[compiler] Init react-mcp-server

Just trying this out as a small hack for fun. Nothing serious is planned.

Inits an MCP server that has 1 assistant prompt and two capabilities.

.eslintrc.js

@@ -615,6 +615,8 @@ module.exports = {
     GetAnimationsOptions: 'readonly',
     Animatable: 'readonly',
     ScrollTimeline: 'readonly',
+    EventListenerOptionsOrUseCapture: 'readonly',
+    FocusOptions: 'readonly',
 
     spyOnDev: 'readonly',
     spyOnDevAndProd: 'readonly',

.github/ISSUE_TEMPLATE/19.md

@@ -1,18 +0,0 @@
----
-name: "⚛React 19 beta issue"
-about: Report a issue with React 19 beta.
-title: '[React 19]'
-labels: 'React 19'
-
----
-
-
-## Summary
-
-<!--
-  Please provide a CodeSandbox (https://codesandbox.io/s/new), a link to a
-  repository on GitHub, or provide a minimal code example that reproduces the
-  problem. You may provide a screenshot of the application if you think it is
-  relevant to your bug report. Here are some tips for providing a minimal
-  example: https://stackoverflow.com/help/mcve.
--->

.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/compiler_playground.yml

@@ -40,8 +40,12 @@ jobs:
         with:
           path: |
             **/node_modules
-          key: compiler-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('compiler/**/yarn.lock') }}
+          key: compiler-and-playground-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('compiler/**/yarn.lock') }}
       - run: yarn install --frozen-lockfile
+        if: steps.node_modules.outputs.cache-hit != 'true'
+        working-directory: compiler
+      - run: yarn install --frozen-lockfile
+        if: steps.node_modules.outputs.cache-hit != 'true'
       - name: Check Playwright version
         id: playwright_version
         run: echo "playwright_version=$(npm ls @playwright/test | grep @playwright | sed 's/.*@//' | head -1)" >> "$GITHUB_OUTPUT"

.github/workflows/compiler_prereleases.yml

@@ -49,8 +49,9 @@ jobs:
         with:
           path: |
             **/node_modules
-          key: compiler-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('compiler/**/yarn.lock') }}
+          key: compiler-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('compiler/yarn.lock') }}
       - run: yarn install --frozen-lockfile
+        if: steps.node_modules.outputs.cache-hit != 'true'
       - name: Publish packages to npm
         run: |
           cp ./scripts/release/ci-npmrc ~/.npmrc

.github/workflows/compiler_typescript.yml

@@ -47,11 +47,13 @@ jobs:
           cache-dependency-path: compiler/yarn.lock
       - name: Restore cached node_modules
         uses: actions/cache@v4
+        id: node_modules
         with:
           path: |
             **/node_modules
-          key: compiler-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('compiler/**/yarn.lock') }}
+          key: compiler-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('compiler/yarn.lock') }}
       - run: yarn install --frozen-lockfile
+        if: steps.node_modules.outputs.cache-hit != 'true'
       - run: yarn workspace babel-plugin-react-compiler lint
 
   # Hardcoded to improve parallelism
@@ -71,8 +73,9 @@ jobs:
         with:
           path: |
             **/node_modules
-          key: compiler-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('compiler/**/yarn.lock') }}
+          key: compiler-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('compiler/yarn.lock') }}
       - run: yarn install --frozen-lockfile
+        if: steps.node_modules.outputs.cache-hit != 'true'
       - run: yarn workspace babel-plugin-react-compiler jest
 
   test:
@@ -96,8 +99,9 @@ jobs:
         with:
           path: |
             **/node_modules
-          key: compiler-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('compiler/**/yarn.lock') }}
+          key: compiler-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('compiler/yarn.lock') }}
       - run: yarn install --frozen-lockfile
+        if: steps.node_modules.outputs.cache-hit != 'true'
       - run: xvfb-run -a yarn workspace ${{ matrix.workspace_name }} test
         if: runner.os == 'Linux' && matrix.workspace_name == 'react-forgive'
       - run: yarn workspace ${{ matrix.workspace_name }} test

.github/workflows/devtools_regression_tests.yml

@@ -40,7 +40,9 @@ jobs:
       - name: Ensure clean build directory
         run: rm -rf build
       - run: yarn install --frozen-lockfile
+        if: steps.node_modules.outputs.cache-hit != 'true'
       - run: yarn --cwd scripts/release install --frozen-lockfile
+        if: steps.node_modules.outputs.cache-hit != 'true'
       - name: Download react-devtools artifacts for base revision
         run: |
           git fetch origin main
@@ -75,6 +77,7 @@ jobs:
       - name: Ensure clean build directory
         run: rm -rf build
       - run: yarn install --frozen-lockfile
+        if: steps.node_modules.outputs.cache-hit != 'true'
       - name: Restore archived build
         uses: actions/download-artifact@v4
         with:
@@ -134,6 +137,7 @@ jobs:
             **/node_modules
           key: runtime-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock') }}
       - run: yarn install --frozen-lockfile
+        if: steps.node_modules.outputs.cache-hit != 'true'
       - name: Restore all archived build artifacts
         uses: actions/download-artifact@v4
       - name: Display structure of build
@@ -169,14 +173,24 @@ jobs:
             **/node_modules
           key: runtime-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock') }}
       - run: yarn install --frozen-lockfile
+        if: steps.node_modules.outputs.cache-hit != 'true'
       - name: Restore all archived build artifacts
         uses: actions/download-artifact@v4
       - name: Display structure of build
         run: ls -R build
-      - name: Playwright install deps
-        run: |
-          npx playwright install
-          sudo npx playwright install-deps
+      - name: Check Playwright version
+        id: playwright_version
+        run: echo "playwright_version=$(npm ls @playwright/test | grep @playwright | sed 's/.*@//' | head -1)" >> "$GITHUB_OUTPUT"
+      - name: Cache Playwright Browsers for version ${{ steps.playwright_version.outputs.playwright_version }}
+        id: cache_playwright_browsers
+        uses: actions/cache@v4
+        with:
+          path: ~/.cache/ms-playwright
+          key: playwright-browsers-v6-${{ runner.arch }}-${{ runner.os }}-${{ steps.playwright_version.outputs.playwright_version }}
+      - run: npx playwright install --with-deps
+        if: steps.cache_playwright_browsers.outputs.cache-hit != 'true'
+      - run: npx playwright install-deps
+        if: steps.cache_playwright_browsers.outputs.cache-hit == 'true'
       - run: ./scripts/ci/download_devtools_regression_build.js ${{ matrix.version }}
       - run: ls -R build-regression
       - run: ./scripts/ci/run_devtools_e2e_tests.js ${{ matrix.version }}

.github/workflows/runtime_build_and_test.yml

@@ -6,12 +6,6 @@ on:
   pull_request:
     paths-ignore:
       - compiler/**
-  workflow_dispatch:
-    inputs:
-      commit_sha:
-        required: false
-        type: string
-        default: ''
 
 permissions: {}
 
@@ -34,7 +28,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
+          ref: ${{ github.event.pull_request.head.sha || github.sha }}
       - name: Check cache hit
         uses: actions/cache/restore@v4
         id: node_modules
@@ -75,7 +69,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
+          ref: ${{ github.event.pull_request.head.sha || github.sha }}
       - name: Check cache hit
         uses: actions/cache/restore@v4
         id: node_modules
@@ -123,7 +117,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
+          ref: ${{ github.event.pull_request.head.sha || github.sha }}
       - uses: actions/github-script@v7
         id: set-matrix
         with:
@@ -142,7 +136,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
+          ref: ${{ github.event.pull_request.head.sha || github.sha }}
       - uses: actions/setup-node@v4
         with:
           node-version-file: '.nvmrc'
@@ -172,7 +166,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
+          ref: ${{ github.event.pull_request.head.sha || github.sha }}
       - uses: actions/setup-node@v4
         with:
           node-version-file: '.nvmrc'
@@ -204,7 +198,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
+          ref: ${{ github.event.pull_request.head.sha || github.sha }}
       - uses: actions/setup-node@v4
         with:
           node-version-file: '.nvmrc'
@@ -260,7 +254,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
+          ref: ${{ github.event.pull_request.head.sha || github.sha }}
       - uses: actions/setup-node@v4
         with:
           node-version-file: '.nvmrc'
@@ -300,7 +294,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
+          ref: ${{ github.event.pull_request.head.sha || github.sha }}
       - uses: actions/setup-node@v4
         with:
           node-version-file: '.nvmrc'
@@ -395,7 +389,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
+          ref: ${{ github.event.pull_request.head.sha || github.sha }}
       - uses: actions/setup-node@v4
         with:
           node-version-file: '.nvmrc'
@@ -432,11 +426,15 @@ jobs:
   process_artifacts_combined:
     name: Process artifacts combined
     needs: [build_and_lint, runtime_node_modules_cache]
+    permissions:
+      # https://github.com/actions/attest-build-provenance
+      id-token: write
+      attestations: write
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
+          ref: ${{ github.event.pull_request.head.sha || github.sha }}
       - uses: actions/setup-node@v4
         with:
           node-version-file: '.nvmrc'
@@ -464,7 +462,7 @@ jobs:
           merge-multiple: true
       - name: Display structure of build
         run: ls -R build
-      - run: echo ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }} >> build/COMMIT_SHA
+      - run: echo ${{ github.event.pull_request.head.sha || github.sha }} >> build/COMMIT_SHA
       - name: Scrape warning messages
         run: |
           mkdir -p ./build/__test_utils__
@@ -474,6 +472,7 @@ jobs:
         # TODO: Migrate scripts to use `build` directory instead of `build2`
       - run: cp ./build.tgz ./build2.tgz
       - name: Archive build artifacts
+        id: upload_artifacts_combined
         uses: actions/upload-artifact@v4
         with:
           name: artifacts_combined
@@ -481,6 +480,17 @@ jobs:
             ./build.tgz
             ./build2.tgz
           if-no-files-found: error
+      - uses: actions/attest-build-provenance@v2
+        # We don't verify builds generated from pull requests not originating from facebook/react.
+        # However, if the PR lands, the run on `main` will generate the attestation which can then
+        # be used to download a build via scripts/release/download-experimental-build.js.
+        #
+        # Note that this means that scripts/release/download-experimental-build.js must be run with
+        # --no-verify when downloading a build from a fork.
+        if: github.event_name == 'push' && github.ref_name == 'main' || github.event.pull_request.head.repo.full_name == github.repository
+        with:
+          subject-name: artifacts_combined.zip
+          subject-digest: sha256:${{ steps.upload_artifacts_combined.outputs.artifact-digest }}
 
   check_error_codes:
     name: Search build artifacts for unminified errors
@@ -489,7 +499,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
+          ref: ${{ github.event.pull_request.head.sha || github.sha }}
       - uses: actions/setup-node@v4
         with:
           node-version-file: '.nvmrc'
@@ -529,7 +539,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
+          ref: ${{ github.event.pull_request.head.sha || github.sha }}
       - uses: actions/setup-node@v4
         with:
           node-version-file: '.nvmrc'
@@ -566,7 +576,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
+          ref: ${{ github.event.pull_request.head.sha || github.sha }}
       - uses: actions/setup-node@v4
         with:
           node-version-file: '.nvmrc'
@@ -607,7 +617,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
+          ref: ${{ github.event.pull_request.head.sha || github.sha }}
       - uses: actions/setup-node@v4
         with:
           node-version-file: '.nvmrc'
@@ -681,7 +691,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
+          ref: ${{ github.event.pull_request.head.sha || github.sha }}
       - uses: actions/setup-node@v4
         with:
           node-version-file: '.nvmrc'
@@ -738,7 +748,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
+          ref: ${{ github.event.pull_request.head.sha || github.sha }}
       - uses: actions/setup-node@v4
         with:
           node-version-file: '.nvmrc'
@@ -783,7 +793,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
+          ref: ${{ github.event.pull_request.head.sha || github.sha }}
       - uses: actions/setup-node@v4
         with:
           node-version-file: '.nvmrc'
@@ -803,14 +813,18 @@ jobs:
       - run: yarn --cwd scripts/release install --frozen-lockfile
         if: steps.node_modules.outputs.cache-hit != 'true'
       - name: Download artifacts for base revision
+        # The build could have been generated from a fork, so we must download the build without
+        # any verification. This is safe since we only use this for sizebot calculation and the
+        # unverified artifact is not used. Additionally this workflow runs in the pull_request
+        # trigger so only restricted permissions are available.
         run: |
-          GH_TOKEN=${{ github.token }} scripts/release/download-experimental-build.js --commit=$(git rev-parse ${{ github.event.pull_request.base.sha }})
+          GH_TOKEN=${{ github.token }} scripts/release/download-experimental-build.js --commit=$(git rev-parse ${{ github.event.pull_request.base.sha }}) ${{ (github.event.pull_request.head.repo.full_name != github.repository && '--noVerify') || ''}}
           mv ./build ./base-build
-      # TODO: The `download-experimental-build` script copies the npm
-      # packages into the `node_modules` directory. This is a historical
-      # quirk of how the release script works. Let's pretend they
-      # don't exist.
       - name: Delete extraneous files
+        # TODO: The `download-experimental-build` script copies the npm
+        # packages into the `node_modules` directory. This is a historical
+        # quirk of how the release script works. Let's pretend they
+        # don't exist.
         run: rm -rf ./base-build/node_modules
       - name: Display structure of base-build from origin/main
         run: ls -R base-build
@@ -828,7 +842,7 @@ jobs:
           node ./scripts/print-warnings/print-warnings.js > build/__test_utils__/ReactAllWarnings.js
       - name: Display structure of build for PR
         run: ls -R build
-      - run: echo ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }} >> build/COMMIT_SHA
+      - run: echo ${{ github.event.pull_request.head.sha || github.sha }} >> build/COMMIT_SHA
       - run: node ./scripts/tasks/danger
       - name: Archive sizebot results
         uses: actions/upload-artifact@v4

.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/runtime_eslint_plugin_e2e.yml

@@ -46,17 +46,20 @@ jobs:
         with:
           path: |
             **/node_modules
-          key: runtime-and-compiler-eslint_e2e-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock', 'compiler/yarn.lock') }}
+          key: runtime-and-compiler-eslint_e2e-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock', 'compiler/yarn.lock', 'fixtures/eslint-v*/yarn.lock') }}
       - name: Ensure clean build directory
         run: rm -rf build
       - run: yarn install --frozen-lockfile
+        if: steps.node_modules.outputs.cache-hit != 'true'
       - run: yarn --cwd compiler install --frozen-lockfile
-      - name: Build plugin
-        working-directory: fixtures/eslint-v${{ matrix.eslint_major }}
-        run: node build.mjs
+        if: steps.node_modules.outputs.cache-hit != 'true'
       - name: Install fixture dependencies
         working-directory: ./fixtures/eslint-v${{ matrix.eslint_major }}
         run: yarn --frozen-lockfile
+        if: steps.node_modules.outputs.cache-hit != 'true'
+      - name: Build plugin
+        working-directory: fixtures/eslint-v${{ matrix.eslint_major }}
+        run: node build.mjs
       - name: Run lint test
         working-directory: ./fixtures/eslint-v${{ matrix.eslint_major }}
         run: yarn lint

.github/workflows/runtime_prereleases.yml

@@ -13,7 +13,16 @@ on:
       dist_tag:
         required: true
         type: string
+      enableFailureNotification:
+        description: 'Whether to notify the team on Discord when the release fails. Useful if this workflow is called from an automation.'
+        required: false
+        type: boolean
     secrets:
+      DISCORD_WEBHOOK_URL:
+        description: 'Discord webhook URL to notify on failure. Only required if enableFailureNotification is true.'
+        required: false
+      GH_TOKEN:
+        required: true
       NPM_TOKEN:
         required: true
 
@@ -29,6 +38,9 @@ jobs:
   publish_prerelease:
     name: Publish prelease (${{ inputs.release_channel }}) ${{ inputs.commit_sha }} @${{ inputs.dist_tag }}
     runs-on: ubuntu-latest
+    permissions:
+      # We use github.token to download the build artifact from a previous runtime_build_and_test.yml run
+      actions: read
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
@@ -46,8 +58,18 @@ jobs:
       - name: Ensure clean build directory
         run: rm -rf build
       - run: yarn install --frozen-lockfile
+        if: steps.node_modules.outputs.cache-hit != 'true'
       - run: yarn --cwd scripts/release install --frozen-lockfile
+        if: steps.node_modules.outputs.cache-hit != 'true'
       - run: |
-          scripts/release/prepare-release-from-ci.js --skipTests -r ${{ inputs.release_channel }} --commit=${{ inputs.commit_sha }}
+          GH_TOKEN=${{ secrets.GH_TOKEN }} scripts/release/prepare-release-from-ci.js --skipTests -r ${{ inputs.release_channel }} --commit=${{ inputs.commit_sha }}
           cp ./scripts/release/ci-npmrc ~/.npmrc
           scripts/release/publish.js --ci --tags ${{ inputs.dist_tag }}
+      - name: Notify Discord on failure
+        if: failure() && inputs.enableFailureNotification == true
+        uses: tsickert/discord-webhook@86dc739f3f165f16dadc5666051c367efa1692f4
+        with:
+          webhook-url: ${{ secrets.DISCORD_WEBHOOK_URL }}
+          embed-author-name: "GitHub Actions"
+          embed-title: 'Publish of $${{ inputs.release_channel }} release failed'
+          embed-url: ${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}/attempts/${{ github.run_attempt }}

.github/workflows/runtime_prereleases_manual.yml

@@ -16,6 +16,9 @@ jobs:
   publish_prerelease_canary:
     name: Publish to Canary channel
     uses: facebook/react/.github/workflows/runtime_prereleases.yml@main
+    permissions:
+      # We use github.token to download the build artifact from a previous runtime_build_and_test.yml run
+      actions: read
     with:
       commit_sha: ${{ inputs.prerelease_commit_sha }}
       release_channel: stable
@@ -32,10 +35,14 @@ jobs:
       dist_tag: canary,next
     secrets:
       NPM_TOKEN: ${{ secrets.NPM_TOKEN }}
+      GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
 
   publish_prerelease_experimental:
     name: Publish to Experimental channel
     uses: facebook/react/.github/workflows/runtime_prereleases.yml@main
+    permissions:
+      # We use github.token to download the build artifact from a previous runtime_build_and_test.yml run
+      actions: read
     # NOTE: Intentionally running these jobs sequentially because npm
     # will sometimes fail if you try to concurrently publish two
     # different versions of the same package, even if they use different
@@ -47,3 +54,4 @@ jobs:
       dist_tag: experimental
     secrets:
       NPM_TOKEN: ${{ secrets.NPM_TOKEN }}
+      GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/runtime_prereleases_nightly.yml

@@ -14,16 +14,25 @@ jobs:
   publish_prerelease_canary:
     name: Publish to Canary channel
     uses: facebook/react/.github/workflows/runtime_prereleases.yml@main
+    permissions:
+      # We use github.token to download the build artifact from a previous runtime_build_and_test.yml run
+      actions: read
     with:
       commit_sha: ${{ github.sha }}
       release_channel: stable
       dist_tag: canary,next
+      enableFailureNotification: true
     secrets:
+      DISCORD_WEBHOOK_URL: ${{ secrets.DISCORD_WEBHOOK_URL }}
       NPM_TOKEN: ${{ secrets.NPM_TOKEN }}
+      GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
 
   publish_prerelease_experimental:
     name: Publish to Experimental channel
     uses: facebook/react/.github/workflows/runtime_prereleases.yml@main
+    permissions:
+      # We use github.token to download the build artifact from a previous runtime_build_and_test.yml run
+      actions: read
     # NOTE: Intentionally running these jobs sequentially because npm
     # will sometimes fail if you try to concurrently publish two
     # different versions of the same package, even if they use different
@@ -33,5 +42,8 @@ jobs:
       commit_sha: ${{ github.sha }}
       release_channel: experimental
       dist_tag: experimental
+      enableFailureNotification: true
     secrets:
+      DISCORD_WEBHOOK_URL: ${{ secrets.DISCORD_WEBHOOK_URL }}
       NPM_TOKEN: ${{ secrets.NPM_TOKEN }}
+      GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/runtime_releases_from_npm_manual.yml

@@ -78,7 +78,9 @@ jobs:
       - name: Ensure clean build directory
         run: rm -rf build
       - run: yarn install --frozen-lockfile
+        if: steps.node_modules.outputs.cache-hit != 'true'
       - run: yarn --cwd scripts/release install --frozen-lockfile
+        if: steps.node_modules.outputs.cache-hit != 'true'
       - run: cp ./scripts/release/ci-npmrc ~/.npmrc
       - if: '${{ inputs.only_packages }}'
         name: 'Prepare ${{ inputs.only_packages }} from NPM'

.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_cleanup_stale_branch_caches.yml

@@ -3,7 +3,8 @@
 name: (Shared) Cleanup Stale Branch Caches
 on:
   schedule:
-    - cron: 0 0 * * *
+    # Every 6 hours
+    - cron: 0 */6 * * *
   workflow_dispatch:
 
 permissions: {}

.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: {}
 

.github/workflows/shared_lint.yml

@@ -29,6 +29,7 @@ jobs:
           cache-dependency-path: yarn.lock
       - name: Restore cached node_modules
         uses: actions/cache@v4
+        id: node_modules
         with:
           path: |
             **/node_modules
@@ -36,6 +37,7 @@ jobs:
       - name: Ensure clean build directory
         run: rm -rf build
       - run: yarn install --frozen-lockfile
+        if: steps.node_modules.outputs.cache-hit != 'true'
       - run: yarn prettier-check
 
   eslint:
@@ -50,6 +52,7 @@ jobs:
           cache-dependency-path: yarn.lock
       - name: Restore cached node_modules
         uses: actions/cache@v4
+        id: node_modules
         with:
           path: |
             **/node_modules
@@ -57,6 +60,7 @@ jobs:
       - name: Ensure clean build directory
         run: rm -rf build
       - run: yarn install --frozen-lockfile
+        if: steps.node_modules.outputs.cache-hit != 'true'
       - run: node ./scripts/tasks/eslint
 
   check_license:
@@ -71,6 +75,7 @@ jobs:
           cache-dependency-path: yarn.lock
       - name: Restore cached node_modules
         uses: actions/cache@v4
+        id: node_modules
         with:
           path: |
             **/node_modules
@@ -78,6 +83,7 @@ jobs:
       - name: Ensure clean build directory
         run: rm -rf build
       - run: yarn install --frozen-lockfile
+        if: steps.node_modules.outputs.cache-hit != 'true'
       - run: ./scripts/ci/check_license.sh
 
   test_print_warnings:
@@ -92,6 +98,7 @@ jobs:
           cache-dependency-path: yarn.lock
       - name: Restore cached node_modules
         uses: actions/cache@v4
+        id: node_modules
         with:
           path: |
             **/node_modules
@@ -99,4 +106,5 @@ jobs:
       - name: Ensure clean build directory
         run: rm -rf build
       - run: yarn install --frozen-lockfile
+        if: steps.node_modules.outputs.cache-hit != 'true'
       - run: ./scripts/ci/test_print_warnings.sh

.nvmrc

@@ -1 +1 @@
-v18.20.1
+v20.19.0

CHANGELOG-canary.md

@@ -1,18 +0,0 @@
-## March 22, 2024 (18.3.0-canary-670811593-20240322)
-
-## React
-- Added `useActionState` to replace `useFormState` and added `pending` value ([#28491](https://github.com/facebook/react/pull/28491)).
-
-## October 5, 2023 (18.3.0-canary-546178f91-20231005)
-
-### React
-
-- Added support for async functions to be passed to `startTransition`. 
-- `useTransition` now triggers the nearest error boundary instead of a global error.
-- Added `useOptimistic`, a new Hook for handling optimistic UI updates. It optimistically updates the UI before receiving confirmation from a server or external source.
-
-### React DOM
-
-- Added support for passing async functions to the `action` prop on `<form>`. When the function passed to `action` is marked with [`'use server'`](https://react.dev/reference/react/use-server), the form is [progressively enhanced](https://developer.mozilla.org/en-US/docs/Glossary/Progressive_Enhancement).
-- Added `useFormStatus`, a new Hook for checking the submission state of a form.
-- Added `useFormState`, a new Hook for updating state upon form submission. When the function passed to `useFormState` is marked with [`'use server'`](https://react.dev/reference/react/use-server), the update is [progressively enhanced](https://developer.mozilla.org/en-US/docs/Glossary/Progressive_Enhancement).

CHANGELOG.md

@@ -1,3 +1,50 @@
+## 19.1.0 (March 28, 2025)
+
+### Owner Stack
+
+An Owner Stack is a string representing the components that are directly responsible for rendering a particular component. You can log Owner Stacks when debugging or use Owner Stacks to enhance error overlays or other development tools. Owner Stacks are only available in development builds. Component Stacks in production are unchanged.
+
+* An Owner Stack is a development-only stack trace that helps identify which components are responsible for rendering a particular component. An Owner Stack is distinct from a Component Stacks, which shows the hierarchy of components leading to an error.
+* The [captureOwnerStack API](https://react.dev/reference/react/captureOwnerStack) is only available in development mode and returns a Owner Stack, if available. The API can be used to enhance error overlays or log component relationships when debugging. [#29923](https://github.com/facebook/react/pull/29923), [#32353](https://github.com/facebook/react/pull/32353), [#30306](https://github.com/facebook/react/pull/30306),
+[#32538](https://github.com/facebook/react/pull/32538), [#32529](https://github.com/facebook/react/pull/32529), [#32538](https://github.com/facebook/react/pull/32538)
+
+### React
+* Enhanced support for Suspense boundaries to be used anywhere, including the client, server, and during hydration. [#32069](https://github.com/facebook/react/pull/32069), [#32163](https://github.com/facebook/react/pull/32163), [#32224](https://github.com/facebook/react/pull/32224), [#32252](https://github.com/facebook/react/pull/32252)
+* Reduced unnecessary client rendering through improved hydration scheduling [#31751](https://github.com/facebook/react/pull/31751)
+* Increased priority of client rendered Suspense boundaries [#31776](https://github.com/facebook/react/pull/31776)
+* Fixed frozen fallback states by rendering unfinished Suspense boundaries on the client. [#31620](https://github.com/facebook/react/pull/31620)
+* Reduced garbage collection pressure by improving Suspense boundary retries. [#31667](https://github.com/facebook/react/pull/31667)
+* Fixed erroneous “Waiting for Paint” log when the passive effect phase was not delayed [#31526](https://github.com/facebook/react/pull/31526)
+* Fixed a regression causing key warnings for flattened positional children in development mode. [#32117](https://github.com/facebook/react/pull/32117)
+* Updated `useId` to use valid CSS selectors, changing format from `:r123:` to `«r123»`. [#32001](https://github.com/facebook/react/pull/32001)
+* Added a dev-only warning for null/undefined created in useEffect, useInsertionEffect, and useLayoutEffect. [#32355](https://github.com/facebook/react/pull/32355)
+* Fixed a bug where dev-only methods were exported in production builds. React.act is no longer available in production builds. [#32200](https://github.com/facebook/react/pull/32200)
+* Improved consistency across prod and dev to improve compatibility with Google Closure Complier and bindings [#31808](https://github.com/facebook/react/pull/31808)
+* Improve passive effect scheduling for consistent task yielding. [#31785](https://github.com/facebook/react/pull/31785)
+* Fixed asserts in React Native when passChildrenWhenCloningPersistedNodes is enabled for OffscreenComponent rendering. [#32528](https://github.com/facebook/react/pull/32528)
+* Fixed component name resolution for Portal [#32640](https://github.com/facebook/react/pull/32640)
+* Added support for beforetoggle and toggle events on the dialog element. #32479 [#32479](https://github.com/facebook/react/pull/32479)
+
+### React DOM
+* Fixed double warning when the `href` attribute is an empty string [#31783](https://github.com/facebook/react/pull/31783)
+ * Fixed an edge case where `getHoistableRoot()` didn’t work properly when the container was a Document [#32321](https://github.com/facebook/react/pull/32321)
+* Removed support for using HTML comments (e.g. `<!-- -->`) as a DOM container. [#32250](https://github.com/facebook/react/pull/32250)
+* Added support for `<script>` and `<template>` tags to be nested within `<select>` tags. [#31837](https://github.com/facebook/react/pull/31837)
+* Fixed responsive images to be preloaded as HTML instead of headers [#32445](https://github.com/facebook/react/pull/32445)
+
+### use-sync-external-store
+* Added `exports` field to `package.json` for `use-sync-external-store` to support various entrypoints. [#25231](https://github.com/facebook/react/pull/25231)
+
+### React Server Components
+* Added `unstable_prerender`, a new experimental API for prerendering React Server Components on the server [#31724](https://github.com/facebook/react/pull/31724)
+* Fixed an issue where streams would hang when receiving new chunks after a global error [#31840](https://github.com/facebook/react/pull/31840), [#31851](https://github.com/facebook/react/pull/31851)
+* Fixed an issue where pending chunks were counted twice. [#31833](https://github.com/facebook/react/pull/31833)
+* Added support for streaming in edge environments [#31852](https://github.com/facebook/react/pull/31852)
+* Added support for sending custom error names from a server so that they are available in the client for console replaying. [#32116](https://github.com/facebook/react/pull/32116)
+* Updated the server component wire format to remove IDs for hints and console.log because they have no return value [#31671](https://github.com/facebook/react/pull/31671)
+* Exposed `registerServerReference` in client builds to handle server references in different environments. [#32534](https://github.com/facebook/react/pull/32534)
+* Added react-server-dom-parcel package which integrates Server Components with the [Parcel bundler](https://parceljs.org/) [#31725](https://github.com/facebook/react/pull/31725), [#32132](https://github.com/facebook/react/pull/32132), [#31799](https://github.com/facebook/react/pull/31799), [#32294](https://github.com/facebook/react/pull/32294), [#31741](https://github.com/facebook/react/pull/31741)
+
 ## 19.0.0 (December 5, 2024)
 
 Below is a list of all new features, APIs, deprecations, and breaking changes. Read [React 19 release post](https://react.dev/blog/2024/04/25/react-19) and [React 19 upgrade guide](https://react.dev/blog/2024/04/25/react-19-upgrade-guide) for more information.

ReactVersions.js

@@ -18,7 +18,7 @@
 //
 //   0.0.0-experimental-241c4467e-20200129
 
-const ReactVersion = '19.1.1';
+const ReactVersion = '19.2.0';
 
 // The label used by the @canary channel. Represents the upcoming release's
 // stability. Most of the time, this will be "canary", but we may temporarily
@@ -33,8 +33,8 @@ const canaryChannelLabel = 'canary';
 const rcNumber = 0;
 
 const stablePackages = {
-  'eslint-plugin-react-hooks': '5.2.0',
-  'jest-react': '0.16.0',
+  'eslint-plugin-react-hooks': '6.0.0',
+  'jest-react': '0.17.0',
   react: ReactVersion,
   'react-art': ReactVersion,
   'react-dom': ReactVersion,
@@ -42,12 +42,12 @@ const stablePackages = {
   'react-server-dom-turbopack': ReactVersion,
   'react-server-dom-parcel': ReactVersion,
   'react-is': ReactVersion,
-  'react-reconciler': '0.32.0',
-  'react-refresh': '0.17.0',
+  'react-reconciler': '0.33.0',
+  'react-refresh': '0.18.0',
   'react-test-renderer': ReactVersion,
-  'use-subscription': '1.11.0',
-  'use-sync-external-store': '1.5.0',
-  scheduler: '0.26.0',
+  'use-subscription': '1.12.0',
+  'use-sync-external-store': '1.6.0',
+  scheduler: '0.27.0',
 };
 
 // These packages do not exist in the @canary or @latest channel, only

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

@@ -19,7 +19,9 @@ import BabelPluginReactCompiler, {
   PluginOptions,
   CompilerPipelineValue,
   parsePluginOptions,
-} from 'babel-plugin-react-compiler/src';
+  printReactiveFunctionWithOutlined,
+  printFunctionWithOutlined,
+} from 'babel-plugin-react-compiler';
 import clsx from 'clsx';
 import invariant from 'invariant';
 import {useSnackbar} from 'notistack';
@@ -41,8 +43,6 @@ import {
   default as Output,
   PrintedCompilerPipelineValue,
 } from './Output';
-import {printFunctionWithOutlined} from 'babel-plugin-react-compiler/src/HIR/PrintHIR';
-import {printReactiveFunctionWithOutlined} from 'babel-plugin-react-compiler/src/ReactiveScopes/PrintReactiveFunction';
 import {transformFromAstSync} from '@babel/core';
 
 function parseInput(

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

@@ -6,7 +6,7 @@
  */
 
 import MonacoEditor, {loader, type Monaco} from '@monaco-editor/react';
-import {CompilerErrorDetail} from 'babel-plugin-react-compiler/src';
+import {CompilerErrorDetail} from 'babel-plugin-react-compiler';
 import invariant from 'invariant';
 import type {editor} from 'monaco-editor';
 import * as monaco from 'monaco-editor';

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

@@ -11,7 +11,7 @@ import {
   InformationCircleIcon,
 } from '@heroicons/react/outline';
 import MonacoEditor, {DiffEditor} from '@monaco-editor/react';
-import {type CompilerError} from 'babel-plugin-react-compiler/src';
+import {type CompilerError} from 'babel-plugin-react-compiler';
 import parserBabel from 'prettier/plugins/babel';
 import * as prettierPluginEstree from 'prettier/plugins/estree';
 import * as prettier from 'prettier/standalone';

compiler/apps/playground/lib/reactCompilerMonacoDiagnostics.ts

@@ -6,10 +6,7 @@
  */
 
 import {Monaco} from '@monaco-editor/react';
-import {
-  CompilerErrorDetail,
-  ErrorSeverity,
-} from 'babel-plugin-react-compiler/src';
+import {CompilerErrorDetail, ErrorSeverity} from 'babel-plugin-react-compiler';
 import {MarkerSeverity, type editor} from 'monaco-editor';
 
 function mapReactCompilerSeverityToMonaco(
@@ -54,7 +51,7 @@ export function renderReactCompilerMarkers({
   model,
   details,
 }: ReactCompilerMarkerConfig): void {
-  let markers = [];
+  const markers: Array<editor.IMarkerData> = [];
   for (const detail of details) {
     const marker = mapReactCompilerDiagnosticToMonacoMarker(detail, monaco);
     if (marker == null) {

compiler/apps/playground/package.json

@@ -4,7 +4,7 @@
   "private": true,
   "scripts": {
     "dev": "cd ../.. && concurrently --kill-others -n compiler,runtime,playground \"yarn workspace babel-plugin-react-compiler run watch\" \"yarn workspace react-compiler-runtime run watch\" \"wait-on packages/babel-plugin-react-compiler/dist/index.js && cd apps/playground && NODE_ENV=development next dev\"",
-    "build:compiler": "cd ../.. && concurrently -n compiler,runtime \"yarn workspace babel-plugin-react-compiler run build\" \"yarn workspace react-compiler-runtime run build\"",
+    "build:compiler": "cd ../.. && concurrently -n compiler,runtime \"yarn workspace babel-plugin-react-compiler run build --dts\" \"yarn workspace react-compiler-runtime run build\"",
     "build": "yarn build:compiler && next build",
     "postbuild": "node ./scripts/downloadFonts.js",
     "preinstall": "cd ../.. && yarn install --frozen-lockfile",

compiler/package.json

@@ -37,7 +37,7 @@
     "prettier": "^3.3.3",
     "prettier-plugin-hermes-parser": "^0.26.0",
     "prompt-promise": "^1.0.3",
-    "rimraf": "^5.0.10",
+    "rimraf": "^6.0.1",
     "to-fast-properties": "^2.0.0",
     "tsup": "^8.4.0",
     "typescript": "^5.4.3",

compiler/packages/babel-plugin-react-compiler/package.json

@@ -12,12 +12,12 @@
     "build": "rimraf dist && tsup",
     "test": "./scripts/link-react-compiler-runtime.sh && yarn snap:ci",
     "jest": "yarn build && ts-node node_modules/.bin/jest",
-    "snap": "node ../snap/dist/main.js",
+    "snap": "yarn workspace snap run snap",
     "snap:build": "yarn workspace snap run build",
     "snap:ci": "yarn snap:build && yarn snap",
     "ts:analyze-trace": "scripts/ts-analyze-trace.sh",
     "lint": "yarn eslint src",
-    "watch": "yarn build --watch"
+    "watch": "yarn build --dts --watch"
   },
   "dependencies": {
     "@babel/types": "^7.26.0"

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

@@ -73,7 +73,7 @@ export default function BabelPluginReactCompiler(
             pass.filename ?? null,
             opts.logger,
             opts.environment,
-            result?.retryErrors ?? [],
+            result,
           );
           if (ENABLE_REACT_COMPILER_TIMINGS === true) {
             performance.mark(`${filename}:end`, {

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';
@@ -24,16 +20,17 @@ 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,
   findProgramSuppressions,
   suppressionsToCompilerError,
 } from './Suppression';
+import {GeneratedSource} from '../HIR';
 
 export type CompilerPass = {
   opts: PluginOptions;
@@ -271,8 +268,9 @@ function isFilePartOfSources(
   return false;
 }
 
-type CompileProgramResult = {
+export type CompileProgramResult = {
   retryErrors: Array<{fn: BabelFn; error: CompilerError}>;
+  inferredEffectLocations: Set<t.SourceLocation>;
 };
 /**
  * `compileProgram` is directly invoked by the react-compiler babel plugin, so
@@ -299,8 +297,12 @@ 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
@@ -369,6 +371,7 @@ export function compileProgram(
     },
   );
   const retryErrors: Array<{fn: BabelFn; error: CompilerError}> = [];
+  const inferredEffectLocations = new Set<t.SourceLocation>();
   const processFn = (
     fn: BabelFn,
     fnType: ReactFunctionType,
@@ -410,7 +413,7 @@ export function compileProgram(
             environment,
             fnType,
             'all_features',
-            useMemoCacheIdentifier.name,
+            programContext,
             pass.opts.logger,
             pass.filename,
             pass.code,
@@ -445,7 +448,7 @@ export function compileProgram(
             environment,
             fnType,
             'no_inferred_memo',
-            useMemoCacheIdentifier.name,
+            programContext,
             pass.opts.logger,
             pass.filename,
             pass.code,
@@ -453,7 +456,7 @@ export function compileProgram(
         };
         if (
           !compileResult.compiledFn.hasFireRewrite &&
-          !compileResult.compiledFn.hasLoweredContextAccess
+          !compileResult.compiledFn.hasInferredEffect
         ) {
           return null;
         }
@@ -509,6 +512,14 @@ export function compileProgram(
     if (!pass.opts.noEmit) {
       return compileResult.compiledFn;
     }
+    /**
+     * inferEffectDependencies + noEmit is currently only used for linting. In
+     * this mode, add source locations for where the compiler *can* infer effect
+     * dependencies.
+     */
+    for (const loc of compileResult.compiledFn.inferredEffectLocations) {
+      if (loc !== GeneratedSource) inferredEffectLocations.add(loc);
+    }
     return null;
   };
 
@@ -554,79 +565,29 @@ 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);
@@ -635,24 +596,9 @@ 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};
+  return {retryErrors, inferredEffectLocations};
 }
 
 function shouldSkipCompilation(
@@ -683,7 +629,7 @@ function shouldSkipCompilation(
   if (
     hasMemoCacheFunctionImport(
       program,
-      getReactCompilerRuntimeModule(pass.opts),
+      getReactCompilerRuntimeModule(pass.opts.target),
     )
   ) {
     return true;
@@ -1177,16 +1123,18 @@ 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,
@@ -1194,6 +1142,6 @@ function getReactCompilerRuntimeModule(opts: PluginOptions): string {
         suggestions: null,
       },
     );
-    return opts.target.runtimeModule;
+    return target.runtimeModule;
   }
 }

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

@@ -11,6 +11,7 @@ import {
 import {getOrInsertWith} from '../Utils/utils';
 import {Environment} from '../HIR';
 import {DEFAULT_EXPORT} from '../HIR/Environment';
+import {CompileProgramResult} from './Program';
 
 function throwInvalidReact(
   options: Omit<CompilerErrorDetailOptions, 'severity'>,
@@ -36,12 +37,16 @@ function assertValidEffectImportReference(
     const parent = path.parentPath;
     if (parent != null && parent.isCallExpression()) {
       const args = parent.get('arguments');
+      const maybeCalleeLoc = path.node.loc;
+      const hasInferredEffect =
+        maybeCalleeLoc != null &&
+        context.inferredEffectLocations.has(maybeCalleeLoc);
       /**
        * Only error on untransformed references of the form `useMyEffect(...)`
        * or `moduleNamespace.useMyEffect(...)`, with matching argument counts.
        * TODO: do we also want a mode to also hard error on non-call references?
        */
-      if (args.length === numArgs) {
+      if (args.length === numArgs && !hasInferredEffect) {
         const maybeErrorDiagnostic = matchCompilerDiagnostic(
           path,
           context.transformErrors,
@@ -97,7 +102,7 @@ export default function validateNoUntransformedReferences(
   filename: string | null,
   logger: Logger | null,
   env: EnvironmentConfig,
-  transformErrors: Array<{fn: NodePath<t.Node>; error: CompilerError}>,
+  compileResult: CompileProgramResult | null,
 ): void {
   const moduleLoadChecks = new Map<
     string,
@@ -126,7 +131,7 @@ export default function validateNoUntransformedReferences(
     }
   }
   if (moduleLoadChecks.size > 0) {
-    transformProgram(path, moduleLoadChecks, filename, logger, transformErrors);
+    transformProgram(path, moduleLoadChecks, filename, logger, compileResult);
   }
 }
 
@@ -136,6 +141,7 @@ type TraversalState = {
   logger: Logger | null;
   filename: string | null;
   transformErrors: Array<{fn: NodePath<t.Node>; error: CompilerError}>;
+  inferredEffectLocations: Set<t.SourceLocation>;
 };
 type CheckInvalidReferenceFn = (
   paths: Array<NodePath<t.Node>>,
@@ -223,14 +229,16 @@ function transformProgram(
   moduleLoadChecks: Map<string, Map<string, CheckInvalidReferenceFn>>,
   filename: string | null,
   logger: Logger | null,
-  transformErrors: Array<{fn: NodePath<t.Node>; error: CompilerError}>,
+  compileResult: CompileProgramResult | null,
 ): void {
   const traversalState: TraversalState = {
     shouldInvalidateScopes: true,
     program: path,
     filename,
     logger,
-    transformErrors,
+    transformErrors: compileResult?.retryErrors ?? [],
+    inferredEffectLocations:
+      compileResult?.inferredEffectLocations ?? new Set(),
   };
   path.traverse({
     ImportDeclaration(path: NodePath<t.ImportDeclaration>) {

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

@@ -2406,6 +2406,19 @@ function lowerExpression(
         kind: 'TypeCastExpression',
         value: lowerExpressionToTemporary(builder, expr.get('expression')),
         typeAnnotation: typeAnnotation.node,
+        typeAnnotationKind: 'cast',
+        type: lowerType(typeAnnotation.node),
+        loc: exprLoc,
+      };
+    }
+    case 'TSSatisfiesExpression': {
+      let expr = exprPath as NodePath<t.TSSatisfiesExpression>;
+      const typeAnnotation = expr.get('typeAnnotation');
+      return {
+        kind: 'TypeCastExpression',
+        value: lowerExpressionToTemporary(builder, expr.get('expression')),
+        typeAnnotation: typeAnnotation.node,
+        typeAnnotationKind: 'satisfies',
         type: lowerType(typeAnnotation.node),
         loc: exprLoc,
       };
@@ -2417,6 +2430,7 @@ function lowerExpression(
         kind: 'TypeCastExpression',
         value: lowerExpressionToTemporary(builder, expr.get('expression')),
         typeAnnotation: typeAnnotation.node,
+        typeAnnotationKind: 'as',
         type: lowerType(typeAnnotation.node),
         loc: exprLoc,
       };

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

@@ -11,10 +11,12 @@ import {fromZodError} from 'zod-validation-error';
 import {CompilerError} from '../CompilerError';
 import {
   CompilationMode,
+  defaultOptions,
   Logger,
   PanicThresholdOptions,
   parsePluginOptions,
   PluginOptions,
+  ProgramContext,
 } from '../Entrypoint';
 import {Err, Ok, Result} from '../Utils/Result';
 import {
@@ -84,6 +86,8 @@ 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')}),
@@ -776,6 +780,7 @@ export function parseConfigPragmaForTests(
   const environment = parseConfigPragmaEnvironmentForTest(pragma);
   let compilationMode: CompilationMode = defaults.compilationMode;
   let panicThreshold: PanicThresholdOptions = 'all_errors';
+  let noEmit: boolean = defaultOptions.noEmit;
   for (const token of pragma.split(' ')) {
     if (!token.startsWith('@')) {
       continue;
@@ -801,12 +806,17 @@ export function parseConfigPragmaForTests(
         panicThreshold = 'none';
         break;
       }
+      case '@noEmit': {
+        noEmit = true;
+        break;
+      }
     }
   }
   return parsePluginOptions({
     environment,
     compilationMode,
     panicThreshold,
+    noEmit,
   });
 }
 
@@ -846,9 +856,10 @@ export class Environment {
   config: EnvironmentConfig;
   fnType: ReactFunctionType;
   compilerMode: CompilerMode;
-  useMemoCacheIdentifier: string;
-  hasLoweredContextAccess: boolean;
+  programContext: ProgramContext;
   hasFireRewrite: boolean;
+  hasInferredEffect: boolean;
+  inferredEffectLocations: Set<SourceLocation> = new Set();
 
   #contextIdentifiers: Set<t.Identifier>;
   #hoistedIdentifiers: Set<t.Identifier>;
@@ -862,7 +873,7 @@ export class Environment {
     logger: Logger | null,
     filename: string | null,
     code: string | null,
-    useMemoCacheIdentifier: string,
+    programContext: ProgramContext,
   ) {
     this.#scope = scope;
     this.fnType = fnType;
@@ -871,11 +882,11 @@ 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 +948,10 @@ 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
   | {
@@ -908,13 +910,21 @@ export type InstructionValue =
       value: Place;
       loc: SourceLocation;
     }
-  | {
+  | ({
       kind: 'TypeCastExpression';
       value: Place;
-      typeAnnotation: t.FlowType | t.TSType;
       type: Type;
       loc: SourceLocation;
-    }
+    } & (
+      | {
+          typeAnnotation: t.FlowType;
+          typeAnnotationKind: 'cast';
+        }
+      | {
+          typeAnnotation: t.TSType;
+          typeAnnotationKind: 'as' | 'satisfies';
+        }
+    ))
   | JsxExpression
   | {
       kind: 'ObjectExpression';
@@ -1165,18 +1175,21 @@ 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 +1407,7 @@ 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 +1426,11 @@ 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 +1444,7 @@ export function isMutableEffect(
     case Effect.Capture:
     case Effect.Store:
     case Effect.ConditionallyMutate:
+    case Effect.ConditionallyMutateIterator:
     case Effect.Mutate: {
       return true;
     }
@@ -1649,6 +1664,14 @@ 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/HIR/index.ts

@@ -32,5 +32,5 @@ export {
 } from './HIRBuilder';
 export {mergeConsecutiveBlocks} from './MergeConsecutiveBlocks';
 export {mergeOverlappingReactiveScopesHIR} from './MergeOverlappingReactiveScopesHIR';
-export {printFunction, printHIR} from './PrintHIR';
+export {printFunction, printHIR, printFunctionWithOutlined} from './PrintHIR';
 export {pruneUnusedLabelsHIR} from './PruneUnusedLabelsHIR';

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

@@ -217,6 +217,7 @@ export function inferEffectDependencies(fn: HIRFunction): void {
             // Step 2: push the inferred deps array as an argument of the useEffect
             value.args.push({...depsPlace, effect: Effect.Freeze});
             rewriteInstrs.set(instr.id, newInstructions);
+            fn.env.inferredEffectLocations.add(callee.loc);
           } else if (loadGlobals.has(value.args[0].identifier.id)) {
             // Global functions have no reactive dependencies, so we can insert an empty array
             newInstructions.push({
@@ -227,6 +228,7 @@ export function inferEffectDependencies(fn: HIRFunction): void {
             });
             value.args.push({...depsPlace, effect: Effect.Freeze});
             rewriteInstrs.set(instr.id, newInstructions);
+            fn.env.inferredEffectLocations.add(callee.loc);
           }
         }
       }
@@ -249,6 +251,7 @@ 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 +101,10 @@ 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;
+  inferredEffectLocations: Set<SourceLocation>;
 
   /**
    * This is true if the compiler has compiled a fire to a useFire call
@@ -160,6 +162,7 @@ export function codegenFunction(
     compiled.body = t.blockStatement([
       createHookGuard(
         hookGuard,
+        fn.env.programContext,
         compiled.body.body,
         GuardKind.PushHookGuard,
         GuardKind.PopHookGuard,
@@ -170,13 +173,15 @@ 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 +264,54 @@ 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 +388,9 @@ function codegenReactiveFunction(
     prunedMemoBlocks: countMemoBlockVisitor.prunedMemoBlocks,
     prunedMemoValues: countMemoBlockVisitor.prunedMemoValues,
     outlined: [],
-    hasLoweredContextAccess: fn.env.hasLoweredContextAccess,
     hasFireRewrite: fn.env.hasFireRewrite,
+    hasInferredEffect: fn.env.hasInferredEffect,
+    inferredEffectLocations: fn.env.inferredEffectLocations,
   });
 }
 
@@ -553,13 +579,18 @@ 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 +744,14 @@ 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 +773,7 @@ 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 +785,7 @@ 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 +1547,15 @@ 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 +1605,7 @@ function createCallExpression(
       t.blockStatement([
         createHookGuard(
           hookGuard,
+          env.programContext,
           [t.returnStatement(callExpr)],
           GuardKind.AllowHook,
           GuardKind.DisallowHook,
@@ -2085,10 +2115,17 @@ function codegenInstructionValue(
     }
     case 'TypeCastExpression': {
       if (t.isTSType(instrValue.typeAnnotation)) {
-        value = t.tsAsExpression(
-          codegenPlaceToExpression(cx, instrValue.value),
-          instrValue.typeAnnotation,
-        );
+        if (instrValue.typeAnnotationKind === 'satisfies') {
+          value = t.tsSatisfiesExpression(
+            codegenPlaceToExpression(cx, instrValue.value),
+            instrValue.typeAnnotation,
+          );
+        } else {
+          value = t.tsAsExpression(
+            codegenPlaceToExpression(cx, instrValue.value),
+            instrValue.typeAnnotation,
+          );
+        }
       } else {
         value = t.typeCastExpression(
           codegenPlaceToExpression(cx, instrValue.value),

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/ReactiveScopes/index.ts

@@ -14,7 +14,10 @@ export {extractScopeDeclarationsFromDestructuring} from './ExtractScopeDeclarati
 export {inferReactiveScopeVariables} from './InferReactiveScopeVariables';
 export {memoizeFbtAndMacroOperandsInSameScope} from './MemoizeFbtAndMacroOperandsInSameScope';
 export {mergeReactiveScopesThatInvalidateTogether} from './MergeReactiveScopesThatInvalidateTogether';
-export {printReactiveFunction} from './PrintReactiveFunction';
+export {
+  printReactiveFunction,
+  printReactiveFunctionWithOutlined,
+} from './PrintReactiveFunction';
 export {promoteUsedTemporaries} from './PromoteUsedTemporaries';
 export {propagateEarlyReturns} from './PropagateEarlyReturns';
 export {pruneAllReactiveScopes} from './PruneAllReactiveScopes';

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__/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/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>