Merge 760c59fa84 into sapling-pr-archive-poteto

.github/workflows/compiler_discord_notify.yml

@@ -1,7 +1,7 @@
 name: (Compiler) Discord Notify
 
 on:
-  pull_request:
+  pull_request_target:
     types: [opened, ready_for_review]
     paths:
       - compiler/**

.github/workflows/runtime_discord_notify.yml

@@ -1,7 +1,7 @@
 name: (Runtime) Discord Notify
 
 on:
-  pull_request:
+  pull_request_target:
     types: [opened, ready_for_review]
     paths-ignore:
       - compiler/**

.github/workflows/shared_check_maintainer.yml

@@ -6,10 +6,6 @@ on:
       actor:
         required: true
         type: string
-      is_remote:
-        required: false
-        type: boolean
-        default: false
     outputs:
       is_core_team:
         value: ${{ jobs.check_maintainer.outputs.is_core_team }}
@@ -30,7 +26,6 @@ jobs:
     outputs:
       is_core_team: ${{ steps.check_if_actor_is_maintainer.outputs.result }}
     steps:
-      - uses: actions/checkout@v4
       - name: Check if actor is maintainer
         id: check_if_actor_is_maintainer
         uses: actions/github-script@v7
@@ -38,33 +33,20 @@ jobs:
           script: |
             const fs = require('fs');
             const actor = '${{ inputs.actor }}';
-            let isRemote = ${{ inputs.is_remote }};
-            if (typeof isRemote === 'string') {
-              isRemote = isRemote === 'true';
+            const res = await github.rest.repos.getContent({
+              owner: 'facebook',
+              repo: 'react',
+              path: 'MAINTAINERS',
+              ref: 'main',
+              headers: { Accept: 'application/vnd.github+json' }
+            });
+            if (res.status !== 200) {
+              console.error(res);
+              throw new Error('Unable to fetch MAINTAINERS file');
             }
-            if (typeof isRemote !== 'boolean') {
-              throw new Error(`Invalid \`isRemote\` input. Expected a boolean, got: ${isRemote}`);
-            }
-
-            let content = null;
-            if (isRemote === true) {
-              const res = await github.rest.repos.getContent({
-                owner: 'facebook',
-                repo: 'react',
-                path: 'MAINTAINERS',
-                ref: 'main',
-                headers: { Accept: 'application/vnd.github+json' }
-              });
-              if (res.status !== 200) {
-                console.error(res);
-                throw new Error('Unable to fetch MAINTAINERS file');
-              }
-              content = Buffer.from(res.data.content, 'base64').toString();
-            } else {
-              content = await fs.readFileSync('./MAINTAINERS', { encoding: 'utf8' });
-            }
-            if (content === null) {
-              throw new Error('Unable to retrieve local or http MAINTAINERS file');
+            content = Buffer.from(res.data.content, 'base64').toString();
+            if (content == null || typeof content !== 'string') {
+              throw new Error('Unable to retrieve MAINTAINERS file');
             }
 
             const maintainers = new Set(content.split('\n'));

.github/workflows/shared_label_core_team_prs.yml

@@ -1,7 +1,7 @@
 name: (Shared) Label Core Team PRs
 
 on:
-  pull_request:
+  pull_request_target:
 
 permissions: {}
 

compiler/packages/babel-plugin-react-compiler/scripts/jest/e2e-forget.config.js

@@ -7,7 +7,4 @@
 
 const makeE2EConfig = require('../jest/makeE2EConfig');
 
-const config = makeE2EConfig('e2e with forget', true);
-config.setupFilesAfterEnv = ['<rootDir>/../scripts/jest/setupEnvE2E.js'];
-
-module.exports = config;
+module.exports = makeE2EConfig('e2e with forget', true);

compiler/packages/babel-plugin-react-compiler/scripts/jest/makeTransform.ts

@@ -5,19 +5,16 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {jsx} from '@babel/plugin-syntax-jsx';
 import babelJest from 'babel-jest';
-import {compile} from 'babel-plugin-react-compiler';
+import {
+  validateEnvironmentConfig,
+  EnvironmentConfig,
+} from 'babel-plugin-react-compiler';
 import {execSync} from 'child_process';
 
 import type {NodePath, Visitor} from '@babel/traverse';
-import type {CallExpression, FunctionDeclaration} from '@babel/types';
-import * as t from '@babel/types';
-import {
-  EnvironmentConfig,
-  validateEnvironmentConfig,
-} from 'babel-plugin-react-compiler';
-import {basename} from 'path';
+import type {CallExpression} from '@babel/types';
+import BabelPluginReactCompiler from 'babel-plugin-react-compiler';
 
 /**
  * -- IMPORTANT --
@@ -28,10 +25,19 @@ import {basename} from 'path';
 const e2eTransformerCacheKey = 1;
 const forgetOptions: EnvironmentConfig = validateEnvironmentConfig({
   enableAssumeHooksFollowRulesOfReact: true,
-  enableFunctionOutlining: false,
 });
 const debugMode = process.env['DEBUG_FORGET_COMPILER'] != null;
 
+const compilerCacheKey = execSync(
+  'yarn --silent --cwd ../.. hash packages/babel-plugin-react-compiler/dist',
+)
+  .toString()
+  .trim();
+
+if (debugMode) {
+  console.log('cachebreaker', compilerCacheKey);
+}
+
 module.exports = (useForget: boolean) => {
   function createTransformer() {
     return babelJest.createTransformer({
@@ -42,15 +48,14 @@ module.exports = (useForget: boolean) => {
           plugins: [
             useForget
               ? [
-                  ReactForgetFunctionTransform,
+                  BabelPluginReactCompiler,
                   {
+                    environment: forgetOptions,
                     /*
                      * Jest hashes the babel config as a cache breaker.
                      * (see https://github.com/jestjs/jest/blob/v29.6.2/packages/babel-jest/src/index.ts#L84)
                      */
-                    compilerCacheKey: execSync(
-                      'yarn --silent --cwd ../.. hash packages/babel-plugin-react-compiler/dist',
-                    ).toString(),
+                    compilerCacheKey,
                     transformOptionsCacheKey: forgetOptions,
                     e2eTransformerCacheKey,
                   },
@@ -105,104 +110,3 @@ module.exports = (useForget: boolean) => {
     createTransformer,
   };
 };
-
-// Mostly copied from react/scripts/babel/transform-forget.js
-function isReactComponentLike(fn: NodePath<FunctionDeclaration>): boolean {
-  let isReactComponent = false;
-  let hasNoUseForgetDirective = false;
-
-  /*
-   * React components start with an upper case letter,
-   * React hooks start with `use`
-   */
-  if (
-    fn.node.id == null ||
-    (fn.node.id.name[0].toUpperCase() !== fn.node.id.name[0] &&
-      !/^use[A-Z0-9]/.test(fn.node.id.name))
-  ) {
-    return false;
-  }
-
-  fn.traverse({
-    DirectiveLiteral(path) {
-      if (path.node.value === 'use no forget') {
-        hasNoUseForgetDirective = true;
-      }
-    },
-
-    JSX(path) {
-      // Is there is a JSX node created in the current function context?
-      if (path.scope.getFunctionParent()?.path.node === fn.node) {
-        isReactComponent = true;
-      }
-    },
-
-    CallExpression(path) {
-      // Is there hook usage?
-      if (
-        path.node.callee.type === 'Identifier' &&
-        !/^use[A-Z0-9]/.test(path.node.callee.name)
-      ) {
-        isReactComponent = true;
-      }
-    },
-  });
-
-  if (hasNoUseForgetDirective) {
-    return false;
-  }
-
-  return isReactComponent;
-}
-
-function ReactForgetFunctionTransform() {
-  const compiledFns = new Set();
-  const visitor = {
-    FunctionDeclaration(fn: NodePath<FunctionDeclaration>, state: any): void {
-      if (compiledFns.has(fn.node)) {
-        return;
-      }
-
-      if (!isReactComponentLike(fn)) {
-        return;
-      }
-      if (debugMode) {
-        const filename = basename(state.file.opts.filename);
-        if (fn.node.loc && fn.node.id) {
-          console.log(
-            ` Compiling ${filename}:${fn.node.loc.start.line}:${fn.node.loc.start.column}  ${fn.node.id.name}`,
-          );
-        } else {
-          console.log(` Compiling ${filename} ${fn.node.id?.name}`);
-        }
-      }
-
-      const compiled = compile(
-        fn,
-        forgetOptions,
-        'Other',
-        'all_features',
-        '_c',
-        null,
-        null,
-        null,
-      );
-      compiledFns.add(compiled);
-
-      const fun = t.functionDeclaration(
-        compiled.id,
-        compiled.params,
-        compiled.body,
-        compiled.generator,
-        compiled.async,
-      );
-      fn.replaceWith(fun);
-      fn.skip();
-    },
-  };
-  return {
-    name: 'react-forget-e2e',
-    inherits: jsx,
-    visitor,
-  };
-}

compiler/packages/babel-plugin-react-compiler/scripts/jest/setupEnvE2E.js

@@ -1,16 +0,0 @@
-/**
- * Copyright (c) Meta Platforms, Inc. and affiliates.
- *
- * This source code is licensed under the MIT license found in the
- * LICENSE file in the root directory of this source tree.
- */
-
-const ReactCompilerRuntime = require('react/compiler-runtime');
-
-/*
- * Our e2e babel transform currently only compiles functions, not programs.
- * As a result, our e2e transpiled code does not contain an import for the
- * memo cache function. As a temporary hack, we add a `_c` global, which is
- * the name that is used for the import by default.
- */
-globalThis._c = ReactCompilerRuntime.c;

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

@@ -7,8 +7,9 @@
 
 import {NodePath} from '@babel/core';
 import * as t from '@babel/types';
-import {PluginOptions} from './Options';
 import {CompilerError} from '../CompilerError';
+import {ProgramContext} from './Imports';
+import {ExternalFunction} from '..';
 
 /**
  * Gating rewrite for function declarations which are referenced before their
@@ -34,7 +35,8 @@ import {CompilerError} from '../CompilerError';
 function insertAdditionalFunctionDeclaration(
   fnPath: NodePath<t.FunctionDeclaration>,
   compiled: t.FunctionDeclaration,
-  gating: NonNullable<PluginOptions['gating']>,
+  programContext: ProgramContext,
+  gatingFunctionIdentifierName: string,
 ): void {
   const originalFnName = fnPath.node.id;
   const originalFnParams = fnPath.node.params;
@@ -57,14 +59,14 @@ function insertAdditionalFunctionDeclaration(
     loc: fnPath.node.loc ?? null,
   });
 
-  const gatingCondition = fnPath.scope.generateUidIdentifier(
-    `${gating.importSpecifierName}_result`,
+  const gatingCondition = t.identifier(
+    programContext.newUid(`${gatingFunctionIdentifierName}_result`),
   );
-  const unoptimizedFnName = fnPath.scope.generateUidIdentifier(
-    `${originalFnName.name}_unoptimized`,
+  const unoptimizedFnName = t.identifier(
+    programContext.newUid(`${originalFnName.name}_unoptimized`),
   );
-  const optimizedFnName = fnPath.scope.generateUidIdentifier(
-    `${originalFnName.name}_optimized`,
+  const optimizedFnName = t.identifier(
+    programContext.newUid(`${originalFnName.name}_optimized`),
   );
   /**
    * Step 1: rename existing functions
@@ -115,7 +117,7 @@ function insertAdditionalFunctionDeclaration(
     t.variableDeclaration('const', [
       t.variableDeclarator(
         gatingCondition,
-        t.callExpression(t.identifier(gating.importSpecifierName), []),
+        t.callExpression(t.identifier(gatingFunctionIdentifierName), []),
       ),
     ]),
   );
@@ -129,19 +131,26 @@ export function insertGatedFunctionDeclaration(
     | t.FunctionDeclaration
     | t.ArrowFunctionExpression
     | t.FunctionExpression,
-  gating: NonNullable<PluginOptions['gating']>,
+  programContext: ProgramContext,
+  gating: ExternalFunction,
   referencedBeforeDeclaration: boolean,
 ): void {
+  const gatingImportedName = programContext.addImportSpecifier(gating).name;
   if (referencedBeforeDeclaration && fnPath.isFunctionDeclaration()) {
     CompilerError.invariant(compiled.type === 'FunctionDeclaration', {
       reason: 'Expected compiled node type to match input type',
       description: `Got ${compiled.type} but expected FunctionDeclaration`,
       loc: fnPath.node.loc ?? null,
     });
-    insertAdditionalFunctionDeclaration(fnPath, compiled, gating);
+    insertAdditionalFunctionDeclaration(
+      fnPath,
+      compiled,
+      programContext,
+      gatingImportedName,
+    );
   } else {
     const gatingExpression = t.conditionalExpression(
-      t.callExpression(t.identifier(gating.importSpecifierName), []),
+      t.callExpression(t.identifier(gatingImportedName), []),
       buildFunctionExpression(compiled),
       buildFunctionExpression(fnPath.node),
     );

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

@@ -7,9 +7,19 @@
 
 import {NodePath} from '@babel/core';
 import * as t from '@babel/types';
+import {Scope as BabelScope} from '@babel/traverse';
+
 import {CompilerError, ErrorSeverity} from '../CompilerError';
-import {EnvironmentConfig, ExternalFunction, GeneratedSource} from '../HIR';
-import {getOrInsertDefault} from '../Utils/utils';
+import {
+  EnvironmentConfig,
+  GeneratedSource,
+  NonLocalImportSpecifier,
+} from '../HIR';
+import {getOrInsertWith} from '../Utils/utils';
+import {ExternalFunction, isHookName} from '../HIR/Environment';
+import {Err, Ok, Result} from '../Utils/Result';
+import {CompilerReactTarget} from './Options';
+import {getReactCompilerRuntimeModule} from './Program';
 
 export function validateRestrictedImports(
   path: NodePath<t.Program>,
@@ -42,50 +52,209 @@ export function validateRestrictedImports(
   }
 }
 
-export function addImportsToProgram(
-  path: NodePath<t.Program>,
-  importList: Array<ExternalFunction>,
-): void {
-  const identifiers: Set<string> = new Set();
-  const sortedImports: Map<string, Array<string>> = new Map();
-  for (const {importSpecifierName, source} of importList) {
-    /*
-     * Codegen currently does not rename import specifiers, so we do additional
-     * validation here
-     */
-    CompilerError.invariant(identifiers.has(importSpecifierName) === false, {
-      reason: `Encountered conflicting import specifier for ${importSpecifierName} in Forget config.`,
-      description: null,
-      loc: GeneratedSource,
-      suggestions: null,
-    });
-    CompilerError.invariant(
-      path.scope.hasBinding(importSpecifierName) === false,
-      {
-        reason: `Encountered conflicting import specifiers for ${importSpecifierName} in generated program.`,
-        description: null,
-        loc: GeneratedSource,
-        suggestions: null,
-      },
-    );
-    identifiers.add(importSpecifierName);
+export class ProgramContext {
+  /* Program and environment context */
+  scope: BabelScope;
+  reactRuntimeModule: string;
+  hookPattern: string | null;
 
-    const importSpecifierNameList = getOrInsertDefault(
-      sortedImports,
-      source,
-      [],
-    );
-    importSpecifierNameList.push(importSpecifierName);
+  // known generated or referenced identifiers in the program
+  knownReferencedNames: Set<string> = new Set();
+  // generated imports
+  imports: Map<string, Map<string, NonLocalImportSpecifier>> = new Map();
+
+  constructor(
+    program: NodePath<t.Program>,
+    reactRuntimeModule: CompilerReactTarget,
+    hookPattern: string | null,
+  ) {
+    this.hookPattern = hookPattern;
+    this.scope = program.scope;
+    this.reactRuntimeModule = getReactCompilerRuntimeModule(reactRuntimeModule);
   }
 
+  isHookName(name: string): boolean {
+    if (this.hookPattern == null) {
+      return isHookName(name);
+    } else {
+      const match = new RegExp(this.hookPattern).exec(name);
+      return (
+        match != null && typeof match[1] === 'string' && isHookName(match[1])
+      );
+    }
+  }
+
+  hasReference(name: string): boolean {
+    return (
+      this.knownReferencedNames.has(name) ||
+      this.scope.hasBinding(name) ||
+      this.scope.hasGlobal(name) ||
+      this.scope.hasReference(name)
+    );
+  }
+
+  newUid(name: string): string {
+    /**
+     * Don't call babel's generateUid for known hook imports, as
+     * InferTypes might eventually type `HookKind` based on callee naming
+     * convention and `_useFoo` is not named as a hook.
+     *
+     * Local uid generation is susceptible to check-before-use bugs since we're
+     * checking for naming conflicts / references long before we actually insert
+     * the import. (see similar logic in HIRBuilder:resolveBinding)
+     */
+    let uid;
+    if (this.isHookName(name)) {
+      uid = name;
+      let i = 0;
+      while (this.hasReference(uid)) {
+        this.knownReferencedNames.add(uid);
+        uid = `${name}_${i++}`;
+      }
+    } else if (!this.hasReference(name)) {
+      uid = name;
+    } else {
+      uid = this.scope.generateUid(name);
+    }
+    this.knownReferencedNames.add(uid);
+    return uid;
+  }
+
+  addMemoCacheImport(): NonLocalImportSpecifier {
+    return this.addImportSpecifier(
+      {
+        source: this.reactRuntimeModule,
+        importSpecifierName: 'c',
+      },
+      '_c',
+    );
+  }
+
+  /**
+   *
+   * @param externalFunction
+   * @param nameHint if defined, will be used as the name of the import specifier
+   * @returns
+   */
+  addImportSpecifier(
+    {source: module, importSpecifierName: specifier}: ExternalFunction,
+    nameHint?: string,
+  ): NonLocalImportSpecifier {
+    const maybeBinding = this.imports.get(module)?.get(specifier);
+    if (maybeBinding != null) {
+      return {...maybeBinding};
+    }
+
+    const binding: NonLocalImportSpecifier = {
+      kind: 'ImportSpecifier',
+      name: this.newUid(nameHint ?? specifier),
+      module,
+      imported: specifier,
+    };
+    getOrInsertWith(this.imports, module, () => new Map()).set(specifier, {
+      ...binding,
+    });
+    return binding;
+  }
+
+  addNewReference(name: string): void {
+    this.knownReferencedNames.add(name);
+  }
+
+  assertGlobalBinding(
+    name: string,
+    localScope?: BabelScope,
+  ): Result<void, CompilerError> {
+    const scope = localScope ?? this.scope;
+    if (!scope.hasReference(name) && !scope.hasBinding(name)) {
+      return Ok(undefined);
+    }
+    const error = new CompilerError();
+    error.push({
+      severity: ErrorSeverity.Todo,
+      reason: 'Encountered conflicting global in generated program',
+      description: `Conflict from local binding ${name}`,
+      loc: scope.getBinding(name)?.path.node.loc ?? null,
+      suggestions: null,
+    });
+    return Err(error);
+  }
+}
+
+function getExistingImports(
+  program: NodePath<t.Program>,
+): Map<string, NodePath<t.ImportDeclaration>> {
+  const existingImports = new Map<string, NodePath<t.ImportDeclaration>>();
+  program.traverse({
+    ImportDeclaration(path) {
+      if (isNonNamespacedImport(path)) {
+        existingImports.set(path.node.source.value, path);
+      }
+    },
+  });
+  return existingImports;
+}
+
+export function addImportsToProgram(
+  path: NodePath<t.Program>,
+  programContext: ProgramContext,
+): void {
+  const existingImports = getExistingImports(path);
   const stmts: Array<t.ImportDeclaration> = [];
-  for (const [source, importSpecifierNameList] of sortedImports) {
-    const importSpecifiers = importSpecifierNameList.map(name => {
-      const id = t.identifier(name);
-      return t.importSpecifier(id, id);
+  const sortedModules = [...programContext.imports.entries()].sort(([a], [b]) =>
+    a.localeCompare(b),
+  );
+  for (const [moduleName, importsMap] of sortedModules) {
+    for (const [specifierName, loweredImport] of importsMap) {
+      /**
+       * Assert that the import identifier hasn't already be declared in the program.
+       * Note: we use getBinding here since `Scope.hasBinding` pessimistically returns true
+       * for all allocated uids (from `Scope.getUid`)
+       */
+      CompilerError.invariant(
+        path.scope.getBinding(loweredImport.name) == null,
+        {
+          reason:
+            'Encountered conflicting import specifiers in generated program',
+          description: `Conflict from import ${loweredImport.module}:(${loweredImport.imported} as ${loweredImport.name}).`,
+          loc: GeneratedSource,
+          suggestions: null,
+        },
+      );
+      CompilerError.invariant(
+        loweredImport.module === moduleName &&
+          loweredImport.imported === specifierName,
+        {
+          reason:
+            'Found inconsistent import specifier. This is an internal bug.',
+          description: `Expected import ${moduleName}:${specifierName} but found ${loweredImport.module}:${loweredImport.imported}`,
+          loc: GeneratedSource,
+        },
+      );
+    }
+    const sortedImport: Array<NonLocalImportSpecifier> = [
+      ...importsMap.values(),
+    ].sort(({imported: a}, {imported: b}) => a.localeCompare(b));
+    const importSpecifiers = sortedImport.map(specifier => {
+      return t.importSpecifier(
+        t.identifier(specifier.name),
+        t.identifier(specifier.imported),
+      );
     });
 
-    stmts.push(t.importDeclaration(importSpecifiers, t.stringLiteral(source)));
+    /**
+     * If an existing import of this module exists (ie `import { ... } from
+     * '<moduleName>'`), inject new imported specifiers into the list of
+     * destructured variables.
+     */
+    const maybeExistingImports = existingImports.get(moduleName);
+    if (maybeExistingImports != null) {
+      maybeExistingImports.pushContainer('specifiers', importSpecifiers);
+    } else {
+      stmts.push(
+        t.importDeclaration(importSpecifiers, t.stringLiteral(moduleName)),
+      );
+    }
   }
   path.unshiftContainer('body', stmts);
 }
@@ -93,13 +262,12 @@ export function addImportsToProgram(
 /*
  * Matches `import { ... } from <moduleName>;`
  * but not `import * as React from <moduleName>;`
+ *         `import type { Foo } from <moduleName>;`
  */
 function isNonNamespacedImport(
   importDeclPath: NodePath<t.ImportDeclaration>,
-  moduleName: string,
 ): boolean {
   return (
-    importDeclPath.get('source').node.value === moduleName &&
     importDeclPath
       .get('specifiers')
       .every(specifier => specifier.isImportSpecifier()) &&
@@ -107,94 +275,3 @@ function isNonNamespacedImport(
     importDeclPath.node.importKind !== 'typeof'
   );
 }
-
-function hasExistingNonNamespacedImportOfModule(
-  program: NodePath<t.Program>,
-  moduleName: string,
-): boolean {
-  let hasExistingImport = false;
-  program.traverse({
-    ImportDeclaration(importDeclPath) {
-      if (isNonNamespacedImport(importDeclPath, moduleName)) {
-        hasExistingImport = true;
-      }
-    },
-  });
-
-  return hasExistingImport;
-}
-
-/*
- * If an existing import of React exists (ie `import { ... } from '<moduleName>'`), inject useMemoCache
- * into the list of destructured variables.
- */
-function addMemoCacheFunctionSpecifierToExistingImport(
-  program: NodePath<t.Program>,
-  moduleName: string,
-  identifierName: string,
-): boolean {
-  let didInsertUseMemoCache = false;
-  program.traverse({
-    ImportDeclaration(importDeclPath) {
-      if (
-        !didInsertUseMemoCache &&
-        isNonNamespacedImport(importDeclPath, moduleName)
-      ) {
-        importDeclPath.pushContainer(
-          'specifiers',
-          t.importSpecifier(t.identifier(identifierName), t.identifier('c')),
-        );
-        didInsertUseMemoCache = true;
-      }
-    },
-  });
-  return didInsertUseMemoCache;
-}
-
-export function updateMemoCacheFunctionImport(
-  program: NodePath<t.Program>,
-  moduleName: string,
-  useMemoCacheIdentifier: string,
-): void {
-  /*
-   * If there isn't already an import of * as React, insert it so useMemoCache doesn't
-   * throw
-   */
-  const hasExistingImport = hasExistingNonNamespacedImportOfModule(
-    program,
-    moduleName,
-  );
-
-  if (hasExistingImport) {
-    const didUpdateImport = addMemoCacheFunctionSpecifierToExistingImport(
-      program,
-      moduleName,
-      useMemoCacheIdentifier,
-    );
-    if (!didUpdateImport) {
-      throw new Error(
-        `Expected an ImportDeclaration of \`${moduleName}\` in order to update ImportSpecifiers with useMemoCache`,
-      );
-    }
-  } else {
-    addMemoCacheFunctionImportDeclaration(
-      program,
-      moduleName,
-      useMemoCacheIdentifier,
-    );
-  }
-}
-
-function addMemoCacheFunctionImportDeclaration(
-  program: NodePath<t.Program>,
-  moduleName: string,
-  localName: string,
-): void {
-  program.unshiftContainer(
-    'body',
-    t.importDeclaration(
-      [t.importSpecifier(t.identifier(localName), t.identifier('c'))],
-      t.stringLiteral(moduleName),
-    ),
-  );
-}

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} from '.';
+import {Logger, ProgramContext} from '.';
 import {
   HIRFunction,
   ReactiveFunction,
@@ -117,7 +117,7 @@ function run(
   config: EnvironmentConfig,
   fnType: ReactFunctionType,
   mode: CompilerMode,
-  useMemoCacheIdentifier: string,
+  programContext: ProgramContext,
   logger: Logger | null,
   filename: string | null,
   code: string | null,
@@ -132,7 +132,7 @@ function run(
     logger,
     filename,
     code,
-    useMemoCacheIdentifier,
+    programContext,
   );
   env.logger?.debugLogIRs?.({
     kind: 'debug',
@@ -552,7 +552,7 @@ export function compileFn(
   config: EnvironmentConfig,
   fnType: ReactFunctionType,
   mode: CompilerMode,
-  useMemoCacheIdentifier: string,
+  programContext: ProgramContext,
   logger: Logger | null,
   filename: string | null,
   code: string | null,
@@ -562,7 +562,7 @@ export function compileFn(
     config,
     fnType,
     mode,
-    useMemoCacheIdentifier,
+    programContext,
     logger,
     filename,
     code,

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

@@ -12,11 +12,7 @@ import {
   CompilerErrorDetail,
   ErrorSeverity,
 } from '../CompilerError';
-import {
-  EnvironmentConfig,
-  ExternalFunction,
-  ReactFunctionType,
-} from '../HIR/Environment';
+import {EnvironmentConfig, ReactFunctionType} from '../HIR/Environment';
 import {CodegenFunction} from '../ReactiveScopes';
 import {isComponentDeclaration} from '../Utils/ComponentDeclaration';
 import {isHookDeclaration} from '../Utils/HookDeclaration';
@@ -24,10 +20,10 @@ import {assertExhaustive} from '../Utils/utils';
 import {insertGatedFunctionDeclaration} from './Gating';
 import {
   addImportsToProgram,
-  updateMemoCacheFunctionImport,
+  ProgramContext,
   validateRestrictedImports,
 } from './Imports';
-import {PluginOptions} from './Options';
+import {CompilerReactTarget, PluginOptions} from './Options';
 import {compileFn} from './Pipeline';
 import {
   filterSuppressionsThatAffectFunction,
@@ -299,8 +295,12 @@ export function compileProgram(
     handleError(restrictedImportsErr, pass, null);
     return null;
   }
-  const useMemoCacheIdentifier = program.scope.generateUidIdentifier('c');
 
+  const programContext = new ProgramContext(
+    program,
+    pass.opts.target,
+    environment.hookPattern,
+  );
   /*
    * Record lint errors and critical errors as depending on Forget's config,
    * we may still need to run Forget's analysis on every function (even if we
@@ -410,7 +410,7 @@ export function compileProgram(
             environment,
             fnType,
             'all_features',
-            useMemoCacheIdentifier.name,
+            programContext,
             pass.opts.logger,
             pass.filename,
             pass.code,
@@ -445,7 +445,7 @@ export function compileProgram(
             environment,
             fnType,
             'no_inferred_memo',
-            useMemoCacheIdentifier.name,
+            programContext,
             pass.opts.logger,
             pass.filename,
             pass.code,
@@ -453,7 +453,7 @@ export function compileProgram(
         };
         if (
           !compileResult.compiledFn.hasFireRewrite &&
-          !compileResult.compiledFn.hasLoweredContextAccess
+          !compileResult.compiledFn.hasInferredEffect
         ) {
           return null;
         }
@@ -554,79 +554,29 @@ export function compileProgram(
   if (moduleScopeOptOutDirectives.length > 0) {
     return null;
   }
-  let gating: null | {
-    gatingFn: ExternalFunction;
-    referencedBeforeDeclared: Set<CompileResult>;
-  } = null;
-  if (pass.opts.gating != null) {
-    gating = {
-      gatingFn: pass.opts.gating,
-      referencedBeforeDeclared:
-        getFunctionReferencedBeforeDeclarationAtTopLevel(program, compiledFns),
-    };
-  }
-
-  const hasLoweredContextAccess = compiledFns.some(
-    c => c.compiledFn.hasLoweredContextAccess,
-  );
-  const externalFunctions: Array<ExternalFunction> = [];
-  try {
-    // TODO: check for duplicate import specifiers
-    if (gating != null) {
-      externalFunctions.push(gating.gatingFn);
-    }
-
-    const lowerContextAccess = environment.lowerContextAccess;
-    if (lowerContextAccess && hasLoweredContextAccess) {
-      externalFunctions.push(lowerContextAccess);
-    }
-
-    const enableEmitInstrumentForget = environment.enableEmitInstrumentForget;
-    if (enableEmitInstrumentForget != null) {
-      externalFunctions.push(enableEmitInstrumentForget.fn);
-      if (enableEmitInstrumentForget.gating != null) {
-        externalFunctions.push(enableEmitInstrumentForget.gating);
-      }
-    }
-
-    if (environment.enableEmitFreeze != null) {
-      externalFunctions.push(environment.enableEmitFreeze);
-    }
-
-    if (environment.enableEmitHookGuards != null) {
-      externalFunctions.push(environment.enableEmitHookGuards);
-    }
-
-    if (environment.enableChangeDetectionForDebugging != null) {
-      externalFunctions.push(environment.enableChangeDetectionForDebugging);
-    }
-
-    const hasFireRewrite = compiledFns.some(c => c.compiledFn.hasFireRewrite);
-    if (environment.enableFire && hasFireRewrite) {
-      externalFunctions.push({
-        source: getReactCompilerRuntimeModule(pass.opts),
-        importSpecifierName: 'useFire',
-      });
-    }
-  } catch (err) {
-    handleError(err, pass, null);
-    return null;
-  }
-
   /*
    * Only insert Forget-ified functions if we have not encountered a critical
    * error elsewhere in the file, regardless of bailout mode.
    */
+  const referencedBeforeDeclared =
+    pass.opts.gating != null
+      ? getFunctionReferencedBeforeDeclarationAtTopLevel(program, compiledFns)
+      : null;
   for (const result of compiledFns) {
     const {kind, originalFn, compiledFn} = result;
     const transformedFn = createNewFunctionNode(originalFn, compiledFn);
 
-    if (gating != null && kind === 'original') {
+    if (referencedBeforeDeclared != null && kind === 'original') {
+      CompilerError.invariant(pass.opts.gating != null, {
+        reason: "Expected 'gating' import to be present",
+        loc: null,
+      });
       insertGatedFunctionDeclaration(
         originalFn,
         transformedFn,
-        gating.gatingFn,
-        gating.referencedBeforeDeclared.has(result),
+        programContext,
+        pass.opts.gating,
+        referencedBeforeDeclared.has(result),
       );
     } else {
       originalFn.replaceWith(transformedFn);
@@ -635,22 +585,7 @@ export function compileProgram(
 
   // Forget compiled the component, we need to update existing imports of useMemoCache
   if (compiledFns.length > 0) {
-    let needsMemoCacheFunctionImport = false;
-    for (const fn of compiledFns) {
-      if (fn.compiledFn.memoSlotsUsed > 0) {
-        needsMemoCacheFunctionImport = true;
-        break;
-      }
-    }
-
-    if (needsMemoCacheFunctionImport) {
-      updateMemoCacheFunctionImport(
-        program,
-        getReactCompilerRuntimeModule(pass.opts),
-        useMemoCacheIdentifier.name,
-      );
-    }
-    addImportsToProgram(program, externalFunctions);
+    addImportsToProgram(program, programContext);
   }
   return {retryErrors};
 }
@@ -683,7 +618,7 @@ function shouldSkipCompilation(
   if (
     hasMemoCacheFunctionImport(
       program,
-      getReactCompilerRuntimeModule(pass.opts),
+      getReactCompilerRuntimeModule(pass.opts.target),
     )
   ) {
     return true;
@@ -1008,31 +943,39 @@ function callsHooksOrCreatesJsx(
   return invokesHooks || createsJsx;
 }
 
+function isNonNode(node?: t.Expression | null): boolean {
+  if (!node) {
+    return true;
+  }
+  switch (node.type) {
+    case 'ObjectExpression':
+    case 'ArrowFunctionExpression':
+    case 'FunctionExpression':
+    case 'BigIntLiteral':
+    case 'ClassExpression':
+    case 'NewExpression': // technically `new Array()` is legit, but unlikely
+      return true;
+  }
+  return false;
+}
+
 function returnsNonNode(
   node: NodePath<
     t.FunctionDeclaration | t.ArrowFunctionExpression | t.FunctionExpression
   >,
 ): boolean {
-  let hasReturn = false;
   let returnsNonNode = false;
+  if (
+    // node.traverse#ArrowFunctionExpression isn't called for the root node
+    node.type === 'ArrowFunctionExpression' &&
+    node.node.body.type !== 'BlockStatement'
+  ) {
+    returnsNonNode = isNonNode(node.node.body);
+  }
 
   node.traverse({
     ReturnStatement(ret) {
-      hasReturn = true;
-      const argument = ret.node.argument;
-      if (argument == null) {
-        returnsNonNode = true;
-      } else {
-        switch (argument.type) {
-          case 'ObjectExpression':
-          case 'ArrowFunctionExpression':
-          case 'FunctionExpression':
-          case 'BigIntLiteral':
-          case 'ClassExpression':
-          case 'NewExpression': // technically `new Array()` is legit, but unlikely
-            returnsNonNode = true;
-        }
-      }
+      returnsNonNode = isNonNode(ret.node.argument);
     },
     // Skip traversing all nested functions and their return statements
     ArrowFunctionExpression: skipNestedFunctions(node),
@@ -1041,7 +984,7 @@ function returnsNonNode(
     ObjectMethod: node => node.skip(),
   });
 
-  return !hasReturn || returnsNonNode;
+  return returnsNonNode;
 }
 
 /*
@@ -1169,16 +1112,18 @@ function getFunctionReferencedBeforeDeclarationAtTopLevel(
   return referencedBeforeDeclaration;
 }
 
-function getReactCompilerRuntimeModule(opts: PluginOptions): string {
-  if (opts.target === '19') {
+export function getReactCompilerRuntimeModule(
+  target: CompilerReactTarget,
+): string {
+  if (target === '19') {
     return 'react/compiler-runtime'; // from react namespace
-  } else if (opts.target === '17' || opts.target === '18') {
+  } else if (target === '17' || target === '18') {
     return 'react-compiler-runtime'; // npm package
   } else {
     CompilerError.invariant(
-      opts.target != null &&
-        opts.target.kind === 'donotuse_meta_internal' &&
-        typeof opts.target.runtimeModule === 'string',
+      target != null &&
+        target.kind === 'donotuse_meta_internal' &&
+        typeof target.runtimeModule === 'string',
       {
         reason: 'Expected target to already be validated',
         description: null,
@@ -1186,6 +1131,6 @@ function getReactCompilerRuntimeModule(opts: PluginOptions): string {
         suggestions: null,
       },
     );
-    return opts.target.runtimeModule;
+    return target.runtimeModule;
   }
 }

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

@@ -15,6 +15,7 @@ import {
   PanicThresholdOptions,
   parsePluginOptions,
   PluginOptions,
+  ProgramContext,
 } from '../Entrypoint';
 import {Err, Ok, Result} from '../Utils/Result';
 import {
@@ -84,6 +85,8 @@ export const InstrumentationSchema = z
   );
 
 export type ExternalFunction = z.infer<typeof ExternalFunctionSchema>;
+export const USE_FIRE_FUNCTION_NAME = 'useFire';
+export const EMIT_FREEZE_GLOBAL_GATING = '__DEV__';
 
 export const MacroMethodSchema = z.union([
   z.object({type: z.literal('wildcard')}),
@@ -846,9 +849,9 @@ export class Environment {
   config: EnvironmentConfig;
   fnType: ReactFunctionType;
   compilerMode: CompilerMode;
-  useMemoCacheIdentifier: string;
-  hasLoweredContextAccess: boolean;
+  programContext: ProgramContext;
   hasFireRewrite: boolean;
+  hasInferredEffect: boolean;
 
   #contextIdentifiers: Set<t.Identifier>;
   #hoistedIdentifiers: Set<t.Identifier>;
@@ -862,7 +865,7 @@ export class Environment {
     logger: Logger | null,
     filename: string | null,
     code: string | null,
-    useMemoCacheIdentifier: string,
+    programContext: ProgramContext,
   ) {
     this.#scope = scope;
     this.fnType = fnType;
@@ -871,11 +874,11 @@ export class Environment {
     this.filename = filename;
     this.code = code;
     this.logger = logger;
-    this.useMemoCacheIdentifier = useMemoCacheIdentifier;
+    this.programContext = programContext;
     this.#shapes = new Map(DEFAULT_SHAPES);
     this.#globals = new Map(DEFAULT_GLOBALS);
-    this.hasLoweredContextAccess = false;
     this.hasFireRewrite = false;
+    this.hasInferredEffect = false;
 
     if (
       config.disableMemoizationForDebugging &&
@@ -937,6 +940,10 @@ export class Environment {
     return makeScopeId(this.#nextScope++);
   }
 
+  get scope(): BabelScope {
+    return this.#scope;
+  }
+
   logErrors(errors: Result<void, CompilerError>): void {
     if (errors.isOk() || this.logger == null) {
       return;

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

@@ -10,7 +10,10 @@ import {
   BUILTIN_SHAPES,
   BuiltInArrayId,
   BuiltInFireId,
+  BuiltInMapId,
   BuiltInMixedReadonlyId,
+  BuiltInObjectId,
+  BuiltInSetId,
   BuiltInUseActionStateId,
   BuiltInUseContextHookId,
   BuiltInUseEffectHookId,
@@ -45,29 +48,23 @@ export const DEFAULT_SHAPES: ShapeRegistry = new Map(BUILTIN_SHAPES);
 
 // Hack until we add ObjectShapes for all globals
 const UNTYPED_GLOBALS: Set<string> = new Set([
-  'String',
   'Object',
   'Function',
-  'Number',
   'RegExp',
   'Date',
   'Error',
-  'Function',
   'TypeError',
   'RangeError',
   'ReferenceError',
   'SyntaxError',
   'URIError',
   'EvalError',
-  'Boolean',
   'DataView',
   'Float32Array',
   'Float64Array',
   'Int8Array',
   'Int16Array',
   'Int32Array',
-  'Map',
-  'Set',
   'WeakMap',
   'Uint8Array',
   'Uint8ClampedArray',
@@ -75,16 +72,8 @@ const UNTYPED_GLOBALS: Set<string> = new Set([
   'Uint32Array',
   'ArrayBuffer',
   'JSON',
-  'parseFloat',
-  'parseInt',
   'console',
-  'isNaN',
   'eval',
-  'isFinite',
-  'encodeURI',
-  'decodeURI',
-  'encodeURIComponent',
-  'decodeURIComponent',
 ]);
 
 const TYPED_GLOBALS: Array<[string, BuiltInType]> = [
@@ -101,6 +90,23 @@ const TYPED_GLOBALS: Array<[string, BuiltInType]> = [
           returnValueKind: ValueKind.Mutable,
         }),
       ],
+      [
+        /**
+         * Object.fromEntries(iterable)
+         * iterable: An iterable, such as an Array or Map, containing a list of
+         *           objects. Each object should have two properties.
+         * Returns a new object whose properties are given by the entries of the
+         * iterable.
+         */
+        'fromEntries',
+        addFunction(DEFAULT_SHAPES, [], {
+          positionalParams: [Effect.ConditionallyMutate],
+          restParam: null,
+          returnType: {kind: 'Object', shapeId: BuiltInObjectId},
+          calleeEffect: Effect.Read,
+          returnValueKind: ValueKind.Mutable,
+        }),
+      ],
     ]),
   ],
   [
@@ -132,7 +138,7 @@ const TYPED_GLOBALS: Array<[string, BuiltInType]> = [
         'from',
         addFunction(DEFAULT_SHAPES, [], {
           positionalParams: [
-            Effect.ConditionallyMutate,
+            Effect.ConditionallyMutateIterator,
             Effect.ConditionallyMutate,
             Effect.ConditionallyMutate,
           ],
@@ -372,6 +378,118 @@ const TYPED_GLOBALS: Array<[string, BuiltInType]> = [
       returnValueKind: ValueKind.Primitive,
     }),
   ],
+  [
+    'parseInt',
+    addFunction(DEFAULT_SHAPES, [], {
+      positionalParams: [],
+      restParam: Effect.Read,
+      returnType: {kind: 'Primitive'},
+      calleeEffect: Effect.Read,
+      returnValueKind: ValueKind.Primitive,
+    }),
+  ],
+  [
+    'parseFloat',
+    addFunction(DEFAULT_SHAPES, [], {
+      positionalParams: [],
+      restParam: Effect.Read,
+      returnType: {kind: 'Primitive'},
+      calleeEffect: Effect.Read,
+      returnValueKind: ValueKind.Primitive,
+    }),
+  ],
+  [
+    'isNaN',
+    addFunction(DEFAULT_SHAPES, [], {
+      positionalParams: [],
+      restParam: Effect.Read,
+      returnType: {kind: 'Primitive'},
+      calleeEffect: Effect.Read,
+      returnValueKind: ValueKind.Primitive,
+    }),
+  ],
+  [
+    'isFinite',
+    addFunction(DEFAULT_SHAPES, [], {
+      positionalParams: [],
+      restParam: Effect.Read,
+      returnType: {kind: 'Primitive'},
+      calleeEffect: Effect.Read,
+      returnValueKind: ValueKind.Primitive,
+    }),
+  ],
+  [
+    'encodeURI',
+    addFunction(DEFAULT_SHAPES, [], {
+      positionalParams: [],
+      restParam: Effect.Read,
+      returnType: {kind: 'Primitive'},
+      calleeEffect: Effect.Read,
+      returnValueKind: ValueKind.Primitive,
+    }),
+  ],
+  [
+    'encodeURIComponent',
+    addFunction(DEFAULT_SHAPES, [], {
+      positionalParams: [],
+      restParam: Effect.Read,
+      returnType: {kind: 'Primitive'},
+      calleeEffect: Effect.Read,
+      returnValueKind: ValueKind.Primitive,
+    }),
+  ],
+  [
+    'decodeURI',
+    addFunction(DEFAULT_SHAPES, [], {
+      positionalParams: [],
+      restParam: Effect.Read,
+      returnType: {kind: 'Primitive'},
+      calleeEffect: Effect.Read,
+      returnValueKind: ValueKind.Primitive,
+    }),
+  ],
+  [
+    'decodeURIComponent',
+    addFunction(DEFAULT_SHAPES, [], {
+      positionalParams: [],
+      restParam: Effect.Read,
+      returnType: {kind: 'Primitive'},
+      calleeEffect: Effect.Read,
+      returnValueKind: ValueKind.Primitive,
+    }),
+  ],
+  [
+    'Map',
+    addFunction(
+      DEFAULT_SHAPES,
+      [],
+      {
+        positionalParams: [Effect.ConditionallyMutateIterator],
+        restParam: null,
+        returnType: {kind: 'Object', shapeId: BuiltInMapId},
+        calleeEffect: Effect.Read,
+        returnValueKind: ValueKind.Mutable,
+      },
+      null,
+      true,
+    ),
+  ],
+  [
+    'Set',
+    addFunction(
+      DEFAULT_SHAPES,
+      [],
+      {
+        positionalParams: [Effect.ConditionallyMutateIterator],
+        restParam: null,
+        returnType: {kind: 'Object', shapeId: BuiltInSetId},
+        calleeEffect: Effect.Read,
+        returnValueKind: ValueKind.Mutable,
+      },
+      null,
+      true,
+    ),
+  ],
   // TODO: rest of Global objects
 ];
 

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

@@ -10,7 +10,7 @@ import * as t from '@babel/types';
 import {CompilerError, CompilerErrorDetailOptions} from '../CompilerError';
 import {assertExhaustive} from '../Utils/utils';
 import {Environment, ReactFunctionType} from './Environment';
-import {HookKind} from './ObjectShape';
+import type {HookKind} from './ObjectShape';
 import {Type, makeType} from './Types';
 import {z} from 'zod';
 
@@ -829,6 +829,13 @@ export type CallExpression = {
   typeArguments?: Array<t.FlowType>;
 };
 
+export type NewExpression = {
+  kind: 'NewExpression';
+  callee: Place;
+  args: Array<Place | SpreadPattern>;
+  loc: SourceLocation;
+};
+
 export type LoadLocal = {
   kind: 'LoadLocal';
   place: Place;
@@ -894,12 +901,7 @@ export type InstructionValue =
       right: Place;
       loc: SourceLocation;
     }
-  | {
-      kind: 'NewExpression';
-      callee: Place;
-      args: Array<Place | SpreadPattern>;
-      loc: SourceLocation;
-    }
+  | NewExpression
   | CallExpression
   | MethodCall
   | {
@@ -1165,18 +1167,21 @@ export type VariableBinding =
   // bindings declard outside the current component/hook
   | NonLocalBinding;
 
+// `import {bar as baz} from 'foo'`: name=baz, module=foo, imported=bar
+export type NonLocalImportSpecifier = {
+  kind: 'ImportSpecifier';
+  name: string;
+  module: string;
+  imported: string;
+};
+
 export type NonLocalBinding =
   // `import Foo from 'foo'`: name=Foo, module=foo
   | {kind: 'ImportDefault'; name: string; module: string}
   // `import * as Foo from 'foo'`: name=Foo, module=foo
   | {kind: 'ImportNamespace'; name: string; module: string}
-  // `import {bar as baz} from 'foo'`: name=baz, module=foo, imported=bar
-  | {
-      kind: 'ImportSpecifier';
-      name: string;
-      module: string;
-      imported: string;
-    }
+  // `import {bar as baz} from 'foo'`
+  | NonLocalImportSpecifier
   // let, const, function, etc declared in the module but outside the current component/hook
   | {kind: 'ModuleLocal'; name: string}
   // an unresolved binding
@@ -1394,6 +1399,7 @@ export enum Effect {
   Read = 'read',
   // This reference reads and stores the value
   Capture = 'capture',
+  ConditionallyMutateIterator = 'mutate-iterator?',
   /*
    * This reference *may* write to (mutate) the value. This covers two similar cases:
    * - The compiler is being conservative and assuming that a value *may* be mutated
@@ -1412,11 +1418,11 @@ export enum Effect {
   // This reference may alias to (mutate) the value
   Store = 'store',
 }
-
 export const EffectSchema = z.enum([
   Effect.Read,
   Effect.Mutate,
   Effect.ConditionallyMutate,
+  Effect.ConditionallyMutateIterator,
   Effect.Capture,
   Effect.Store,
   Effect.Freeze,
@@ -1430,6 +1436,7 @@ export function isMutableEffect(
     case Effect.Capture:
     case Effect.Store:
     case Effect.ConditionallyMutate:
+    case Effect.ConditionallyMutateIterator:
     case Effect.Mutate: {
       return true;
     }
@@ -1649,6 +1656,14 @@ export function isArrayType(id: Identifier): boolean {
   return id.type.kind === 'Object' && id.type.shapeId === 'BuiltInArray';
 }
 
+export function isMapType(id: Identifier): boolean {
+  return id.type.kind === 'Object' && id.type.shapeId === 'BuiltInMap';
+}
+
+export function isSetType(id: Identifier): boolean {
+  return id.type.kind === 'Object' && id.type.shapeId === 'BuiltInSet';
+}
+
 export function isPropsType(id: Identifier): boolean {
   return id.type.kind === 'Object' && id.type.shapeId === 'BuiltInProps';
 }

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

@@ -331,6 +331,7 @@ export default class HIRBuilder {
           type: makeType(),
           loc: node.loc ?? GeneratedSource,
         };
+        this.#env.programContext.addNewReference(name);
         this.#bindings.set(name, {node, identifier});
         return identifier;
       } else if (mapping.node === node) {

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

@@ -44,6 +44,7 @@ export function addFunction(
   properties: Iterable<[string, BuiltInType | PolyType]>,
   fn: Omit<FunctionSignature, 'hookKind'>,
   id: string | null = null,
+  isConstructor: boolean = false,
 ): FunctionType {
   const shapeId = id ?? createAnonId();
   addShape(registry, shapeId, properties, {
@@ -54,6 +55,7 @@ export function addFunction(
     kind: 'Function',
     return: fn.returnType,
     shapeId,
+    isConstructor,
   };
 }
 
@@ -73,6 +75,7 @@ export function addHook(
     kind: 'Function',
     return: fn.returnType,
     shapeId,
+    isConstructor: false,
   };
 }
 
@@ -198,6 +201,8 @@ export type ObjectShape = {
 export type ShapeRegistry = Map<string, ObjectShape>;
 export const BuiltInPropsId = 'BuiltInProps';
 export const BuiltInArrayId = 'BuiltInArray';
+export const BuiltInSetId = 'BuiltInSet';
+export const BuiltInMapId = 'BuiltInMap';
 export const BuiltInFunctionId = 'BuiltInFunction';
 export const BuiltInJsxId = 'BuiltInJsx';
 export const BuiltInObjectId = 'BuiltInObject';
@@ -451,6 +456,313 @@ addObject(BUILTIN_SHAPES, BuiltInObjectId, [
    */
 ]);
 
+/* Built-in Set shape */
+addObject(BUILTIN_SHAPES, BuiltInSetId, [
+  [
+    /**
+     * add(value)
+     * Parameters
+     *   value: the value of the element to add to the Set object.
+     * Returns the Set object with added value.
+     */
+    'add',
+    addFunction(BUILTIN_SHAPES, [], {
+      positionalParams: [Effect.Capture],
+      restParam: null,
+      returnType: {kind: 'Object', shapeId: BuiltInSetId},
+      calleeEffect: Effect.Store,
+      // returnValueKind is technically dependent on the ValueKind of the set itself
+      returnValueKind: ValueKind.Mutable,
+    }),
+  ],
+  [
+    /**
+     * clear()
+     * Parameters none
+     * Returns undefined
+     */
+    'clear',
+    addFunction(BUILTIN_SHAPES, [], {
+      positionalParams: [],
+      restParam: null,
+      returnType: PRIMITIVE_TYPE,
+      calleeEffect: Effect.Store,
+      returnValueKind: ValueKind.Primitive,
+    }),
+  ],
+  [
+    /**
+     * setInstance.delete(value)
+     * Returns true if value was already in Set; otherwise false.
+     */
+    'delete',
+    addFunction(BUILTIN_SHAPES, [], {
+      positionalParams: [Effect.Read],
+      restParam: null,
+      returnType: PRIMITIVE_TYPE,
+      calleeEffect: Effect.Store,
+      returnValueKind: ValueKind.Primitive,
+    }),
+  ],
+  [
+    'has',
+    addFunction(BUILTIN_SHAPES, [], {
+      positionalParams: [Effect.Read],
+      restParam: null,
+      returnType: PRIMITIVE_TYPE,
+      calleeEffect: Effect.Read,
+      returnValueKind: ValueKind.Primitive,
+    }),
+  ],
+  ['size', PRIMITIVE_TYPE],
+  [
+    /**
+     * difference(other)
+     * Parameters
+     *   other: A Set object, or set-like object.
+     * Returns a new Set object containing elements in this set but not in the other set.
+     */
+    'difference',
+    addFunction(BUILTIN_SHAPES, [], {
+      positionalParams: [Effect.Capture],
+      restParam: null,
+      returnType: {kind: 'Object', shapeId: BuiltInSetId},
+      calleeEffect: Effect.Capture,
+      returnValueKind: ValueKind.Mutable,
+    }),
+  ],
+  [
+    /**
+     * union(other)
+     * Parameters
+     *   other: A Set object, or set-like object.
+     * Returns a new Set object containing elements in either this set or the other set.
+     */
+    'union',
+    addFunction(BUILTIN_SHAPES, [], {
+      positionalParams: [Effect.Capture],
+      restParam: null,
+      returnType: {kind: 'Object', shapeId: BuiltInSetId},
+      calleeEffect: Effect.Capture,
+      returnValueKind: ValueKind.Mutable,
+    }),
+  ],
+  [
+    /**
+     * symmetricalDifference(other)
+     * Parameters
+     *   other: A Set object, or set-like object.
+     * A new Set object containing elements which are in either this set or the other set, but not in both.
+     */
+    'symmetricalDifference',
+    addFunction(BUILTIN_SHAPES, [], {
+      positionalParams: [Effect.Capture],
+      restParam: null,
+      returnType: {kind: 'Object', shapeId: BuiltInSetId},
+      calleeEffect: Effect.Capture,
+      returnValueKind: ValueKind.Mutable,
+    }),
+  ],
+  [
+    /**
+     * isSubsetOf(other)
+     * Parameters
+     *   other: A Set object, or set-like object.
+     * Returns true if all elements in this set are also in the other set, and false otherwise.
+     */
+    'isSubsetOf',
+    addFunction(BUILTIN_SHAPES, [], {
+      positionalParams: [Effect.Read],
+      restParam: null,
+      returnType: PRIMITIVE_TYPE,
+      calleeEffect: Effect.Read,
+      returnValueKind: ValueKind.Primitive,
+    }),
+  ],
+  [
+    /**
+     * isSupersetOf(other)
+     * Parameters
+     *  other: A Set object, or set-like object.
+     * Returns true if all elements in the other set are also in this set, and false otherwise.
+     */
+    'isSupersetOf',
+    addFunction(BUILTIN_SHAPES, [], {
+      positionalParams: [Effect.Read],
+      restParam: null,
+      returnType: PRIMITIVE_TYPE,
+      calleeEffect: Effect.Read,
+      returnValueKind: ValueKind.Primitive,
+    }),
+  ],
+  [
+    /**
+     * forEach(callbackFn)
+     * forEach(callbackFn, thisArg)
+     */
+    'forEach',
+    addFunction(BUILTIN_SHAPES, [], {
+      /**
+       * see Array.map explanation for why arguments are marked `ConditionallyMutate`
+       */
+      positionalParams: [],
+      restParam: Effect.ConditionallyMutate,
+      returnType: PRIMITIVE_TYPE,
+      calleeEffect: Effect.ConditionallyMutate,
+      returnValueKind: ValueKind.Primitive,
+      noAlias: true,
+      mutableOnlyIfOperandsAreMutable: true,
+    }),
+  ],
+  /**
+   * Iterators
+   */
+  [
+    'entries',
+    addFunction(BUILTIN_SHAPES, [], {
+      positionalParams: [],
+      restParam: null,
+      returnType: {kind: 'Poly'},
+      calleeEffect: Effect.Capture,
+      returnValueKind: ValueKind.Mutable,
+    }),
+  ],
+  [
+    'keys',
+    addFunction(BUILTIN_SHAPES, [], {
+      positionalParams: [],
+      restParam: null,
+      returnType: {kind: 'Poly'},
+      calleeEffect: Effect.Capture,
+      returnValueKind: ValueKind.Mutable,
+    }),
+  ],
+  [
+    'values',
+    addFunction(BUILTIN_SHAPES, [], {
+      positionalParams: [],
+      restParam: null,
+      returnType: {kind: 'Poly'},
+      calleeEffect: Effect.Capture,
+      returnValueKind: ValueKind.Mutable,
+    }),
+  ],
+]);
+addObject(BUILTIN_SHAPES, BuiltInMapId, [
+  [
+    /**
+     * clear()
+     * Parameters none
+     * Returns undefined
+     */
+    'clear',
+    addFunction(BUILTIN_SHAPES, [], {
+      positionalParams: [],
+      restParam: null,
+      returnType: PRIMITIVE_TYPE,
+      calleeEffect: Effect.Store,
+      returnValueKind: ValueKind.Primitive,
+    }),
+  ],
+  [
+    'delete',
+    addFunction(BUILTIN_SHAPES, [], {
+      positionalParams: [Effect.Read],
+      restParam: null,
+      returnType: PRIMITIVE_TYPE,
+      calleeEffect: Effect.Store,
+      returnValueKind: ValueKind.Primitive,
+    }),
+  ],
+  [
+    'get',
+    addFunction(BUILTIN_SHAPES, [], {
+      positionalParams: [Effect.Read],
+      restParam: null,
+      returnType: {kind: 'Poly'},
+      calleeEffect: Effect.Capture,
+      returnValueKind: ValueKind.Mutable,
+    }),
+  ],
+  [
+    'has',
+    addFunction(BUILTIN_SHAPES, [], {
+      positionalParams: [Effect.Read],
+      restParam: null,
+      returnType: PRIMITIVE_TYPE,
+      calleeEffect: Effect.Read,
+      returnValueKind: ValueKind.Primitive,
+    }),
+  ],
+  [
+    /**
+     * Params
+     *   key: the key of the element to add to the Map object. The key may be
+     *   any JavaScript type (any primitive value or any type of JavaScript
+     *   object).
+     *   value: the value of the element to add to the Map object.
+     * Returns the Map object.
+     */
+    'set',
+    addFunction(BUILTIN_SHAPES, [], {
+      positionalParams: [Effect.Capture, Effect.Capture],
+      restParam: null,
+      returnType: {kind: 'Object', shapeId: BuiltInMapId},
+      calleeEffect: Effect.Store,
+      returnValueKind: ValueKind.Mutable,
+    }),
+  ],
+  ['size', PRIMITIVE_TYPE],
+  [
+    'forEach',
+    addFunction(BUILTIN_SHAPES, [], {
+      /**
+       * see Array.map explanation for why arguments are marked `ConditionallyMutate`
+       */
+      positionalParams: [],
+      restParam: Effect.ConditionallyMutate,
+      returnType: PRIMITIVE_TYPE,
+      calleeEffect: Effect.ConditionallyMutate,
+      returnValueKind: ValueKind.Primitive,
+      noAlias: true,
+      mutableOnlyIfOperandsAreMutable: true,
+    }),
+  ],
+  /**
+   * Iterators
+   */
+  [
+    'entries',
+    addFunction(BUILTIN_SHAPES, [], {
+      positionalParams: [],
+      restParam: null,
+      returnType: {kind: 'Poly'},
+      calleeEffect: Effect.Capture,
+      returnValueKind: ValueKind.Mutable,
+    }),
+  ],
+  [
+    'keys',
+    addFunction(BUILTIN_SHAPES, [], {
+      positionalParams: [],
+      restParam: null,
+      returnType: {kind: 'Poly'},
+      calleeEffect: Effect.Capture,
+      returnValueKind: ValueKind.Mutable,
+    }),
+  ],
+  [
+    'values',
+    addFunction(BUILTIN_SHAPES, [], {
+      positionalParams: [],
+      restParam: null,
+      returnType: {kind: 'Poly'},
+      calleeEffect: Effect.Capture,
+      returnValueKind: ValueKind.Mutable,
+    }),
+  ],
+]);
+
 addObject(BUILTIN_SHAPES, BuiltInUseStateId, [
   ['0', {kind: 'Poly'}],
   [

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

@@ -38,6 +38,7 @@ export type FunctionType = {
   kind: 'Function';
   shapeId: string | null;
   return: Type;
+  isConstructor: boolean;
 };
 
 export type ObjectType = {
@@ -111,6 +112,7 @@ export function duplicateType(type: Type): Type {
         kind: 'Function',
         return: duplicateType(type.return),
         shapeId: type.shapeId,
+        isConstructor: type.isConstructor,
       };
     }
     case 'Object': {

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

@@ -249,6 +249,7 @@ export function inferEffectDependencies(fn: HIRFunction): void {
     // Renumber instructions and fix scope ranges
     markInstructionIds(fn.body);
     fixScopeAndIdentifierRanges(fn.body);
+    fn.env.hasInferredEffect = true;
   }
 }
 

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

@@ -11,7 +11,10 @@ import {
   Identifier,
   InstructionId,
   InstructionKind,
+  isArrayType,
+  isMapType,
   isRefOrRefValue,
+  isSetType,
   makeInstructionId,
   Place,
 } from '../HIR/HIR';
@@ -90,6 +93,17 @@ function inferPlace(
         infer(place, instrId);
       }
       return;
+    case Effect.ConditionallyMutateIterator: {
+      const identifier = place.identifier;
+      if (
+        !isArrayType(identifier) &&
+        !isSetType(identifier) &&
+        !isMapType(identifier)
+      ) {
+        infer(place, instrId);
+      }
+      return;
+    }
     case Effect.ConditionallyMutate:
     case Effect.Mutate: {
       infer(place, instrId);

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

@@ -230,6 +230,7 @@ export function inferReactivePlaces(fn: HIRFunction): void {
               case Effect.Capture:
               case Effect.Store:
               case Effect.ConditionallyMutate:
+              case Effect.ConditionallyMutateIterator:
               case Effect.Mutate: {
                 if (isMutable(instruction, operand)) {
                   reactiveIdentifiers.markReactive(operand);

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

@@ -12,6 +12,7 @@ import {
   BasicBlock,
   BlockId,
   CallExpression,
+  NewExpression,
   Effect,
   FunctionEffect,
   GeneratedSource,
@@ -23,12 +24,15 @@ import {
   Phi,
   Place,
   SpreadPattern,
+  TInstruction,
   Type,
   ValueKind,
   ValueReason,
   isArrayType,
+  isMapType,
   isMutableEffect,
   isObjectType,
+  isSetType,
 } from '../HIR/HIR';
 import {FunctionSignature} from '../HIR/ObjectShape';
 import {
@@ -38,7 +42,6 @@ import {
   printSourceLocation,
 } from '../HIR/PrintHIR';
 import {
-  eachCallArgument,
   eachInstructionOperand,
   eachInstructionValueOperand,
   eachPatternOperand,
@@ -251,7 +254,7 @@ type FreezeAction = {values: Set<InstructionValue>; reason: Set<ValueReason>};
 
 // Maintains a mapping of top-level variables to the kind of value they hold
 class InferenceState {
-  #env: Environment;
+  env: Environment;
 
   // The kind of each value, based on its allocation site
   #values: Map<InstructionValue, AbstractValue>;
@@ -267,7 +270,7 @@ class InferenceState {
     values: Map<InstructionValue, AbstractValue>,
     variables: Map<IdentifierId, Set<InstructionValue>>,
   ) {
-    this.#env = env;
+    this.env = env;
     this.#values = values;
     this.#variables = variables;
   }
@@ -409,8 +412,8 @@ class InferenceState {
       });
       if (
         value.kind === 'FunctionExpression' &&
-        (this.#env.config.enablePreserveExistingMemoizationGuarantees ||
-          this.#env.config.enableTransitivelyFreezeFunctionExpressions)
+        (this.env.config.enablePreserveExistingMemoizationGuarantees ||
+          this.env.config.enableTransitivelyFreezeFunctionExpressions)
       ) {
         for (const operand of value.loweredFunc.func.context) {
           const operandValues = this.#variables.get(operand.identifier.id);
@@ -468,6 +471,25 @@ class InferenceState {
         }
         break;
       }
+      case Effect.ConditionallyMutateIterator: {
+        if (
+          valueKind.kind === ValueKind.Mutable ||
+          valueKind.kind === ValueKind.Context
+        ) {
+          if (
+            isArrayType(place.identifier) ||
+            isSetType(place.identifier) ||
+            isMapType(place.identifier)
+          ) {
+            effect = Effect.Capture;
+          } else {
+            effect = Effect.ConditionallyMutate;
+          }
+        } else {
+          effect = Effect.Read;
+        }
+        break;
+      }
       case Effect.Mutate: {
         effect = Effect.Mutate;
         break;
@@ -590,7 +612,7 @@ class InferenceState {
       return null;
     } else {
       return new InferenceState(
-        this.#env,
+        this.env,
         nextValues ?? new Map(this.#values),
         nextVariables ?? new Map(this.#variables),
       );
@@ -604,7 +626,7 @@ class InferenceState {
    */
   clone(): InferenceState {
     return new InferenceState(
-      this.#env,
+      this.env,
       new Map(this.#values),
       new Map(this.#variables),
     );
@@ -879,9 +901,7 @@ function inferBlock(
             state.referenceAndRecordEffects(
               freezeActions,
               element.place,
-              isArrayType(element.place.identifier)
-                ? Effect.Capture
-                : Effect.ConditionallyMutate,
+              Effect.ConditionallyMutateIterator,
               ValueReason.Other,
             );
           } else if (element.kind === 'Identifier') {
@@ -904,43 +924,12 @@ function inferBlock(
         break;
       }
       case 'NewExpression': {
-        /**
-         * For new expressions, we infer a `read` effect on the Class / Function type
-         * to avoid extending mutable ranges of locally created classes, e.g.
-         * ```js
-         * const MyClass = getClass();
-         * const value = new MyClass(val1, val2)
-         *                   ^ (read)   ^ (conditionally mutate)
-         * ```
-         *
-         * Risks:
-         * Classes / functions created during render could technically capture and
-         * mutate their enclosing scope, which we currently do not detect.
-         */
-        const valueKind: AbstractValue = {
-          kind: ValueKind.Mutable,
-          reason: new Set([ValueReason.Other]),
-          context: new Set(),
-        };
-        state.referenceAndRecordEffects(
+        inferCallEffects(
+          state,
+          instr as TInstruction<NewExpression>,
           freezeActions,
-          instrValue.callee,
-          Effect.Read,
-          ValueReason.Other,
+          getFunctionCallSignature(env, instrValue.callee.identifier.type),
         );
-
-        for (const operand of eachCallArgument(instrValue.args)) {
-          state.referenceAndRecordEffects(
-            freezeActions,
-            operand,
-            Effect.ConditionallyMutate,
-            ValueReason.Other,
-          );
-        }
-
-        state.initialize(instrValue, valueKind);
-        state.define(instr.lvalue, instrValue);
-        instr.lvalue.effect = Effect.ConditionallyMutate;
         continuation = {kind: 'funeffects'};
         break;
       }
@@ -1238,62 +1227,12 @@ function inferBlock(
         break;
       }
       case 'CallExpression': {
-        const signature = getFunctionCallSignature(
-          env,
-          instrValue.callee.identifier.type,
+        inferCallEffects(
+          state,
+          instr as TInstruction<CallExpression>,
+          freezeActions,
+          getFunctionCallSignature(env, instrValue.callee.identifier.type),
         );
-
-        const effects =
-          signature !== null ? getFunctionEffects(instrValue, signature) : null;
-        const returnValueKind: AbstractValue =
-          signature !== null
-            ? {
-                kind: signature.returnValueKind,
-                reason: new Set([
-                  signature.returnValueReason ??
-                    ValueReason.KnownReturnSignature,
-                ]),
-                context: new Set(),
-              }
-            : {
-                kind: ValueKind.Mutable,
-                reason: new Set([ValueReason.Other]),
-                context: new Set(),
-              };
-        let hasCaptureArgument = false;
-        for (let i = 0; i < instrValue.args.length; i++) {
-          const arg = instrValue.args[i];
-          const place = arg.kind === 'Identifier' ? arg : arg.place;
-          state.referenceAndRecordEffects(
-            freezeActions,
-            place,
-            getArgumentEffect(effects != null ? effects[i] : null, arg),
-            ValueReason.Other,
-          );
-          hasCaptureArgument ||= place.effect === Effect.Capture;
-        }
-        if (signature !== null) {
-          state.referenceAndRecordEffects(
-            freezeActions,
-            instrValue.callee,
-            signature.calleeEffect,
-            ValueReason.Other,
-          );
-        } else {
-          state.referenceAndRecordEffects(
-            freezeActions,
-            instrValue.callee,
-            Effect.ConditionallyMutate,
-            ValueReason.Other,
-          );
-        }
-        hasCaptureArgument ||= instrValue.callee.effect === Effect.Capture;
-
-        state.initialize(instrValue, returnValueKind);
-        state.define(instr.lvalue, instrValue);
-        instr.lvalue.effect = hasCaptureArgument
-          ? Effect.Store
-          : Effect.ConditionallyMutate;
         continuation = {kind: 'funeffects'};
         break;
       }
@@ -1311,102 +1250,12 @@ function inferBlock(
           Effect.Read,
           ValueReason.Other,
         );
-
-        const signature = getFunctionCallSignature(
-          env,
-          instrValue.property.identifier.type,
+        inferCallEffects(
+          state,
+          instr as TInstruction<MethodCall>,
+          freezeActions,
+          getFunctionCallSignature(env, instrValue.property.identifier.type),
         );
-
-        const returnValueKind: AbstractValue =
-          signature !== null
-            ? {
-                kind: signature.returnValueKind,
-                reason: new Set([
-                  signature.returnValueReason ??
-                    ValueReason.KnownReturnSignature,
-                ]),
-                context: new Set(),
-              }
-            : {
-                kind: ValueKind.Mutable,
-                reason: new Set([ValueReason.Other]),
-                context: new Set(),
-              };
-
-        if (
-          signature !== null &&
-          signature.mutableOnlyIfOperandsAreMutable &&
-          areArgumentsImmutableAndNonMutating(state, instrValue.args)
-        ) {
-          /*
-           * None of the args are mutable or mutate their params, we can downgrade to
-           * treating as all reads (except that the receiver may be captured)
-           */
-          for (const arg of instrValue.args) {
-            const place = arg.kind === 'Identifier' ? arg : arg.place;
-            state.referenceAndRecordEffects(
-              freezeActions,
-              place,
-              Effect.Read,
-              ValueReason.Other,
-            );
-          }
-          state.referenceAndRecordEffects(
-            freezeActions,
-            instrValue.receiver,
-            Effect.Capture,
-            ValueReason.Other,
-          );
-          state.initialize(instrValue, returnValueKind);
-          state.define(instr.lvalue, instrValue);
-          instr.lvalue.effect =
-            instrValue.receiver.effect === Effect.Capture
-              ? Effect.Store
-              : Effect.ConditionallyMutate;
-          continuation = {kind: 'funeffects'};
-          break;
-        }
-
-        const effects =
-          signature !== null ? getFunctionEffects(instrValue, signature) : null;
-        let hasCaptureArgument = false;
-        for (let i = 0; i < instrValue.args.length; i++) {
-          const arg = instrValue.args[i];
-          const place = arg.kind === 'Identifier' ? arg : arg.place;
-          /*
-           * If effects are inferred for an argument, we should fail invalid
-           * mutating effects
-           */
-          state.referenceAndRecordEffects(
-            freezeActions,
-            place,
-            getArgumentEffect(effects != null ? effects[i] : null, arg),
-            ValueReason.Other,
-          );
-          hasCaptureArgument ||= place.effect === Effect.Capture;
-        }
-        if (signature !== null) {
-          state.referenceAndRecordEffects(
-            freezeActions,
-            instrValue.receiver,
-            signature.calleeEffect,
-            ValueReason.Other,
-          );
-        } else {
-          state.referenceAndRecordEffects(
-            freezeActions,
-            instrValue.receiver,
-            Effect.ConditionallyMutate,
-            ValueReason.Other,
-          );
-        }
-        hasCaptureArgument ||= instrValue.receiver.effect === Effect.Capture;
-
-        state.initialize(instrValue, returnValueKind);
-        state.define(instr.lvalue, instrValue);
-        instr.lvalue.effect = hasCaptureArgument
-          ? Effect.Store
-          : Effect.ConditionallyMutate;
         continuation = {kind: 'funeffects'};
         break;
       }
@@ -1813,7 +1662,13 @@ function inferBlock(
           kind === ValueKind.Mutable || kind === ValueKind.Context;
         let effect;
         let valueKind: AbstractValue;
-        if (!isMutable || isArrayType(instrValue.collection.identifier)) {
+        const iterator = instrValue.collection.identifier;
+        if (
+          !isMutable ||
+          isArrayType(iterator) ||
+          isMapType(iterator) ||
+          isSetType(iterator)
+        ) {
           // Case 1, assume iterator is a separate mutable object
           effect = {
             kind: Effect.Read,
@@ -1854,7 +1709,7 @@ function inferBlock(
         state.referenceAndRecordEffects(
           freezeActions,
           instrValue.iterator,
-          Effect.ConditionallyMutate,
+          Effect.ConditionallyMutateIterator,
           ValueReason.Other,
         );
         /**
@@ -1983,7 +1838,7 @@ export function getFunctionCallSignature(
  * @returns Inferred effects of function arguments, or null if inference fails.
  */
 export function getFunctionEffects(
-  fn: MethodCall | CallExpression,
+  fn: MethodCall | CallExpression | NewExpression,
   sig: FunctionSignature,
 ): Array<Effect> | null {
   const results = [];
@@ -2012,6 +1867,33 @@ export function getFunctionEffects(
   return results;
 }
 
+export function isKnownMutableEffect(effect: Effect): boolean {
+  switch (effect) {
+    case Effect.Store:
+    case Effect.ConditionallyMutate:
+    case Effect.ConditionallyMutateIterator:
+    case Effect.Mutate: {
+      return true;
+    }
+
+    case Effect.Unknown: {
+      CompilerError.invariant(false, {
+        reason: 'Unexpected unknown effect',
+        description: null,
+        loc: GeneratedSource,
+        suggestions: null,
+      });
+    }
+    case Effect.Read:
+    case Effect.Capture:
+    case Effect.Freeze: {
+      return false;
+    }
+    default: {
+      assertExhaustive(effect, `Unexpected effect \`${effect}\``);
+    }
+  }
+}
 /**
  * Returns true if all of the arguments are both non-mutable (immutable or frozen)
  * _and_ are not functions which might mutate their arguments. Note that function
@@ -2023,10 +1905,20 @@ function areArgumentsImmutableAndNonMutating(
   args: MethodCall['args'],
 ): boolean {
   for (const arg of args) {
+    if (arg.kind === 'Identifier' && arg.identifier.type.kind === 'Function') {
+      const fnShape = state.env.getFunctionSignature(arg.identifier.type);
+      if (fnShape != null) {
+        return (
+          !fnShape.positionalParams.some(isKnownMutableEffect) &&
+          (fnShape.restParam == null ||
+            !isKnownMutableEffect(fnShape.restParam))
+        );
+      }
+    }
     const place = arg.kind === 'Identifier' ? arg : arg.place;
+
     const kind = state.kind(place).kind;
     switch (kind) {
-      case ValueKind.Global:
       case ValueKind.Primitive:
       case ValueKind.Frozen: {
         /*
@@ -2037,6 +1929,10 @@ function areArgumentsImmutableAndNonMutating(
         break;
       }
       default: {
+        /**
+         * Globals, module locals, and other locally defined functions may
+         * mutate their arguments.
+         */
         return false;
       }
     }
@@ -2079,9 +1975,128 @@ function getArgumentEffect(
         });
       }
       // effects[i] is Effect.Capture | Effect.Read | Effect.Store
-      return Effect.ConditionallyMutate;
+      return Effect.ConditionallyMutateIterator;
     }
   } else {
     return Effect.ConditionallyMutate;
   }
 }
+
+function inferCallEffects(
+  state: InferenceState,
+  instr:
+    | TInstruction<CallExpression>
+    | TInstruction<MethodCall>
+    | TInstruction<NewExpression>,
+  freezeActions: Array<FreezeAction>,
+  signature: FunctionSignature | null,
+): void {
+  const instrValue = instr.value;
+  const returnValueKind: AbstractValue =
+    signature !== null
+      ? {
+          kind: signature.returnValueKind,
+          reason: new Set([
+            signature.returnValueReason ?? ValueReason.KnownReturnSignature,
+          ]),
+          context: new Set(),
+        }
+      : {
+          kind: ValueKind.Mutable,
+          reason: new Set([ValueReason.Other]),
+          context: new Set(),
+        };
+
+  if (
+    instrValue.kind === 'MethodCall' &&
+    signature !== null &&
+    signature.mutableOnlyIfOperandsAreMutable &&
+    areArgumentsImmutableAndNonMutating(state, instrValue.args)
+  ) {
+    /*
+     * None of the args are mutable or mutate their params, we can downgrade to
+     * treating as all reads (except that the receiver may be captured)
+     */
+    for (const arg of instrValue.args) {
+      const place = arg.kind === 'Identifier' ? arg : arg.place;
+      state.referenceAndRecordEffects(
+        freezeActions,
+        place,
+        Effect.Read,
+        ValueReason.Other,
+      );
+    }
+    state.referenceAndRecordEffects(
+      freezeActions,
+      instrValue.receiver,
+      Effect.Capture,
+      ValueReason.Other,
+    );
+    state.initialize(instrValue, returnValueKind);
+    state.define(instr.lvalue, instrValue);
+    instr.lvalue.effect =
+      instrValue.receiver.effect === Effect.Capture
+        ? Effect.Store
+        : Effect.ConditionallyMutate;
+    return;
+  }
+
+  const effects =
+    signature !== null ? getFunctionEffects(instrValue, signature) : null;
+  let hasCaptureArgument = false;
+  for (let i = 0; i < instrValue.args.length; i++) {
+    const arg = instrValue.args[i];
+    const place = arg.kind === 'Identifier' ? arg : arg.place;
+    /*
+     * If effects are inferred for an argument, we should fail invalid
+     * mutating effects
+     */
+    state.referenceAndRecordEffects(
+      freezeActions,
+      place,
+      getArgumentEffect(effects != null ? effects[i] : null, arg),
+      ValueReason.Other,
+    );
+    hasCaptureArgument ||= place.effect === Effect.Capture;
+  }
+  const callee =
+    instrValue.kind === 'MethodCall' ? instrValue.receiver : instrValue.callee;
+  if (signature !== null) {
+    state.referenceAndRecordEffects(
+      freezeActions,
+      callee,
+      signature.calleeEffect,
+      ValueReason.Other,
+    );
+  } else {
+    /**
+     * For new expressions, we infer a `read` effect on the Class / Function type
+     * to avoid extending mutable ranges of locally created classes, e.g.
+     * ```js
+     * const MyClass = getClass();
+     * const value = new MyClass(val1, val2)
+     *                   ^ (read)   ^ (conditionally mutate)
+     * ```
+     *
+     * Risks:
+     * Classes / functions created during render could technically capture and
+     * mutate their enclosing scope, which we currently do not detect.
+     */
+
+    state.referenceAndRecordEffects(
+      freezeActions,
+      callee,
+      instrValue.kind === 'NewExpression'
+        ? Effect.Read
+        : Effect.ConditionallyMutate,
+      ValueReason.Other,
+    );
+  }
+  hasCaptureArgument ||= callee.effect === Effect.Capture;
+
+  state.initialize(instrValue, returnValueKind);
+  state.define(instr.lvalue, instrValue);
+  instr.lvalue.effect = hasCaptureArgument
+    ? Effect.Store
+    : Effect.ConditionallyMutate;
+}

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

@@ -18,6 +18,7 @@ import {
   Instruction,
   LoadGlobal,
   LoadLocal,
+  NonLocalImportSpecifier,
   Place,
   PropertyLoad,
   isUseContextHookType,
@@ -35,7 +36,7 @@ import {inferTypes} from '../TypeInference';
 
 export function lowerContextAccess(
   fn: HIRFunction,
-  loweredContextCallee: ExternalFunction,
+  loweredContextCalleeConfig: ExternalFunction,
 ): void {
   const contextAccess: Map<IdentifierId, CallExpression> = new Map();
   const contextKeys: Map<IdentifierId, Array<string>> = new Map();
@@ -79,6 +80,8 @@ export function lowerContextAccess(
     }
   }
 
+  let importLoweredContextCallee: NonLocalImportSpecifier | null = null;
+
   if (contextAccess.size > 0 && contextKeys.size > 0) {
     for (const [, block] of fn.body.blocks) {
       let nextInstructions: Array<Instruction> | null = null;
@@ -91,9 +94,13 @@ export function lowerContextAccess(
           isUseContextHookType(value.callee.identifier) &&
           contextKeys.has(lvalue.identifier.id)
         ) {
+          importLoweredContextCallee ??=
+            fn.env.programContext.addImportSpecifier(
+              loweredContextCalleeConfig,
+            );
           const loweredContextCalleeInstr = emitLoadLoweredContextCallee(
             fn.env,
-            loweredContextCallee,
+            importLoweredContextCallee,
           );
 
           if (nextInstructions === null) {
@@ -122,21 +129,16 @@ export function lowerContextAccess(
     }
     markInstructionIds(fn.body);
     inferTypes(fn);
-    fn.env.hasLoweredContextAccess = true;
   }
 }
 
 function emitLoadLoweredContextCallee(
   env: Environment,
-  loweredContextCallee: ExternalFunction,
+  importedLowerContextCallee: NonLocalImportSpecifier,
 ): Instruction {
   const loadGlobal: LoadGlobal = {
     kind: 'LoadGlobal',
-    binding: {
-      kind: 'ImportNamespace',
-      module: loweredContextCallee.source,
-      name: loweredContextCallee.importSpecifierName,
-    },
+    binding: {...importedLowerContextCallee},
     loc: GeneratedSource,
   };
 

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

@@ -196,7 +196,7 @@ function process(
     return null;
   }
 
-  const props = collectProps(jsx);
+  const props = collectProps(fn.env, jsx);
   if (!props) return null;
 
   const outlinedTag = fn.env.generateGloballyUniqueIdentifierName(null).value;
@@ -217,6 +217,7 @@ type OutlinedJsxAttribute = {
 };
 
 function collectProps(
+  env: Environment,
   instructions: Array<JsxInstruction>,
 ): Array<OutlinedJsxAttribute> | null {
   let id = 1;
@@ -227,6 +228,7 @@ function collectProps(
       newName = `${oldName}${id++}`;
     }
     seen.add(newName);
+    env.programContext.addNewReference(newName);
     return newName;
   }
 

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

@@ -52,7 +52,8 @@ import {assertExhaustive} from '../Utils/utils';
 import {buildReactiveFunction} from './BuildReactiveFunction';
 import {SINGLE_CHILD_FBT_TAGS} from './MemoizeFbtAndMacroOperandsInSameScope';
 import {ReactiveFunctionVisitor, visitReactiveFunction} from './visitors';
-import {ReactFunctionType} from '../HIR/Environment';
+import {EMIT_FREEZE_GLOBAL_GATING, ReactFunctionType} from '../HIR/Environment';
+import {ProgramContext} from '../Entrypoint';
 
 export const MEMO_CACHE_SENTINEL = 'react.memo_cache_sentinel';
 export const EARLY_RETURN_SENTINEL = 'react.early_return_sentinel';
@@ -100,9 +101,9 @@ export type CodegenFunction = {
   }>;
 
   /**
-   * This is true if the compiler has the lowered useContext calls.
+   * This is true if the compiler has compiled inferred effect dependencies
    */
-  hasLoweredContextAccess: boolean;
+  hasInferredEffect: boolean;
 
   /**
    * This is true if the compiler has compiled a fire to a useFire call
@@ -160,6 +161,7 @@ export function codegenFunction(
     compiled.body = t.blockStatement([
       createHookGuard(
         hookGuard,
+        fn.env.programContext,
         compiled.body.body,
         GuardKind.PushHookGuard,
         GuardKind.PopHookGuard,
@@ -170,13 +172,15 @@ export function codegenFunction(
   const cacheCount = compiled.memoSlotsUsed;
   if (cacheCount !== 0) {
     const preface: Array<t.Statement> = [];
+    const useMemoCacheIdentifier =
+      fn.env.programContext.addMemoCacheImport().name;
 
     // The import declaration for `useMemoCache` is inserted in the Babel plugin
     preface.push(
       t.variableDeclaration('const', [
         t.variableDeclarator(
           t.identifier(cx.synthesizeName('$')),
-          t.callExpression(t.identifier(fn.env.useMemoCacheIdentifier), [
+          t.callExpression(t.identifier(useMemoCacheIdentifier), [
             t.numericLiteral(cacheCount),
           ]),
         ),
@@ -259,34 +263,54 @@ export function codegenFunction(
      * Technically, this is a conditional hook call. However, we expect
      * __DEV__ and gating identifier to be runtime constants
      */
-    let gating: t.Expression;
-    if (
-      emitInstrumentForget.gating != null &&
+    const gating =
+      emitInstrumentForget.gating != null
+        ? t.identifier(
+            fn.env.programContext.addImportSpecifier(
+              emitInstrumentForget.gating,
+            ).name,
+          )
+        : null;
+
+    const globalGating =
       emitInstrumentForget.globalGating != null
-    ) {
-      gating = t.logicalExpression(
-        '&&',
-        t.identifier(emitInstrumentForget.globalGating),
-        t.identifier(emitInstrumentForget.gating.importSpecifierName),
+        ? t.identifier(emitInstrumentForget.globalGating)
+        : null;
+
+    if (emitInstrumentForget.globalGating != null) {
+      const assertResult = fn.env.programContext.assertGlobalBinding(
+        emitInstrumentForget.globalGating,
       );
-    } else if (emitInstrumentForget.gating != null) {
-      gating = t.identifier(emitInstrumentForget.gating.importSpecifierName);
+      if (assertResult.isErr()) {
+        return assertResult;
+      }
+    }
+
+    let ifTest: t.Expression;
+    if (gating != null && globalGating != null) {
+      ifTest = t.logicalExpression('&&', globalGating, gating);
+    } else if (gating != null) {
+      ifTest = gating;
     } else {
-      CompilerError.invariant(emitInstrumentForget.globalGating != null, {
+      CompilerError.invariant(globalGating != null, {
         reason:
           'Bad config not caught! Expected at least one of gating or globalGating',
         loc: null,
         suggestions: null,
       });
-      gating = t.identifier(emitInstrumentForget.globalGating);
+      ifTest = globalGating;
     }
+
+    const instrumentFnIdentifier = fn.env.programContext.addImportSpecifier(
+      emitInstrumentForget.fn,
+    ).name;
     const test: t.IfStatement = t.ifStatement(
-      gating,
+      ifTest,
       t.expressionStatement(
-        t.callExpression(
-          t.identifier(emitInstrumentForget.fn.importSpecifierName),
-          [t.stringLiteral(fn.id), t.stringLiteral(fn.env.filename ?? '')],
-        ),
+        t.callExpression(t.identifier(instrumentFnIdentifier), [
+          t.stringLiteral(fn.id),
+          t.stringLiteral(fn.env.filename ?? ''),
+        ]),
       ),
     );
     compiled.body.body.unshift(test);
@@ -363,8 +387,8 @@ function codegenReactiveFunction(
     prunedMemoBlocks: countMemoBlockVisitor.prunedMemoBlocks,
     prunedMemoValues: countMemoBlockVisitor.prunedMemoValues,
     outlined: [],
-    hasLoweredContextAccess: fn.env.hasLoweredContextAccess,
     hasFireRewrite: fn.env.hasFireRewrite,
+    hasInferredEffect: fn.env.hasInferredEffect,
   });
 }
 
@@ -553,13 +577,18 @@ function codegenBlockNoReset(
 
 function wrapCacheDep(cx: Context, value: t.Expression): t.Expression {
   if (cx.env.config.enableEmitFreeze != null && cx.env.isInferredMemoEnabled) {
-    // The import declaration for emitFreeze is inserted in the Babel plugin
+    const emitFreezeIdentifier = cx.env.programContext.addImportSpecifier(
+      cx.env.config.enableEmitFreeze,
+    ).name;
+    cx.env.programContext
+      .assertGlobalBinding(EMIT_FREEZE_GLOBAL_GATING, cx.env.scope)
+      .unwrap();
     return t.conditionalExpression(
-      t.identifier('__DEV__'),
-      t.callExpression(
-        t.identifier(cx.env.config.enableEmitFreeze.importSpecifierName),
-        [value, t.stringLiteral(cx.fnName)],
-      ),
+      t.identifier(EMIT_FREEZE_GLOBAL_GATING),
+      t.callExpression(t.identifier(emitFreezeIdentifier), [
+        value,
+        t.stringLiteral(cx.fnName),
+      ]),
       value,
     );
   } else {
@@ -713,16 +742,14 @@ function codegenReactiveScope(
   let computationBlock = codegenBlock(cx, block);
 
   let memoStatement;
-  if (
-    cx.env.config.enableChangeDetectionForDebugging != null &&
-    changeExpressions.length > 0
-  ) {
+  const detectionFunction = cx.env.config.enableChangeDetectionForDebugging;
+  if (detectionFunction != null && changeExpressions.length > 0) {
     const loc =
       typeof scope.loc === 'symbol'
         ? 'unknown location'
         : `(${scope.loc.start.line}:${scope.loc.end.line})`;
-    const detectionFunction =
-      cx.env.config.enableChangeDetectionForDebugging.importSpecifierName;
+    const importedDetectionFunctionIdentifier =
+      cx.env.programContext.addImportSpecifier(detectionFunction).name;
     const cacheLoadOldValueStatements: Array<t.Statement> = [];
     const changeDetectionStatements: Array<t.Statement> = [];
     const idempotenceDetectionStatements: Array<t.Statement> = [];
@@ -744,7 +771,7 @@ function codegenReactiveScope(
       );
       changeDetectionStatements.push(
         t.expressionStatement(
-          t.callExpression(t.identifier(detectionFunction), [
+          t.callExpression(t.identifier(importedDetectionFunctionIdentifier), [
             t.identifier(loadName),
             t.cloneNode(name, true),
             t.stringLiteral(name.name),
@@ -756,7 +783,7 @@ function codegenReactiveScope(
       );
       idempotenceDetectionStatements.push(
         t.expressionStatement(
-          t.callExpression(t.identifier(detectionFunction), [
+          t.callExpression(t.identifier(importedDetectionFunctionIdentifier), [
             t.cloneNode(slot, true),
             t.cloneNode(name, true),
             t.stringLiteral(name.name),
@@ -1518,15 +1545,15 @@ const createStringLiteral = withLoc(t.stringLiteral);
 
 function createHookGuard(
   guard: ExternalFunction,
+  context: ProgramContext,
   stmts: Array<t.Statement>,
   before: GuardKind,
   after: GuardKind,
 ): t.TryStatement {
+  const guardFnName = context.addImportSpecifier(guard).name;
   function createHookGuardImpl(kind: number): t.ExpressionStatement {
     return t.expressionStatement(
-      t.callExpression(t.identifier(guard.importSpecifierName), [
-        t.numericLiteral(kind),
-      ]),
+      t.callExpression(t.identifier(guardFnName), [t.numericLiteral(kind)]),
     );
   }
 
@@ -1576,6 +1603,7 @@ function createCallExpression(
       t.blockStatement([
         createHookGuard(
           hookGuard,
+          env.programContext,
           [t.returnStatement(callExpr)],
           GuardKind.AllowHook,
           GuardKind.DisallowHook,

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

@@ -5,6 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
+import {CompilerError} from '..';
 import {
   DeclarationId,
   InstructionKind,
@@ -27,7 +28,17 @@ export function pruneHoistedContexts(fn: ReactiveFunction): void {
   visitReactiveFunction(fn, new Visitor(), hoistedIdentifiers);
 }
 
-type HoistedIdentifiers = Map<DeclarationId, InstructionKind>;
+const REWRITTEN_HOISTED_CONST: unique symbol = Symbol(
+  'REWRITTEN_HOISTED_CONST',
+);
+const REWRITTEN_HOISTED_LET: unique symbol = Symbol('REWRITTEN_HOISTED_LET');
+
+type HoistedIdentifiers = Map<
+  DeclarationId,
+  | InstructionKind
+  | typeof REWRITTEN_HOISTED_CONST
+  | typeof REWRITTEN_HOISTED_LET
+>;
 
 class Visitor extends ReactiveFunctionTransform<HoistedIdentifiers> {
   override transformInstruction(
@@ -35,6 +46,10 @@ class Visitor extends ReactiveFunctionTransform<HoistedIdentifiers> {
     state: HoistedIdentifiers,
   ): Transformed<ReactiveStatement> {
     this.visitInstruction(instruction, state);
+
+    /**
+     * Remove hoisted declarations to preserve TDZ
+     */
     if (
       instruction.value.kind === 'DeclareContext' &&
       instruction.value.lvalue.kind === 'HoistedConst'
@@ -68,31 +83,75 @@ class Visitor extends ReactiveFunctionTransform<HoistedIdentifiers> {
       return {kind: 'remove'};
     }
 
-    if (
-      instruction.value.kind === 'StoreContext' &&
-      state.has(instruction.value.lvalue.place.identifier.declarationId)
-    ) {
+    if (instruction.value.kind === 'StoreContext') {
       const kind = state.get(
         instruction.value.lvalue.place.identifier.declarationId,
-      )!;
-      return {
-        kind: 'replace',
-        value: {
-          kind: 'instruction',
-          instruction: {
-            ...instruction,
+      );
+      if (kind != null) {
+        CompilerError.invariant(kind !== REWRITTEN_HOISTED_CONST, {
+          reason: 'Expected exactly one store to a hoisted const variable',
+          loc: instruction.loc,
+        });
+        if (
+          kind === InstructionKind.Const ||
+          kind === InstructionKind.Function
+        ) {
+          state.set(
+            instruction.value.lvalue.place.identifier.declarationId,
+            REWRITTEN_HOISTED_CONST,
+          );
+          return {
+            kind: 'replace',
             value: {
-              ...instruction.value,
-              lvalue: {
-                ...instruction.value.lvalue,
-                kind,
+              kind: 'instruction',
+              instruction: {
+                ...instruction,
+                value: {
+                  ...instruction.value,
+                  lvalue: {
+                    ...instruction.value.lvalue,
+                    kind,
+                  },
+                  type: null,
+                  kind: 'StoreLocal',
+                },
               },
-              type: null,
-              kind: 'StoreLocal',
             },
-          },
-        },
-      };
+          };
+        } else if (kind !== REWRITTEN_HOISTED_LET) {
+          /**
+           * Context variables declared with let may have reassignments. Only
+           * insert a `DeclareContext` for the first encountered `StoreContext`
+           * instruction.
+           */
+          state.set(
+            instruction.value.lvalue.place.identifier.declarationId,
+            REWRITTEN_HOISTED_LET,
+          );
+          return {
+            kind: 'replace-many',
+            value: [
+              {
+                kind: 'instruction',
+                instruction: {
+                  id: instruction.id,
+                  lvalue: null,
+                  value: {
+                    kind: 'DeclareContext',
+                    lvalue: {
+                      kind: InstructionKind.Let,
+                      place: {...instruction.value.lvalue.place},
+                    },
+                    loc: instruction.value.loc,
+                  },
+                  loc: instruction.loc,
+                },
+              },
+              {kind: 'instruction', instruction},
+            ],
+          };
+        }
+      }
     }
 
     return {kind: 'keep'};

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

@@ -5,6 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
+import {ProgramContext} from '..';
 import {CompilerError} from '../CompilerError';
 import {
   DeclarationId,
@@ -47,7 +48,7 @@ import {ReactiveFunctionVisitor, visitReactiveFunction} from './visitors';
  */
 export function renameVariables(fn: ReactiveFunction): Set<string> {
   const globals = collectReferencedGlobals(fn);
-  const scopes = new Scopes(globals);
+  const scopes = new Scopes(globals, fn.env.programContext);
   renameVariablesImpl(fn, new Visitor(), scopes);
   return new Set([...scopes.names, ...globals]);
 }
@@ -124,10 +125,12 @@ class Scopes {
   #seen: Map<DeclarationId, IdentifierName> = new Map();
   #stack: Array<Map<string, DeclarationId>> = [new Map()];
   #globals: Set<string>;
+  #programContext: ProgramContext;
   names: Set<ValidIdentifierName> = new Set();
 
-  constructor(globals: Set<string>) {
+  constructor(globals: Set<string>, programContext: ProgramContext) {
     this.#globals = globals;
+    this.#programContext = programContext;
   }
 
   visit(identifier: Identifier): void {
@@ -156,6 +159,7 @@ class Scopes {
         name = `${originalName.value}$${id++}`;
       }
     }
+    this.#programContext.addNewReference(name);
     const identifierName = makeIdentifierName(name);
     identifier.name = identifierName;
     this.#seen.set(identifier.declarationId, identifierName);

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

@@ -28,6 +28,7 @@ import {
   isUseEffectHookType,
   LoadLocal,
   makeInstructionId,
+  NonLocalImportSpecifier,
   Place,
   promoteTemporary,
 } from '../HIR';
@@ -36,6 +37,7 @@ import {getOrInsertWith} from '../Utils/utils';
 import {BuiltInFireId, DefaultNonmutatingHook} from '../HIR/ObjectShape';
 import {eachInstructionOperand} from '../HIR/visitors';
 import {printSourceLocationLine} from '../HIR/PrintHIR';
+import {USE_FIRE_FUNCTION_NAME} from '../HIR/Environment';
 
 /*
  * TODO(jmbrown):
@@ -56,6 +58,7 @@ export function transformFire(fn: HIRFunction): void {
 }
 
 function replaceFireFunctions(fn: HIRFunction, context: Context): void {
+  let importedUseFire: NonLocalImportSpecifier | null = null;
   let hasRewrite = false;
   for (const [, block] of fn.body.blocks) {
     const rewriteInstrs = new Map<InstructionId, Array<Instruction>>();
@@ -87,7 +90,15 @@ function replaceFireFunctions(fn: HIRFunction, context: Context): void {
           ] of capturedCallees.entries()) {
             if (!context.hasCalleeWithInsertedFire(fireCalleePlace)) {
               context.addCalleeWithInsertedFire(fireCalleePlace);
-              const loadUseFireInstr = makeLoadUseFireInstruction(fn.env);
+
+              importedUseFire ??= fn.env.programContext.addImportSpecifier({
+                source: fn.env.programContext.reactRuntimeModule,
+                importSpecifierName: USE_FIRE_FUNCTION_NAME,
+              });
+              const loadUseFireInstr = makeLoadUseFireInstruction(
+                fn.env,
+                importedUseFire,
+              );
               const loadFireCalleeInstr = makeLoadFireCalleeInstruction(
                 fn.env,
                 fireCalleeInfo.capturedCalleeIdentifier,
@@ -404,18 +415,16 @@ function ensureNoMoreFireUses(fn: HIRFunction, context: Context): void {
   }
 }
 
-function makeLoadUseFireInstruction(env: Environment): Instruction {
+function makeLoadUseFireInstruction(
+  env: Environment,
+  importedLoadUseFire: NonLocalImportSpecifier,
+): Instruction {
   const useFirePlace = createTemporaryPlace(env, GeneratedSource);
   useFirePlace.effect = Effect.Read;
   useFirePlace.identifier.type = DefaultNonmutatingHook;
   const instrValue: InstructionValue = {
     kind: 'LoadGlobal',
-    binding: {
-      kind: 'ImportSpecifier',
-      name: 'useFire',
-      module: 'react',
-      imported: 'useFire',
-    },
+    binding: {...importedLoadUseFire},
     loc: GeneratedSource,
   };
   return {

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

@@ -261,6 +261,7 @@ function* generateInstructionTypes(
         kind: 'Function',
         shapeId: null,
         return: returnType,
+        isConstructor: false,
       });
       yield equation(left, returnType);
       break;
@@ -277,6 +278,7 @@ function* generateInstructionTypes(
         kind: 'Function',
         shapeId: null,
         return: returnType,
+        isConstructor: false,
       });
       yield equation(left, returnType);
       break;
@@ -333,6 +335,7 @@ function* generateInstructionTypes(
         kind: 'Function',
         return: returnType,
         shapeId: null,
+        isConstructor: false,
       });
 
       yield equation(left, returnType);
@@ -405,6 +408,7 @@ function* generateInstructionTypes(
         kind: 'Function',
         shapeId: BuiltInFunctionId,
         return: value.loweredFunc.func.returnType,
+        isConstructor: false,
       });
       break;
     }
@@ -425,9 +429,20 @@ function* generateInstructionTypes(
       yield equation(left, {kind: 'Object', shapeId: BuiltInJsxId});
       break;
     }
+    case 'NewExpression': {
+      const returnType = makeType();
+      yield equation(value.callee.identifier.type, {
+        kind: 'Function',
+        return: returnType,
+        shapeId: null,
+        isConstructor: true,
+      });
+
+      yield equation(left, returnType);
+      break;
+    }
     case 'PropertyStore':
     case 'DeclareLocal':
-    case 'NewExpression':
     case 'RegExpLiteral':
     case 'MetaProperty':
     case 'ComputedStore':
@@ -505,7 +520,11 @@ class Unifier {
       return;
     }
 
-    if (tB.kind === 'Function' && tA.kind === 'Function') {
+    if (
+      tB.kind === 'Function' &&
+      tA.kind === 'Function' &&
+      tA.isConstructor === tB.isConstructor
+    ) {
       this.unify(tA.return, tB.return);
       return;
     }
@@ -648,6 +667,7 @@ class Unifier {
           kind: 'Function',
           return: returnType,
           shapeId: type.shapeId,
+          isConstructor: type.isConstructor,
         };
       }
       case 'ObjectMethod':

compiler/packages/babel-plugin-react-compiler/src/__tests__/e2e/constant-prop.e2e.js

@@ -12,6 +12,7 @@ globalThis.constantValue = 'global test value';
 
 test('literal-constant-propagation', () => {
   function Component() {
+    'use memo';
     const x = 'test value 1';
     return <div>{x}</div>;
   }
@@ -38,6 +39,7 @@ test('literal-constant-propagation', () => {
 
 test('global-constant-propagation', () => {
   function Component() {
+    'use memo';
     const x = constantValue;
 
     return <div>{x}</div>;
@@ -65,6 +67,7 @@ test('global-constant-propagation', () => {
 
 test('lambda-constant-propagation', () => {
   function Component() {
+    'use memo';
     const x = 'test value 1';
     const getDiv = () => <div>{x}</div>;
     return getDiv();
@@ -92,6 +95,7 @@ test('lambda-constant-propagation', () => {
 
 test('lambda-constant-propagation-of-phi-node', () => {
   function Component({noopCallback}) {
+    'use memo';
     const x = 'test value 1';
     if (constantValue) {
       noopCallback();

compiler/packages/babel-plugin-react-compiler/src/__tests__/e2e/update-button.e2e.js

@@ -16,6 +16,7 @@ function Button({label}) {
 
 let currentTheme = 'light';
 function useTheme() {
+  'use memo';
   return currentTheme;
 }
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/e2e/update-expressions.e2e.js

@@ -10,6 +10,7 @@ import * as React from 'react';
 import {expectLogsAndClear, log} from './expectLogs';
 
 function Counter(props) {
+  'use memo';
   let value = props.value;
   let a = value++;
   expect(a).toBe(props.value); // postfix

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/array-from-arg1-captures-arg0.expect.md

@@ -50,28 +50,55 @@ import { useIdentity, Stringify } from "shared-runtime";
  * (2) the 1st argument might mutate its callee
  */
 function Component(t0) {
-  const $ = _c(4);
+  const $ = _c(10);
   const { value } = t0;
-  const arr = [{ value: "foo" }, { value: "bar" }, { value }];
-  useIdentity();
-  const derived = Array.from(arr, _temp);
   let t1;
-  if ($[0] !== derived) {
-    t1 = derived.at(-1);
-    $[0] = derived;
-    $[1] = t1;
-  } else {
-    t1 = $[1];
-  }
   let t2;
-  if ($[2] !== t1) {
-    t2 = <Stringify>{t1}</Stringify>;
-    $[2] = t1;
-    $[3] = t2;
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+    t1 = { value: "foo" };
+    t2 = { value: "bar" };
+    $[0] = t1;
+    $[1] = t2;
   } else {
-    t2 = $[3];
+    t1 = $[0];
+    t2 = $[1];
   }
-  return t2;
+  let t3;
+  if ($[2] !== value) {
+    t3 = [t1, t2, { value }];
+    $[2] = value;
+    $[3] = t3;
+  } else {
+    t3 = $[3];
+  }
+  const arr = t3;
+  useIdentity();
+  let t4;
+  if ($[4] !== arr) {
+    t4 = Array.from(arr, _temp);
+    $[4] = arr;
+    $[5] = t4;
+  } else {
+    t4 = $[5];
+  }
+  const derived = t4;
+  let t5;
+  if ($[6] !== derived) {
+    t5 = derived.at(-1);
+    $[6] = derived;
+    $[7] = t5;
+  } else {
+    t5 = $[7];
+  }
+  let t6;
+  if ($[8] !== t5) {
+    t6 = <Stringify>{t5}</Stringify>;
+    $[8] = t5;
+    $[9] = t6;
+  } else {
+    t6 = $[9];
+  }
+  return t6;
 }
 function _temp(x, idx) {
   return { ...x, id: idx };

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/array-from-captures-arg0.expect.md

@@ -50,28 +50,55 @@ import { useIdentity, Stringify } from "shared-runtime";
  * (2) the 1st argument might mutate its callee
  */
 function Component(t0) {
-  const $ = _c(4);
+  const $ = _c(10);
   const { value } = t0;
-  const arr = [{ value: "foo" }, { value: "bar" }, { value }];
-  useIdentity();
-  const derived = Array.from(arr);
   let t1;
-  if ($[0] !== derived) {
-    t1 = derived.at(-1);
-    $[0] = derived;
-    $[1] = t1;
-  } else {
-    t1 = $[1];
-  }
   let t2;
-  if ($[2] !== t1) {
-    t2 = <Stringify>{t1}</Stringify>;
-    $[2] = t1;
-    $[3] = t2;
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+    t1 = { value: "foo" };
+    t2 = { value: "bar" };
+    $[0] = t1;
+    $[1] = t2;
   } else {
-    t2 = $[3];
+    t1 = $[0];
+    t2 = $[1];
   }
-  return t2;
+  let t3;
+  if ($[2] !== value) {
+    t3 = [t1, t2, { value }];
+    $[2] = value;
+    $[3] = t3;
+  } else {
+    t3 = $[3];
+  }
+  const arr = t3;
+  useIdentity();
+  let t4;
+  if ($[4] !== arr) {
+    t4 = Array.from(arr);
+    $[4] = arr;
+    $[5] = t4;
+  } else {
+    t4 = $[5];
+  }
+  const derived = t4;
+  let t5;
+  if ($[6] !== derived) {
+    t5 = derived.at(-1);
+    $[6] = derived;
+    $[7] = t5;
+  } else {
+    t5 = $[7];
+  }
+  let t6;
+  if ($[8] !== t5) {
+    t6 = <Stringify>{t5}</Stringify>;
+    $[8] = t5;
+    $[9] = t6;
+  } else {
+    t6 = $[9];
+  }
+  return t6;
 }
 
 export const FIXTURE_ENTRYPOINT = {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/array-from-maybemutates-arg0.expect.md

@@ -7,14 +7,19 @@ import {mutateAndReturn, Stringify, useIdentity} from 'shared-runtime';
 function Component({value}) {
   const arr = [{value: 'foo'}, {value: 'bar'}, {value}];
   useIdentity();
-  const derived = Array.from(arr, mutateAndReturn);
-  return <Stringify>{derived.at(-1)}</Stringify>;
+  const derived = Array.from(arr).map(mutateAndReturn);
+  return (
+    <Stringify>
+      {derived.at(0)}
+      {derived.at(-1)}
+    </Stringify>
+  );
 }
 
 export const FIXTURE_ENTRYPOINT = {
   fn: Component,
   params: [{value: 5}],
-  sequentialRenders: [{value: 5}, {value: 6}, {value: 6}],
+  sequentialRenders: [{value: 5}, {value: 6}, {value: 6}, {value: 7}],
 };
 
 ```
@@ -26,39 +31,54 @@ import { c as _c } from "react/compiler-runtime";
 import { mutateAndReturn, Stringify, useIdentity } from "shared-runtime";
 
 function Component(t0) {
-  const $ = _c(4);
+  const $ = _c(7);
   const { value } = t0;
   const arr = [{ value: "foo" }, { value: "bar" }, { value }];
   useIdentity();
-  const derived = Array.from(arr, mutateAndReturn);
+  const derived = Array.from(arr).map(mutateAndReturn);
   let t1;
   if ($[0] !== derived) {
-    t1 = derived.at(-1);
+    t1 = derived.at(0);
     $[0] = derived;
     $[1] = t1;
   } else {
     t1 = $[1];
   }
   let t2;
-  if ($[2] !== t1) {
-    t2 = <Stringify>{t1}</Stringify>;
-    $[2] = t1;
+  if ($[2] !== derived) {
+    t2 = derived.at(-1);
+    $[2] = derived;
     $[3] = t2;
   } else {
     t2 = $[3];
   }
-  return t2;
+  let t3;
+  if ($[4] !== t1 || $[5] !== t2) {
+    t3 = (
+      <Stringify>
+        {t1}
+        {t2}
+      </Stringify>
+    );
+    $[4] = t1;
+    $[5] = t2;
+    $[6] = t3;
+  } else {
+    t3 = $[6];
+  }
+  return t3;
 }
 
 export const FIXTURE_ENTRYPOINT = {
   fn: Component,
   params: [{ value: 5 }],
-  sequentialRenders: [{ value: 5 }, { value: 6 }, { value: 6 }],
+  sequentialRenders: [{ value: 5 }, { value: 6 }, { value: 6 }, { value: 7 }],
 };
 
 ```
       
 ### Eval output
-(kind: ok) <div>{"children":{"value":5,"wat0":"joe"}}</div>
-<div>{"children":{"value":6,"wat0":"joe"}}</div>
-<div>{"children":{"value":6,"wat0":"joe"}}</div>
+(kind: ok) <div>{"children":[{"value":"foo","wat0":"joe"},{"value":5,"wat0":"joe"}]}</div>
+<div>{"children":[{"value":"foo","wat0":"joe"},{"value":6,"wat0":"joe"}]}</div>
+<div>{"children":[{"value":"foo","wat0":"joe"},{"value":6,"wat0":"joe"}]}</div>
+<div>{"children":[{"value":"foo","wat0":"joe"},{"value":7,"wat0":"joe"}]}</div>

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/array-from-maybemutates-arg0.js

@@ -3,12 +3,17 @@ import {mutateAndReturn, Stringify, useIdentity} from 'shared-runtime';
 function Component({value}) {
   const arr = [{value: 'foo'}, {value: 'bar'}, {value}];
   useIdentity();
-  const derived = Array.from(arr, mutateAndReturn);
-  return <Stringify>{derived.at(-1)}</Stringify>;
+  const derived = Array.from(arr).map(mutateAndReturn);
+  return (
+    <Stringify>
+      {derived.at(0)}
+      {derived.at(-1)}
+    </Stringify>
+  );
 }
 
 export const FIXTURE_ENTRYPOINT = {
   fn: Component,
   params: [{value: 5}],
-  sequentialRenders: [{value: 5}, {value: 6}, {value: 6}],
+  sequentialRenders: [{value: 5}, {value: 6}, {value: 6}, {value: 7}],
 };

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/arrow-function-with-implicit-return.expect.md

@@ -0,0 +1,39 @@
+
+## Input
+
+```javascript
+// @compilationMode(infer)
+const Test = () => <div />;
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Test,
+  params: [{}],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @compilationMode(infer)
+const Test = () => {
+  const $ = _c(1);
+  let t0;
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+    t0 = <div />;
+    $[0] = t0;
+  } else {
+    t0 = $[0];
+  }
+  return t0;
+};
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Test,
+  params: [{}],
+};
+
+```
+      
+### Eval output
+(kind: ok) <div></div>

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/arrow-function-with-implicit-return.js

@@ -0,0 +1,7 @@
+// @compilationMode(infer)
+const Test = () => <div />;
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Test,
+  params: [{}],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/babel-existing-react-runtime-import.expect.md

@@ -0,0 +1,73 @@
+
+## Input
+
+```javascript
+import * as React from 'react';
+import {someImport} from 'react/compiler-runtime';
+import {calculateExpensiveNumber} from 'shared-runtime';
+
+function Component(props) {
+  const [x] = React.useState(0);
+  const expensiveNumber = React.useMemo(() => calculateExpensiveNumber(x), [x]);
+
+  return (
+    <div>
+      {expensiveNumber}
+      {`${someImport}`}
+    </div>
+  );
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [],
+};
+
+```
+
+## Code
+
+```javascript
+import * as React from "react";
+import { someImport, c as _c } from "react/compiler-runtime";
+import { calculateExpensiveNumber } from "shared-runtime";
+
+function Component(props) {
+  const $ = _c(4);
+  const [x] = React.useState(0);
+  let t0;
+  let t1;
+  if ($[0] !== x) {
+    t1 = calculateExpensiveNumber(x);
+    $[0] = x;
+    $[1] = t1;
+  } else {
+    t1 = $[1];
+  }
+  t0 = t1;
+  const expensiveNumber = t0;
+  let t2;
+  if ($[2] !== expensiveNumber) {
+    t2 = (
+      <div>
+        {expensiveNumber}
+        {`${someImport}`}
+      </div>
+    );
+    $[2] = expensiveNumber;
+    $[3] = t2;
+  } else {
+    t2 = $[3];
+  }
+  return t2;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [],
+};
+
+```
+      
+### Eval output
+(kind: ok) <div>0undefined</div>

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/babel-existing-react-runtime-import.js

@@ -0,0 +1,20 @@
+import * as React from 'react';
+import {someImport} from 'react/compiler-runtime';
+import {calculateExpensiveNumber} from 'shared-runtime';
+
+function Component(props) {
+  const [x] = React.useState(0);
+  const expensiveNumber = React.useMemo(() => calculateExpensiveNumber(x), [x]);
+
+  return (
+    <div>
+      {expensiveNumber}
+      {`${someImport}`}
+    </div>
+  );
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/codegen-emit-imports-same-source.expect.md

@@ -14,9 +14,9 @@ function useFoo(props) {
 
 ```javascript
 import {
-  useRenderCounter,
-  shouldInstrument,
   makeReadOnly,
+  shouldInstrument,
+  useRenderCounter,
 } from "react-compiler-runtime";
 import { c as _c } from "react/compiler-runtime"; // @enableEmitFreeze @enableEmitInstrumentForget
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/codegen-instrument-forget-test.expect.md

@@ -23,7 +23,7 @@ function Foo(props) {
 ## Code
 
 ```javascript
-import { useRenderCounter, shouldInstrument } from "react-compiler-runtime";
+import { shouldInstrument, useRenderCounter } from "react-compiler-runtime";
 import { c as _c } from "react/compiler-runtime"; // @enableEmitInstrumentForget @compilationMode(annotation)
 
 function Bar(props) {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/conflict-codegen-instrument-forget.expect.md

@@ -0,0 +1,97 @@
+
+## Input
+
+```javascript
+// @enableEmitInstrumentForget @compilationMode(annotation)
+
+import {identity} from 'shared-runtime';
+
+function Bar(props) {
+  'use forget';
+  const shouldInstrument = identity(null);
+  const _shouldInstrument = identity(null);
+  const _x2 = () => {
+    const _shouldInstrument2 = 'hello world';
+    return identity({_shouldInstrument2});
+  };
+  return (
+    <div style={shouldInstrument} other={_shouldInstrument}>
+      {props.bar}
+    </div>
+  );
+}
+
+function Foo(props) {
+  'use forget';
+  return <Foo>{props.bar}</Foo>;
+}
+
+```
+
+## Code
+
+```javascript
+import {
+  shouldInstrument as _shouldInstrument3,
+  useRenderCounter,
+} from "react-compiler-runtime";
+import { c as _c } from "react/compiler-runtime"; // @enableEmitInstrumentForget @compilationMode(annotation)
+
+import { identity } from "shared-runtime";
+
+function Bar(props) {
+  "use forget";
+  if (DEV && _shouldInstrument3)
+    useRenderCounter("Bar", "/conflict-codegen-instrument-forget.ts");
+  const $ = _c(4);
+  let t0;
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+    t0 = identity(null);
+    $[0] = t0;
+  } else {
+    t0 = $[0];
+  }
+  const shouldInstrument = t0;
+  let t1;
+  if ($[1] === Symbol.for("react.memo_cache_sentinel")) {
+    t1 = identity(null);
+    $[1] = t1;
+  } else {
+    t1 = $[1];
+  }
+  const _shouldInstrument = t1;
+  let t2;
+  if ($[2] !== props.bar) {
+    t2 = (
+      <div style={shouldInstrument} other={_shouldInstrument}>
+        {props.bar}
+      </div>
+    );
+    $[2] = props.bar;
+    $[3] = t2;
+  } else {
+    t2 = $[3];
+  }
+  return t2;
+}
+
+function Foo(props) {
+  "use forget";
+  if (DEV && _shouldInstrument3)
+    useRenderCounter("Foo", "/conflict-codegen-instrument-forget.ts");
+  const $ = _c(2);
+  let t0;
+  if ($[0] !== props.bar) {
+    t0 = <Foo>{props.bar}</Foo>;
+    $[0] = props.bar;
+    $[1] = t0;
+  } else {
+    t0 = $[1];
+  }
+  return t0;
+}
+
+```
+      
+### Eval output
+(kind: exception) Fixture not implemented

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/conflict-codegen-instrument-forget.js

@@ -0,0 +1,23 @@
+// @enableEmitInstrumentForget @compilationMode(annotation)
+
+import {identity} from 'shared-runtime';
+
+function Bar(props) {
+  'use forget';
+  const shouldInstrument = identity(null);
+  const _shouldInstrument = identity(null);
+  const _x2 = () => {
+    const _shouldInstrument2 = 'hello world';
+    return identity({_shouldInstrument2});
+  };
+  return (
+    <div style={shouldInstrument} other={_shouldInstrument}>
+      {props.bar}
+    </div>
+  );
+}
+
+function Foo(props) {
+  'use forget';
+  return <Foo>{props.bar}</Foo>;
+}

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

@@ -0,0 +1,37 @@
+
+## Input
+
+```javascript
+// @enableEmitFreeze @instrumentForget
+
+let makeReadOnly = 'conflicting identifier';
+function useFoo(props) {
+  return foo(props.x);
+}
+
+```
+
+## Code
+
+```javascript
+import { makeReadOnly as _makeReadOnly } from "react-compiler-runtime";
+import { c as _c } from "react/compiler-runtime"; // @enableEmitFreeze @instrumentForget
+
+let makeReadOnly = "conflicting identifier";
+function useFoo(props) {
+  const $ = _c(2);
+  let t0;
+  if ($[0] !== props.x) {
+    t0 = foo(props.x);
+    $[0] = props.x;
+    $[1] = __DEV__ ? _makeReadOnly(t0, "useFoo") : t0;
+  } else {
+    t0 = $[1];
+  }
+  return t0;
+}
+
+```
+      
+### Eval output
+(kind: exception) Fixture not implemented

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

@@ -0,0 +1,33 @@
+
+## Input
+
+```javascript
+// @enableEmitFreeze @instrumentForget
+function useFoo(props) {
+  return foo(props.x, __DEV__);
+}
+
+```
+
+## Code
+
+```javascript
+import { makeReadOnly } from "react-compiler-runtime";
+import { c as _c } from "react/compiler-runtime"; // @enableEmitFreeze @instrumentForget
+function useFoo(props) {
+  const $ = _c(2);
+  let t0;
+  if ($[0] !== props.x) {
+    t0 = foo(props.x, __DEV__);
+    $[0] = props.x;
+    $[1] = __DEV__ ? makeReadOnly(t0, "useFoo") : t0;
+  } else {
+    t0 = $[1];
+  }
+  return t0;
+}
+
+```
+      
+### Eval output
+(kind: exception) Fixture not implemented

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/emit-freeze-nonconflicting-global-reference.js

@@ -0,0 +1,4 @@
+// @enableEmitFreeze @instrumentForget
+function useFoo(props) {
+  return foo(props.x, __DEV__);
+}

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.codegen-error-on-conflicting-imports.expect.md

@@ -1,21 +0,0 @@
-
-## Input
-
-```javascript
-// @enableEmitFreeze @instrumentForget
-
-let makeReadOnly = 'conflicting identifier';
-function useFoo(props) {
-  return foo(props.x);
-}
-
-```
-
-
-## Error
-
-```
-Invariant: Encountered conflicting import specifiers for makeReadOnly in generated program.
-```
-          
-      

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

@@ -0,0 +1,27 @@
+
+## Input
+
+```javascript
+// @enableEmitFreeze @instrumentForget
+function useFoo(props) {
+  const __DEV__ = 'conflicting global';
+  console.log(__DEV__);
+  return foo(props.x);
+}
+
+```
+
+
+## Error
+
+```
+  1 | // @enableEmitFreeze @instrumentForget
+  2 | function useFoo(props) {
+> 3 |   const __DEV__ = 'conflicting global';
+    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Todo: Encountered conflicting global in generated program. Conflict from local binding __DEV__ (3:3)
+  4 |   console.log(__DEV__);
+  5 |   return foo(props.x);
+  6 | }
+```
+          
+      

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

@@ -0,0 +1,6 @@
+// @enableEmitFreeze @instrumentForget
+function useFoo(props) {
+  const __DEV__ = 'conflicting global';
+  console.log(__DEV__);
+  return foo(props.x);
+}

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/gating/arrow-function-expr-gating-test.expect.md

@@ -18,8 +18,8 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag";
-import { c as _c } from "react/compiler-runtime"; // @gating
+import { c as _c } from "react/compiler-runtime";
+import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag"; // @gating
 import { Stringify } from "shared-runtime";
 const ErrorView = isForgetEnabled_Fixtures()
   ? (t0) => {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/gating/codegen-instrument-forget-gating-test.expect.md

@@ -36,9 +36,9 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag";
-import { useRenderCounter, shouldInstrument } from "react-compiler-runtime";
-import { c as _c } from "react/compiler-runtime"; // @enableEmitInstrumentForget @compilationMode(annotation) @gating
+import { shouldInstrument, useRenderCounter } from "react-compiler-runtime";
+import { c as _c } from "react/compiler-runtime";
+import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag"; // @enableEmitInstrumentForget @compilationMode(annotation) @gating
 const Bar = isForgetEnabled_Fixtures()
   ? function Bar(props) {
       "use forget";

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/gating/component-syntax-ref-gating.flow.expect.md

@@ -20,14 +20,14 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag";
 import { c as _c } from "react/compiler-runtime";
+import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag";
 import { Stringify } from "shared-runtime";
 import * as React from "react";
 
 const Foo = React.forwardRef(Foo_withRef);
-const _isForgetEnabled_Fixtures_result = isForgetEnabled_Fixtures();
-function _Foo_withRef_optimized(_$$empty_props_placeholder$$, ref) {
+const isForgetEnabled_Fixtures_result = isForgetEnabled_Fixtures();
+function Foo_withRef_optimized(_$$empty_props_placeholder$$, ref) {
   const $ = _c(2);
   let t0;
   if ($[0] !== ref) {
@@ -39,16 +39,15 @@ function _Foo_withRef_optimized(_$$empty_props_placeholder$$, ref) {
   }
   return t0;
 }
-function _Foo_withRef_unoptimized(
+function Foo_withRef_unoptimized(
   _$$empty_props_placeholder$$: $ReadOnly<{}>,
   ref: React.RefSetter<Controls>,
 ): React.Node {
   return <Stringify ref={ref} />;
 }
 function Foo_withRef(arg0, arg1) {
-  if (_isForgetEnabled_Fixtures_result)
-    return _Foo_withRef_optimized(arg0, arg1);
-  else return _Foo_withRef_unoptimized(arg0, arg1);
+  if (isForgetEnabled_Fixtures_result) return Foo_withRef_optimized(arg0, arg1);
+  else return Foo_withRef_unoptimized(arg0, arg1);
 }
 
 export const FIXTURE_ENTRYPOINT = {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/gating/conflicting-gating-fn.expect.md

@@ -0,0 +1,62 @@
+
+## Input
+
+```javascript
+// @gating
+
+export const isForgetEnabled_Fixtures = () => {
+  'use no forget';
+  return false;
+};
+
+export function Bar(props) {
+  'use forget';
+  return <div>{props.bar}</div>;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: eval('Bar'),
+  params: [{bar: 2}],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime";
+import { isForgetEnabled_Fixtures as _isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag"; // @gating
+
+export const isForgetEnabled_Fixtures = () => {
+  "use no forget";
+  return false;
+};
+
+export const Bar = _isForgetEnabled_Fixtures()
+  ? function Bar(props) {
+      "use forget";
+      const $ = _c(2);
+      let t0;
+      if ($[0] !== props.bar) {
+        t0 = <div>{props.bar}</div>;
+        $[0] = props.bar;
+        $[1] = t0;
+      } else {
+        t0 = $[1];
+      }
+      return t0;
+    }
+  : function Bar(props) {
+      "use forget";
+      return <div>{props.bar}</div>;
+    };
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: eval("Bar"),
+  params: [{ bar: 2 }],
+};
+
+```
+      
+### Eval output
+(kind: ok) <div>2</div>

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/gating/conflicting-gating-fn.js

@@ -0,0 +1,16 @@
+// @gating
+
+export const isForgetEnabled_Fixtures = () => {
+  'use no forget';
+  return false;
+};
+
+export function Bar(props) {
+  'use forget';
+  return <div>{props.bar}</div>;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: eval('Bar'),
+  params: [{bar: 2}],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/gating/gating-access-function-name-in-component.expect.md

@@ -18,8 +18,8 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag";
-import { c as _c } from "react/compiler-runtime"; // @gating
+import { c as _c } from "react/compiler-runtime";
+import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag"; // @gating
 const Component = isForgetEnabled_Fixtures()
   ? function Component() {
       const $ = _c(1);

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/gating/gating-nonreferenced-identifier-collision.expect.md

@@ -24,8 +24,8 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag";
-import { c as _c } from "react/compiler-runtime"; // @gating
+import { c as _c } from "react/compiler-runtime";
+import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag"; // @gating
 import { identity, useHook as useRenamed } from "shared-runtime";
 const _ = {
   useHook: isForgetEnabled_Fixtures() ? () => {} : () => {},

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/gating/gating-preserves-function-properties.expect.md

@@ -26,8 +26,8 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag";
-import { c as _c } from "react/compiler-runtime"; // @gating
+import { c as _c } from "react/compiler-runtime";
+import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag"; // @gating
 const Component = isForgetEnabled_Fixtures()
   ? function Component() {
       const $ = _c(1);

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/gating/gating-test-export-default-function.expect.md

@@ -27,8 +27,8 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag";
-import { c as _c } from "react/compiler-runtime"; // @gating @compilationMode(annotation)
+import { c as _c } from "react/compiler-runtime";
+import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag"; // @gating @compilationMode(annotation)
 const Bar = isForgetEnabled_Fixtures()
   ? function Bar(props) {
       "use forget";

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/gating/gating-test-export-function-and-default.expect.md

@@ -34,8 +34,8 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag";
-import { c as _c } from "react/compiler-runtime"; // @gating @compilationMode(annotation)
+import { c as _c } from "react/compiler-runtime";
+import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag"; // @gating @compilationMode(annotation)
 const Bar = isForgetEnabled_Fixtures()
   ? function Bar(props) {
       "use forget";

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/gating/gating-test-export-function.expect.md

@@ -27,8 +27,8 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag";
-import { c as _c } from "react/compiler-runtime"; // @gating @compilationMode(annotation)
+import { c as _c } from "react/compiler-runtime";
+import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag"; // @gating @compilationMode(annotation)
 export const Bar = isForgetEnabled_Fixtures()
   ? function Bar(props) {
       "use forget";

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

@@ -27,8 +27,8 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag";
-import { c as _c } from "react/compiler-runtime"; // @gating @compilationMode(annotation)
+import { c as _c } from "react/compiler-runtime";
+import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag"; // @gating @compilationMode(annotation)
 const Bar = isForgetEnabled_Fixtures()
   ? function Bar(props) {
       "use forget";

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/gating/gating-use-before-decl-ref.expect.md

@@ -21,14 +21,14 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag";
-import { c as _c } from "react/compiler-runtime"; // @gating
+import { c as _c } from "react/compiler-runtime";
+import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag"; // @gating
 import { createRef, forwardRef } from "react";
 import { Stringify } from "shared-runtime";
 
 const Foo = forwardRef(Foo_withRef);
-const _isForgetEnabled_Fixtures_result = isForgetEnabled_Fixtures();
-function _Foo_withRef_optimized(props, ref) {
+const isForgetEnabled_Fixtures_result = isForgetEnabled_Fixtures();
+function Foo_withRef_optimized(props, ref) {
   const $ = _c(3);
   let t0;
   if ($[0] !== props || $[1] !== ref) {
@@ -41,13 +41,12 @@ function _Foo_withRef_optimized(props, ref) {
   }
   return t0;
 }
-function _Foo_withRef_unoptimized(props, ref) {
+function Foo_withRef_unoptimized(props, ref) {
   return <Stringify ref={ref} {...props} />;
 }
 function Foo_withRef(arg0, arg1) {
-  if (_isForgetEnabled_Fixtures_result)
-    return _Foo_withRef_optimized(arg0, arg1);
-  else return _Foo_withRef_unoptimized(arg0, arg1);
+  if (isForgetEnabled_Fixtures_result) return Foo_withRef_optimized(arg0, arg1);
+  else return Foo_withRef_unoptimized(arg0, arg1);
 }
 
 export const FIXTURE_ENTRYPOINT = {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/gating/gating-use-before-decl.expect.md

@@ -22,14 +22,14 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag";
-import { c as _c } from "react/compiler-runtime"; // @gating
+import { c as _c } from "react/compiler-runtime";
+import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag"; // @gating
 import { memo } from "react";
 import { Stringify } from "shared-runtime";
 
 export default memo(Foo);
-const _isForgetEnabled_Fixtures_result = isForgetEnabled_Fixtures();
-function _Foo_optimized(t0) {
+const isForgetEnabled_Fixtures_result = isForgetEnabled_Fixtures();
+function Foo_optimized(t0) {
   "use memo";
   const $ = _c(3);
   const { prop1, prop2 } = t0;
@@ -44,13 +44,13 @@ function _Foo_optimized(t0) {
   }
   return t1;
 }
-function _Foo_unoptimized({ prop1, prop2 }) {
+function Foo_unoptimized({ prop1, prop2 }) {
   "use memo";
   return <Stringify prop1={prop1} prop2={prop2} />;
 }
 function Foo(arg0) {
-  if (_isForgetEnabled_Fixtures_result) return _Foo_optimized(arg0);
-  else return _Foo_unoptimized(arg0);
+  if (isForgetEnabled_Fixtures_result) return Foo_optimized(arg0);
+  else return Foo_unoptimized(arg0);
 }
 
 export const FIXTURE_ENTRYPOINT = {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/gating/gating-with-hoisted-type-reference.flow.expect.md

@@ -23,8 +23,8 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag";
 import { c as _c } from "react/compiler-runtime";
+import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag";
 import { memo } from "react";
 
 type Props = React.ElementConfig<typeof Component>;

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/gating/infer-function-expression-React-memo-gating.expect.md

@@ -13,8 +13,8 @@ export default React.forwardRef(function notNamedLikeAComponent(props) {
 ## Code
 
 ```javascript
-import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag";
-import { c as _c } from "react/compiler-runtime"; // @gating @compilationMode(infer)
+import { c as _c } from "react/compiler-runtime";
+import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag"; // @gating @compilationMode(infer)
 import React from "react";
 export default React.forwardRef(
   isForgetEnabled_Fixtures()

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/gating/invalid-fnexpr-reference.expect.md

@@ -23,8 +23,8 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag";
-import { c as _c } from "react/compiler-runtime"; // @gating
+import { c as _c } from "react/compiler-runtime";
+import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag"; // @gating
 import * as React from "react";
 
 let Foo;

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/gating/multi-arrow-expr-export-default-gating-test.expect.md

@@ -19,8 +19,8 @@ export default props => (
 ## Code
 
 ```javascript
-import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag";
-import { c as _c } from "react/compiler-runtime"; // @gating
+import { c as _c } from "react/compiler-runtime";
+import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag"; // @gating
 import { Stringify } from "shared-runtime";
 
 const ErrorView = isForgetEnabled_Fixtures()

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/gating/multi-arrow-expr-export-gating-test.expect.md

@@ -24,8 +24,8 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag";
-import { c as _c } from "react/compiler-runtime"; // @gating
+import { c as _c } from "react/compiler-runtime";
+import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag"; // @gating
 import { Stringify } from "shared-runtime";
 
 const ErrorView = isForgetEnabled_Fixtures()

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/gating/multi-arrow-expr-gating-test.expect.md

@@ -26,8 +26,8 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag";
-import { c as _c } from "react/compiler-runtime"; // @gating
+import { c as _c } from "react/compiler-runtime";
+import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag"; // @gating
 import { Stringify } from "shared-runtime";
 
 const ErrorView = isForgetEnabled_Fixtures()

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/gating/reassigned-fnexpr-variable.expect.md

@@ -31,8 +31,8 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag";
-import { c as _c } from "react/compiler-runtime"; // @gating
+import { c as _c } from "react/compiler-runtime";
+import { isForgetEnabled_Fixtures } from "ReactForgetFeatureFlag"; // @gating
 import * as React from "react";
 
 /**

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/global-types/call-spread-argument-set.expect.md

@@ -0,0 +1,66 @@
+
+## Input
+
+```javascript
+import {useIdentity} from 'shared-runtime';
+
+/**
+ * Forked version of call-spread-argument-mutable-iterator that is known to not mutate
+ * the spread argument since it is a Set
+ */
+function useFoo() {
+  const s = new Set([1, 2]);
+  useIdentity(null);
+  return [Math.max(...s), s];
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useFoo,
+  params: [{}],
+  sequentialRenders: [{}, {}],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime";
+import { useIdentity } from "shared-runtime";
+
+/**
+ * Forked version of call-spread-argument-mutable-iterator that is known to not mutate
+ * the spread argument since it is a Set
+ */
+function useFoo() {
+  const $ = _c(2);
+  let t0;
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+    t0 = new Set([1, 2]);
+    $[0] = t0;
+  } else {
+    t0 = $[0];
+  }
+  const s = t0;
+  useIdentity(null);
+  let t1;
+  if ($[1] === Symbol.for("react.memo_cache_sentinel")) {
+    t1 = [Math.max(...s), s];
+    $[1] = t1;
+  } else {
+    t1 = $[1];
+  }
+  return t1;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useFoo,
+  params: [{}],
+  sequentialRenders: [{}, {}],
+};
+
+```
+      
+### Eval output
+(kind: ok) [2,{"kind":"Set","value":[1,2]}]
+[2,{"kind":"Set","value":[1,2]}]

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/global-types/call-spread-argument-set.ts

@@ -0,0 +1,17 @@
+import {useIdentity} from 'shared-runtime';
+
+/**
+ * Forked version of call-spread-argument-mutable-iterator that is known to not mutate
+ * the spread argument since it is a Set
+ */
+function useFoo() {
+  const s = new Set([1, 2]);
+  useIdentity(null);
+  return [Math.max(...s), s];
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useFoo,
+  params: [{}],
+  sequentialRenders: [{}, {}],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/global-types/map-constructor.expect.md

@@ -0,0 +1,77 @@
+
+## Input
+
+```javascript
+import {makeArray} from 'shared-runtime';
+
+function useHook({el1, el2}) {
+  const s = new Map();
+  s.set(el1, makeArray(el1));
+  s.set(el2, makeArray(el2));
+  return s.size;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useHook,
+  params: [{el1: 1, el2: 'foo'}],
+  sequentialRenders: [
+    {el1: 1, el2: 'foo'},
+    {el1: 2, el2: 'foo'},
+  ],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime";
+import { makeArray } from "shared-runtime";
+
+function useHook(t0) {
+  const $ = _c(7);
+  const { el1, el2 } = t0;
+  let s;
+  if ($[0] !== el1 || $[1] !== el2) {
+    s = new Map();
+    let t1;
+    if ($[3] !== el1) {
+      t1 = makeArray(el1);
+      $[3] = el1;
+      $[4] = t1;
+    } else {
+      t1 = $[4];
+    }
+    s.set(el1, t1);
+    let t2;
+    if ($[5] !== el2) {
+      t2 = makeArray(el2);
+      $[5] = el2;
+      $[6] = t2;
+    } else {
+      t2 = $[6];
+    }
+    s.set(el2, t2);
+    $[0] = el1;
+    $[1] = el2;
+    $[2] = s;
+  } else {
+    s = $[2];
+  }
+  return s.size;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useHook,
+  params: [{ el1: 1, el2: "foo" }],
+  sequentialRenders: [
+    { el1: 1, el2: "foo" },
+    { el1: 2, el2: "foo" },
+  ],
+};
+
+```
+      
+### Eval output
+(kind: ok) 2
+2

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/global-types/map-constructor.ts

@@ -0,0 +1,17 @@
+import {makeArray} from 'shared-runtime';
+
+function useHook({el1, el2}) {
+  const s = new Map();
+  s.set(el1, makeArray(el1));
+  s.set(el2, makeArray(el2));
+  return s.size;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useHook,
+  params: [{el1: 1, el2: 'foo'}],
+  sequentialRenders: [
+    {el1: 1, el2: 'foo'},
+    {el1: 2, el2: 'foo'},
+  ],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/global-types/repro-array-filter-capture-mutate-bug.expect.md

@@ -0,0 +1,113 @@
+
+## Input
+
+```javascript
+import {mutateAndReturn, Stringify, useIdentity} from 'shared-runtime';
+
+/**
+ * Repro for bug with `mutableOnlyIfOperandsAreMutable` flag
+ * Found differences in evaluator results
+  * Non-forget (expected):
+  * (kind: ok)
+  * <div>{"children":[{"value":"foo","wat0":"joe"},{"value":5,"wat0":"joe"}]}</div>
+  * <div>{"children":[{"value":"foo","wat0":"joe"},{"value":6,"wat0":"joe"}]}</div>
+  * <div>{"children":[{"value":"foo","wat0":"joe"},{"value":6,"wat0":"joe"}]}</div>
+  * Forget:
+  * (kind: ok)
+  * <div>{"children":[{"value":"foo","wat0":"joe"},{"value":5,"wat0":"joe"}]}</div>
+  * <div>{"children":[{"value":"foo","wat0":"joe","wat1":"joe"},{"value":6,"wat0":"joe"}]}</div>
+  * <div>{"children":[{"value":"foo","wat0":"joe","wat1":"joe"},{"value":6,"wat0":"joe"}]}</div>
+
+ */
+function Component({value}) {
+  const arr = [{value: 'foo'}, {value: 'bar'}, {value}];
+  useIdentity(null);
+  const derived = arr.filter(mutateAndReturn);
+  return (
+    <Stringify>
+      {derived.at(0)}
+      {derived.at(-1)}
+    </Stringify>
+  );
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{value: 5}],
+  sequentialRenders: [{value: 5}, {value: 6}, {value: 6}],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime";
+import { mutateAndReturn, Stringify, useIdentity } from "shared-runtime";
+
+/**
+ * Repro for bug with `mutableOnlyIfOperandsAreMutable` flag
+ * Found differences in evaluator results
+  * Non-forget (expected):
+  * (kind: ok)
+  * <div>{"children":[{"value":"foo","wat0":"joe"},{"value":5,"wat0":"joe"}]}</div>
+  * <div>{"children":[{"value":"foo","wat0":"joe"},{"value":6,"wat0":"joe"}]}</div>
+  * <div>{"children":[{"value":"foo","wat0":"joe"},{"value":6,"wat0":"joe"}]}</div>
+  * Forget:
+  * (kind: ok)
+  * <div>{"children":[{"value":"foo","wat0":"joe"},{"value":5,"wat0":"joe"}]}</div>
+  * <div>{"children":[{"value":"foo","wat0":"joe","wat1":"joe"},{"value":6,"wat0":"joe"}]}</div>
+  * <div>{"children":[{"value":"foo","wat0":"joe","wat1":"joe"},{"value":6,"wat0":"joe"}]}</div>
+
+ */
+function Component(t0) {
+  const $ = _c(7);
+  const { value } = t0;
+  const arr = [{ value: "foo" }, { value: "bar" }, { value }];
+  useIdentity(null);
+  const derived = arr.filter(mutateAndReturn);
+  let t1;
+  if ($[0] !== derived) {
+    t1 = derived.at(0);
+    $[0] = derived;
+    $[1] = t1;
+  } else {
+    t1 = $[1];
+  }
+  let t2;
+  if ($[2] !== derived) {
+    t2 = derived.at(-1);
+    $[2] = derived;
+    $[3] = t2;
+  } else {
+    t2 = $[3];
+  }
+  let t3;
+  if ($[4] !== t1 || $[5] !== t2) {
+    t3 = (
+      <Stringify>
+        {t1}
+        {t2}
+      </Stringify>
+    );
+    $[4] = t1;
+    $[5] = t2;
+    $[6] = t3;
+  } else {
+    t3 = $[6];
+  }
+  return t3;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{ value: 5 }],
+  sequentialRenders: [{ value: 5 }, { value: 6 }, { value: 6 }],
+};
+
+```
+      
+### Eval output
+(kind: ok) <div>{"children":[{"value":"foo","wat0":"joe"},{"value":5,"wat0":"joe"}]}</div>
+<div>{"children":[{"value":"foo","wat0":"joe"},{"value":6,"wat0":"joe"}]}</div>
+<div>{"children":[{"value":"foo","wat0":"joe"},{"value":6,"wat0":"joe"}]}</div>

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/global-types/repro-array-filter-capture-mutate-bug.tsx

@@ -0,0 +1,34 @@
+import {mutateAndReturn, Stringify, useIdentity} from 'shared-runtime';
+
+/**
+ * Repro for bug with `mutableOnlyIfOperandsAreMutable` flag
+ * Found differences in evaluator results
+  * Non-forget (expected):
+  * (kind: ok)
+  * <div>{"children":[{"value":"foo","wat0":"joe"},{"value":5,"wat0":"joe"}]}</div>
+  * <div>{"children":[{"value":"foo","wat0":"joe"},{"value":6,"wat0":"joe"}]}</div>
+  * <div>{"children":[{"value":"foo","wat0":"joe"},{"value":6,"wat0":"joe"}]}</div>
+  * Forget:
+  * (kind: ok)
+  * <div>{"children":[{"value":"foo","wat0":"joe"},{"value":5,"wat0":"joe"}]}</div>
+  * <div>{"children":[{"value":"foo","wat0":"joe","wat1":"joe"},{"value":6,"wat0":"joe"}]}</div>
+  * <div>{"children":[{"value":"foo","wat0":"joe","wat1":"joe"},{"value":6,"wat0":"joe"}]}</div>
+
+ */
+function Component({value}) {
+  const arr = [{value: 'foo'}, {value: 'bar'}, {value}];
+  useIdentity(null);
+  const derived = arr.filter(mutateAndReturn);
+  return (
+    <Stringify>
+      {derived.at(0)}
+      {derived.at(-1)}
+    </Stringify>
+  );
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{value: 5}],
+  sequentialRenders: [{value: 5}, {value: 6}, {value: 6}],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/global-types/repro-array-filter-known-nonmutate-Boolean.expect.md

@@ -0,0 +1,118 @@
+
+## Input
+
+```javascript
+import {Stringify, useIdentity} from 'shared-runtime';
+
+/**
+ * Also see repro-array-map-known-mutate-shape, which calls a global function
+ * that mutates its operands.
+ */
+function Component({value}) {
+  const arr = [{value: 'foo'}, {value: 'bar'}, {value}];
+  useIdentity(null);
+  const derived = arr.filter(Boolean);
+  return (
+    <Stringify>
+      {derived.at(0)}
+      {derived.at(-1)}
+    </Stringify>
+  );
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{value: 5}],
+  sequentialRenders: [{value: 5}, {value: 6}, {value: 6}],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime";
+import { Stringify, useIdentity } from "shared-runtime";
+
+/**
+ * Also see repro-array-map-known-mutate-shape, which calls a global function
+ * that mutates its operands.
+ */
+function Component(t0) {
+  const $ = _c(13);
+  const { value } = t0;
+  let t1;
+  let t2;
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+    t1 = { value: "foo" };
+    t2 = { value: "bar" };
+    $[0] = t1;
+    $[1] = t2;
+  } else {
+    t1 = $[0];
+    t2 = $[1];
+  }
+  let t3;
+  if ($[2] !== value) {
+    t3 = [t1, t2, { value }];
+    $[2] = value;
+    $[3] = t3;
+  } else {
+    t3 = $[3];
+  }
+  const arr = t3;
+  useIdentity(null);
+  let t4;
+  if ($[4] !== arr) {
+    t4 = arr.filter(Boolean);
+    $[4] = arr;
+    $[5] = t4;
+  } else {
+    t4 = $[5];
+  }
+  const derived = t4;
+  let t5;
+  if ($[6] !== derived) {
+    t5 = derived.at(0);
+    $[6] = derived;
+    $[7] = t5;
+  } else {
+    t5 = $[7];
+  }
+  let t6;
+  if ($[8] !== derived) {
+    t6 = derived.at(-1);
+    $[8] = derived;
+    $[9] = t6;
+  } else {
+    t6 = $[9];
+  }
+  let t7;
+  if ($[10] !== t5 || $[11] !== t6) {
+    t7 = (
+      <Stringify>
+        {t5}
+        {t6}
+      </Stringify>
+    );
+    $[10] = t5;
+    $[11] = t6;
+    $[12] = t7;
+  } else {
+    t7 = $[12];
+  }
+  return t7;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{ value: 5 }],
+  sequentialRenders: [{ value: 5 }, { value: 6 }, { value: 6 }],
+};
+
+```
+      
+### Eval output
+(kind: ok) <div>{"children":[{"value":"foo"},{"value":5}]}</div>
+<div>{"children":[{"value":"foo"},{"value":6}]}</div>
+<div>{"children":[{"value":"foo"},{"value":6}]}</div>

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/global-types/repro-array-filter-known-nonmutate-Boolean.tsx

@@ -0,0 +1,23 @@
+import {Stringify, useIdentity} from 'shared-runtime';
+
+/**
+ * Also see repro-array-map-known-mutate-shape, which calls a global function
+ * that mutates its operands.
+ */
+function Component({value}) {
+  const arr = [{value: 'foo'}, {value: 'bar'}, {value}];
+  useIdentity(null);
+  const derived = arr.filter(Boolean);
+  return (
+    <Stringify>
+      {derived.at(0)}
+      {derived.at(-1)}
+    </Stringify>
+  );
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{value: 5}],
+  sequentialRenders: [{value: 5}, {value: 6}, {value: 6}],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/global-types/repro-array-map-capture-mutate-bug.expect.md

@@ -0,0 +1,91 @@
+
+## Input
+
+```javascript
+import {mutateAndReturn, Stringify, useIdentity} from 'shared-runtime';
+
+/**
+ * Copy of repro-array-map-capture-mutate-bug, showing that the same issue applies to any
+ * function call which captures its callee when applying an operand.
+ */
+function Component({value}) {
+  const arr = [{value: 'foo'}, {value: 'bar'}, {value}];
+  useIdentity(null);
+  const derived = arr.map(mutateAndReturn);
+  return (
+    <Stringify>
+      {derived.at(0)}
+      {derived.at(-1)}
+    </Stringify>
+  );
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{value: 5}],
+  sequentialRenders: [{value: 5}, {value: 6}, {value: 6}],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime";
+import { mutateAndReturn, Stringify, useIdentity } from "shared-runtime";
+
+/**
+ * Copy of repro-array-map-capture-mutate-bug, showing that the same issue applies to any
+ * function call which captures its callee when applying an operand.
+ */
+function Component(t0) {
+  const $ = _c(7);
+  const { value } = t0;
+  const arr = [{ value: "foo" }, { value: "bar" }, { value }];
+  useIdentity(null);
+  const derived = arr.map(mutateAndReturn);
+  let t1;
+  if ($[0] !== derived) {
+    t1 = derived.at(0);
+    $[0] = derived;
+    $[1] = t1;
+  } else {
+    t1 = $[1];
+  }
+  let t2;
+  if ($[2] !== derived) {
+    t2 = derived.at(-1);
+    $[2] = derived;
+    $[3] = t2;
+  } else {
+    t2 = $[3];
+  }
+  let t3;
+  if ($[4] !== t1 || $[5] !== t2) {
+    t3 = (
+      <Stringify>
+        {t1}
+        {t2}
+      </Stringify>
+    );
+    $[4] = t1;
+    $[5] = t2;
+    $[6] = t3;
+  } else {
+    t3 = $[6];
+  }
+  return t3;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{ value: 5 }],
+  sequentialRenders: [{ value: 5 }, { value: 6 }, { value: 6 }],
+};
+
+```
+      
+### Eval output
+(kind: ok) <div>{"children":[{"value":"foo","wat0":"joe"},{"value":5,"wat0":"joe"}]}</div>
+<div>{"children":[{"value":"foo","wat0":"joe"},{"value":6,"wat0":"joe"}]}</div>
+<div>{"children":[{"value":"foo","wat0":"joe"},{"value":6,"wat0":"joe"}]}</div>

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/global-types/repro-array-map-capture-mutate-bug.tsx

@@ -0,0 +1,23 @@
+import {mutateAndReturn, Stringify, useIdentity} from 'shared-runtime';
+
+/**
+ * Copy of repro-array-map-capture-mutate-bug, showing that the same issue applies to any
+ * function call which captures its callee when applying an operand.
+ */
+function Component({value}) {
+  const arr = [{value: 'foo'}, {value: 'bar'}, {value}];
+  useIdentity(null);
+  const derived = arr.map(mutateAndReturn);
+  return (
+    <Stringify>
+      {derived.at(0)}
+      {derived.at(-1)}
+    </Stringify>
+  );
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{value: 5}],
+  sequentialRenders: [{value: 5}, {value: 6}, {value: 6}],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/global-types/repro-array-map-known-mutate-shape.expect.md

@@ -0,0 +1,100 @@
+
+## Input
+
+```javascript
+import {Stringify, useIdentity} from 'shared-runtime';
+
+/**
+ * Also see repro-array-map-known-nonmutate-Boolean, which calls a global
+ * function that does *not* mutate its operands.
+ */
+function Component({value}) {
+  const arr = [
+    new Set([['foo', 2]]).values(),
+    new Set([['bar', 4]]).values(),
+    [['baz', value]],
+  ];
+  useIdentity(null);
+  const derived = arr.map(Object.fromEntries);
+  return (
+    <Stringify>
+      {derived.at(0)}
+      {derived.at(-1)}
+    </Stringify>
+  );
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{value: 5}],
+  sequentialRenders: [{value: 5}, {value: 6}, {value: 6}],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime";
+import { Stringify, useIdentity } from "shared-runtime";
+
+/**
+ * Also see repro-array-map-known-nonmutate-Boolean, which calls a global
+ * function that does *not* mutate its operands.
+ */
+function Component(t0) {
+  const $ = _c(7);
+  const { value } = t0;
+  const arr = [
+    new Set([["foo", 2]]).values(),
+    new Set([["bar", 4]]).values(),
+    [["baz", value]],
+  ];
+
+  useIdentity(null);
+  const derived = arr.map(Object.fromEntries);
+  let t1;
+  if ($[0] !== derived) {
+    t1 = derived.at(0);
+    $[0] = derived;
+    $[1] = t1;
+  } else {
+    t1 = $[1];
+  }
+  let t2;
+  if ($[2] !== derived) {
+    t2 = derived.at(-1);
+    $[2] = derived;
+    $[3] = t2;
+  } else {
+    t2 = $[3];
+  }
+  let t3;
+  if ($[4] !== t1 || $[5] !== t2) {
+    t3 = (
+      <Stringify>
+        {t1}
+        {t2}
+      </Stringify>
+    );
+    $[4] = t1;
+    $[5] = t2;
+    $[6] = t3;
+  } else {
+    t3 = $[6];
+  }
+  return t3;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{ value: 5 }],
+  sequentialRenders: [{ value: 5 }, { value: 6 }, { value: 6 }],
+};
+
+```
+      
+### Eval output
+(kind: ok) <div>{"children":[{"foo":2},{"baz":5}]}</div>
+<div>{"children":[{"foo":2},{"baz":6}]}</div>
+<div>{"children":[{"foo":2},{"baz":6}]}</div>

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/global-types/repro-array-map-known-mutate-shape.tsx

@@ -0,0 +1,27 @@
+import {Stringify, useIdentity} from 'shared-runtime';
+
+/**
+ * Also see repro-array-map-known-nonmutate-Boolean, which calls a global
+ * function that does *not* mutate its operands.
+ */
+function Component({value}) {
+  const arr = [
+    new Set([['foo', 2]]).values(),
+    new Set([['bar', 4]]).values(),
+    [['baz', value]],
+  ];
+  useIdentity(null);
+  const derived = arr.map(Object.fromEntries);
+  return (
+    <Stringify>
+      {derived.at(0)}
+      {derived.at(-1)}
+    </Stringify>
+  );
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{value: 5}],
+  sequentialRenders: [{value: 5}, {value: 6}, {value: 6}],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/global-types/set-add-mutate.expect.md

@@ -0,0 +1,76 @@
+
+## Input
+
+```javascript
+import {makeArray} from 'shared-runtime';
+
+function useHook({el1, el2}) {
+  const s = new Set();
+  const arr = makeArray(el1);
+  s.add(arr);
+  // Mutate after store
+  arr.push(el2);
+
+  s.add(makeArray(el2));
+  return s.size;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useHook,
+  params: [{el1: 1, el2: 'foo'}],
+  sequentialRenders: [
+    {el1: 1, el2: 'foo'},
+    {el1: 2, el2: 'foo'},
+  ],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime";
+import { makeArray } from "shared-runtime";
+
+function useHook(t0) {
+  const $ = _c(5);
+  const { el1, el2 } = t0;
+  let s;
+  if ($[0] !== el1 || $[1] !== el2) {
+    s = new Set();
+    const arr = makeArray(el1);
+    s.add(arr);
+
+    arr.push(el2);
+    let t1;
+    if ($[3] !== el2) {
+      t1 = makeArray(el2);
+      $[3] = el2;
+      $[4] = t1;
+    } else {
+      t1 = $[4];
+    }
+    s.add(t1);
+    $[0] = el1;
+    $[1] = el2;
+    $[2] = s;
+  } else {
+    s = $[2];
+  }
+  return s.size;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useHook,
+  params: [{ el1: 1, el2: "foo" }],
+  sequentialRenders: [
+    { el1: 1, el2: "foo" },
+    { el1: 2, el2: "foo" },
+  ],
+};
+
+```
+      
+### Eval output
+(kind: ok) 2
+2

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/global-types/set-add-mutate.ts

@@ -0,0 +1,21 @@
+import {makeArray} from 'shared-runtime';
+
+function useHook({el1, el2}) {
+  const s = new Set();
+  const arr = makeArray(el1);
+  s.add(arr);
+  // Mutate after store
+  arr.push(el2);
+
+  s.add(makeArray(el2));
+  return s.size;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useHook,
+  params: [{el1: 1, el2: 'foo'}],
+  sequentialRenders: [
+    {el1: 1, el2: 'foo'},
+    {el1: 2, el2: 'foo'},
+  ],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/global-types/set-constructor-arg.expect.md

@@ -0,0 +1,108 @@
+
+## Input
+
+```javascript
+const MODULE_LOCAL = new Set([4, 5, 6]);
+function useFoo({propArr}: {propArr: Array<number>}) {
+  /* Array can be memoized separately of the Set */
+  const s1 = new Set([1, 2, 3]);
+  s1.add(propArr[0]);
+
+  /* but `.values` cannot be memoized separately */
+  const s2 = new Set(MODULE_LOCAL.values());
+  s2.add(propArr[1]);
+
+  const s3 = new Set(s2.values());
+  s3.add(propArr[2]);
+
+  /**
+   * s4 should be memoized separately from s3
+   */
+  const s4 = new Set(s3);
+  s4.add(propArr[3]);
+  return [s1, s2, s3, s4];
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useFoo,
+  params: [{propArr: [7, 8, 9]}],
+  sequentialRenders: [{propArr: [7, 8, 9]}, {propArr: [7, 8, 10]}],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime";
+const MODULE_LOCAL = new Set([4, 5, 6]);
+function useFoo(t0) {
+  const $ = _c(15);
+  const { propArr } = t0;
+  let t1;
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+    t1 = [1, 2, 3];
+    $[0] = t1;
+  } else {
+    t1 = $[0];
+  }
+  let s1;
+  if ($[1] !== propArr[0]) {
+    s1 = new Set(t1);
+    s1.add(propArr[0]);
+    $[1] = propArr[0];
+    $[2] = s1;
+  } else {
+    s1 = $[2];
+  }
+  let s2;
+  let s3;
+  if ($[3] !== propArr[1] || $[4] !== propArr[2]) {
+    s2 = new Set(MODULE_LOCAL.values());
+    s2.add(propArr[1]);
+
+    s3 = new Set(s2.values());
+    s3.add(propArr[2]);
+    $[3] = propArr[1];
+    $[4] = propArr[2];
+    $[5] = s2;
+    $[6] = s3;
+  } else {
+    s2 = $[5];
+    s3 = $[6];
+  }
+  let s4;
+  if ($[7] !== propArr[3] || $[8] !== s3) {
+    s4 = new Set(s3);
+    s4.add(propArr[3]);
+    $[7] = propArr[3];
+    $[8] = s3;
+    $[9] = s4;
+  } else {
+    s4 = $[9];
+  }
+  let t2;
+  if ($[10] !== s1 || $[11] !== s2 || $[12] !== s3 || $[13] !== s4) {
+    t2 = [s1, s2, s3, s4];
+    $[10] = s1;
+    $[11] = s2;
+    $[12] = s3;
+    $[13] = s4;
+    $[14] = t2;
+  } else {
+    t2 = $[14];
+  }
+  return t2;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useFoo,
+  params: [{ propArr: [7, 8, 9] }],
+  sequentialRenders: [{ propArr: [7, 8, 9] }, { propArr: [7, 8, 10] }],
+};
+
+```
+      
+### Eval output
+(kind: ok) [{"kind":"Set","value":[1,2,3,7]},{"kind":"Set","value":[4,5,6,8]},{"kind":"Set","value":[4,5,6,8,9]},{"kind":"Set","value":[4,5,6,8,9,null]}]
+[{"kind":"Set","value":[1,2,3,7]},{"kind":"Set","value":[4,5,6,8]},{"kind":"Set","value":[4,5,6,8,10]},{"kind":"Set","value":[4,5,6,8,10,null]}]

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/global-types/set-constructor-arg.ts

@@ -0,0 +1,26 @@
+const MODULE_LOCAL = new Set([4, 5, 6]);
+function useFoo({propArr}: {propArr: Array<number>}) {
+  /* Array can be memoized separately of the Set */
+  const s1 = new Set([1, 2, 3]);
+  s1.add(propArr[0]);
+
+  /* but `.values` cannot be memoized separately */
+  const s2 = new Set(MODULE_LOCAL.values());
+  s2.add(propArr[1]);
+
+  const s3 = new Set(s2.values());
+  s3.add(propArr[2]);
+
+  /**
+   * s4 should be memoized separately from s3
+   */
+  const s4 = new Set(s3);
+  s4.add(propArr[3]);
+  return [s1, s2, s3, s4];
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useFoo,
+  params: [{propArr: [7, 8, 9]}],
+  sequentialRenders: [{propArr: [7, 8, 9]}, {propArr: [7, 8, 10]}],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/global-types/set-constructor.expect.md

@@ -0,0 +1,77 @@
+
+## Input
+
+```javascript
+import {makeArray} from 'shared-runtime';
+
+function useHook({el1, el2}) {
+  const s = new Set();
+  s.add(makeArray(el1));
+  s.add(makeArray(el2));
+  return s.size;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useHook,
+  params: [{el1: 1, el2: 'foo'}],
+  sequentialRenders: [
+    {el1: 1, el2: 'foo'},
+    {el1: 2, el2: 'foo'},
+  ],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime";
+import { makeArray } from "shared-runtime";
+
+function useHook(t0) {
+  const $ = _c(7);
+  const { el1, el2 } = t0;
+  let s;
+  if ($[0] !== el1 || $[1] !== el2) {
+    s = new Set();
+    let t1;
+    if ($[3] !== el1) {
+      t1 = makeArray(el1);
+      $[3] = el1;
+      $[4] = t1;
+    } else {
+      t1 = $[4];
+    }
+    s.add(t1);
+    let t2;
+    if ($[5] !== el2) {
+      t2 = makeArray(el2);
+      $[5] = el2;
+      $[6] = t2;
+    } else {
+      t2 = $[6];
+    }
+    s.add(t2);
+    $[0] = el1;
+    $[1] = el2;
+    $[2] = s;
+  } else {
+    s = $[2];
+  }
+  return s.size;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useHook,
+  params: [{ el1: 1, el2: "foo" }],
+  sequentialRenders: [
+    { el1: 1, el2: "foo" },
+    { el1: 2, el2: "foo" },
+  ],
+};
+
+```
+      
+### Eval output
+(kind: ok) 2
+2

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/global-types/set-constructor.ts

@@ -0,0 +1,17 @@
+import {makeArray} from 'shared-runtime';
+
+function useHook({el1, el2}) {
+  const s = new Set();
+  s.add(makeArray(el1));
+  s.add(makeArray(el2));
+  return s.size;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useHook,
+  params: [{el1: 1, el2: 'foo'}],
+  sequentialRenders: [
+    {el1: 1, el2: 'foo'},
+    {el1: 2, el2: 'foo'},
+  ],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/global-types/set-copy-constructor-mutate.expect.md

@@ -0,0 +1,82 @@
+
+## Input
+
+```javascript
+import {makeArray, mutate} from 'shared-runtime';
+
+function useFoo({propArr}: {propArr: Array<number>}) {
+  const s1 = new Set<number | Array<number>>([1, 2, 3]);
+  s1.add(makeArray(propArr[0]));
+
+  const s2 = new Set(s1);
+  // this may also may mutate s1
+  mutate(s2);
+
+  return [s1, s2];
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useFoo,
+  params: [{propArr: [7, 8, 9]}],
+  sequentialRenders: [
+    {propArr: [7, 8, 9]},
+    {propArr: [7, 8, 9]},
+    {propArr: [7, 8, 10]},
+  ],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime";
+import { makeArray, mutate } from "shared-runtime";
+
+function useFoo(t0) {
+  const $ = _c(6);
+  const { propArr } = t0;
+  let s1;
+  let s2;
+  if ($[0] !== propArr[0]) {
+    s1 = new Set([1, 2, 3]);
+    s1.add(makeArray(propArr[0]));
+
+    s2 = new Set(s1);
+
+    mutate(s2);
+    $[0] = propArr[0];
+    $[1] = s1;
+    $[2] = s2;
+  } else {
+    s1 = $[1];
+    s2 = $[2];
+  }
+  let t1;
+  if ($[3] !== s1 || $[4] !== s2) {
+    t1 = [s1, s2];
+    $[3] = s1;
+    $[4] = s2;
+    $[5] = t1;
+  } else {
+    t1 = $[5];
+  }
+  return t1;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useFoo,
+  params: [{ propArr: [7, 8, 9] }],
+  sequentialRenders: [
+    { propArr: [7, 8, 9] },
+    { propArr: [7, 8, 9] },
+    { propArr: [7, 8, 10] },
+  ],
+};
+
+```
+      
+### Eval output
+(kind: ok) [{"kind":"Set","value":[1,2,3,[7]]},{"kind":"Set","value":[1,2,3,"[[ cyclic ref *2 ]]"]}]
+[{"kind":"Set","value":[1,2,3,[7]]},{"kind":"Set","value":[1,2,3,"[[ cyclic ref *2 ]]"]}]
+[{"kind":"Set","value":[1,2,3,[7]]},{"kind":"Set","value":[1,2,3,"[[ cyclic ref *2 ]]"]}]

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/global-types/set-copy-constructor-mutate.ts

@@ -0,0 +1,22 @@
+import {makeArray, mutate} from 'shared-runtime';
+
+function useFoo({propArr}: {propArr: Array<number>}) {
+  const s1 = new Set<number | Array<number>>([1, 2, 3]);
+  s1.add(makeArray(propArr[0]));
+
+  const s2 = new Set(s1);
+  // this may also may mutate s1
+  mutate(s2);
+
+  return [s1, s2];
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useFoo,
+  params: [{propArr: [7, 8, 9]}],
+  sequentialRenders: [
+    {propArr: [7, 8, 9]},
+    {propArr: [7, 8, 9]},
+    {propArr: [7, 8, 10]},
+  ],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/global-types/set-for-of-iterate-values.expect.md

@@ -0,0 +1,65 @@
+
+## Input
+
+```javascript
+import {makeArray, useHook} from 'shared-runtime';
+
+function useFoo({propArr}: {propArr: Array<number>}) {
+  const s1 = new Set<number | Array<number>>([1, 2, 3]);
+  s1.add(makeArray(propArr[0]));
+
+  useHook();
+  const s2 = new Set();
+  for (const el of s1.values()) {
+    s2.add(el);
+  }
+
+  return [s1, s2];
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useFoo,
+  params: [{propArr: [7, 8, 9]}],
+  sequentialRenders: [
+    {propArr: [7, 8, 9]},
+    {propArr: [7, 8, 9]},
+    {propArr: [7, 8, 10]},
+  ],
+};
+
+```
+
+## Code
+
+```javascript
+import { makeArray, useHook } from "shared-runtime";
+
+function useFoo(t0) {
+  const { propArr } = t0;
+  const s1 = new Set([1, 2, 3]);
+  s1.add(makeArray(propArr[0]));
+
+  useHook();
+  const s2 = new Set();
+  for (const el of s1.values()) {
+    s2.add(el);
+  }
+  return [s1, s2];
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useFoo,
+  params: [{ propArr: [7, 8, 9] }],
+  sequentialRenders: [
+    { propArr: [7, 8, 9] },
+    { propArr: [7, 8, 9] },
+    { propArr: [7, 8, 10] },
+  ],
+};
+
+```
+      
+### Eval output
+(kind: ok) [{"kind":"Set","value":[1,2,3,[7]]},{"kind":"Set","value":[1,2,3,"[[ cyclic ref *2 ]]"]}]
+[{"kind":"Set","value":[1,2,3,[7]]},{"kind":"Set","value":[1,2,3,"[[ cyclic ref *2 ]]"]}]
+[{"kind":"Set","value":[1,2,3,[7]]},{"kind":"Set","value":[1,2,3,"[[ cyclic ref *2 ]]"]}]

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/global-types/set-for-of-iterate-values.ts

@@ -0,0 +1,24 @@
+import {makeArray, useHook} from 'shared-runtime';
+
+function useFoo({propArr}: {propArr: Array<number>}) {
+  const s1 = new Set<number | Array<number>>([1, 2, 3]);
+  s1.add(makeArray(propArr[0]));
+
+  useHook();
+  const s2 = new Set();
+  for (const el of s1.values()) {
+    s2.add(el);
+  }
+
+  return [s1, s2];
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useFoo,
+  params: [{propArr: [7, 8, 9]}],
+  sequentialRenders: [
+    {propArr: [7, 8, 9]},
+    {propArr: [7, 8, 9]},
+    {propArr: [7, 8, 10]},
+  ],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/global-types/set-foreach-mutate.expect.md

@@ -0,0 +1,57 @@
+
+## Input
+
+```javascript
+import {mutateAndReturn, Stringify, useIdentity} from 'shared-runtime';
+
+function Component({value}) {
+  const arr = [{value: 'foo'}, {value: 'bar'}, {value}];
+  useIdentity();
+  const derived = new Set(arr).forEach(mutateAndReturn);
+  return <Stringify>{[...derived]}</Stringify>;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{value: 5}],
+  sequentialRenders: [{value: 5}, {value: 6}, {value: 6}, {value: 7}],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime";
+import { mutateAndReturn, Stringify, useIdentity } from "shared-runtime";
+
+function Component(t0) {
+  const $ = _c(2);
+  const { value } = t0;
+  const arr = [{ value: "foo" }, { value: "bar" }, { value }];
+  useIdentity();
+  const derived = new Set(arr).forEach(mutateAndReturn);
+  let t1;
+  if ($[0] !== derived) {
+    t1 = <Stringify>{[...derived]}</Stringify>;
+    $[0] = derived;
+    $[1] = t1;
+  } else {
+    t1 = $[1];
+  }
+  return t1;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{ value: 5 }],
+  sequentialRenders: [{ value: 5 }, { value: 6 }, { value: 6 }, { value: 7 }],
+};
+
+```
+      
+### Eval output
+(kind: ok) [[ (exception in render) TypeError: derived is not iterable ]]
+[[ (exception in render) TypeError: derived is not iterable ]]
+[[ (exception in render) TypeError: derived is not iterable ]]
+[[ (exception in render) TypeError: derived is not iterable ]]

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/global-types/set-foreach-mutate.tsx

@@ -0,0 +1,14 @@
+import {mutateAndReturn, Stringify, useIdentity} from 'shared-runtime';
+
+function Component({value}) {
+  const arr = [{value: 'foo'}, {value: 'bar'}, {value}];
+  useIdentity();
+  const derived = new Set(arr).forEach(mutateAndReturn);
+  return <Stringify>{[...derived]}</Stringify>;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{value: 5}],
+  sequentialRenders: [{value: 5}, {value: 6}, {value: 6}, {value: 7}],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/hoisting-invalid-tdz-let.expect.md

@@ -0,0 +1,59 @@
+
+## Input
+
+```javascript
+function Foo() {
+  const getX = () => x;
+  console.log(getX());
+
+  let x = 4;
+  x += 5;
+
+  return <Stringify getX={getX} shouldInvokeFns={true} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Foo,
+  params: [],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime";
+function Foo() {
+  const $ = _c(2);
+  let getX;
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+    getX = () => x;
+    console.log(getX());
+
+    let x;
+    x = 4;
+    x = x + 5;
+    $[0] = getX;
+  } else {
+    getX = $[0];
+  }
+  x;
+  let t0;
+  if ($[1] === Symbol.for("react.memo_cache_sentinel")) {
+    t0 = <Stringify getX={getX} shouldInvokeFns={true} />;
+    $[1] = t0;
+  } else {
+    t0 = $[1];
+  }
+  return t0;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Foo,
+  params: [],
+};
+
+```
+      
+### Eval output
+(kind: exception) Cannot access 'x' before initialization

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/hoisting-invalid-tdz-let.js

@@ -0,0 +1,14 @@
+function Foo() {
+  const getX = () => x;
+  console.log(getX());
+
+  let x = 4;
+  x += 5;
+
+  return <Stringify getX={getX} shouldInvokeFns={true} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Foo,
+  params: [],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/hoisting-nested-let-declaration-2.expect.md

@@ -36,7 +36,8 @@ function hoisting(cond) {
         items.push(bar());
       };
 
-      let bar = _temp;
+      let bar;
+      bar = _temp;
       foo();
     }
     $[0] = cond;

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/hoisting-nested-let-declaration.expect.md

@@ -41,9 +41,11 @@ function hoisting() {
       return result;
     };
 
-    let foo = () => bar + baz;
+    let foo;
+    foo = () => bar + baz;
 
-    let bar = 3;
+    let bar;
+    bar = 3;
     const baz = 2;
     t0 = qux();
     $[0] = t0;

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/hoisting-reassigned-let-declaration.expect.md

@@ -0,0 +1,67 @@
+
+## Input
+
+```javascript
+import {CONST_NUMBER0, CONST_NUMBER1, Stringify} from 'shared-runtime';
+
+function useHook({cond}) {
+  'use memo';
+  const getX = () => x;
+
+  let x = CONST_NUMBER0;
+  if (cond) {
+    x += CONST_NUMBER1;
+  }
+  return <Stringify getX={getX} shouldInvokeFns={true} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useHook,
+  params: [{cond: true}],
+  sequentialRenders: [{cond: true}, {cond: true}, {cond: false}],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime";
+import { CONST_NUMBER0, CONST_NUMBER1, Stringify } from "shared-runtime";
+
+function useHook(t0) {
+  "use memo";
+  const $ = _c(2);
+  const { cond } = t0;
+  let t1;
+  if ($[0] !== cond) {
+    const getX = () => x;
+
+    let x;
+    x = CONST_NUMBER0;
+    if (cond) {
+      x = x + CONST_NUMBER1;
+      x;
+    }
+
+    t1 = <Stringify getX={getX} shouldInvokeFns={true} />;
+    $[0] = cond;
+    $[1] = t1;
+  } else {
+    t1 = $[1];
+  }
+  return t1;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: useHook,
+  params: [{ cond: true }],
+  sequentialRenders: [{ cond: true }, { cond: true }, { cond: false }],
+};
+
+```
+      
+### Eval output
+(kind: ok) <div>{"getX":{"kind":"Function","result":1},"shouldInvokeFns":true}</div>
+<div>{"getX":{"kind":"Function","result":1},"shouldInvokeFns":true}</div>
+<div>{"getX":{"kind":"Function","result":0},"shouldInvokeFns":true}</div>