[compiler] Allow manual dependencies to have different optionality than inferred deps

Since adding this validation we've already changed our inference to use knowledge from manual memoization to inform when values are frozen and which values are non-nullable. To align with that, if the user chooses to use different optionality btw the deps and the memo block/callback, that's fine. The key is that eg `x?.y` will invalidate whenever `x.y` would, so from a memoization correctness perspective its fine. It's not our job to be a type checker: if a value is potentially nullable, it should likely  use a nullable property access in both places but TypeScript/Flow can check that.

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

@@ -304,6 +304,30 @@ export class CompilerError extends Error {
   disabledDetails: Array<CompilerErrorDetail | CompilerDiagnostic> = [];
   printedMessage: string | null = null;
 
+  static simpleInvariant(
+    condition: unknown,
+    options: {
+      reason: CompilerDiagnosticOptions['reason'];
+      description?: CompilerDiagnosticOptions['description'];
+      loc: SourceLocation;
+    },
+  ): asserts condition {
+    if (!condition) {
+      const errors = new CompilerError();
+      errors.pushDiagnostic(
+        CompilerDiagnostic.create({
+          reason: options.reason,
+          description: options.description ?? null,
+          category: ErrorCategory.Invariant,
+        }).withDetails({
+          kind: 'error',
+          loc: options.loc,
+          message: options.reason,
+        }),
+      );
+      throw errors;
+    }
+  }
   static invariant(
     condition: unknown,
     options: Omit<CompilerDiagnosticOptions, 'category'>,
@@ -576,7 +600,8 @@ function printErrorSummary(category: ErrorCategory, message: string): string {
     case ErrorCategory.Suppression:
     case ErrorCategory.Syntax:
     case ErrorCategory.UseMemo:
-    case ErrorCategory.VoidUseMemo: {
+    case ErrorCategory.VoidUseMemo:
+    case ErrorCategory.MemoDependencies: {
       heading = 'Error';
       break;
     }
@@ -634,6 +659,10 @@ export enum ErrorCategory {
    * Checks that manual memoization is preserved
    */
   PreserveManualMemo = 'PreserveManualMemo',
+  /**
+   * Checks for exhaustive useMemo/useCallback dependencies without extraneous values
+   */
+  MemoDependencies = 'MemoDependencies',
   /**
    * Checks for known incompatible libraries
    */
@@ -1031,6 +1060,16 @@ function getRuleForCategoryImpl(category: ErrorCategory): LintRule {
         preset: LintRulePreset.RecommendedLatest,
       };
     }
+    case ErrorCategory.MemoDependencies: {
+      return {
+        category,
+        severity: ErrorSeverity.Error,
+        name: 'memo-dependencies',
+        description:
+          'Validates that useMemo() and useCallback() specify comprehensive dependencies without extraneous values. See [`useMemo()` docs](https://react.dev/reference/react/useMemo) for more information.',
+        preset: LintRulePreset.RecommendedLatest,
+      };
+    }
     case ErrorCategory.IncompatibleLibrary: {
       return {
         category,

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

@@ -102,14 +102,25 @@ export type PluginOptions = Partial<{
 
   panicThreshold: PanicThresholdOptions;
 
-  /*
+  /**
+   * @deprecated
+   *
    * When enabled, Forget will continue statically analyzing and linting code, but skip over codegen
    * passes.
    *
+   * NOTE: ignored if `outputMode` is specified
+   *
    * Defaults to false
    */
   noEmit: boolean;
 
+  /**
+   * If specified, overrides `noEmit` and controls the output mode of the compiler.
+   *
+   * Defaults to null
+   */
+  outputMode: CompilerOutputMode | null;
+
   /*
    * Determines the strategy for determining which functions to compile. Note that regardless of
    * which mode is enabled, a component can be opted out by adding the string literal
@@ -212,6 +223,19 @@ const CompilationModeSchema = z.enum([
 
 export type CompilationMode = z.infer<typeof CompilationModeSchema>;
 
+const CompilerOutputModeSchema = z.enum([
+  // Build optimized for SSR, with client features removed
+  'ssr',
+  // Build optimized for the client, with auto memoization
+  'client',
+  // Build optimized for the client without auto memo
+  'client-no-memo',
+  // Lint mode, the output is unused but validations should run
+  'lint',
+]);
+
+export type CompilerOutputMode = z.infer<typeof CompilerOutputModeSchema>;
+
 /**
  * Represents 'events' that may occur during compilation. Events are only
  * recorded when a logger is set (through the config).
@@ -293,6 +317,7 @@ export const defaultOptions: ParsedPluginOptions = {
   logger: null,
   gating: null,
   noEmit: false,
+  outputMode: null,
   dynamicGating: null,
   eslintSuppressionRules: null,
   flowSuppressions: true,

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

@@ -8,7 +8,7 @@
 import {NodePath} from '@babel/traverse';
 import * as t from '@babel/types';
 import prettyFormat from 'pretty-format';
-import {Logger, ProgramContext} from '.';
+import {CompilerOutputMode, Logger, ProgramContext} from '.';
 import {
   HIRFunction,
   ReactiveFunction,
@@ -24,7 +24,6 @@ import {
   pruneUnusedLabelsHIR,
 } from '../HIR';
 import {
-  CompilerMode,
   Environment,
   EnvironmentConfig,
   ReactFunctionType,
@@ -105,6 +104,8 @@ import {inferMutationAliasingRanges} from '../Inference/InferMutationAliasingRan
 import {validateNoDerivedComputationsInEffects} from '../Validation/ValidateNoDerivedComputationsInEffects';
 import {validateNoDerivedComputationsInEffects_exp} from '../Validation/ValidateNoDerivedComputationsInEffects_exp';
 import {nameAnonymousFunctions} from '../Transform/NameAnonymousFunctions';
+import {optimizeForSSR} from '../Optimization/OptimizeForSSR';
+import {validateExhaustiveDependencies} from '../Validation/ValidateExhaustiveDependencies';
 import {validateSourceLocations} from '../Validation/ValidateSourceLocations';
 
 export type CompilerPipelineValue =
@@ -119,7 +120,7 @@ function run(
   >,
   config: EnvironmentConfig,
   fnType: ReactFunctionType,
-  mode: CompilerMode,
+  mode: CompilerOutputMode,
   programContext: ProgramContext,
   logger: Logger | null,
   filename: string | null,
@@ -169,7 +170,7 @@ function runWithEnvironment(
   validateUseMemo(hir).unwrap();
 
   if (
-    env.isInferredMemoEnabled &&
+    env.enableDropManualMemoization &&
     !env.config.enablePreserveExistingManualUseMemo &&
     !env.config.disableMemoizationForDebugging &&
     !env.config.enableChangeDetectionForDebugging
@@ -205,7 +206,7 @@ function runWithEnvironment(
   inferTypes(hir);
   log({kind: 'hir', name: 'InferTypes', value: hir});
 
-  if (env.isInferredMemoEnabled) {
+  if (env.enableValidations) {
     if (env.config.validateHooksUsage) {
       validateHooksUsage(hir).unwrap();
     }
@@ -231,12 +232,17 @@ function runWithEnvironment(
 
   const mutabilityAliasingErrors = inferMutationAliasingEffects(hir);
   log({kind: 'hir', name: 'InferMutationAliasingEffects', value: hir});
-  if (env.isInferredMemoEnabled) {
+  if (env.enableValidations) {
     if (mutabilityAliasingErrors.isErr()) {
       throw mutabilityAliasingErrors.unwrapErr();
     }
   }
 
+  if (env.outputMode === 'ssr') {
+    optimizeForSSR(hir);
+    log({kind: 'hir', name: 'OptimizeForSSR', value: hir});
+  }
+
   // Note: Has to come after infer reference effects because "dead" code may still affect inference
   deadCodeElimination(hir);
   log({kind: 'hir', name: 'DeadCodeElimination', value: hir});
@@ -253,14 +259,14 @@ function runWithEnvironment(
     isFunctionExpression: false,
   });
   log({kind: 'hir', name: 'InferMutationAliasingRanges', value: hir});
-  if (env.isInferredMemoEnabled) {
+  if (env.enableValidations) {
     if (mutabilityAliasingRangeErrors.isErr()) {
       throw mutabilityAliasingRangeErrors.unwrapErr();
     }
     validateLocalsNotReassignedAfterRender(hir);
   }
 
-  if (env.isInferredMemoEnabled) {
+  if (env.enableValidations) {
     if (env.config.assertValidMutableRanges) {
       assertValidMutableRanges(hir);
     }
@@ -297,6 +303,11 @@ function runWithEnvironment(
   inferReactivePlaces(hir);
   log({kind: 'hir', name: 'InferReactivePlaces', value: hir});
 
+  if (env.config.validateExhaustiveMemoizationDependencies) {
+    // NOTE: this relies on reactivity inference running first
+    validateExhaustiveDependencies(hir).unwrap();
+  }
+
   rewriteInstructionKindsBasedOnReassignment(hir);
   log({
     kind: 'hir',
@@ -304,11 +315,11 @@ function runWithEnvironment(
     value: hir,
   });
 
-  if (env.isInferredMemoEnabled) {
-    if (env.config.validateStaticComponents) {
-      env.logErrors(validateStaticComponents(hir));
-    }
+  if (env.enableValidations && env.config.validateStaticComponents) {
+    env.logErrors(validateStaticComponents(hir));
+  }
 
+  if (env.enableMemoization) {
     /**
      * Only create reactive scopes (which directly map to generated memo blocks)
      * if inferred memoization is enabled. This makes all later passes which
@@ -580,7 +591,7 @@ export function compileFn(
   >,
   config: EnvironmentConfig,
   fnType: ReactFunctionType,
-  mode: CompilerMode,
+  mode: CompilerOutputMode,
   programContext: ProgramContext,
   logger: Logger | null,
   filename: string | null,

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

@@ -24,6 +24,7 @@ import {
   validateRestrictedImports,
 } from './Imports';
 import {
+  CompilerOutputMode,
   CompilerReactTarget,
   ParsedPluginOptions,
   PluginOptions,
@@ -399,7 +400,15 @@ export function compileProgram(
    */
   const suppressions = findProgramSuppressions(
     pass.comments,
-    pass.opts.eslintSuppressionRules ?? DEFAULT_ESLINT_SUPPRESSIONS,
+    /*
+     * If the compiler is validating hooks rules and exhaustive memo dependencies, we don't need to check
+     * for React ESLint suppressions
+     */
+    pass.opts.environment.validateExhaustiveMemoizationDependencies &&
+      pass.opts.environment.validateHooksUsage
+      ? null
+      : (pass.opts.eslintSuppressionRules ?? DEFAULT_ESLINT_SUPPRESSIONS),
+    // Always bail on Flow suppressions
     pass.opts.flowSuppressions,
   );
 
@@ -421,9 +430,17 @@ export function compileProgram(
   );
   const compiledFns: Array<CompileResult> = [];
 
+  // outputMode takes precedence if specified
+  const outputMode: CompilerOutputMode =
+    pass.opts.outputMode ?? (pass.opts.noEmit ? 'lint' : 'client');
   while (queue.length !== 0) {
     const current = queue.shift()!;
-    const compiled = processFn(current.fn, current.fnType, programContext);
+    const compiled = processFn(
+      current.fn,
+      current.fnType,
+      programContext,
+      outputMode,
+    );
 
     if (compiled != null) {
       for (const outlined of compiled.outlined) {
@@ -581,6 +598,7 @@ function processFn(
   fn: BabelFn,
   fnType: ReactFunctionType,
   programContext: ProgramContext,
+  outputMode: CompilerOutputMode,
 ): null | CodegenFunction {
   let directives: {
     optIn: t.Directive | null;
@@ -616,18 +634,27 @@ function processFn(
   }
 
   let compiledFn: CodegenFunction;
-  const compileResult = tryCompileFunction(fn, fnType, programContext);
+  const compileResult = tryCompileFunction(
+    fn,
+    fnType,
+    programContext,
+    outputMode,
+  );
   if (compileResult.kind === 'error') {
     if (directives.optOut != null) {
       logError(compileResult.error, programContext, fn.node.loc ?? null);
     } else {
       handleError(compileResult.error, programContext, fn.node.loc ?? null);
     }
-    const retryResult = retryCompileFunction(fn, fnType, programContext);
-    if (retryResult == null) {
+    if (outputMode === 'client') {
+      const retryResult = retryCompileFunction(fn, fnType, programContext);
+      if (retryResult == null) {
+        return null;
+      }
+      compiledFn = retryResult;
+    } else {
       return null;
     }
-    compiledFn = retryResult;
   } else {
     compiledFn = compileResult.compiledFn;
   }
@@ -663,7 +690,7 @@ function processFn(
 
   if (programContext.hasModuleScopeOptOut) {
     return null;
-  } else if (programContext.opts.noEmit) {
+  } else if (programContext.opts.outputMode === 'lint') {
     /**
      * inferEffectDependencies + noEmit is currently only used for linting. In
      * this mode, add source locations for where the compiler *can* infer effect
@@ -693,6 +720,7 @@ function tryCompileFunction(
   fn: BabelFn,
   fnType: ReactFunctionType,
   programContext: ProgramContext,
+  outputMode: CompilerOutputMode,
 ):
   | {kind: 'compile'; compiledFn: CodegenFunction}
   | {kind: 'error'; error: unknown} {
@@ -719,7 +747,7 @@ function tryCompileFunction(
         fn,
         programContext.opts.environment,
         fnType,
-        'all_features',
+        outputMode,
         programContext,
         programContext.opts.logger,
         programContext.filename,
@@ -757,7 +785,7 @@ function retryCompileFunction(
       fn,
       environment,
       fnType,
-      'no_inferred_memo',
+      'client-no-memo',
       programContext,
       programContext.opts.logger,
       programContext.filename,

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

@@ -78,7 +78,7 @@ export function filterSuppressionsThatAffectFunction(
 
 export function findProgramSuppressions(
   programComments: Array<t.Comment>,
-  ruleNames: Array<string>,
+  ruleNames: Array<string> | null,
   flowSuppressions: boolean,
 ): Array<SuppressionRange> {
   const suppressionRanges: Array<SuppressionRange> = [];
@@ -89,7 +89,7 @@ export function findProgramSuppressions(
   let disableNextLinePattern: RegExp | null = null;
   let disablePattern: RegExp | null = null;
   let enablePattern: RegExp | null = null;
-  if (ruleNames.length !== 0) {
+  if (ruleNames != null && ruleNames.length !== 0) {
     const rulePattern = `(${ruleNames.join('|')})`;
     disableNextLinePattern = new RegExp(
       `eslint-disable-next-line ${rulePattern}`,

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

@@ -9,7 +9,7 @@ import * as t from '@babel/types';
 import {ZodError, z} from 'zod/v4';
 import {fromZodError} from 'zod-validation-error/v4';
 import {CompilerError} from '../CompilerError';
-import {Logger, ProgramContext} from '../Entrypoint';
+import {CompilerOutputMode, Logger, ProgramContext} from '../Entrypoint';
 import {Err, Ok, Result} from '../Utils/Result';
 import {
   DEFAULT_GLOBALS,
@@ -51,6 +51,7 @@ import {Scope as BabelScope, NodePath} from '@babel/traverse';
 import {TypeSchema} from './TypeSchema';
 import {FlowTypeEnv} from '../Flood/Types';
 import {defaultModuleTypeProvider} from './DefaultModuleTypeProvider';
+import {assertExhaustive} from '../Utils/utils';
 
 export const ReactElementSymbolSchema = z.object({
   elementSymbol: z.union([
@@ -217,6 +218,11 @@ export const EnvironmentConfigSchema = z.object({
    */
   validatePreserveExistingMemoizationGuarantees: z.boolean().default(true),
 
+  /**
+   * Validate that dependencies supplied to manual memoization calls are exhaustive.
+   */
+  validateExhaustiveMemoizationDependencies: z.boolean().default(false),
+
   /**
    * When this is true, rather than pruning existing manual memoization but ensuring or validating
    * that the memoized values remain memoized, the compiler will simply not prune existing calls to
@@ -730,7 +736,7 @@ export class Environment {
   code: string | null;
   config: EnvironmentConfig;
   fnType: ReactFunctionType;
-  compilerMode: CompilerMode;
+  outputMode: CompilerOutputMode;
   programContext: ProgramContext;
   hasFireRewrite: boolean;
   hasInferredEffect: boolean;
@@ -745,7 +751,7 @@ export class Environment {
   constructor(
     scope: BabelScope,
     fnType: ReactFunctionType,
-    compilerMode: CompilerMode,
+    outputMode: CompilerOutputMode,
     config: EnvironmentConfig,
     contextIdentifiers: Set<t.Identifier>,
     parentFunction: NodePath<t.Function>, // the outermost function being compiled
@@ -756,7 +762,7 @@ export class Environment {
   ) {
     this.#scope = scope;
     this.fnType = fnType;
-    this.compilerMode = compilerMode;
+    this.outputMode = outputMode;
     this.config = config;
     this.filename = filename;
     this.code = code;
@@ -852,8 +858,65 @@ export class Environment {
     return this.#flowTypeEnvironment;
   }
 
-  get isInferredMemoEnabled(): boolean {
-    return this.compilerMode !== 'no_inferred_memo';
+  get enableDropManualMemoization(): boolean {
+    switch (this.outputMode) {
+      case 'lint': {
+        // linting drops to be more compatible with compiler analysis
+        return true;
+      }
+      case 'client':
+      case 'ssr': {
+        return true;
+      }
+      case 'client-no-memo': {
+        return false;
+      }
+      default: {
+        assertExhaustive(
+          this.outputMode,
+          `Unexpected output mode '${this.outputMode}'`,
+        );
+      }
+    }
+  }
+
+  get enableMemoization(): boolean {
+    switch (this.outputMode) {
+      case 'client':
+      case 'lint': {
+        // linting also enables memoization so that we can check if manual memoization is preserved
+        return true;
+      }
+      case 'ssr':
+      case 'client-no-memo': {
+        return false;
+      }
+      default: {
+        assertExhaustive(
+          this.outputMode,
+          `Unexpected output mode '${this.outputMode}'`,
+        );
+      }
+    }
+  }
+
+  get enableValidations(): boolean {
+    switch (this.outputMode) {
+      case 'client':
+      case 'lint':
+      case 'ssr': {
+        return true;
+      }
+      case 'client-no-memo': {
+        return false;
+      }
+      default: {
+        assertExhaustive(
+          this.outputMode,
+          `Unexpected output mode '${this.outputMode}'`,
+        );
+      }
+    }
   }
 
   get nextIdentifierId(): IdentifierId {

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

@@ -817,6 +817,11 @@ export type StartMemoize = {
    * (e.g. useMemo without a second arg)
    */
   deps: Array<ManualMemoDependency> | null;
+  /**
+   * The source location of the dependencies argument. Used for
+   * emitting diagnostics with a suggested replacement
+   */
+  depsLoc: SourceLocation | null;
   loc: SourceLocation;
 };
 export type FinishMemoize = {
@@ -1680,6 +1685,28 @@ export function areEqualPaths(a: DependencyPath, b: DependencyPath): boolean {
     )
   );
 }
+export function isSubPath(
+  subpath: DependencyPath,
+  path: DependencyPath,
+): boolean {
+  return (
+    subpath.length <= path.length &&
+    subpath.every(
+      (item, ix) =>
+        item.property === path[ix].property &&
+        item.optional === path[ix].optional,
+    )
+  );
+}
+export function isSubPathIgnoringOptionals(
+  subpath: DependencyPath,
+  path: DependencyPath,
+): boolean {
+  return (
+    subpath.length <= path.length &&
+    subpath.every((item, ix) => item.property === path[ix].property)
+  );
+}
 
 export function getPlaceScope(
   id: InstructionId,
@@ -1823,6 +1850,10 @@ export function isPrimitiveType(id: Identifier): boolean {
   return id.type.kind === 'Primitive';
 }
 
+export function isPlainObjectType(id: Identifier): boolean {
+  return id.type.kind === 'Object' && id.type.shapeId === 'BuiltInObject';
+}
+
 export function isArrayType(id: Identifier): boolean {
   return id.type.kind === 'Object' && id.type.shapeId === 'BuiltInArray';
 }

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

@@ -42,7 +42,7 @@ type IdentifierSidemap = {
   functions: Map<IdentifierId, TInstruction<FunctionExpression>>;
   manualMemos: Map<IdentifierId, ManualMemoCallee>;
   react: Set<IdentifierId>;
-  maybeDepsLists: Map<IdentifierId, Array<Place>>;
+  maybeDepsLists: Map<IdentifierId, {loc: SourceLocation; deps: Array<Place>}>;
   maybeDeps: Map<IdentifierId, ManualMemoDependency>;
   optionals: Set<IdentifierId>;
 };
@@ -159,10 +159,10 @@ function collectTemporaries(
     }
     case 'ArrayExpression': {
       if (value.elements.every(e => e.kind === 'Identifier')) {
-        sidemap.maybeDepsLists.set(
-          instr.lvalue.identifier.id,
-          value.elements as Array<Place>,
-        );
+        sidemap.maybeDepsLists.set(instr.lvalue.identifier.id, {
+          loc: value.loc,
+          deps: value.elements as Array<Place>,
+        });
       }
       break;
     }
@@ -182,6 +182,7 @@ function makeManualMemoizationMarkers(
   fnExpr: Place,
   env: Environment,
   depsList: Array<ManualMemoDependency> | null,
+  depsLoc: SourceLocation | null,
   memoDecl: Place,
   manualMemoId: number,
 ): [TInstruction<StartMemoize>, TInstruction<FinishMemoize>] {
@@ -197,6 +198,7 @@ function makeManualMemoizationMarkers(
          * as dependencies
          */
         deps: depsList,
+        depsLoc,
         loc: fnExpr.loc,
       },
       effects: null,
@@ -287,86 +289,85 @@ function extractManualMemoizationArgs(
   sidemap: IdentifierSidemap,
   errors: CompilerError,
 ): {
-  fnPlace: Place | null;
+  fnPlace: Place;
   depsList: Array<ManualMemoDependency> | null;
-} {
+  depsLoc: SourceLocation | null;
+} | null {
   const [fnPlace, depsListPlace] = instr.value.args as Array<
     Place | SpreadPattern | undefined
   >;
-  if (fnPlace == null) {
+  if (fnPlace == null || fnPlace.kind !== 'Identifier') {
     errors.pushDiagnostic(
       CompilerDiagnostic.create({
         category: ErrorCategory.UseMemo,
         reason: `Expected a callback function to be passed to ${kind}`,
-        description: `Expected a callback function to be passed to ${kind}`,
+        description:
+          kind === 'useCallback'
+            ? 'The first argument to useCallback() must be a function to cache'
+            : 'The first argument to useMemo() must be a function that calculates a result to cache',
         suggestions: null,
       }).withDetails({
         kind: 'error',
         loc: instr.value.loc,
-        message: `Expected a callback function to be passed to ${kind}`,
+        message:
+          kind === 'useCallback'
+            ? `Expected a callback function`
+            : `Expected a memoization function`,
       }),
     );
-    return {fnPlace: null, depsList: null};
+    return null;
   }
-  if (fnPlace.kind === 'Spread' || depsListPlace?.kind === 'Spread') {
+  if (depsListPlace == null) {
+    return {
+      fnPlace,
+      depsList: null,
+      depsLoc: null,
+    };
+  }
+  const maybeDepsList =
+    depsListPlace.kind === 'Identifier'
+      ? sidemap.maybeDepsLists.get(depsListPlace.identifier.id)
+      : null;
+  if (maybeDepsList == null) {
     errors.pushDiagnostic(
       CompilerDiagnostic.create({
         category: ErrorCategory.UseMemo,
-        reason: `Unexpected spread argument to ${kind}`,
-        description: `Unexpected spread argument to ${kind}`,
+        reason: `Expected the dependency list for ${kind} to be an array literal`,
+        description: `Expected the dependency list for ${kind} to be an array literal`,
         suggestions: null,
       }).withDetails({
         kind: 'error',
-        loc: instr.value.loc,
-        message: `Unexpected spread argument to ${kind}`,
+        loc:
+          depsListPlace?.kind === 'Identifier' ? depsListPlace.loc : instr.loc,
+        message: `Expected the dependency list for ${kind} to be an array literal`,
       }),
     );
-    return {fnPlace: null, depsList: null};
+    return null;
   }
-  let depsList: Array<ManualMemoDependency> | null = null;
-  if (depsListPlace != null) {
-    const maybeDepsList = sidemap.maybeDepsLists.get(
-      depsListPlace.identifier.id,
-    );
-    if (maybeDepsList == null) {
+  const depsList: Array<ManualMemoDependency> = [];
+  for (const dep of maybeDepsList.deps) {
+    const maybeDep = sidemap.maybeDeps.get(dep.identifier.id);
+    if (maybeDep == null) {
       errors.pushDiagnostic(
         CompilerDiagnostic.create({
           category: ErrorCategory.UseMemo,
-          reason: `Expected the dependency list for ${kind} to be an array literal`,
-          description: `Expected the dependency list for ${kind} to be an array literal`,
+          reason: `Expected the dependency list to be an array of simple expressions (e.g. \`x\`, \`x.y.z\`, \`x?.y?.z\`)`,
+          description: `Expected the dependency list to be an array of simple expressions (e.g. \`x\`, \`x.y.z\`, \`x?.y?.z\`)`,
           suggestions: null,
         }).withDetails({
           kind: 'error',
-          loc: depsListPlace.loc,
-          message: `Expected the dependency list for ${kind} to be an array literal`,
+          loc: dep.loc,
+          message: `Expected the dependency list to be an array of simple expressions (e.g. \`x\`, \`x.y.z\`, \`x?.y?.z\`)`,
         }),
       );
-      return {fnPlace, depsList: null};
-    }
-    depsList = [];
-    for (const dep of maybeDepsList) {
-      const maybeDep = sidemap.maybeDeps.get(dep.identifier.id);
-      if (maybeDep == null) {
-        errors.pushDiagnostic(
-          CompilerDiagnostic.create({
-            category: ErrorCategory.UseMemo,
-            reason: `Expected the dependency list to be an array of simple expressions (e.g. \`x\`, \`x.y.z\`, \`x?.y?.z\`)`,
-            description: `Expected the dependency list to be an array of simple expressions (e.g. \`x\`, \`x.y.z\`, \`x?.y?.z\`)`,
-            suggestions: null,
-          }).withDetails({
-            kind: 'error',
-            loc: dep.loc,
-            message: `Expected the dependency list to be an array of simple expressions (e.g. \`x\`, \`x.y.z\`, \`x?.y?.z\`)`,
-          }),
-        );
-      } else {
-        depsList.push(maybeDep);
-      }
+    } else {
+      depsList.push(maybeDep);
     }
   }
   return {
     fnPlace,
     depsList,
+    depsLoc: maybeDepsList.loc,
   };
 }
 
@@ -427,16 +428,17 @@ export function dropManualMemoization(
 
         const manualMemo = sidemap.manualMemos.get(id);
         if (manualMemo != null) {
-          const {fnPlace, depsList} = extractManualMemoizationArgs(
+          const memoDetails = extractManualMemoizationArgs(
             instr as TInstruction<CallExpression> | TInstruction<MethodCall>,
             manualMemo.kind,
             sidemap,
             errors,
           );
 
-          if (fnPlace == null) {
+          if (memoDetails == null) {
             continue;
           }
+          const {fnPlace, depsList, depsLoc} = memoDetails;
 
           instr.value = getManualMemoizationReplacement(
             fnPlace,
@@ -487,6 +489,7 @@ export function dropManualMemoization(
               fnPlace,
               func.env,
               depsList,
+              depsLoc,
               memoDecl,
               nextManualMemoId++,
             );

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

@@ -2452,7 +2452,7 @@ function computeEffectsForLegacySignature(
       }),
     });
   }
-  if (signature.knownIncompatible != null && state.env.isInferredMemoEnabled) {
+  if (signature.knownIncompatible != null && state.env.enableValidations) {
     const errors = new CompilerError();
     errors.pushDiagnostic(
       CompilerDiagnostic.create({

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

@@ -7,6 +7,8 @@
 
 import {
   BlockId,
+  Environment,
+  getHookKind,
   HIRFunction,
   Identifier,
   IdentifierId,
@@ -68,9 +70,14 @@ export function deadCodeElimination(fn: HIRFunction): void {
 }
 
 class State {
+  env: Environment;
   named: Set<string> = new Set();
   identifiers: Set<IdentifierId> = new Set();
 
+  constructor(env: Environment) {
+    this.env = env;
+  }
+
   // Mark the identifier as being referenced (not dead code)
   reference(identifier: Identifier): void {
     this.identifiers.add(identifier.id);
@@ -112,7 +119,7 @@ function findReferencedIdentifiers(fn: HIRFunction): State {
   const hasLoop = hasBackEdge(fn);
   const reversedBlocks = [...fn.body.blocks.values()].reverse();
 
-  const state = new State();
+  const state = new State(fn.env);
   let size = state.count;
   do {
     size = state.count;
@@ -310,12 +317,27 @@ function pruneableValue(value: InstructionValue, state: State): boolean {
       // explicitly retain debugger statements to not break debugging workflows
       return false;
     }
-    case 'Await':
     case 'CallExpression':
+    case 'MethodCall': {
+      if (state.env.outputMode === 'ssr') {
+        const calleee =
+          value.kind === 'CallExpression' ? value.callee : value.property;
+        const hookKind = getHookKind(state.env, calleee.identifier);
+        switch (hookKind) {
+          case 'useState':
+          case 'useReducer':
+          case 'useRef': {
+            // unused refs can be removed
+            return true;
+          }
+        }
+      }
+      return false;
+    }
+    case 'Await':
     case 'ComputedDelete':
     case 'ComputedStore':
     case 'PropertyDelete':
-    case 'MethodCall':
     case 'PropertyStore':
     case 'StoreGlobal': {
       /*

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

@@ -0,0 +1,269 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {CompilerError} from '..';
+import {
+  CallExpression,
+  getHookKind,
+  HIRFunction,
+  IdentifierId,
+  InstructionValue,
+  isArrayType,
+  isPlainObjectType,
+  isPrimitiveType,
+  isSetStateType,
+  isStartTransitionType,
+  LoadLocal,
+  StoreLocal,
+} from '../HIR';
+import {
+  eachInstructionValueOperand,
+  eachTerminalOperand,
+} from '../HIR/visitors';
+import {retainWhere} from '../Utils/utils';
+
+/**
+ * Optimizes the code for running specifically in an SSR environment. This optimization
+ * asssumes that setState will not be called during render during initial mount, which
+ * allows inlining useState/useReducer.
+ *
+ * Optimizations:
+ * - Inline useState/useReducer
+ * - Remove effects
+ * - Remove refs where known to be unused during render (eg directly passed to a dom node)
+ * - Remove event handlers
+ *
+ * Note that an earlier pass already inlines useMemo/useCallback
+ */
+export function optimizeForSSR(fn: HIRFunction): void {
+  const inlinedState = new Map<IdentifierId, InstructionValue>();
+  /**
+   * First pass identifies useState/useReducer which can be safely inlined. Any use
+   * of the hook return other than destructuring (with a specific pattern) prevents
+   * inlining.
+   *
+   * Supported cases:
+   * - `const [state, ] = useState( <primitive-array-or-object> )`
+   * - `const [state, ] = useReducer(..., <value>)`
+   * - `const [state, ] = useReducer[..., <value>, <init>]`
+   */
+  for (const block of fn.body.blocks.values()) {
+    for (const instr of block.instructions) {
+      const {value} = instr;
+      switch (value.kind) {
+        case 'Destructure': {
+          if (
+            inlinedState.has(value.value.identifier.id) &&
+            value.lvalue.pattern.kind === 'ArrayPattern' &&
+            value.lvalue.pattern.items.length >= 1 &&
+            value.lvalue.pattern.items[0].kind === 'Identifier'
+          ) {
+            // Allow destructuring of inlined states
+            continue;
+          }
+          break;
+        }
+        case 'MethodCall':
+        case 'CallExpression': {
+          const calleee =
+            value.kind === 'CallExpression' ? value.callee : value.property;
+          const hookKind = getHookKind(fn.env, calleee.identifier);
+          switch (hookKind) {
+            case 'useReducer': {
+              if (
+                value.args.length === 2 &&
+                value.args[1].kind === 'Identifier'
+              ) {
+                const arg = value.args[1];
+                const replace: LoadLocal = {
+                  kind: 'LoadLocal',
+                  place: arg,
+                  loc: arg.loc,
+                };
+                inlinedState.set(instr.lvalue.identifier.id, replace);
+              } else if (
+                value.args.length === 3 &&
+                value.args[1].kind === 'Identifier' &&
+                value.args[2].kind === 'Identifier'
+              ) {
+                const arg = value.args[1];
+                const initializer = value.args[2];
+                const replace: CallExpression = {
+                  kind: 'CallExpression',
+                  callee: initializer,
+                  args: [arg],
+                  loc: value.loc,
+                };
+                inlinedState.set(instr.lvalue.identifier.id, replace);
+              }
+              break;
+            }
+            case 'useState': {
+              if (
+                value.args.length === 1 &&
+                value.args[0].kind === 'Identifier'
+              ) {
+                const arg = value.args[0];
+                if (
+                  isPrimitiveType(arg.identifier) ||
+                  isPlainObjectType(arg.identifier) ||
+                  isArrayType(arg.identifier)
+                ) {
+                  const replace: LoadLocal = {
+                    kind: 'LoadLocal',
+                    place: arg,
+                    loc: arg.loc,
+                  };
+                  inlinedState.set(instr.lvalue.identifier.id, replace);
+                }
+              }
+              break;
+            }
+          }
+        }
+      }
+      // Any use of useState/useReducer return besides destructuring prevents inlining
+      if (inlinedState.size !== 0) {
+        for (const operand of eachInstructionValueOperand(value)) {
+          inlinedState.delete(operand.identifier.id);
+        }
+      }
+    }
+    if (inlinedState.size !== 0) {
+      for (const operand of eachTerminalOperand(block.terminal)) {
+        inlinedState.delete(operand.identifier.id);
+      }
+    }
+  }
+  for (const block of fn.body.blocks.values()) {
+    for (const instr of block.instructions) {
+      const {value} = instr;
+      switch (value.kind) {
+        case 'FunctionExpression': {
+          if (hasKnownNonRenderCall(value.loweredFunc.func)) {
+            instr.value = {
+              kind: 'Primitive',
+              value: undefined,
+              loc: value.loc,
+            };
+          }
+          break;
+        }
+        case 'JsxExpression': {
+          if (
+            value.tag.kind === 'BuiltinTag' &&
+            value.tag.name.indexOf('-') === -1
+          ) {
+            const tag = value.tag.name;
+            retainWhere(value.props, prop => {
+              return (
+                prop.kind === 'JsxSpreadAttribute' ||
+                (!isKnownEventHandler(tag, prop.name) && prop.name !== 'ref')
+              );
+            });
+          }
+          break;
+        }
+        case 'Destructure': {
+          if (inlinedState.has(value.value.identifier.id)) {
+            // Canonical check is part of determining if state can inline, this is for TS
+            CompilerError.invariant(
+              value.lvalue.pattern.kind === 'ArrayPattern' &&
+                value.lvalue.pattern.items.length >= 1 &&
+                value.lvalue.pattern.items[0].kind === 'Identifier',
+              {
+                reason:
+                  'Expected a valid destructuring pattern for inlined state',
+                description: null,
+                details: [
+                  {
+                    kind: 'error',
+                    message: 'Expected a valid destructuring pattern',
+                    loc: value.loc,
+                  },
+                ],
+              },
+            );
+            const store: StoreLocal = {
+              kind: 'StoreLocal',
+              loc: value.loc,
+              type: null,
+              lvalue: {
+                kind: value.lvalue.kind,
+                place: value.lvalue.pattern.items[0],
+              },
+              value: value.value,
+            };
+            instr.value = store;
+          }
+          break;
+        }
+        case 'MethodCall':
+        case 'CallExpression': {
+          const calleee =
+            value.kind === 'CallExpression' ? value.callee : value.property;
+          const hookKind = getHookKind(fn.env, calleee.identifier);
+          switch (hookKind) {
+            case 'useEffectEvent': {
+              if (
+                value.args.length === 1 &&
+                value.args[0].kind === 'Identifier'
+              ) {
+                const load: LoadLocal = {
+                  kind: 'LoadLocal',
+                  place: value.args[0],
+                  loc: value.loc,
+                };
+                instr.value = load;
+              }
+              break;
+            }
+            case 'useEffect':
+            case 'useLayoutEffect':
+            case 'useInsertionEffect': {
+              // Drop effects
+              instr.value = {
+                kind: 'Primitive',
+                value: undefined,
+                loc: value.loc,
+              };
+              break;
+            }
+            case 'useReducer':
+            case 'useState': {
+              const replace = inlinedState.get(instr.lvalue.identifier.id);
+              if (replace != null) {
+                instr.value = replace;
+              }
+              break;
+            }
+          }
+        }
+      }
+    }
+  }
+}
+
+function hasKnownNonRenderCall(fn: HIRFunction): boolean {
+  for (const block of fn.body.blocks.values()) {
+    for (const instr of block.instructions) {
+      if (
+        instr.value.kind === 'CallExpression' &&
+        (isSetStateType(instr.value.callee.identifier) ||
+          isStartTransitionType(instr.value.callee.identifier))
+      ) {
+        return true;
+      }
+    }
+  }
+  return false;
+}
+
+const EVENT_HANDLER_PATTERN = /^on[A-Z]/;
+function isKnownEventHandler(_tag: string, prop: string): boolean {
+  return EVENT_HANDLER_PATTERN.test(prop);
+}

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

@@ -159,7 +159,7 @@ export function codegenFunction(
   const compiled = compileResult.unwrap();
 
   const hookGuard = fn.env.config.enableEmitHookGuards;
-  if (hookGuard != null && fn.env.isInferredMemoEnabled) {
+  if (hookGuard != null && fn.env.outputMode === 'client') {
     compiled.body = t.blockStatement([
       createHookGuard(
         hookGuard,
@@ -259,7 +259,7 @@ export function codegenFunction(
   if (
     emitInstrumentForget != null &&
     fn.id != null &&
-    fn.env.isInferredMemoEnabled
+    fn.env.outputMode === 'client'
   ) {
     /*
      * Technically, this is a conditional hook call. However, we expect
@@ -591,7 +591,10 @@ function codegenBlockNoReset(
 }
 
 function wrapCacheDep(cx: Context, value: t.Expression): t.Expression {
-  if (cx.env.config.enableEmitFreeze != null && cx.env.isInferredMemoEnabled) {
+  if (
+    cx.env.config.enableEmitFreeze != null &&
+    cx.env.outputMode === 'client'
+  ) {
     const emitFreezeIdentifier = cx.env.programContext.addImportSpecifier(
       cx.env.config.enableEmitFreeze,
     ).name;
@@ -1772,7 +1775,7 @@ function createCallExpression(
   }
 
   const hookGuard = env.config.enableEmitHookGuards;
-  if (hookGuard != null && isHook && env.isInferredMemoEnabled) {
+  if (hookGuard != null && isHook && env.outputMode === 'client') {
     const iife = t.functionExpression(
       null,
       [],

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

@@ -0,0 +1,834 @@
+/**
+ * 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 prettyFormat from 'pretty-format';
+import {
+  CompilerDiagnostic,
+  CompilerError,
+  CompilerSuggestionOperation,
+  SourceLocation,
+} from '..';
+import {CompilerSuggestion, ErrorCategory} from '../CompilerError';
+import {
+  areEqualPaths,
+  BlockId,
+  DependencyPath,
+  FinishMemoize,
+  HIRFunction,
+  Identifier,
+  IdentifierId,
+  InstructionKind,
+  isStableType,
+  isSubPath,
+  isSubPathIgnoringOptionals,
+  isUseRefType,
+  LoadGlobal,
+  ManualMemoDependency,
+  Place,
+  StartMemoize,
+} from '../HIR';
+import {
+  eachInstructionLValue,
+  eachInstructionValueLValue,
+  eachInstructionValueOperand,
+  eachTerminalOperand,
+} from '../HIR/visitors';
+import {Result} from '../Utils/Result';
+import {retainWhere} from '../Utils/utils';
+
+const DEBUG = false;
+
+/**
+ * Validates that existing manual memoization had exhaustive dependencies.
+ * Memoization with missing or extra reactive dependencies is invalid React
+ * and compilation can change behavior, causing a value to be computed more
+ * or less times.
+ *
+ * TODOs:
+ * - Handle cases of mixed optional and non-optional versions of the same path,
+ *   eg referecing both x.y.z and x.y?.z in the same memo block. we should collapse
+ *   this into a single canonical dep that we look for in the manual deps. see the
+ *   existing exhaustive deps rule for implementation.
+ * - Handle cases where the user deps were not simple identifiers + property chains.
+ *   We try to detect this in ValidateUseMemo but we miss some cases. The problem
+ *   is that invalid forms can be value blocks or function calls that don't get
+ *   removed by DCE, leaving a structure like:
+ *
+ * StartMemoize
+ * t0 = <value to memoize>
+ * ...non-DCE'd code for manual deps...
+ * FinishMemoize decl=t0
+ *
+ * When we go to compute the dependencies, we then think that the user's manual dep
+ * logic is part of what the memo computation logic.
+ */
+export function validateExhaustiveDependencies(
+  fn: HIRFunction,
+): Result<void, CompilerError> {
+  const reactive = collectReactiveIdentifiersHIR(fn);
+
+  const temporaries: Map<IdentifierId, Temporary> = new Map();
+  for (const param of fn.params) {
+    const place = param.kind === 'Identifier' ? param : param.place;
+    temporaries.set(place.identifier.id, {
+      kind: 'Local',
+      identifier: place.identifier,
+      path: [],
+      context: false,
+      loc: place.loc,
+    });
+  }
+  const error = new CompilerError();
+  let startMemo: StartMemoize | null = null;
+
+  function onStartMemoize(
+    value: StartMemoize,
+    dependencies: Set<InferredDependency>,
+    locals: Set<IdentifierId>,
+  ): void {
+    CompilerError.simpleInvariant(startMemo == null, {
+      reason: 'Unexpected nested memo calls',
+      loc: value.loc,
+    });
+    startMemo = value;
+    dependencies.clear();
+    locals.clear();
+  }
+  function onFinishMemoize(
+    value: FinishMemoize,
+    dependencies: Set<InferredDependency>,
+    locals: Set<IdentifierId>,
+  ): void {
+    CompilerError.simpleInvariant(
+      startMemo != null && startMemo.manualMemoId === value.manualMemoId,
+      {
+        reason: 'Found FinishMemoize without corresponding StartMemoize',
+        loc: value.loc,
+      },
+    );
+    visitCandidateDependency(value.decl, temporaries, dependencies, locals);
+    const inferred: Array<InferredDependency> = Array.from(dependencies);
+    // Sort dependencies by name and path, with shorter/non-optional paths first
+    inferred.sort((a, b) => {
+      if (a.kind === 'Global' && b.kind == 'Global') {
+        return a.binding.name.localeCompare(b.binding.name);
+      } else if (a.kind == 'Local' && b.kind == 'Local') {
+        CompilerError.simpleInvariant(
+          a.identifier.name != null &&
+            a.identifier.name.kind === 'named' &&
+            b.identifier.name != null &&
+            b.identifier.name.kind === 'named',
+          {
+            reason: 'Expected dependencies to be named variables',
+            loc: a.loc,
+          },
+        );
+        if (a.identifier.id !== b.identifier.id) {
+          return a.identifier.name.value.localeCompare(b.identifier.name.value);
+        }
+        if (a.path.length !== b.path.length) {
+          // if a's path is shorter this returns a negative, sorting a first
+          return a.path.length - b.path.length;
+        }
+        for (let i = 0; i < a.path.length; i++) {
+          const aProperty = a.path[i];
+          const bProperty = b.path[i];
+          const aOptional = aProperty.optional ? 0 : 1;
+          const bOptional = bProperty.optional ? 0 : 1;
+          if (aOptional !== bOptional) {
+            // sort non-optionals first
+            return aOptional - bOptional;
+          } else if (aProperty.property !== bProperty.property) {
+            return String(aProperty.property).localeCompare(
+              String(bProperty.property),
+            );
+          }
+        }
+        return 0;
+      } else {
+        const aName =
+          a.kind === 'Global' ? a.binding.name : a.identifier.name?.value;
+        const bName =
+          b.kind === 'Global' ? b.binding.name : b.identifier.name?.value;
+        if (aName != null && bName != null) {
+          return aName.localeCompare(bName);
+        }
+        return 0;
+      }
+    });
+    // remove redundant inferred dependencies
+    retainWhere(inferred, (dep, ix) => {
+      const match = inferred.findIndex(prevDep => {
+        return (
+          isEqualTemporary(prevDep, dep) ||
+          (prevDep.kind === 'Local' &&
+            dep.kind === 'Local' &&
+            prevDep.identifier.id === dep.identifier.id &&
+            isSubPath(prevDep.path, dep.path))
+        );
+      });
+      // only retain entries that don't have a prior match
+      return match === -1 || match >= ix;
+    });
+    // Validate that all manual dependencies belong there
+    if (DEBUG) {
+      console.log('manual');
+      console.log(
+        (startMemo.deps ?? [])
+          .map(x => '  ' + printManualMemoDependency(x))
+          .join('\n'),
+      );
+      console.log('inferred');
+      console.log(
+        inferred.map(x => '  ' + printInferredDependency(x)).join('\n'),
+      );
+    }
+    const manualDependencies = startMemo.deps ?? [];
+    const matched: Set<ManualMemoDependency> = new Set();
+    const missing: Array<Extract<InferredDependency, {kind: 'Local'}>> = [];
+    const extra: Array<ManualMemoDependency> = [];
+    for (const inferredDependency of inferred) {
+      if (inferredDependency.kind === 'Global') {
+        for (const manualDependency of manualDependencies) {
+          if (
+            manualDependency.root.kind === 'Global' &&
+            manualDependency.root.identifierName ===
+              inferredDependency.binding.name
+          ) {
+            matched.add(manualDependency);
+            extra.push(manualDependency);
+          }
+        }
+        continue;
+      }
+      CompilerError.simpleInvariant(inferredDependency.kind === 'Local', {
+        reason: 'Unexpected function dependency',
+        loc: value.loc,
+      });
+      /**
+       * Dependencies technically only need to include reactive values. However,
+       * reactivity inference for general values is subtle since it involves all
+       * of our complex control and data flow analysis. To keep results more
+       * stable and predictable to developers, we intentionally stay closer to
+       * the rules of the classic exhaustive-deps rule. Values should be included
+       * as dependencies if either of the following is true:
+       * - They're reactive
+       * - They're non-reactive and not a known-stable value type.
+       *
+       * Thus `const ref: Ref = cond ? ref1 : ref2` has to be a dependency
+       * (assuming `cond` is reactive) since it's reactive despite being a ref.
+       *
+       * Similarly, `const x = [1,2,3]` has to be a dependency since even
+       * though it's non reactive, it's not a known stable type.
+       *
+       * TODO: consider reimplementing a simpler form of reactivity inference.
+       * Ideally we'd consider `const ref: Ref = cond ? ref1 : ref2` as a required
+       * dependency even if our data/control flow tells us that `cond` is non-reactive.
+       * It's simpler for developers to reason about based on a more structural/AST
+       * driven approach.
+       */
+      const isRequiredDependency =
+        reactive.has(inferredDependency.identifier.id) ||
+        !isStableType(inferredDependency.identifier);
+      let hasMatchingManualDependency = false;
+      for (const manualDependency of manualDependencies) {
+        if (
+          manualDependency.root.kind === 'NamedLocal' &&
+          manualDependency.root.value.identifier.id ===
+            inferredDependency.identifier.id &&
+          (areEqualPaths(manualDependency.path, inferredDependency.path) ||
+            isSubPathIgnoringOptionals(
+              manualDependency.path,
+              inferredDependency.path,
+            ))
+        ) {
+          hasMatchingManualDependency = true;
+          matched.add(manualDependency);
+          if (!isRequiredDependency) {
+            extra.push(manualDependency);
+          }
+        }
+      }
+      if (isRequiredDependency && !hasMatchingManualDependency) {
+        missing.push(inferredDependency);
+      }
+    }
+
+    for (const dep of startMemo.deps ?? []) {
+      if (matched.has(dep)) {
+        continue;
+      }
+      extra.push(dep);
+    }
+
+    /*
+     * For compatiblity with the existing exhaustive-deps rule, we allow
+     * known-stable values as dependencies even if the value is not reactive.
+     * This allows code that takes a dep on a non-reactive setState function
+     * to pass, for example.
+     */
+    retainWhere(extra, dep => {
+      const isNonReactiveStableValue =
+        dep.root.kind === 'NamedLocal' &&
+        !dep.root.value.reactive &&
+        isStableType(dep.root.value.identifier);
+      return !isNonReactiveStableValue;
+    });
+
+    if (missing.length !== 0 || extra.length !== 0) {
+      let suggestions: Array<CompilerSuggestion> | null = null;
+      if (startMemo.depsLoc != null && typeof startMemo.depsLoc !== 'symbol') {
+        suggestions = [
+          {
+            description: 'Update dependencies',
+            range: [startMemo.depsLoc.start.index, startMemo.depsLoc.end.index],
+            op: CompilerSuggestionOperation.Replace,
+            text: `[${inferred.map(printInferredDependency).join(', ')}]`,
+          },
+        ];
+      }
+      if (missing.length !== 0) {
+        const diagnostic = CompilerDiagnostic.create({
+          category: ErrorCategory.MemoDependencies,
+          reason: 'Found non-exhaustive dependencies',
+          description:
+            'Missing dependencies can cause a value not to update when those inputs change, ' +
+            'resulting in stale UI',
+          suggestions,
+        });
+        for (const dep of missing) {
+          let reactiveStableValueHint = '';
+          if (isStableType(dep.identifier)) {
+            reactiveStableValueHint =
+              '. Refs, setState functions, and other "stable" values generally do not need to be added as dependencies, but this variable may change over time to point to different values';
+          }
+          diagnostic.withDetails({
+            kind: 'error',
+            message: `Missing dependency \`${printInferredDependency(dep)}\`${reactiveStableValueHint}`,
+            loc: dep.loc,
+          });
+        }
+        error.pushDiagnostic(diagnostic);
+      } else if (extra.length !== 0) {
+        const diagnostic = CompilerDiagnostic.create({
+          category: ErrorCategory.MemoDependencies,
+          reason: 'Found unnecessary memoization dependencies',
+          description:
+            'Unnecessary dependencies can cause a value to update more often than necessary, ' +
+            'which can cause effects to run more than expected',
+        });
+        diagnostic.withDetails({
+          kind: 'error',
+          message: `Unnecessary dependencies ${extra.map(dep => `\`${printManualMemoDependency(dep)}\``).join(', ')}`,
+          loc: startMemo.depsLoc ?? value.loc,
+        });
+        error.pushDiagnostic(diagnostic);
+      }
+    }
+
+    dependencies.clear();
+    locals.clear();
+    startMemo = null;
+  }
+
+  collectDependencies(
+    fn,
+    temporaries,
+    {
+      onStartMemoize,
+      onFinishMemoize,
+    },
+    false, // isFunctionExpression
+  );
+  return error.asResult();
+}
+
+function addDependency(
+  dep: Temporary,
+  dependencies: Set<InferredDependency>,
+  locals: Set<IdentifierId>,
+): void {
+  if (dep.kind === 'Function') {
+    for (const x of dep.dependencies) {
+      addDependency(x, dependencies, locals);
+    }
+  } else if (dep.kind === 'Global') {
+    dependencies.add(dep);
+  } else if (!locals.has(dep.identifier.id)) {
+    dependencies.add(dep);
+  }
+}
+
+function visitCandidateDependency(
+  place: Place,
+  temporaries: Map<IdentifierId, Temporary>,
+  dependencies: Set<InferredDependency>,
+  locals: Set<IdentifierId>,
+): void {
+  const dep = temporaries.get(place.identifier.id);
+  if (dep != null) {
+    addDependency(dep, dependencies, locals);
+  }
+}
+
+/**
+ * This function determines the dependencies of the given function relative to
+ * its external context. Dependencies are collected eagerly, the first time an
+ * external variable is referenced, as opposed to trying to delay or aggregate
+ * calculation of dependencies until they are later "used".
+ *
+ * For example, in
+ *
+ * ```
+ * function f() {
+ *   let x = y; // we record a dependency on `y` here
+ *   ...
+ *   use(x); // as opposed to trying to delay that dependency until here
+ * }
+ * ```
+ *
+ * That said, LoadLocal/LoadContext does not immediately take a dependency,
+ * we store the dependency in a temporary and set it as used when that temporary
+ * is referenced as an operand.
+ *
+ * As we proceed through the function we track local variables that it creates
+ * and don't consider later references to these variables as dependencies.
+ *
+ * For function expressions we first collect the function's dependencies by
+ * calling this function recursively, _without_ taking into account whether
+ * the "external" variables it accesses are actually external or just locals
+ * in the parent. We then prune any locals and immediately consider any
+ * remaining externals that it accesses as a dependency:
+ *
+ * ```
+ * function Component() {
+ *   const local = ...;
+ *   const f = () => { return [external, local] };
+ * }
+ * ```
+ *
+ * Here we calculate `f` as having dependencies `external, `local` and save
+ * this into `temporaries`. We then also immediately take these as dependencies
+ * at the Component scope, at which point we filter out `local` as a local variable,
+ * leaving just a dependency on `external`.
+ *
+ * When calling this function on a top-level component or hook, the collected dependencies
+ * will only contain the globals that it accesses which isn't useful. Instead, passing
+ * onStartMemoize/onFinishMemoize callbacks allows looking at the dependencies within
+ * blocks of manual memoization.
+ */
+function collectDependencies(
+  fn: HIRFunction,
+  temporaries: Map<IdentifierId, Temporary>,
+  callbacks: {
+    onStartMemoize: (
+      startMemo: StartMemoize,
+      dependencies: Set<InferredDependency>,
+      locals: Set<IdentifierId>,
+    ) => void;
+    onFinishMemoize: (
+      finishMemo: FinishMemoize,
+      dependencies: Set<InferredDependency>,
+      locals: Set<IdentifierId>,
+    ) => void;
+  } | null,
+  isFunctionExpression: boolean,
+): Extract<Temporary, {kind: 'Function'}> {
+  const optionals = findOptionalPlaces(fn);
+  if (DEBUG) {
+    console.log(prettyFormat(optionals));
+  }
+  const locals: Set<IdentifierId> = new Set();
+  if (isFunctionExpression) {
+    for (const param of fn.params) {
+      const place = param.kind === 'Identifier' ? param : param.place;
+      locals.add(place.identifier.id);
+    }
+  }
+
+  const dependencies: Set<InferredDependency> = new Set();
+  function visit(place: Place): void {
+    visitCandidateDependency(place, temporaries, dependencies, locals);
+  }
+  for (const block of fn.body.blocks.values()) {
+    for (const phi of block.phis) {
+      let deps: Array<Temporary> | null = null;
+      for (const operand of phi.operands.values()) {
+        const dep = temporaries.get(operand.identifier.id);
+        if (dep == null) {
+          continue;
+        }
+        if (deps == null) {
+          deps = [dep];
+        } else {
+          deps.push(dep);
+        }
+      }
+      if (deps == null) {
+        continue;
+      } else if (deps.length === 1) {
+        temporaries.set(phi.place.identifier.id, deps[0]!);
+      } else {
+        temporaries.set(phi.place.identifier.id, {
+          kind: 'Function',
+          dependencies: new Set(deps),
+        });
+      }
+    }
+
+    for (const instr of block.instructions) {
+      const {lvalue, value} = instr;
+      switch (value.kind) {
+        case 'LoadGlobal': {
+          temporaries.set(lvalue.identifier.id, {
+            kind: 'Global',
+            binding: value.binding,
+          });
+          break;
+        }
+        case 'LoadContext':
+        case 'LoadLocal': {
+          if (locals.has(value.place.identifier.id)) {
+            break;
+          }
+          const temp = temporaries.get(value.place.identifier.id);
+          if (temp != null) {
+            if (temp.kind === 'Local') {
+              const local: Temporary = {...temp, loc: value.place.loc};
+              temporaries.set(lvalue.identifier.id, local);
+            } else {
+              temporaries.set(lvalue.identifier.id, temp);
+            }
+          }
+          break;
+        }
+        case 'DeclareLocal': {
+          const local: Temporary = {
+            kind: 'Local',
+            identifier: value.lvalue.place.identifier,
+            path: [],
+            context: false,
+            loc: value.lvalue.place.loc,
+          };
+          temporaries.set(value.lvalue.place.identifier.id, local);
+          locals.add(value.lvalue.place.identifier.id);
+          break;
+        }
+        case 'StoreLocal': {
+          if (value.lvalue.place.identifier.name == null) {
+            const temp = temporaries.get(value.value.identifier.id);
+            if (temp != null) {
+              temporaries.set(value.lvalue.place.identifier.id, temp);
+            }
+            break;
+          }
+          visit(value.value);
+          if (value.lvalue.kind !== InstructionKind.Reassign) {
+            const local: Temporary = {
+              kind: 'Local',
+              identifier: value.lvalue.place.identifier,
+              path: [],
+              context: false,
+              loc: value.lvalue.place.loc,
+            };
+            temporaries.set(value.lvalue.place.identifier.id, local);
+            locals.add(value.lvalue.place.identifier.id);
+          }
+          break;
+        }
+        case 'DeclareContext': {
+          const local: Temporary = {
+            kind: 'Local',
+            identifier: value.lvalue.place.identifier,
+            path: [],
+            context: true,
+            loc: value.lvalue.place.loc,
+          };
+          temporaries.set(value.lvalue.place.identifier.id, local);
+          break;
+        }
+        case 'StoreContext': {
+          visit(value.value);
+          if (value.lvalue.kind !== InstructionKind.Reassign) {
+            const local: Temporary = {
+              kind: 'Local',
+              identifier: value.lvalue.place.identifier,
+              path: [],
+              context: true,
+              loc: value.lvalue.place.loc,
+            };
+            temporaries.set(value.lvalue.place.identifier.id, local);
+            locals.add(value.lvalue.place.identifier.id);
+          }
+          break;
+        }
+        case 'Destructure': {
+          visit(value.value);
+          if (value.lvalue.kind !== InstructionKind.Reassign) {
+            for (const lvalue of eachInstructionValueLValue(value)) {
+              const local: Temporary = {
+                kind: 'Local',
+                identifier: lvalue.identifier,
+                path: [],
+                context: false,
+                loc: lvalue.loc,
+              };
+              temporaries.set(lvalue.identifier.id, local);
+              locals.add(lvalue.identifier.id);
+            }
+          }
+          break;
+        }
+        case 'PropertyLoad': {
+          if (
+            typeof value.property === 'number' ||
+            (isUseRefType(value.object.identifier) &&
+              value.property === 'current')
+          ) {
+            visit(value.object);
+            break;
+          }
+          const object = temporaries.get(value.object.identifier.id);
+          if (object != null && object.kind === 'Local') {
+            const optional = optionals.get(value.object.identifier.id) ?? false;
+            const local: Temporary = {
+              kind: 'Local',
+              identifier: object.identifier,
+              context: object.context,
+              path: [
+                ...object.path,
+                {
+                  optional,
+                  property: value.property,
+                },
+              ],
+              loc: value.loc,
+            };
+            temporaries.set(lvalue.identifier.id, local);
+          }
+          break;
+        }
+        case 'FunctionExpression':
+        case 'ObjectMethod': {
+          const functionDeps = collectDependencies(
+            value.loweredFunc.func,
+            temporaries,
+            null,
+            true, // isFunctionExpression
+          );
+          temporaries.set(lvalue.identifier.id, functionDeps);
+          addDependency(functionDeps, dependencies, locals);
+          break;
+        }
+        case 'StartMemoize': {
+          const onStartMemoize = callbacks?.onStartMemoize;
+          if (onStartMemoize != null) {
+            onStartMemoize(value, dependencies, locals);
+          }
+          break;
+        }
+        case 'FinishMemoize': {
+          const onFinishMemoize = callbacks?.onFinishMemoize;
+          if (onFinishMemoize != null) {
+            onFinishMemoize(value, dependencies, locals);
+          }
+          break;
+        }
+        case 'MethodCall': {
+          // Ignore the method itself
+          for (const operand of eachInstructionValueOperand(value)) {
+            if (operand.identifier.id === value.property.identifier.id) {
+              continue;
+            }
+            visit(operand);
+          }
+          break;
+        }
+        default: {
+          for (const operand of eachInstructionValueOperand(value)) {
+            visit(operand);
+          }
+          for (const lvalue of eachInstructionLValue(instr)) {
+            locals.add(lvalue.identifier.id);
+          }
+        }
+      }
+    }
+    for (const operand of eachTerminalOperand(block.terminal)) {
+      if (optionals.has(operand.identifier.id)) {
+        continue;
+      }
+      visit(operand);
+    }
+  }
+  return {kind: 'Function', dependencies};
+}
+
+function printInferredDependency(dep: InferredDependency): string {
+  switch (dep.kind) {
+    case 'Global': {
+      return dep.binding.name;
+    }
+    case 'Local': {
+      CompilerError.simpleInvariant(
+        dep.identifier.name != null && dep.identifier.name.kind === 'named',
+        {
+          reason: 'Expected dependencies to be named variables',
+          loc: dep.loc,
+        },
+      );
+      return `${dep.identifier.name.value}${dep.path.map(p => (p.optional ? '?' : '') + '.' + p.property).join('')}`;
+    }
+  }
+}
+
+function printManualMemoDependency(dep: ManualMemoDependency): string {
+  let identifierName: string;
+  if (dep.root.kind === 'Global') {
+    identifierName = dep.root.identifierName;
+  } else {
+    const name = dep.root.value.identifier.name;
+    CompilerError.simpleInvariant(name != null && name.kind === 'named', {
+      reason: 'Expected manual dependencies to be named variables',
+      loc: dep.root.value.loc,
+    });
+    identifierName = name.value;
+  }
+  return `${identifierName}${dep.path.map(p => (p.optional ? '?' : '') + '.' + p.property).join('')}`;
+}
+
+function isEqualTemporary(a: Temporary, b: Temporary): boolean {
+  switch (a.kind) {
+    case 'Function': {
+      return false;
+    }
+    case 'Global': {
+      return b.kind === 'Global' && a.binding.name === b.binding.name;
+    }
+    case 'Local': {
+      return (
+        b.kind === 'Local' &&
+        a.identifier.id === b.identifier.id &&
+        areEqualPaths(a.path, b.path)
+      );
+    }
+  }
+}
+
+type Temporary =
+  | {kind: 'Global'; binding: LoadGlobal['binding']}
+  | {
+      kind: 'Local';
+      identifier: Identifier;
+      path: DependencyPath;
+      context: boolean;
+      loc: SourceLocation;
+    }
+  | {kind: 'Function'; dependencies: Set<Temporary>};
+type InferredDependency = Extract<Temporary, {kind: 'Local' | 'Global'}>;
+
+function collectReactiveIdentifiersHIR(fn: HIRFunction): Set<IdentifierId> {
+  const reactive = new Set<IdentifierId>();
+  for (const block of fn.body.blocks.values()) {
+    for (const instr of block.instructions) {
+      for (const lvalue of eachInstructionLValue(instr)) {
+        if (lvalue.reactive) {
+          reactive.add(lvalue.identifier.id);
+        }
+      }
+      for (const operand of eachInstructionValueOperand(instr.value)) {
+        if (operand.reactive) {
+          reactive.add(operand.identifier.id);
+        }
+      }
+    }
+    for (const operand of eachTerminalOperand(block.terminal)) {
+      if (operand.reactive) {
+        reactive.add(operand.identifier.id);
+      }
+    }
+  }
+  return reactive;
+}
+
+export function findOptionalPlaces(
+  fn: HIRFunction,
+): Map<IdentifierId, boolean> {
+  const optionals = new Map<IdentifierId, boolean>();
+  const visited: Set<BlockId> = new Set();
+  for (const [, block] of fn.body.blocks) {
+    if (visited.has(block.id)) {
+      continue;
+    }
+    if (block.terminal.kind === 'optional') {
+      visited.add(block.id);
+      const optionalTerminal = block.terminal;
+      let testBlock = fn.body.blocks.get(block.terminal.test)!;
+      const queue: Array<boolean | null> = [block.terminal.optional];
+      loop: while (true) {
+        visited.add(testBlock.id);
+        const terminal = testBlock.terminal;
+        switch (terminal.kind) {
+          case 'branch': {
+            const isOptional = queue.pop();
+            CompilerError.simpleInvariant(isOptional !== undefined, {
+              reason:
+                'Expected an optional value for each optional test condition',
+              loc: terminal.test.loc,
+            });
+            if (isOptional != null) {
+              optionals.set(terminal.test.identifier.id, isOptional);
+            }
+            if (terminal.fallthrough === optionalTerminal.fallthrough) {
+              // found it
+              const consequent = fn.body.blocks.get(terminal.consequent)!;
+              const last = consequent.instructions.at(-1);
+              if (last !== undefined && last.value.kind === 'StoreLocal') {
+                if (isOptional != null) {
+                  optionals.set(last.value.value.identifier.id, isOptional);
+                }
+              }
+              break loop;
+            } else {
+              testBlock = fn.body.blocks.get(terminal.fallthrough)!;
+            }
+            break;
+          }
+          case 'optional': {
+            queue.push(terminal.optional);
+            testBlock = fn.body.blocks.get(terminal.test)!;
+            break;
+          }
+          case 'logical':
+          case 'ternary': {
+            queue.push(null);
+            testBlock = fn.body.blocks.get(terminal.test)!;
+            break;
+          }
+
+          case 'sequence': {
+            // Do we need sequence?? In any case, don't push to queue bc there is no corresponding branch terminal
+            testBlock = fn.body.blocks.get(terminal.block)!;
+            break;
+          }
+          default: {
+            CompilerError.simpleInvariant(false, {
+              reason: `Unexpected terminal in optional`,
+              loc: terminal.loc,
+            });
+          }
+        }
+      }
+      CompilerError.simpleInvariant(queue.length === 0, {
+        reason:
+          'Expected a matching number of conditional blocks and branch points',
+        loc: block.terminal.loc,
+      });
+    }
+  }
+  return optionals;
+}

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

@@ -242,7 +242,7 @@ export function validateNoDerivedComputationsInEffects_exp(
     iterationCount++;
     CompilerError.invariant(iterationCount < MAX_FIXPOINT_ITERATIONS, {
       reason:
-        '[ValidateNoDerivedComputationsInEffects] Fixpoint iteration failed to converge',
+        '[ValidateNoDerivedComputationsInEffects] Fixpoint iteration failed to converge.',
       description: `Fixpoint iteration exceeded ${MAX_FIXPOINT_ITERATIONS} iterations while tracking derivations. This suggests a cyclic dependency in the derivation cache.`,
       details: [
         {
@@ -388,7 +388,7 @@ function recordInstructionDerivations(
           dependencies: deps,
         });
       }
-    } else if (isUseStateType(lvalue.identifier) && value.args.length > 0) {
+    } else if (isUseStateType(lvalue.identifier)) {
       typeOfValue = 'fromState';
       context.derivationCache.addDerivationEntry(
         lvalue,

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/compile-files-with-exhaustive-deps-violation-in-effects.expect.md

@@ -0,0 +1,91 @@
+
+## Input
+
+```javascript
+// @validateExhaustiveMemoizationDependencies
+
+import {useMemo} from 'react';
+import {ValidateMemoization} from 'shared-runtime';
+
+function Component({x}) {
+  useEffect(
+    () => {
+      console.log(x);
+      // eslint-disable-next-line react-hooks/exhaustive-deps
+    },
+    [
+      /* intentionally missing deps */
+    ]
+  );
+
+  const memo = useMemo(() => {
+    return [x];
+  }, [x]);
+
+  return <ValidateMemoization inputs={[x]} output={memo} />;
+}
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @validateExhaustiveMemoizationDependencies
+
+import { useMemo } from "react";
+import { ValidateMemoization } from "shared-runtime";
+
+function Component(t0) {
+  const $ = _c(10);
+  const { x } = t0;
+  let t1;
+  if ($[0] !== x) {
+    t1 = () => {
+      console.log(x);
+    };
+    $[0] = x;
+    $[1] = t1;
+  } else {
+    t1 = $[1];
+  }
+  let t2;
+  if ($[2] === Symbol.for("react.memo_cache_sentinel")) {
+    t2 = [];
+    $[2] = t2;
+  } else {
+    t2 = $[2];
+  }
+  useEffect(t1, t2);
+  let t3;
+  if ($[3] !== x) {
+    t3 = [x];
+    $[3] = x;
+    $[4] = t3;
+  } else {
+    t3 = $[4];
+  }
+  const memo = t3;
+  let t4;
+  if ($[5] !== x) {
+    t4 = [x];
+    $[5] = x;
+    $[6] = t4;
+  } else {
+    t4 = $[6];
+  }
+  let t5;
+  if ($[7] !== memo || $[8] !== t4) {
+    t5 = <ValidateMemoization inputs={t4} output={memo} />;
+    $[7] = memo;
+    $[8] = t4;
+    $[9] = t5;
+  } else {
+    t5 = $[9];
+  }
+  return t5;
+}
+
+```
+      
+### Eval output
+(kind: exception) Fixture not implemented

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/compile-files-with-exhaustive-deps-violation-in-effects.js

@@ -0,0 +1,22 @@
+// @validateExhaustiveMemoizationDependencies
+
+import {useMemo} from 'react';
+import {ValidateMemoization} from 'shared-runtime';
+
+function Component({x}) {
+  useEffect(
+    () => {
+      console.log(x);
+      // eslint-disable-next-line react-hooks/exhaustive-deps
+    },
+    [
+      /* intentionally missing deps */
+    ]
+  );
+
+  const memo = useMemo(() => {
+    return [x];
+  }, [x]);
+
+  return <ValidateMemoization inputs={[x]} output={memo} />;
+}

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/effect-derived-computations/usestate-derived-from-prop-no-show-in-data-flow-tree.expect.md

@@ -64,6 +64,7 @@ function Component(t0) {
 ## Logs
 
 ```
+{"kind":"CompileError","detail":{"options":{"description":"Using an effect triggers an additional render which can hurt performance and user experience, potentially briefly showing stale values to the user\n\nThis setState call is setting a derived value that depends on the following reactive sources:\n\nState: [second]\n\nData Flow Tree:\n└── second (State)\n\nSee: https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state","category":"EffectDerivationsOfState","reason":"You might not need an effect. Derive values in render, not effects.","details":[{"kind":"error","loc":{"start":{"line":14,"column":4,"index":443},"end":{"line":14,"column":8,"index":447},"filename":"usestate-derived-from-prop-no-show-in-data-flow-tree.ts","identifierName":"setS"},"message":"This should be computed during render, not in an effect"}]}},"fnLoc":null}
 {"kind":"CompileSuccess","fnLoc":{"start":{"line":3,"column":0,"index":64},"end":{"line":18,"column":1,"index":500},"filename":"usestate-derived-from-prop-no-show-in-data-flow-tree.ts"},"fnName":"Component","memoSlots":5,"memoBlocks":2,"memoValues":3,"prunedMemoBlocks":0,"prunedMemoValues":0}
 ```
       

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

@@ -0,0 +1,109 @@
+
+## Input
+
+```javascript
+// @validateExhaustiveMemoizationDependencies
+import {useMemo} from 'react';
+import {Stringify} from 'shared-runtime';
+
+function Component({x, y, z}) {
+  const a = useMemo(() => {
+    return x?.y.z?.a;
+    // error: too precise
+  }, [x?.y.z?.a.b]);
+  const b = useMemo(() => {
+    return x.y.z?.a;
+    // ok, not our job to type check nullability
+  }, [x.y.z.a]);
+  const c = useMemo(() => {
+    return x?.y.z.a?.b;
+    // error: too precise
+  }, [x?.y.z.a?.b.z]);
+  const d = useMemo(() => {
+    return x?.y?.[(console.log(y), z?.b)];
+    // ok
+  }, [x?.y, y, z?.b]);
+  const e = useMemo(() => {
+    const e = [];
+    e.push(x);
+    return e;
+    // ok
+  }, [x]);
+  const f = useMemo(() => {
+    return [];
+    // error: unnecessary
+  }, [x, y.z, z?.y?.a, UNUSED_GLOBAL]);
+  const ref1 = useRef(null);
+  const ref2 = useRef(null);
+  const ref = z ? ref1 : ref2;
+  const cb = useMemo(() => {
+    return () => {
+      return ref.current;
+    };
+    // error: ref is a stable type but reactive
+  }, []);
+  return <Stringify results={[a, b, c, d, e, f, cb]} />;
+}
+
+```
+
+
+## Error
+
+```
+Found 4 errors:
+
+Error: Found non-exhaustive dependencies
+
+Missing dependencies can cause a value not to update when those inputs change, resulting in stale UI.
+
+error.invalid-exhaustive-deps.ts:7:11
+   5 | function Component({x, y, z}) {
+   6 |   const a = useMemo(() => {
+>  7 |     return x?.y.z?.a;
+     |            ^^^^^^^^^ Missing dependency `x?.y.z?.a`
+   8 |     // error: too precise
+   9 |   }, [x?.y.z?.a.b]);
+  10 |   const b = useMemo(() => {
+
+Error: Found non-exhaustive dependencies
+
+Missing dependencies can cause a value not to update when those inputs change, resulting in stale UI.
+
+error.invalid-exhaustive-deps.ts:15:11
+  13 |   }, [x.y.z.a]);
+  14 |   const c = useMemo(() => {
+> 15 |     return x?.y.z.a?.b;
+     |            ^^^^^^^^^^^ Missing dependency `x?.y.z.a?.b`
+  16 |     // error: too precise
+  17 |   }, [x?.y.z.a?.b.z]);
+  18 |   const d = useMemo(() => {
+
+Error: Found unnecessary memoization dependencies
+
+Unnecessary dependencies can cause a value to update more often than necessary, which can cause effects to run more than expected.
+
+error.invalid-exhaustive-deps.ts:31:5
+  29 |     return [];
+  30 |     // error: unnecessary
+> 31 |   }, [x, y.z, z?.y?.a, UNUSED_GLOBAL]);
+     |      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Unnecessary dependencies `x`, `y.z`, `z?.y?.a`, `UNUSED_GLOBAL`
+  32 |   const ref1 = useRef(null);
+  33 |   const ref2 = useRef(null);
+  34 |   const ref = z ? ref1 : ref2;
+
+Error: Found non-exhaustive dependencies
+
+Missing dependencies can cause a value not to update when those inputs change, resulting in stale UI.
+
+error.invalid-exhaustive-deps.ts:37:13
+  35 |   const cb = useMemo(() => {
+  36 |     return () => {
+> 37 |       return ref.current;
+     |              ^^^ Missing dependency `ref`. Refs, setState functions, and other "stable" values generally do not need to be added as dependencies, but this variable may change over time to point to different values
+  38 |     };
+  39 |     // error: ref is a stable type but reactive
+  40 |   }, []);
+```
+          
+      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-exhaustive-deps.js

@@ -0,0 +1,42 @@
+// @validateExhaustiveMemoizationDependencies
+import {useMemo} from 'react';
+import {Stringify} from 'shared-runtime';
+
+function Component({x, y, z}) {
+  const a = useMemo(() => {
+    return x?.y.z?.a;
+    // error: too precise
+  }, [x?.y.z?.a.b]);
+  const b = useMemo(() => {
+    return x.y.z?.a;
+    // ok, not our job to type check nullability
+  }, [x.y.z.a]);
+  const c = useMemo(() => {
+    return x?.y.z.a?.b;
+    // error: too precise
+  }, [x?.y.z.a?.b.z]);
+  const d = useMemo(() => {
+    return x?.y?.[(console.log(y), z?.b)];
+    // ok
+  }, [x?.y, y, z?.b]);
+  const e = useMemo(() => {
+    const e = [];
+    e.push(x);
+    return e;
+    // ok
+  }, [x]);
+  const f = useMemo(() => {
+    return [];
+    // error: unnecessary
+  }, [x, y.z, z?.y?.a, UNUSED_GLOBAL]);
+  const ref1 = useRef(null);
+  const ref2 = useRef(null);
+  const ref = z ? ref1 : ref2;
+  const cb = useMemo(() => {
+    return () => {
+      return ref.current;
+    };
+    // error: ref is a stable type but reactive
+  }, []);
+  return <Stringify results={[a, b, c, d, e, f, cb]} />;
+}

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/exhaustive-deps-allow-nonreactive-stable-types-as-extra-deps.expect.md

@@ -0,0 +1,100 @@
+
+## Input
+
+```javascript
+// @validateExhaustiveMemoizationDependencies
+import {
+  useCallback,
+  useTransition,
+  useState,
+  useOptimistic,
+  useActionState,
+  useRef,
+  useReducer,
+} from 'react';
+
+function useFoo() {
+  const [s, setState] = useState();
+  const ref = useRef(null);
+  const [t, startTransition] = useTransition();
+  const [u, addOptimistic] = useOptimistic();
+  const [v, dispatch] = useReducer(() => {}, null);
+  const [isPending, dispatchAction] = useActionState(() => {}, null);
+
+  return useCallback(() => {
+    dispatch();
+    startTransition(() => {});
+    addOptimistic();
+    setState(null);
+    dispatchAction();
+    ref.current = true;
+  }, [
+    // intentionally adding unnecessary deps on nonreactive stable values
+    // to check that they're allowed
+    dispatch,
+    startTransition,
+    addOptimistic,
+    setState,
+    dispatchAction,
+    ref,
+  ]);
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useFoo,
+  params: [],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @validateExhaustiveMemoizationDependencies
+import {
+  useCallback,
+  useTransition,
+  useState,
+  useOptimistic,
+  useActionState,
+  useRef,
+  useReducer,
+} from "react";
+
+function useFoo() {
+  const $ = _c(1);
+  const [, setState] = useState();
+  const ref = useRef(null);
+  const [, startTransition] = useTransition();
+  const [, addOptimistic] = useOptimistic();
+  const [, dispatch] = useReducer(_temp, null);
+  const [, dispatchAction] = useActionState(_temp2, null);
+  let t0;
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+    t0 = () => {
+      dispatch();
+      startTransition(_temp3);
+      addOptimistic();
+      setState(null);
+      dispatchAction();
+      ref.current = true;
+    };
+    $[0] = t0;
+  } else {
+    t0 = $[0];
+  }
+  return t0;
+}
+function _temp3() {}
+function _temp2() {}
+function _temp() {}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useFoo,
+  params: [],
+};
+
+```
+      
+### Eval output
+(kind: ok) "[[ function params=0 ]]"

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/exhaustive-deps-allow-nonreactive-stable-types-as-extra-deps.js

@@ -0,0 +1,42 @@
+// @validateExhaustiveMemoizationDependencies
+import {
+  useCallback,
+  useTransition,
+  useState,
+  useOptimistic,
+  useActionState,
+  useRef,
+  useReducer,
+} from 'react';
+
+function useFoo() {
+  const [s, setState] = useState();
+  const ref = useRef(null);
+  const [t, startTransition] = useTransition();
+  const [u, addOptimistic] = useOptimistic();
+  const [v, dispatch] = useReducer(() => {}, null);
+  const [isPending, dispatchAction] = useActionState(() => {}, null);
+
+  return useCallback(() => {
+    dispatch();
+    startTransition(() => {});
+    addOptimistic();
+    setState(null);
+    dispatchAction();
+    ref.current = true;
+  }, [
+    // intentionally adding unnecessary deps on nonreactive stable values
+    // to check that they're allowed
+    dispatch,
+    startTransition,
+    addOptimistic,
+    setState,
+    dispatchAction,
+    ref,
+  ]);
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useFoo,
+  params: [],
+};

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

@@ -0,0 +1,159 @@
+
+## Input
+
+```javascript
+// @validateExhaustiveMemoizationDependencies
+import {useMemo} from 'react';
+import {makeObject_Primitives, Stringify} from 'shared-runtime';
+
+function useHook1(x) {
+  return useMemo(() => {
+    return x?.y.z?.a;
+  }, [x?.y.z?.a]);
+}
+function useHook2(x) {
+  useMemo(() => {
+    return x.y.z?.a;
+  }, [x.y.z?.a]);
+}
+function useHook3(x) {
+  return useMemo(() => {
+    return x?.y.z.a?.b;
+  }, [x?.y.z.a?.b]);
+}
+function useHook4(x, y, z) {
+  return useMemo(() => {
+    return x?.y?.[(console.log(y), z?.b)];
+  }, [x?.y, y, z?.b]);
+}
+function useHook5(x) {
+  return useMemo(() => {
+    const e = [];
+    const local = makeObject_Primitives(x);
+    const fn = () => {
+      e.push(local);
+    };
+    fn();
+    return e;
+  }, [x]);
+}
+function useHook6(x) {
+  return useMemo(() => {
+    const f = [];
+    f.push(x.y.z);
+    f.push(x.y);
+    f.push(x);
+    return f;
+  }, [x]);
+}
+
+function Component({x, y, z}) {
+  const a = useHook1(x);
+  const b = useHook2(x);
+  const c = useHook3(x);
+  const d = useHook4(x, y, z);
+  const e = useHook5(x);
+  const f = useHook6(x);
+  return <Stringify results={[a, b, c, d, e, f]} />;
+}
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @validateExhaustiveMemoizationDependencies
+import { useMemo } from "react";
+import { makeObject_Primitives, Stringify } from "shared-runtime";
+
+function useHook1(x) {
+  x?.y.z?.a;
+  return x?.y.z?.a;
+}
+
+function useHook2(x) {
+  x.y.z?.a;
+}
+
+function useHook3(x) {
+  x?.y.z.a?.b;
+  return x?.y.z.a?.b;
+}
+
+function useHook4(x, y, z) {
+  x?.y;
+  z?.b;
+  return x?.y?.[(console.log(y), z?.b)];
+}
+
+function useHook5(x) {
+  const $ = _c(2);
+  let e;
+  if ($[0] !== x) {
+    e = [];
+    const local = makeObject_Primitives(x);
+    const fn = () => {
+      e.push(local);
+    };
+
+    fn();
+    $[0] = x;
+    $[1] = e;
+  } else {
+    e = $[1];
+  }
+  return e;
+}
+
+function useHook6(x) {
+  const $ = _c(2);
+  let f;
+  if ($[0] !== x) {
+    f = [];
+    f.push(x.y.z);
+    f.push(x.y);
+    f.push(x);
+    $[0] = x;
+    $[1] = f;
+  } else {
+    f = $[1];
+  }
+  return f;
+}
+
+function Component(t0) {
+  const $ = _c(7);
+  const { x, y, z } = t0;
+  const a = useHook1(x);
+  const b = useHook2(x);
+  const c = useHook3(x);
+  const d = useHook4(x, y, z);
+  const e = useHook5(x);
+  const f = useHook6(x);
+  let t1;
+  if (
+    $[0] !== a ||
+    $[1] !== b ||
+    $[2] !== c ||
+    $[3] !== d ||
+    $[4] !== e ||
+    $[5] !== f
+  ) {
+    t1 = <Stringify results={[a, b, c, d, e, f]} />;
+    $[0] = a;
+    $[1] = b;
+    $[2] = c;
+    $[3] = d;
+    $[4] = e;
+    $[5] = f;
+    $[6] = t1;
+  } else {
+    t1 = $[6];
+  }
+  return t1;
+}
+
+```
+      
+### Eval output
+(kind: exception) Fixture not implemented

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/exhaustive-deps.js

@@ -0,0 +1,54 @@
+// @validateExhaustiveMemoizationDependencies
+import {useMemo} from 'react';
+import {makeObject_Primitives, Stringify} from 'shared-runtime';
+
+function useHook1(x) {
+  return useMemo(() => {
+    return x?.y.z?.a;
+  }, [x?.y.z?.a]);
+}
+function useHook2(x) {
+  useMemo(() => {
+    return x.y.z?.a;
+  }, [x.y.z?.a]);
+}
+function useHook3(x) {
+  return useMemo(() => {
+    return x?.y.z.a?.b;
+  }, [x?.y.z.a?.b]);
+}
+function useHook4(x, y, z) {
+  return useMemo(() => {
+    return x?.y?.[(console.log(y), z?.b)];
+  }, [x?.y, y, z?.b]);
+}
+function useHook5(x) {
+  return useMemo(() => {
+    const e = [];
+    const local = makeObject_Primitives(x);
+    const fn = () => {
+      e.push(local);
+    };
+    fn();
+    return e;
+  }, [x]);
+}
+function useHook6(x) {
+  return useMemo(() => {
+    const f = [];
+    f.push(x.y.z);
+    f.push(x.y);
+    f.push(x);
+    return f;
+  }, [x]);
+}
+
+function Component({x, y, z}) {
+  const a = useHook1(x);
+  const b = useHook2(x);
+  const c = useHook3(x);
+  const d = useHook4(x, y, z);
+  const e = useHook5(x);
+  const f = useHook6(x);
+  return <Stringify results={[a, b, c, d, e, f]} />;
+}

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

@@ -2,7 +2,7 @@
 ## Input
 
 ```javascript
-// @dynamicGating:{"source":"shared-runtime"} @noEmit
+// @dynamicGating:{"source":"shared-runtime"} @outputMode:"lint"
 
 function Foo() {
   'use memo if(getTrue)';
@@ -19,7 +19,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-// @dynamicGating:{"source":"shared-runtime"} @noEmit
+// @dynamicGating:{"source":"shared-runtime"} @outputMode:"lint"
 
 function Foo() {
   "use memo if(getTrue)";

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/gating/dynamic-gating-noemit.js

@@ -1,4 +1,4 @@
-// @dynamicGating:{"source":"shared-runtime"} @noEmit
+// @dynamicGating:{"source":"shared-runtime"} @outputMode:"lint"
 
 function Foo() {
   'use memo if(getTrue)';

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

@@ -1,66 +0,0 @@
-
-## Input
-
-```javascript
-// @inferEffectDependencies @noEmit @panicThreshold:"none" @loggerTestOnly
-import {print} from 'shared-runtime';
-import useEffectWrapper from 'useEffectWrapper';
-import {AUTODEPS} from 'react';
-
-function Foo({propVal}) {
-  const arr = [propVal];
-  useEffectWrapper(() => print(arr), AUTODEPS);
-
-  const arr2 = [];
-  useEffectWrapper(() => arr2.push(propVal), AUTODEPS);
-  arr2.push(2);
-  return {arr, arr2};
-}
-
-export const FIXTURE_ENTRYPOINT = {
-  fn: Foo,
-  params: [{propVal: 1}],
-  sequentialRenders: [{propVal: 1}, {propVal: 2}],
-};
-
-```
-
-## Code
-
-```javascript
-// @inferEffectDependencies @noEmit @panicThreshold:"none" @loggerTestOnly
-import { print } from "shared-runtime";
-import useEffectWrapper from "useEffectWrapper";
-import { AUTODEPS } from "react";
-
-function Foo({ propVal }) {
-  const arr = [propVal];
-  useEffectWrapper(() => print(arr), AUTODEPS);
-
-  const arr2 = [];
-  useEffectWrapper(() => arr2.push(propVal), AUTODEPS);
-  arr2.push(2);
-  return { arr, arr2 };
-}
-
-export const FIXTURE_ENTRYPOINT = {
-  fn: Foo,
-  params: [{ propVal: 1 }],
-  sequentialRenders: [{ propVal: 1 }, { propVal: 2 }],
-};
-
-```
-
-## 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":{"category":"Immutability","reason":"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":"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}
-```
-      
-### Eval output
-(kind: ok) {"arr":[1],"arr2":[2]}
-{"arr":[2],"arr2":[2]}
-logs: [[ 1 ],[ 2 ]]

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/infer-effect-dependencies/retry-lint-comparison/error.infer-effect-deps-with-rule-violation--lint.expect.md

@@ -0,0 +1,48 @@
+
+## Input
+
+```javascript
+// @inferEffectDependencies @outputMode:"lint" @panicThreshold:"none"
+import {print} from 'shared-runtime';
+import useEffectWrapper from 'useEffectWrapper';
+import {AUTODEPS} from 'react';
+
+function Foo({propVal}) {
+  const arr = [propVal];
+  useEffectWrapper(() => print(arr), AUTODEPS);
+
+  const arr2 = [];
+  useEffectWrapper(() => arr2.push(propVal), AUTODEPS);
+  arr2.push(2);
+  return {arr, arr2};
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Foo,
+  params: [{propVal: 1}],
+  sequentialRenders: [{propVal: 1}, {propVal: 2}],
+};
+
+```
+
+
+## Error
+
+```
+Found 1 error:
+
+Error: Cannot infer dependencies of this effect. This will break your build!
+
+To resolve, either pass a dependency array or fix reported compiler bailout diagnostics.
+
+error.infer-effect-deps-with-rule-violation--lint.ts:8:2
+   6 | function Foo({propVal}) {
+   7 |   const arr = [propVal];
+>  8 |   useEffectWrapper(() => print(arr), AUTODEPS);
+     |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Cannot infer dependencies
+   9 |
+  10 |   const arr2 = [];
+  11 |   useEffectWrapper(() => arr2.push(propVal), AUTODEPS);
+```
+          
+      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/infer-effect-dependencies/retry-lint-comparison/error.infer-effect-deps-with-rule-violation--lint.js

@@ -1,4 +1,4 @@
-// @inferEffectDependencies @noEmit @panicThreshold:"none" @loggerTestOnly
+// @inferEffectDependencies @outputMode:"lint" @panicThreshold:"none"
 import {print} from 'shared-runtime';
 import useEffectWrapper from 'useEffectWrapper';
 import {AUTODEPS} from 'react';

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/infer-effect-dependencies/retry-lint-comparison/error.infer-effect-deps-with-rule-violation-use-memo-opt-in--lint.expect.md

@@ -0,0 +1,49 @@
+
+## Input
+
+```javascript
+// @inferEffectDependencies @outputMode:"lint" @panicThreshold:"none"
+import {print} from 'shared-runtime';
+import useEffectWrapper from 'useEffectWrapper';
+import {AUTODEPS} from 'react';
+
+function Foo({propVal}) {
+  'use memo';
+  const arr = [propVal];
+  useEffectWrapper(() => print(arr), AUTODEPS);
+
+  const arr2 = [];
+  useEffectWrapper(() => arr2.push(propVal), AUTODEPS);
+  arr2.push(2);
+  return {arr, arr2};
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Foo,
+  params: [{propVal: 1}],
+  sequentialRenders: [{propVal: 1}, {propVal: 2}],
+};
+
+```
+
+
+## Error
+
+```
+Found 1 error:
+
+Error: Cannot infer dependencies of this effect. This will break your build!
+
+To resolve, either pass a dependency array or fix reported compiler bailout diagnostics.
+
+error.infer-effect-deps-with-rule-violation-use-memo-opt-in--lint.ts:9:2
+   7 |   'use memo';
+   8 |   const arr = [propVal];
+>  9 |   useEffectWrapper(() => print(arr), AUTODEPS);
+     |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Cannot infer dependencies
+  10 |
+  11 |   const arr2 = [];
+  12 |   useEffectWrapper(() => arr2.push(propVal), AUTODEPS);
+```
+          
+      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/infer-effect-dependencies/retry-lint-comparison/error.infer-effect-deps-with-rule-violation-use-memo-opt-in--lint.js

@@ -1,7 +1,7 @@
-// @compilationMode:"all" @inferEffectDependencies @panicThreshold:"none" @noEmit
+// @inferEffectDependencies @outputMode:"lint" @panicThreshold:"none"
 import {print} from 'shared-runtime';
-import {AUTODEPS} from 'react';
 import useEffectWrapper from 'useEffectWrapper';
+import {AUTODEPS} from 'react';
 
 function Foo({propVal}) {
   'use memo';
@@ -11,7 +11,6 @@ function Foo({propVal}) {
   const arr2 = [];
   useEffectWrapper(() => arr2.push(propVal), AUTODEPS);
   arr2.push(2);
-
   return {arr, arr2};
 }
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/infer-effect-dependencies/retry-lint-comparison/infer-effect-deps-with-rule-violation--compile.expect.md

@@ -0,0 +1,58 @@
+
+## Input
+
+```javascript
+// @inferEffectDependencies @panicThreshold:"none"
+import {print} from 'shared-runtime';
+import useEffectWrapper from 'useEffectWrapper';
+import {AUTODEPS} from 'react';
+
+function Foo({propVal}) {
+  const arr = [propVal];
+  useEffectWrapper(() => print(arr), AUTODEPS);
+
+  const arr2 = [];
+  useEffectWrapper(() => arr2.push(propVal), AUTODEPS);
+  arr2.push(2);
+  return {arr, arr2};
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Foo,
+  params: [{propVal: 1}],
+  sequentialRenders: [{propVal: 1}, {propVal: 2}],
+};
+
+```
+
+## Code
+
+```javascript
+// @inferEffectDependencies @panicThreshold:"none"
+import { print } from "shared-runtime";
+import useEffectWrapper from "useEffectWrapper";
+import { AUTODEPS } from "react";
+
+function Foo(t0) {
+  const { propVal } = t0;
+  const arr = [propVal];
+  useEffectWrapper(() => print(arr), [arr]);
+
+  const arr2 = [];
+  useEffectWrapper(() => arr2.push(propVal), [arr2, propVal]);
+  arr2.push(2);
+  return { arr, arr2 };
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Foo,
+  params: [{ propVal: 1 }],
+  sequentialRenders: [{ propVal: 1 }, { propVal: 2 }],
+};
+
+```
+      
+### Eval output
+(kind: ok) {"arr":[1],"arr2":[2]}
+{"arr":[2],"arr2":[2]}
+logs: [[ 1 ],[ 2 ]]

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/infer-effect-dependencies/retry-lint-comparison/infer-effect-deps-with-rule-violation--compile.js

@@ -1,4 +1,4 @@
-// @inferEffectDependencies @noEmit @panicThreshold:"none" @loggerTestOnly @enableNewMutationAliasingModel
+// @inferEffectDependencies @panicThreshold:"none"
 import {print} from 'shared-runtime';
 import useEffectWrapper from 'useEffectWrapper';
 import {AUTODEPS} from 'react';

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/infer-effect-dependencies/retry-lint-comparison/infer-effect-deps-with-rule-violation-use-memo-opt-in--compile.expect.md

@@ -2,10 +2,10 @@
 ## Input
 
 ```javascript
-// @compilationMode:"all" @inferEffectDependencies @panicThreshold:"none" @noEmit
+// @inferEffectDependencies @panicThreshold:"none"
 import {print} from 'shared-runtime';
-import {AUTODEPS} from 'react';
 import useEffectWrapper from 'useEffectWrapper';
+import {AUTODEPS} from 'react';
 
 function Foo({propVal}) {
   'use memo';
@@ -15,7 +15,6 @@ function Foo({propVal}) {
   const arr2 = [];
   useEffectWrapper(() => arr2.push(propVal), AUTODEPS);
   arr2.push(2);
-
   return {arr, arr2};
 }
 
@@ -30,20 +29,21 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-// @compilationMode:"all" @inferEffectDependencies @panicThreshold:"none" @noEmit
+// @inferEffectDependencies @panicThreshold:"none"
 import { print } from "shared-runtime";
-import { AUTODEPS } from "react";
 import useEffectWrapper from "useEffectWrapper";
+import { AUTODEPS } from "react";
 
-function Foo({ propVal }) {
+function Foo(t0) {
   "use memo";
+  const { propVal } = t0;
+
   const arr = [propVal];
-  useEffectWrapper(() => print(arr), AUTODEPS);
+  useEffectWrapper(() => print(arr), [arr]);
 
   const arr2 = [];
-  useEffectWrapper(() => arr2.push(propVal), AUTODEPS);
+  useEffectWrapper(() => arr2.push(propVal), [arr2, propVal]);
   arr2.push(2);
-
   return { arr, arr2 };
 }
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/infer-effect-dependencies/retry-lint-comparison/infer-effect-deps-with-rule-violation-use-memo-opt-in--compile.js

@@ -0,0 +1,21 @@
+// @inferEffectDependencies @panicThreshold:"none"
+import {print} from 'shared-runtime';
+import useEffectWrapper from 'useEffectWrapper';
+import {AUTODEPS} from 'react';
+
+function Foo({propVal}) {
+  'use memo';
+  const arr = [propVal];
+  useEffectWrapper(() => print(arr), AUTODEPS);
+
+  const arr2 = [];
+  useEffectWrapper(() => arr2.push(propVal), AUTODEPS);
+  arr2.push(2);
+  return {arr, arr2};
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Foo,
+  params: [{propVal: 1}],
+  sequentialRenders: [{propVal: 1}, {propVal: 2}],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/infer-effect-dependencies/retry-lint-comparison/lint-repro.expect.md

@@ -2,7 +2,7 @@
 ## Input
 
 ```javascript
-// @inferEffectDependencies @noEmit
+// @inferEffectDependencies @outputMode:"lint"
 import {print} from 'shared-runtime';
 import useEffectWrapper from 'useEffectWrapper';
 import {AUTODEPS} from 'react';
@@ -17,7 +17,7 @@ function ReactiveVariable({propVal}) {
 ## Code
 
 ```javascript
-// @inferEffectDependencies @noEmit
+// @inferEffectDependencies @outputMode:"lint"
 import { print } from "shared-runtime";
 import useEffectWrapper from "useEffectWrapper";
 import { AUTODEPS } from "react";

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/infer-effect-dependencies/retry-lint-comparison/lint-repro.js

@@ -1,4 +1,4 @@
-// @inferEffectDependencies @noEmit
+// @inferEffectDependencies @outputMode:"lint"
 import {print} from 'shared-runtime';
 import useEffectWrapper from 'useEffectWrapper';
 import {AUTODEPS} from 'react';

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

@@ -1,66 +0,0 @@
-
-## Input
-
-```javascript
-// @inferEffectDependencies @noEmit @panicThreshold:"none" @loggerTestOnly @enableNewMutationAliasingModel
-import {print} from 'shared-runtime';
-import useEffectWrapper from 'useEffectWrapper';
-import {AUTODEPS} from 'react';
-
-function Foo({propVal}) {
-  const arr = [propVal];
-  useEffectWrapper(() => print(arr), AUTODEPS);
-
-  const arr2 = [];
-  useEffectWrapper(() => arr2.push(propVal), AUTODEPS);
-  arr2.push(2);
-  return {arr, arr2};
-}
-
-export const FIXTURE_ENTRYPOINT = {
-  fn: Foo,
-  params: [{propVal: 1}],
-  sequentialRenders: [{propVal: 1}, {propVal: 2}],
-};
-
-```
-
-## Code
-
-```javascript
-// @inferEffectDependencies @noEmit @panicThreshold:"none" @loggerTestOnly @enableNewMutationAliasingModel
-import { print } from "shared-runtime";
-import useEffectWrapper from "useEffectWrapper";
-import { AUTODEPS } from "react";
-
-function Foo({ propVal }) {
-  const arr = [propVal];
-  useEffectWrapper(() => print(arr), AUTODEPS);
-
-  const arr2 = [];
-  useEffectWrapper(() => arr2.push(propVal), AUTODEPS);
-  arr2.push(2);
-  return { arr, arr2 };
-}
-
-export const FIXTURE_ENTRYPOINT = {
-  fn: Foo,
-  params: [{ propVal: 1 }],
-  sequentialRenders: [{ propVal: 1 }, { propVal: 2 }],
-};
-
-```
-
-## 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":{"category":"Immutability","reason":"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":"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}
-```
-      
-### Eval output
-(kind: ok) {"arr":[1],"arr2":[2]}
-{"arr":[2],"arr2":[2]}
-logs: [[ 1 ],[ 2 ]]

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/ssr/optimize-ssr.expect.md

@@ -0,0 +1,60 @@
+
+## Input
+
+```javascript
+// @enableOptimizeForSSR
+function Component() {
+  const [state, setState] = useState(0);
+  const ref = useRef(null);
+  const onChange = e => {
+    setState(e.target.value);
+  };
+  useEffect(() => {
+    log(ref.current.value);
+  });
+  return <input value={state} onChange={onChange} ref={ref} />;
+}
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @enableOptimizeForSSR
+function Component() {
+  const $ = _c(4);
+  const [state, setState] = useState(0);
+  const ref = useRef(null);
+  let t0;
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+    t0 = (e) => {
+      setState(e.target.value);
+    };
+    $[0] = t0;
+  } else {
+    t0 = $[0];
+  }
+  const onChange = t0;
+  let t1;
+  if ($[1] === Symbol.for("react.memo_cache_sentinel")) {
+    t1 = () => {
+      log(ref.current.value);
+    };
+    $[1] = t1;
+  } else {
+    t1 = $[1];
+  }
+  useEffect(t1);
+  let t2;
+  if ($[2] !== state) {
+    t2 = <input value={state} onChange={onChange} ref={ref} />;
+    $[2] = state;
+    $[3] = t2;
+  } else {
+    t2 = $[3];
+  }
+  return t2;
+}
+
+```
+      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/ssr/optimize-ssr.js

@@ -0,0 +1,12 @@
+// @enableOptimizeForSSR
+function Component() {
+  const [state, setState] = useState(0);
+  const ref = useRef(null);
+  const onChange = e => {
+    setState(e.target.value);
+  };
+  useEffect(() => {
+    log(ref.current.value);
+  });
+  return <input value={state} onChange={onChange} ref={ref} />;
+}

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/ssr/ssr-infer-event-handlers-from-setState.expect.md

@@ -0,0 +1,64 @@
+
+## Input
+
+```javascript
+// @enableOptimizeForSSR
+function Component() {
+  const [state, setState] = useState(0);
+  const ref = useRef(null);
+  const onChange = e => {
+    // The known setState call allows us to infer this as an event handler
+    // and prune it
+    setState(e.target.value);
+  };
+  useEffect(() => {
+    log(ref.current.value);
+  });
+  return <CustomInput value={state} onChange={onChange} ref={ref} />;
+}
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @enableOptimizeForSSR
+function Component() {
+  const $ = _c(4);
+  const [state, setState] = useState(0);
+  const ref = useRef(null);
+  let t0;
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+    t0 = (e) => {
+      setState(e.target.value);
+    };
+    $[0] = t0;
+  } else {
+    t0 = $[0];
+  }
+  const onChange = t0;
+  let t1;
+  if ($[1] === Symbol.for("react.memo_cache_sentinel")) {
+    t1 = () => {
+      log(ref.current.value);
+    };
+    $[1] = t1;
+  } else {
+    t1 = $[1];
+  }
+  useEffect(t1);
+  let t2;
+  if ($[2] !== state) {
+    t2 = <CustomInput value={state} onChange={onChange} ref={ref} />;
+    $[2] = state;
+    $[3] = t2;
+  } else {
+    t2 = $[3];
+  }
+  return t2;
+}
+
+```
+      
+### Eval output
+(kind: exception) Fixture not implemented

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/ssr/ssr-infer-event-handlers-from-setState.js

@@ -0,0 +1,14 @@
+// @enableOptimizeForSSR
+function Component() {
+  const [state, setState] = useState(0);
+  const ref = useRef(null);
+  const onChange = e => {
+    // The known setState call allows us to infer this as an event handler
+    // and prune it
+    setState(e.target.value);
+  };
+  useEffect(() => {
+    log(ref.current.value);
+  });
+  return <CustomInput value={state} onChange={onChange} ref={ref} />;
+}

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/ssr/ssr-infer-event-handlers-from-startTransition.expect.md

@@ -0,0 +1,70 @@
+
+## Input
+
+```javascript
+// @enableOptimizeForSSR
+function Component() {
+  const [, startTransition] = useTransition();
+  const [state, setState] = useState(0);
+  const ref = useRef(null);
+  const onChange = e => {
+    // The known startTransition call allows us to infer this as an event handler
+    // and prune it
+    startTransition(() => {
+      setState.call(null, e.target.value);
+    });
+  };
+  useEffect(() => {
+    log(ref.current.value);
+  });
+  return <CustomInput value={state} onChange={onChange} ref={ref} />;
+}
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @enableOptimizeForSSR
+function Component() {
+  const $ = _c(4);
+  const [, startTransition] = useTransition();
+  const [state, setState] = useState(0);
+  const ref = useRef(null);
+  let t0;
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+    t0 = (e) => {
+      startTransition(() => {
+        setState.call(null, e.target.value);
+      });
+    };
+    $[0] = t0;
+  } else {
+    t0 = $[0];
+  }
+  const onChange = t0;
+  let t1;
+  if ($[1] === Symbol.for("react.memo_cache_sentinel")) {
+    t1 = () => {
+      log(ref.current.value);
+    };
+    $[1] = t1;
+  } else {
+    t1 = $[1];
+  }
+  useEffect(t1);
+  let t2;
+  if ($[2] !== state) {
+    t2 = <CustomInput value={state} onChange={onChange} ref={ref} />;
+    $[2] = state;
+    $[3] = t2;
+  } else {
+    t2 = $[3];
+  }
+  return t2;
+}
+
+```
+      
+### Eval output
+(kind: exception) Fixture not implemented

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/ssr/ssr-infer-event-handlers-from-startTransition.js

@@ -0,0 +1,17 @@
+// @enableOptimizeForSSR
+function Component() {
+  const [, startTransition] = useTransition();
+  const [state, setState] = useState(0);
+  const ref = useRef(null);
+  const onChange = e => {
+    // The known startTransition call allows us to infer this as an event handler
+    // and prune it
+    startTransition(() => {
+      setState.call(null, e.target.value);
+    });
+  };
+  useEffect(() => {
+    log(ref.current.value);
+  });
+  return <CustomInput value={state} onChange={onChange} ref={ref} />;
+}

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/ssr/ssr-use-reducer-initializer.expect.md

@@ -0,0 +1,75 @@
+
+## Input
+
+```javascript
+// @enableOptimizeForSSR
+
+import {useReducer} from 'react';
+
+const initializer = x => x;
+
+function Component() {
+  const [state, dispatch] = useReducer((_, next) => next, 0, initializer);
+  const ref = useRef(null);
+  const onChange = e => {
+    dispatch(e.target.value);
+  };
+  useEffect(() => {
+    log(ref.current.value);
+  });
+  return <input value={state} onChange={onChange} ref={ref} />;
+}
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @enableOptimizeForSSR
+
+import { useReducer } from "react";
+
+const initializer = (x) => {
+  return x;
+};
+
+function Component() {
+  const $ = _c(4);
+  const [state, dispatch] = useReducer(_temp, 0, initializer);
+  const ref = useRef(null);
+  let t0;
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+    t0 = (e) => {
+      dispatch(e.target.value);
+    };
+    $[0] = t0;
+  } else {
+    t0 = $[0];
+  }
+  const onChange = t0;
+  let t1;
+  if ($[1] === Symbol.for("react.memo_cache_sentinel")) {
+    t1 = () => {
+      log(ref.current.value);
+    };
+    $[1] = t1;
+  } else {
+    t1 = $[1];
+  }
+  useEffect(t1);
+  let t2;
+  if ($[2] !== state) {
+    t2 = <input value={state} onChange={onChange} ref={ref} />;
+    $[2] = state;
+    $[3] = t2;
+  } else {
+    t2 = $[3];
+  }
+  return t2;
+}
+function _temp(_, next) {
+  return next;
+}
+
+```
+      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/ssr/ssr-use-reducer-initializer.js

@@ -0,0 +1,17 @@
+// @enableOptimizeForSSR
+
+import {useReducer} from 'react';
+
+const initializer = x => x;
+
+function Component() {
+  const [state, dispatch] = useReducer((_, next) => next, 0, initializer);
+  const ref = useRef(null);
+  const onChange = e => {
+    dispatch(e.target.value);
+  };
+  useEffect(() => {
+    log(ref.current.value);
+  });
+  return <input value={state} onChange={onChange} ref={ref} />;
+}

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/ssr/ssr-use-reducer.expect.md

@@ -0,0 +1,69 @@
+
+## Input
+
+```javascript
+// @enableOptimizeForSSR
+
+import {useReducer} from 'react';
+
+function Component() {
+  const [state, dispatch] = useReducer((_, next) => next, 0);
+  const ref = useRef(null);
+  const onChange = e => {
+    dispatch(e.target.value);
+  };
+  useEffect(() => {
+    log(ref.current.value);
+  });
+  return <input value={state} onChange={onChange} ref={ref} />;
+}
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @enableOptimizeForSSR
+
+import { useReducer } from "react";
+
+function Component() {
+  const $ = _c(4);
+  const [state, dispatch] = useReducer(_temp, 0);
+  const ref = useRef(null);
+  let t0;
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+    t0 = (e) => {
+      dispatch(e.target.value);
+    };
+    $[0] = t0;
+  } else {
+    t0 = $[0];
+  }
+  const onChange = t0;
+  let t1;
+  if ($[1] === Symbol.for("react.memo_cache_sentinel")) {
+    t1 = () => {
+      log(ref.current.value);
+    };
+    $[1] = t1;
+  } else {
+    t1 = $[1];
+  }
+  useEffect(t1);
+  let t2;
+  if ($[2] !== state) {
+    t2 = <input value={state} onChange={onChange} ref={ref} />;
+    $[2] = state;
+    $[3] = t2;
+  } else {
+    t2 = $[3];
+  }
+  return t2;
+}
+function _temp(_, next) {
+  return next;
+}
+
+```
+      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/ssr/ssr-use-reducer.js

@@ -0,0 +1,15 @@
+// @enableOptimizeForSSR
+
+import {useReducer} from 'react';
+
+function Component() {
+  const [state, dispatch] = useReducer((_, next) => next, 0);
+  const ref = useRef(null);
+  const onChange = e => {
+    dispatch(e.target.value);
+  };
+  useEffect(() => {
+    log(ref.current.value);
+  });
+  return <input value={state} onChange={onChange} ref={ref} />;
+}

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/use-memo-noemit.expect.md

@@ -2,7 +2,7 @@
 ## Input
 
 ```javascript
-// @noEmit
+// @outputMode:"lint"
 
 function Foo() {
   'use memo';
@@ -19,7 +19,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-// @noEmit
+// @outputMode:"lint"
 
 function Foo() {
   "use memo";

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/use-memo-noemit.js

@@ -1,4 +1,4 @@
-// @noEmit
+// @outputMode:"lint"
 
 function Foo() {
   'use memo';

compiler/packages/eslint-plugin-react-compiler/src/shared/RunReactCompiler.ts

@@ -21,7 +21,7 @@ import {isDeepStrictEqual} from 'util';
 import type {ParseResult} from '@babel/parser';
 
 const COMPILER_OPTIONS: PluginOptions = {
-  noEmit: true,
+  outputMode: 'lint',
   panicThreshold: 'none',
   // Don't emit errors on Flow suppressions--Flow already gave a signal
   flowSuppressions: false,

compiler/packages/snap/src/SproutTodoFilter.ts

@@ -487,6 +487,13 @@ const skipFilter = new Set([
   'lower-context-selector-simple',
   'lower-context-acess-multiple',
   'bug-separate-memoization-due-to-callback-capturing',
+
+  // SSR optimization rewrites files in a way that causes differences or warnings
+  'ssr/optimize-ssr',
+  'ssr/ssr-use-reducer',
+  'ssr/ssr-use-reducer-initializer',
+  'ssr/infer-event-handlers-from-setState',
+  'ssr/infer-event-handlers-from-startTransition',
 ]);
 
 export default skipFilter;

compiler/packages/snap/src/runner.ts

@@ -53,8 +53,10 @@ const opts: RunnerOptions = yargs
   .default('worker-threads', true)
   .boolean('watch')
   .describe('watch', 'Run compiler in watch mode, re-running after changes')
+  .alias('w', 'watch')
   .default('watch', false)
   .boolean('update')
+  .alias('u', 'update')
   .describe('update', 'Update fixtures')
   .default('update', false)
   .boolean('filter')

packages/eslint-plugin-react-hooks/src/shared/RunReactCompiler.ts

@@ -22,7 +22,7 @@ import {isDeepStrictEqual} from 'util';
 import type {ParseResult} from '@babel/parser';
 
 const COMPILER_OPTIONS: PluginOptions = {
-  noEmit: true,
+  outputMode: 'lint',
   panicThreshold: 'none',
   // Don't emit errors on Flow suppressions--Flow already gave a signal
   flowSuppressions: false,

packages/react-devtools-shared/src/__tests__/profilerContext-test.js

@@ -584,4 +584,75 @@ describe('ProfilerContext', () => {
     await utils.actAsync(() => context.selectFiber(childID, 'Child'));
     expect(inspectedElementID).toBe(parentID);
   });
+
+  it('should toggle profiling when the keyboard shortcut is pressed', async () => {
+    // Context providers
+    const Profiler =
+      require('react-devtools-shared/src/devtools/views/Profiler/Profiler').default;
+    const {
+      TimelineContextController,
+    } = require('react-devtools-timeline/src/TimelineContext');
+    const {
+      SettingsContextController,
+    } = require('react-devtools-shared/src/devtools/views/Settings/SettingsContext');
+    const {
+      ModalDialogContextController,
+    } = require('react-devtools-shared/src/devtools/views/ModalDialog');
+
+    // Dom component for profiling to be enabled
+    const Component = () => null;
+    utils.act(() => render(<Component />));
+
+    const profilerContainer = document.createElement('div');
+    document.body.appendChild(profilerContainer);
+
+    // Create a root for the profiler
+    const profilerRoot = ReactDOMClient.createRoot(profilerContainer);
+
+    // Render the profiler
+    utils.act(() => {
+      profilerRoot.render(
+        <Contexts>
+          <SettingsContextController browserTheme="light">
+            <ModalDialogContextController>
+              <TimelineContextController>
+                <Profiler />
+              </TimelineContextController>
+            </ModalDialogContextController>
+          </SettingsContextController>
+        </Contexts>,
+      );
+    });
+
+    // Verify that the profiler is not profiling.
+    expect(store.profilerStore.isProfilingBasedOnUserInput).toBe(false);
+
+    // Trigger the keyboard shortcut.
+    const ownerWindow = profilerContainer.ownerDocument.defaultView;
+    const isMac =
+      typeof navigator !== 'undefined' &&
+      navigator.platform.toUpperCase().indexOf('MAC') >= 0;
+
+    const keyEvent = new KeyboardEvent('keydown', {
+      key: 'e',
+      metaKey: isMac,
+      ctrlKey: !isMac,
+      bubbles: true,
+    });
+
+    // Dispatch keyboard event to toggle profiling on
+    // Try utils.actAsync with recursivelyFlush=false
+    await utils.actAsync(() => {
+      ownerWindow.dispatchEvent(keyEvent);
+    }, false);
+    expect(store.profilerStore.isProfilingBasedOnUserInput).toBe(true);
+
+    // Dispatch keyboard event to toggle profiling off
+    await utils.actAsync(() => {
+      ownerWindow.dispatchEvent(keyEvent);
+    }, false);
+    expect(store.profilerStore.isProfilingBasedOnUserInput).toBe(false);
+
+    document.body.removeChild(profilerContainer);
+  });
 });

packages/react-devtools-shared/src/devtools/views/Profiler/Profiler.js

@@ -8,7 +8,7 @@
  */
 
 import * as React from 'react';
-import {Fragment, useContext} from 'react';
+import {Fragment, useContext, useEffect, useRef, useEffectEvent} from 'react';
 import {ModalDialog} from '../ModalDialog';
 import {ProfilerContext} from './ProfilerContext';
 import TabBar from '../TabBar';
@@ -38,6 +38,11 @@ import {TimelineContext} from 'react-devtools-timeline/src/TimelineContext';
 import styles from './Profiler.css';
 
 function Profiler(_: {}) {
+  const profilerRef = useRef<HTMLDivElement | null>(null);
+  const isMac =
+    typeof navigator !== 'undefined' &&
+    navigator.platform.toUpperCase().indexOf('MAC') >= 0;
+
   const {
     didRecordCommits,
     isProcessingData,
@@ -47,6 +52,8 @@ function Profiler(_: {}) {
     selectedTabID,
     selectTab,
     supportsProfiling,
+    startProfiling,
+    stopProfiling,
   } = useContext(ProfilerContext);
 
   const {file: timelineTraceEventData, searchInputContainerRef} =
@@ -56,6 +63,32 @@ function Profiler(_: {}) {
 
   const isLegacyProfilerSelected = selectedTabID !== 'timeline';
 
+  // Cmd+E to start/stop profiler recording
+  const handleKeyDown = useEffectEvent((event: KeyboardEvent) => {
+    const correctModifier = isMac ? event.metaKey : event.ctrlKey;
+    if (correctModifier && event.key === 'e') {
+      if (isProfiling) {
+        stopProfiling();
+      } else {
+        startProfiling();
+      }
+      event.preventDefault();
+      event.stopPropagation();
+    }
+  });
+
+  useEffect(() => {
+    const div = profilerRef.current;
+    if (!div) {
+      return;
+    }
+    const ownerWindow = div.ownerDocument.defaultView;
+    ownerWindow.addEventListener('keydown', handleKeyDown);
+    return () => {
+      ownerWindow.removeEventListener('keydown', handleKeyDown);
+    };
+  }, []);
+
   let view = null;
   if (didRecordCommits || selectedTabID === 'timeline') {
     switch (selectedTabID) {
@@ -112,7 +145,7 @@ function Profiler(_: {}) {
 
   return (
     <SettingsModalContextController>
-      <div className={styles.Profiler}>
+      <div ref={profilerRef} className={styles.Profiler}>
         <div className={styles.LeftColumn}>
           <div className={styles.Toolbar}>
             <RecordToggle disabled={!supportsProfiling} />

packages/react-devtools-shared/src/devtools/views/Profiler/RecordToggle.js

@@ -30,13 +30,19 @@ export default function RecordToggle({disabled}: Props): React.Node {
     className = styles.ActiveRecordToggle;
   }
 
+  const isMac =
+    typeof navigator !== 'undefined' &&
+    navigator.platform.toUpperCase().indexOf('MAC') >= 0;
+  const shortcut = isMac ? '⌘E' : 'Ctrl+E';
+  const title = `${isProfiling ? 'Stop' : 'Start'} profiling - ${shortcut}`;
+
   return (
     <Button
       className={className}
       disabled={disabled}
       onClick={isProfiling ? stopProfiling : startProfiling}
       testName="ProfilerToggleButton"
-      title={isProfiling ? 'Stop profiling' : 'Start profiling'}>
+      title={title}>
       <ButtonIcon type="record" />
     </Button>
   );