire/bailout-retry/error.todo-syntax.expect.md

@@ -31,7 +31,7 @@ function Component({prop1}) {
 ```
 Found 1 error:
 
-Error: [Fire] Untransformed reference to compiler-required feature.
+Error: Cannot compile `fire`
 
  Todo: (BuildHIR::lowerStatement) Handle TryStatement without a catch clause (11:4)
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/transform-fire/bailout-retry/error.untransformed-fire-reference.expect.md

@@ -15,7 +15,7 @@ console.log(fire == null);
 ```
 Found 1 error:
 
-Error: [Fire] Untransformed reference to compiler-required feature.
+Error: Cannot compile `fire`
 
  null
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/transform-fire/bailout-retry/error.use-no-memo.expect.md

@@ -32,7 +32,7 @@ function Component({props, bar}) {
 ```
 Found 1 error:
 
-Error: [Fire] Untransformed reference to compiler-required feature.
+Error: Cannot compile `fire`
 
  null
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/transform-fire/error.invalid-outside-effect.expect.md

@@ -26,7 +26,7 @@ function Component({props, bar}) {
 ```
 Found 2 errors:
 
-Invariant: Cannot compile `fire`
+Error: Cannot compile `fire`
 
 Cannot use `fire` outside of a useEffect function.
 
@@ -39,7 +39,7 @@ error.invalid-outside-effect.ts:8:2
   10 |   useCallback(() => {
   11 |     fire(foo(props));
 
-Invariant: Cannot compile `fire`
+Error: Cannot compile `fire`
 
 Cannot use `fire` outside of a useEffect function.
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/transform-fire/error.invalid-rewrite-deps-no-array-literal.expect.md

@@ -27,7 +27,7 @@ function Component(props) {
 ```
 Found 1 error:
 
-Invariant: Cannot compile `fire`
+Error: Cannot compile `fire`
 
 You must use an array literal for an effect dependency array when that effect uses `fire()`.
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/transform-fire/error.invalid-rewrite-deps-spread.expect.md

@@ -30,7 +30,7 @@ function Component(props) {
 ```
 Found 1 error:
 
-Invariant: Cannot compile `fire`
+Error: Cannot compile `fire`
 
 You must use an array literal for an effect dependency array when that effect uses `fire()`.
 

compiler/packages/eslint-plugin-react-compiler/__tests__/ImpureFunctionCallsRule-test.ts

@@ -0,0 +1,32 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {ErrorCode} from 'babel-plugin-react-compiler/src/CompilerError';
+import {NoImpureFunctionCallsRule} from '../src/rules/ReactCompilerRule';
+import {normalizeIndent, testRule, makeTestCaseError} from './shared-utils';
+
+testRule('no impure function calls rule', NoImpureFunctionCallsRule, {
+  valid: [],
+  invalid: [
+    {
+      name: 'Known impure function calls are caught',
+      code: normalizeIndent`
+      function Component() {
+        const date = Date.now();
+        const now = performance.now();
+        const rand = Math.random();
+        return <Foo date={date} now={now} rand={rand} />;
+      }
+    `,
+      errors: [
+        makeTestCaseError(ErrorCode.IMPURE_FUNCTIONS),
+        makeTestCaseError(ErrorCode.IMPURE_FUNCTIONS),
+        makeTestCaseError(ErrorCode.IMPURE_FUNCTIONS),
+      ],
+    },
+  ],
+});

compiler/packages/eslint-plugin-react-compiler/__tests__/InvalidHooksRule-test.ts

@@ -0,0 +1,85 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {RulesOfHooksRule} from '../src/rules/ReactCompilerRule';
+import {
+  normalizeIndent,
+  invalidHookRuleErrorMessage,
+  testRule,
+} from './shared-utils';
+
+testRule('rules-of-hooks', RulesOfHooksRule, {
+  valid: [
+    {
+      name: 'Basic example',
+      code: normalizeIndent`
+        function Component() {
+          useHook();
+          return <div>Hello world</div>;
+        }
+      `,
+    },
+    {
+      name: 'Violation with Flow suppression',
+      code: `
+      // Valid since error already suppressed with flow.
+      function useHook() {
+        if (cond) {
+          // $FlowFixMe[react-rule-hook]
+          useConditionalHook();
+        }
+      }
+    `,
+    },
+    {
+      // OK because invariants are only meant for the compiler team's consumption
+      name: '[Invariant] Defined after use',
+      code: normalizeIndent`
+        function Component(props) {
+          let y = function () {
+            m(x);
+          };
+
+          let x = { a };
+          m(x);
+          return y;
+        }
+      `,
+    },
+    {
+      name: "Classes don't throw",
+      code: normalizeIndent`
+        class Foo {
+          #bar() {}
+        }
+      `,
+    },
+  ],
+  invalid: [
+    {
+      name: 'Simple violation',
+      code: normalizeIndent`
+      function useConditional() {
+        if (cond) {
+          useConditionalHook();
+        }
+      }
+    `,
+      errors: [invalidHookRuleErrorMessage],
+    },
+    {
+      name: 'Multiple diagnostics within the same function are surfaced',
+      code: normalizeIndent`
+        function useConditional() {
+          cond ?? useConditionalHook();
+          props.cond && useConditionalHook();
+          return <div>Hello world</div>;
+        }`,
+      errors: [invalidHookRuleErrorMessage, invalidHookRuleErrorMessage],
+    },
+  ],
+});

compiler/packages/eslint-plugin-react-compiler/__tests__/NoAmbiguousJsxRule-test.ts

@@ -0,0 +1,31 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {ErrorCode} from 'babel-plugin-react-compiler/src/CompilerError';
+import {NoAmbiguousJsxRule} from '../src/rules/ReactCompilerRule';
+import {normalizeIndent, testRule, makeTestCaseError} from './shared-utils';
+
+testRule('no ambiguous JSX rule', NoAmbiguousJsxRule, {
+  valid: [],
+  invalid: [
+    {
+      name: 'JSX in try blocks are warned against',
+      code: normalizeIndent`
+      function Component(props) {
+        let el;
+        try {
+          el = <Child />;
+        } catch {
+          return null;
+        }
+        return el;
+      }
+    `,
+      errors: [makeTestCaseError(ErrorCode.JSX_IN_TRY)],
+    },
+  ],
+});