Stop creating Owner Stacks if many have been created recently (#32529)

Co-authored-by: Jack Pope <jackpope1@gmail.com>

.eslintrc.js

@@ -336,11 +336,11 @@ module.exports = {
         'packages/react-devtools-extensions/**/*.js',
         'packages/react-devtools-timeline/**/*.js',
         'packages/react-native-renderer/**/*.js',
+        'packages/eslint-plugin-react-hooks/**/*.js',
         'packages/jest-react/**/*.js',
         'packages/internal-test-utils/**/*.js',
         'packages/**/__tests__/*.js',
         'packages/**/npm/*.js',
-        'compiler/packages/eslint-plugin-react-hooks/**/*.js',
       ],
       rules: {
         'react-internal/prod-error-codes': OFF,
@@ -515,7 +515,7 @@ module.exports = {
       },
     },
     {
-      files: ['compiler/packages/eslint-plugin-react-hooks/src/**/*'],
+      files: ['packages/eslint-plugin-react-hooks/src/**/*'],
       extends: ['plugin:@typescript-eslint/recommended'],
       parser: '@typescript-eslint/parser',
       plugins: ['@typescript-eslint', 'eslint-plugin'],

.github/workflows/compiler_discord_notify.yml

@@ -1,15 +1,20 @@
 name: (Compiler) Discord Notify
 
 on:
-  pull_request_target:
+  pull_request:
     types: [opened, ready_for_review]
     paths:
       - compiler/**
       - .github/workflows/compiler_**.yml
 
+permissions: {}
+
 jobs:
   check_maintainer:
     uses: facebook/react/.github/workflows/shared_check_maintainer.yml@main
+    permissions:
+      # Used by check_maintainer
+      contents: read
     with:
       actor: ${{ github.event.pull_request.user.login }}
 

.github/workflows/compiler_playground.yml

@@ -8,6 +8,8 @@ on:
       - compiler/**
       - .github/workflows/compiler_playground.yml
 
+permissions: {}
+
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref_name }}-${{ github.event.pull_request.number || github.run_id }}
   cancel-in-progress: true
@@ -40,7 +42,19 @@ jobs:
             **/node_modules
           key: compiler-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('compiler/**/yarn.lock') }}
       - run: yarn install --frozen-lockfile
+      - 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 chromium
+        if: steps.cache_playwright_browsers.outputs.cache-hit != 'true'
+      - run: npx playwright install-deps
+        if: steps.cache_playwright_browsers.outputs.cache-hit == 'true'
       - run: CI=true yarn test
       - run: ls -R test-results
         if: '!cancelled()'
@@ -50,3 +64,4 @@ jobs:
         with:
           name: test-results
           path: compiler/apps/playground/test-results
+          if-no-files-found: ignore

.github/workflows/compiler_prereleases.yml

@@ -20,11 +20,12 @@ on:
       NPM_TOKEN:
         required: true
 
+permissions: {}
+
 env:
   TZ: /usr/share/zoneinfo/America/Los_Angeles
   # https://github.com/actions/cache/blob/main/tips-and-workarounds.md#cache-segment-restore-timeout
   SEGMENT_DOWNLOAD_TIMEOUT_MINS: 1
-  GH_TOKEN: ${{ github.token }}
   NPM_TOKEN: ${{ secrets.NPM_TOKEN }}
 
 defaults:

.github/workflows/compiler_prereleases_manual.yml

@@ -15,6 +15,8 @@ on:
         required: true
         type: string
 
+permissions: {}
+
 env:
   TZ: /usr/share/zoneinfo/America/Los_Angeles
 

.github/workflows/compiler_prereleases_nightly.yml

@@ -5,6 +5,8 @@ on:
     # At 10 minutes past 16:00 on Mon, Tue, Wed, Thu, and Fri
     - cron: 10 16 * * 1,2,3,4,5
 
+permissions: {}
+
 env:
   TZ: /usr/share/zoneinfo/America/Los_Angeles
 

.github/workflows/compiler_prereleases_weekly.yml

@@ -5,6 +5,8 @@ on:
     # At 10 minutes past 9:00 on Mon
     - cron: 10 9 * * 1
 
+permissions: {}
+
 env:
   TZ: /usr/share/zoneinfo/America/Los_Angeles
 

.github/workflows/compiler_typescript.yml

@@ -8,6 +8,8 @@ on:
       - compiler/**
       - .github/workflows/compiler_typescript.yml
 
+permissions: {}
+
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref_name }}-${{ github.event.pull_request.number || github.run_id }}
   cancel-in-progress: true

.github/workflows/devtools_regression_tests.yml

@@ -9,6 +9,8 @@ on:
         required: false
         type: string
 
+permissions: {}
+
 env:
   TZ: /usr/share/zoneinfo/America/Los_Angeles
   # https://github.com/actions/cache/blob/main/tips-and-workarounds.md#cache-segment-restore-timeout
@@ -18,6 +20,9 @@ jobs:
   download_build:
     name: Download base build
     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
@@ -47,6 +52,7 @@ jobs:
         with:
           name: build
           path: build
+          if-no-files-found: error
 
   build_devtools_and_process_artifacts:
     name: Build DevTools and process artifacts
@@ -84,17 +90,20 @@ jobs:
         with:
           name: react-devtools
           path: build/devtools.tgz
+          if-no-files-found: error
       # Simplifies getting the extension for local testing
       - name: Archive chrome extension
         uses: actions/upload-artifact@v4
         with:
           name: react-devtools-chrome-extension
           path: build/devtools/chrome-extension.zip
+          if-no-files-found: error
       - name: Archive firefox extension
         uses: actions/upload-artifact@v4
         with:
           name: react-devtools-firefox-extension
           path: build/devtools/firefox-extension.zip
+          if-no-files-found: error
 
   run_devtools_tests_for_versions:
     name: Run DevTools tests for versions
@@ -179,3 +188,4 @@ jobs:
         with:
           name: screenshots
           path: ./tmp/screenshots
+          if-no-files-found: warn

.github/workflows/runtime_build_and_test.yml

@@ -7,6 +7,8 @@ on:
     paths-ignore:
       - compiler/**
 
+permissions: {}
+
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref_name }}-${{ github.event.pull_request.number || github.run_id }}
   cancel-in-progress: true
@@ -41,6 +43,16 @@ jobs:
           node-version-file: '.nvmrc'
           cache: yarn
           cache-dependency-path: yarn.lock
+      - name: Warm with old cache
+        if: steps.node_modules.outputs.cache-hit != 'true'
+        uses: actions/cache/restore@v4
+        with:
+          path: |
+            **/node_modules
+          key: runtime-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock') }}
+          restore-keys: |
+            runtime-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-
+            runtime-node_modules-v6-
       - run: yarn install --frozen-lockfile
         if: steps.node_modules.outputs.cache-hit != 'true'
       - name: Save cache
@@ -74,6 +86,16 @@ jobs:
           cache-dependency-path: |
             yarn.lock
             compiler/yarn.lock
+      - name: Warm with old cache
+        if: steps.node_modules.outputs.cache-hit != 'true'
+        uses: actions/cache/restore@v4
+        with:
+          path: |
+            **/node_modules
+          key: runtime-and-compiler-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock', 'compiler/yarn.lock') }}
+          restore-keys: |
+            runtime-and-compiler-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-
+            runtime-and-compiler-node_modules-v6-
       - run: yarn install --frozen-lockfile
         if: steps.node_modules.outputs.cache-hit != 'true'
       - run: yarn --cwd compiler install --frozen-lockfile
@@ -127,6 +149,9 @@ jobs:
           path: |
             **/node_modules
           key: runtime-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock') }}
+          restore-keys: |
+            runtime-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-
+            runtime-node_modules-v6-
       - name: Ensure clean build directory
         run: rm -rf build
       - run: yarn install --frozen-lockfile
@@ -154,6 +179,9 @@ jobs:
           path: |
             **/node_modules
           key: runtime-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock') }}
+          restore-keys: |
+            runtime-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-
+            runtime-node_modules-v6-
       - name: Ensure clean build directory
         run: rm -rf build
       - run: yarn install --frozen-lockfile
@@ -241,6 +269,9 @@ jobs:
           path: |
             **/node_modules
           key: runtime-and-compiler-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock', 'compiler/yarn.lock') }}
+          restore-keys: |
+            runtime-and-compiler-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-
+            runtime-and-compiler-node_modules-v6-
       - name: Ensure clean build directory
         run: rm -rf build
       - run: yarn install --frozen-lockfile
@@ -282,6 +313,9 @@ jobs:
           path: |
             **/node_modules
           key: runtime-and-compiler-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock', 'compiler/yarn.lock') }}
+          restore-keys: |
+            runtime-and-compiler-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-
+            runtime-and-compiler-node_modules-v6-
       - name: Ensure clean build directory
         run: rm -rf build
       - run: yarn install --frozen-lockfile
@@ -302,6 +336,7 @@ jobs:
         with:
           name: _build_${{ matrix.worker_id }}_${{ matrix.release_channel }}
           path: build
+          if-no-files-found: error
 
   test_build:
     name: yarn test-build
@@ -340,9 +375,16 @@ jobs:
           # TODO: Test more persistent configurations?
         ]
         shard:
-          - 1/3
-          - 2/3
-          - 3/3
+          - 1/10
+          - 2/10
+          - 3/10
+          - 4/10
+          - 5/10
+          - 6/10
+          - 7/10
+          - 8/10
+          - 9/10
+          - 10/10
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
@@ -362,6 +404,9 @@ jobs:
           path: |
             **/node_modules
           key: runtime-and-compiler-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock', 'compiler/yarn.lock') }}
+          restore-keys: |
+            runtime-and-compiler-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-
+            runtime-and-compiler-node_modules-v6-
       - name: Ensure clean build directory
         run: rm -rf build
       - run: yarn install --frozen-lockfile
@@ -398,6 +443,9 @@ jobs:
           path: |
             **/node_modules
           key: runtime-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock') }}
+          restore-keys: |
+            runtime-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-
+            runtime-node_modules-v6-
       - name: Ensure clean build directory
         run: rm -rf build
       - run: yarn install --frozen-lockfile
@@ -426,6 +474,7 @@ jobs:
           path: |
             ./build.tgz
             ./build2.tgz
+          if-no-files-found: error
 
   check_error_codes:
     name: Search build artifacts for unminified errors
@@ -447,6 +496,9 @@ jobs:
           path: |
             **/node_modules
           key: runtime-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock') }}
+          restore-keys: |
+            runtime-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-
+            runtime-node_modules-v6-
       - name: Ensure clean build directory
         run: rm -rf build
       - run: yarn install --frozen-lockfile
@@ -484,6 +536,9 @@ jobs:
           path: |
             **/node_modules
           key: runtime-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock') }}
+          restore-keys: |
+            runtime-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-
+            runtime-node_modules-v6-
       - name: Ensure clean build directory
         run: rm -rf build
       - run: yarn install --frozen-lockfile
@@ -517,7 +572,7 @@ jobs:
         with:
           path: |
             **/node_modules
-          key: fixtures_dom-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock') }}
+          key: fixtures_dom-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock', 'fixtures/dom/yarn.lock') }}
       - name: Ensure clean build directory
         run: rm -rf build
       - run: yarn --cwd fixtures/dom install --frozen-lockfile
@@ -561,11 +616,26 @@ jobs:
         with:
           path: |
             **/node_modules
-          key: fixtures_flight-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock') }}
+          key: fixtures_flight-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock', 'fixtures/flight/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 fixtures/flight 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"
+      - 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 }}
+      - name: Playwright install deps
+        if: steps.cache_playwright_browsers.outputs.cache-hit != 'true'
+        working-directory: fixtures/flight
+        run: npx playwright install --with-deps chromium
       - name: Restore archived build
         uses: actions/download-artifact@v4
         with:
@@ -574,16 +644,6 @@ jobs:
           merge-multiple: true
       - name: Display structure of build
         run: ls -R build
-      - name: Install fixture dependencies
-        working-directory: fixtures/flight
-        run: |
-          yarn install --frozen-lockfile --cache-folder ~/.cache/yarn
-          if [ $? -ne 0 ]; then
-            yarn install --frozen-lockfile --cache-folder ~/.cache/yarn
-          fi
-      - name: Playwright install deps
-        working-directory: fixtures/flight
-        run: npx playwright install --with-deps chromium
       - name: Run tests
         working-directory: fixtures/flight
         run: yarn test
@@ -595,11 +655,13 @@ jobs:
         with:
           name: flight-playwright-report
           path: fixtures/flight/playwright-report
+          if-no-files-found: warn
       - name: Archive Flight fixture artifacts
         uses: actions/upload-artifact@v4
         with:
           name: flight-test-results
           path: fixtures/flight/test-results
+          if-no-files-found: ignore
 
   # ----- DEVTOOLS -----
   build_devtools_and_process_artifacts:
@@ -626,6 +688,9 @@ jobs:
           path: |
             **/node_modules
           key: runtime-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock') }}
+          restore-keys: |
+            runtime-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-
+            runtime-node_modules-v6-
       - name: Ensure clean build directory
         run: rm -rf build
       - run: yarn install --frozen-lockfile
@@ -647,6 +712,7 @@ jobs:
         with:
           name: react-devtools-${{ matrix.browser }}-extension
           path: build/devtools/${{ matrix.browser }}-extension.zip
+          if-no-files-found: error
 
   merge_devtools_artifacts:
     name: Merge DevTools artifacts
@@ -679,6 +745,9 @@ jobs:
           path: |
             **/node_modules
           key: runtime-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock') }}
+          restore-keys: |
+            runtime-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-
+            runtime-node_modules-v6-
       - name: Ensure clean build directory
         run: rm -rf build
       - run: yarn install --frozen-lockfile
@@ -700,7 +769,10 @@ jobs:
   sizebot:
     if: ${{ github.event_name == 'pull_request' && github.ref_name != 'main' && github.event.pull_request.base.ref == 'main' }}
     name: Run sizebot
-    needs: [build_and_lint, runtime_node_modules_cache]
+    needs: [build_and_lint]
+    permissions:
+      # We use github.token to download the build artifact from a previous runtime_build_and_test.yml run
+      actions: read
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
@@ -712,7 +784,7 @@ jobs:
           cache: yarn
           cache-dependency-path: yarn.lock
       - name: Restore cached node_modules
-        uses: actions/cache/restore@v4
+        uses: actions/cache@v4 # note: this does not reuse centralized cache since it has unique cache key
         id: node_modules
         with:
           path: |
@@ -738,8 +810,6 @@ jobs:
         run: ls -R base-build
       - 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 for PR
         uses: actions/download-artifact@v4
         with:
@@ -759,3 +829,4 @@ jobs:
         with:
           name: sizebot-message
           path: sizebot-message.md
+          if-no-files-found: ignore

.github/workflows/runtime_commit_artifacts.yml

@@ -22,6 +22,8 @@ on:
         default: false
         type: boolean
 
+permissions: {}
+
 env:
   TZ: /usr/share/zoneinfo/America/Los_Angeles
   # https://github.com/actions/cache/blob/main/tips-and-workarounds.md#cache-segment-restore-timeout
@@ -30,6 +32,40 @@ env:
 jobs:
   download_artifacts:
     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
+      - name: Restore cached node_modules
+        uses: actions/cache@v4
+        id: node_modules
+        with:
+          path: |
+            **/node_modules
+          key: runtime-release-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock', 'scripts/release/yarn.lock') }}
+      - name: Ensure clean build directory
+        run: rm -rf build
+      - run: yarn install --frozen-lockfile
+        if: steps.node_modules.outputs.cache-hit != 'true'
+      - run: yarn --cwd scripts/release install --frozen-lockfile
+        if: steps.node_modules.outputs.cache-hit != 'true'
+      - name: Download artifacts for base revision
+        run: |
+          GH_TOKEN=${{ github.token }} scripts/release/download-experimental-build.js --commit=${{ inputs.commit_sha || github.event.workflow_run.head_sha || github.sha }}
+      - name: Display structure of build
+        run: ls -R build
+      - name: Archive build
+        uses: actions/upload-artifact@v4
+        with:
+          name: build
+          path: build/
+          if-no-files-found: error
+
+
+  process_artifacts:
+    runs-on: ubuntu-latest
+    needs: [download_artifacts]
     outputs:
       www_branch_count: ${{ steps.check_branches.outputs.www_branch_count }}
       fbsource_branch_count: ${{ steps.check_branches.outputs.fbsource_branch_count }}
@@ -69,25 +105,11 @@ jobs:
         run: |
           echo "www_branch_count=$(git ls-remote --heads origin "refs/heads/meta-www" | wc -l)" >> "$GITHUB_OUTPUT"
           echo "fbsource_branch_count=$(git ls-remote --heads origin "refs/heads/meta-fbsource" | wc -l)" >> "$GITHUB_OUTPUT"
-      - uses: actions/setup-node@v4
+      - name: Restore downloaded build
+        uses: actions/download-artifact@v4
         with:
-          node-version-file: '.nvmrc'
-          cache: yarn
-          cache-dependency-path: yarn.lock
-      - name: Restore cached node_modules
-        uses: actions/cache@v4
-        id: node_modules
-        with:
-          path: |
-            **/node_modules
-          key: runtime-release-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock', 'scripts/release/yarn.lock') }}
-      - name: Ensure clean build directory
-        run: rm -rf build
-      - run: yarn install --frozen-lockfile
-      - run: yarn --cwd scripts/release install --frozen-lockfile
-      - name: Download artifacts for base revision
-        run: |
-          GH_TOKEN=${{ github.token }} scripts/release/download-experimental-build.js --commit=${{ inputs.commit_sha || github.event.workflow_run.head_sha || github.sha }}
+          name: build
+          path: build
       - name: Display structure of build
         run: ls -R build
       - name: Strip @license from eslint plugin and react-refresh
@@ -151,9 +173,9 @@ jobs:
           ls -R ./compiled-rn
       - name: Add REVISION files
         run: |
-          echo ${{ github.sha }} >> ./compiled/facebook-www/REVISION
+          echo ${{ inputs.commit_sha || github.event.workflow_run.head_sha || github.sha }} >> ./compiled/facebook-www/REVISION
           cp ./compiled/facebook-www/REVISION ./compiled/facebook-www/REVISION_TRANSFORMS
-          echo ${{ github.sha}} >> ./compiled-rn/facebook-fbsource/xplat/js/react-native-github/Libraries/Renderer/REVISION
+          echo ${{ inputs.commit_sha || github.event.workflow_run.head_sha || github.sha }} >> ./compiled-rn/facebook-fbsource/xplat/js/react-native-github/Libraries/Renderer/REVISION
       - name: "Get current version string"
         id: get_current_version
         run: |
@@ -170,15 +192,20 @@ jobs:
         with:
           name: compiled
           path: compiled/
+          if-no-files-found: error
       - uses: actions/upload-artifact@v4
         with:
           name: compiled-rn
           path: compiled-rn/
+          if-no-files-found: error
 
   commit_www_artifacts:
-    needs: download_artifacts
-    if: inputs.force == true || (github.ref == 'refs/heads/main' && needs.download_artifacts.outputs.www_branch_count == '0')
+    needs: [download_artifacts, process_artifacts]
+    if: inputs.force == true || (github.ref == 'refs/heads/main' && needs.process_artifacts.outputs.www_branch_count == '0')
     runs-on: ubuntu-latest
+    permissions:
+      # Used to push a commit to builds/facebook-www
+      contents: write
     steps:
       - uses: actions/checkout@v4
         with:
@@ -190,12 +217,12 @@ jobs:
           name: compiled
           path: compiled/
       - name: Revert version changes
-        if: needs.download_artifacts.outputs.last_version_classic != '' && needs.download_artifacts.outputs.last_version_modern != ''
+        if: needs.process_artifacts.outputs.last_version_classic != '' && needs.process_artifacts.outputs.last_version_modern != ''
         env:
-          CURRENT_VERSION_CLASSIC: ${{ needs.download_artifacts.outputs.current_version_classic }}
-          CURRENT_VERSION_MODERN: ${{ needs.download_artifacts.outputs.current_version_modern }}
-          LAST_VERSION_CLASSIC: ${{ needs.download_artifacts.outputs.last_version_classic }}
-          LAST_VERSION_MODERN: ${{ needs.download_artifacts.outputs.last_version_modern }}
+          CURRENT_VERSION_CLASSIC: ${{ needs.process_artifacts.outputs.current_version_classic }}
+          CURRENT_VERSION_MODERN: ${{ needs.process_artifacts.outputs.current_version_modern }}
+          LAST_VERSION_CLASSIC: ${{ needs.process_artifacts.outputs.last_version_classic }}
+          LAST_VERSION_MODERN: ${{ needs.process_artifacts.outputs.last_version_modern }}
         run: |
           echo "Reverting $CURRENT_VERSION_CLASSIC to $LAST_VERSION_CLASSIC"
           grep -rl "$CURRENT_VERSION_CLASSIC" ./compiled || echo "No files found with $CURRENT_VERSION_CLASSIC"
@@ -225,12 +252,12 @@ jobs:
             echo "should_commit=false" >> "$GITHUB_OUTPUT"
           fi
       - name: Re-apply version changes
-        if: inputs.force == true || (steps.check_should_commit.outputs.should_commit == 'true' && needs.download_artifacts.outputs.last_version_classic != '' && needs.download_artifacts.outputs.last_version_modern != '')
+        if: inputs.force == true || (steps.check_should_commit.outputs.should_commit == 'true' && needs.process_artifacts.outputs.last_version_classic != '' && needs.process_artifacts.outputs.last_version_modern != '')
         env:
-          CURRENT_VERSION_CLASSIC: ${{ needs.download_artifacts.outputs.current_version_classic }}
-          CURRENT_VERSION_MODERN: ${{ needs.download_artifacts.outputs.current_version_modern }}
-          LAST_VERSION_CLASSIC: ${{ needs.download_artifacts.outputs.last_version_classic }}
-          LAST_VERSION_MODERN: ${{ needs.download_artifacts.outputs.last_version_modern }}
+          CURRENT_VERSION_CLASSIC: ${{ needs.process_artifacts.outputs.current_version_classic }}
+          CURRENT_VERSION_MODERN: ${{ needs.process_artifacts.outputs.current_version_modern }}
+          LAST_VERSION_CLASSIC: ${{ needs.process_artifacts.outputs.last_version_classic }}
+          LAST_VERSION_MODERN: ${{ needs.process_artifacts.outputs.last_version_modern }}
         run: |
           echo "Re-applying $LAST_VERSION_CLASSIC to $CURRENT_VERSION_CLASSIC"
           grep -rl "$LAST_VERSION_CLASSIC" ./compiled || echo "No files found with $LAST_VERSION_CLASSIC"
@@ -244,8 +271,8 @@ jobs:
       - name: Will commit these changes
         if: inputs.force == true || steps.check_should_commit.outputs.should_commit == 'true'
         run: |
-          echo ":"
-          git status -u
+          git add .
+          git status
       - name: Check commit message
         if: inputs.dry_run
         run: |
@@ -264,8 +291,11 @@ jobs:
         run: git push
 
   commit_fbsource_artifacts:
-    needs: download_artifacts
-    if: inputs.force == true || (github.ref == 'refs/heads/main' && needs.download_artifacts.outputs.fbsource_branch_count == '0')
+    needs: [download_artifacts, process_artifacts]
+    permissions:
+      # Used to push a commit to builds/facebook-fbsource
+      contents: write
+    if: inputs.force == true || (github.ref == 'refs/heads/main' && needs.process_artifacts.outputs.fbsource_branch_count == '0')
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
@@ -278,10 +308,10 @@ jobs:
           name: compiled-rn
           path: compiled-rn/
       - name: Revert version changes
-        if: needs.download_artifacts.outputs.last_version_rn != ''
+        if: needs.process_artifacts.outputs.last_version_rn != ''
         env:
-          CURRENT_VERSION: ${{ needs.download_artifacts.outputs.current_version_rn }}
-          LAST_VERSION: ${{ needs.download_artifacts.outputs.last_version_rn }}
+          CURRENT_VERSION: ${{ needs.process_artifacts.outputs.current_version_rn }}
+          LAST_VERSION: ${{ needs.process_artifacts.outputs.last_version_rn }}
         run: |
           echo "Reverting $CURRENT_VERSION to $LAST_VERSION"
           grep -rl "$CURRENT_VERSION" ./compiled-rn || echo "No files found with $CURRENT_VERSION"
@@ -307,10 +337,10 @@ jobs:
             echo "should_commit=false" >> "$GITHUB_OUTPUT"
           fi
       - name: Re-apply version changes
-        if: inputs.force == true || (steps.check_should_commit.outputs.should_commit == 'true' && needs.download_artifacts.outputs.last_version_rn != '')
+        if: inputs.force == true || (steps.check_should_commit.outputs.should_commit == 'true' && needs.process_artifacts.outputs.last_version_rn != '')
         env:
-          CURRENT_VERSION: ${{ needs.download_artifacts.outputs.current_version_rn }}
-          LAST_VERSION: ${{ needs.download_artifacts.outputs.last_version_rn }}
+          CURRENT_VERSION: ${{ needs.process_artifacts.outputs.current_version_rn }}
+          LAST_VERSION: ${{ needs.process_artifacts.outputs.last_version_rn }}
         run: |
           echo "Re-applying $LAST_VERSION to $CURRENT_VERSION"
           grep -rl "$LAST_VERSION" ./compiled-rn || echo "No files found with $LAST_VERSION"

.github/workflows/runtime_discord_notify.yml

@@ -1,15 +1,20 @@
 name: (Runtime) Discord Notify
 
 on:
-  pull_request_target:
+  pull_request:
     types: [opened, ready_for_review]
     paths-ignore:
       - compiler/**
       - .github/workflows/compiler_**.yml
 
+permissions: {}
+
 jobs:
   check_maintainer:
     uses: facebook/react/.github/workflows/shared_check_maintainer.yml@main
+    permissions:
+      # Used by check_maintainer
+      contents: read
     with:
       actor: ${{ github.event.pull_request.user.login }}
 

.github/workflows/runtime_eslint_plugin_e2e.yml

@@ -7,6 +7,8 @@ on:
     paths-ignore:
       - compiler/**
 
+permissions: {}
+
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref_name }}-${{ github.event.pull_request.number || github.run_id }}
   cancel-in-progress: true

.github/workflows/runtime_fuzz_tests.yml

@@ -8,6 +8,8 @@ on:
       - main
   workflow_dispatch:
 
+permissions: {}
+
 env:
   TZ: /usr/share/zoneinfo/America/Los_Angeles
 

.github/workflows/runtime_prereleases.yml

@@ -17,11 +17,12 @@ on:
       NPM_TOKEN:
         required: true
 
+permissions: {}
+
 env:
   TZ: /usr/share/zoneinfo/America/Los_Angeles
   # https://github.com/actions/cache/blob/main/tips-and-workarounds.md#cache-segment-restore-timeout
   SEGMENT_DOWNLOAD_TIMEOUT_MINS: 1
-  GH_TOKEN: ${{ github.token }}
   NPM_TOKEN: ${{ secrets.NPM_TOKEN }}
 
 jobs:

.github/workflows/runtime_prereleases_manual.yml

@@ -6,6 +6,8 @@ on:
       prerelease_commit_sha:
         required: true
 
+permissions: {}
+
 env:
   TZ: /usr/share/zoneinfo/America/Los_Angeles
 

.github/workflows/runtime_prereleases_nightly.yml

@@ -5,6 +5,8 @@ on:
     # At 10 minutes past 16:00 on Mon, Tue, Wed, Thu, and Fri
     - cron: 10 16 * * 1,2,3,4,5
 
+permissions: {}
+
 env:
   TZ: /usr/share/zoneinfo/America/Los_Angeles
 

.github/workflows/runtime_releases_from_npm_manual.yml

@@ -31,11 +31,12 @@ on:
         type: boolean
         default: false
 
+permissions: {}
+
 env:
   TZ: /usr/share/zoneinfo/America/Los_Angeles
   # https://github.com/actions/cache/blob/main/tips-and-workarounds.md#cache-segment-restore-timeout
   SEGMENT_DOWNLOAD_TIMEOUT_MINS: 1
-  GH_TOKEN: ${{ github.token }}
   NPM_TOKEN: ${{ secrets.NPM_TOKEN }}
 
 jobs:

.github/workflows/shared_check_maintainer.yml

@@ -14,6 +14,8 @@ on:
       is_core_team:
         value: ${{ jobs.check_maintainer.outputs.is_core_team }}
 
+permissions: {}
+
 env:
   TZ: /usr/share/zoneinfo/America/Los_Angeles
   # https://github.com/actions/cache/blob/main/tips-and-workarounds.md#cache-segment-restore-timeout
@@ -22,6 +24,9 @@ env:
 jobs:
   check_maintainer:
     runs-on: ubuntu-latest
+    permissions:
+      # We fetch the contents of the MAINTAINERS file
+      contents: read
     outputs:
       is_core_team: ${{ steps.check_if_actor_is_maintainer.outputs.result }}
     steps:

.github/workflows/shared_cleanup_merged_branch_caches.yml

@@ -1,11 +1,17 @@
 # https://github.com/actions/cache/blob/main/tips-and-workarounds.md#force-deletion-of-caches-overriding-default-cache-eviction-policy
 
-name: (Shared) Cleanup Branch Caches
+name: (Shared) Cleanup Merged Branch Caches
 on:
   pull_request:
     types:
       - closed
   workflow_dispatch:
+    inputs:
+      pr_number:
+        required: true
+        type: string
+
+permissions: {}
 
 jobs:
   cleanup:
@@ -23,13 +29,13 @@ jobs:
 
           ## Setting this to not fail the workflow while deleting cache keys.
           set +e
-          echo "Deleting caches..."
           for cacheKey in $cacheKeysForPR
           do
               gh cache delete $cacheKey
+              echo "Deleting $cacheKey"
           done
           echo "Done"
         env:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           GH_REPO: ${{ github.repository }}
-          BRANCH: refs/pull/${{ github.event.pull_request.number }}/merge
+          BRANCH: refs/pull/${{ inputs.pr_number || github.event.pull_request.number }}/merge

.github/workflows/shared_cleanup_stale_branch_caches.yml

@@ -0,0 +1,35 @@
+# https://github.com/actions/cache/blob/main/tips-and-workarounds.md#force-deletion-of-caches-overriding-default-cache-eviction-policy
+
+name: (Shared) Cleanup Stale Branch Caches
+on:
+  schedule:
+    - cron: 0 0 * * *
+  workflow_dispatch:
+
+permissions: {}
+
+jobs:
+  cleanup:
+    runs-on: ubuntu-latest
+    permissions:
+      # `actions:write` permission is required to delete caches
+      #   See also: https://docs.github.com/en/rest/actions/cache?apiVersion=2022-11-28#delete-a-github-actions-cache-for-a-repository-using-a-cache-id
+      actions: write
+      contents: read
+    steps:
+      - name: Cleanup
+        run: |
+          echo "Fetching list of cache keys"
+          cacheKeysForPR=$(gh cache list --limit 100 --json id,ref --jq '.[] | select(.ref != "refs/heads/main") | .id')
+
+          ## Setting this to not fail the workflow while deleting cache keys.
+          set +e
+          for cacheKey in $cacheKeysForPR
+          do
+              gh cache delete $cacheKey
+              echo "Deleting $cacheKey"
+          done
+          echo "Done"
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          GH_REPO: ${{ github.repository }}

.github/workflows/shared_close_direct_sync_branch_prs.yml

@@ -5,6 +5,8 @@ on:
     branches:
       - 'builds/facebook-**'
 
+permissions: {}
+
 env:
   TZ: /usr/share/zoneinfo/America/Los_Angeles
   # https://github.com/actions/cache/blob/main/tips-and-workarounds.md#cache-segment-restore-timeout
@@ -13,6 +15,9 @@ env:
 jobs:
   close_pr:
     runs-on: ubuntu-latest
+    permissions:
+      # Used to create a review and close PRs
+      pull-requests: write
     steps:
       - name: Close PR
         uses: actions/github-script@v7

.github/workflows/shared_label_core_team_prs.yml

@@ -1,7 +1,9 @@
 name: (Shared) Label Core Team PRs
 
 on:
-  pull_request_target:
+  pull_request:
+
+permissions: {}
 
 env:
   TZ: /usr/share/zoneinfo/America/Los_Angeles
@@ -11,6 +13,9 @@ env:
 jobs:
   check_maintainer:
     uses: facebook/react/.github/workflows/shared_check_maintainer.yml@main
+    permissions:
+      # Used by check_maintainer
+      contents: read
     with:
       actor: ${{ github.event.pull_request.user.login }}
 
@@ -18,6 +23,11 @@ jobs:
     if: ${{ needs.check_maintainer.outputs.is_core_team == 'true' }}
     runs-on: ubuntu-latest
     needs: check_maintainer
+    permissions:
+      # Used to add labels on issues
+      issues: write
+      # Used to add labels on PRs
+      pull-requests: write
     steps:
       - name: Label PR as React Core Team
         uses: actions/github-script@v7

.github/workflows/shared_lint.yml

@@ -5,6 +5,8 @@ on:
     branches: [main]
   pull_request:
 
+permissions: {}
+
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref_name }}-${{ github.event.pull_request.number || github.run_id }}
   cancel-in-progress: true

.github/workflows/shared_stale.yml

@@ -6,6 +6,8 @@ on:
     - cron: '0 * * * *'
   workflow_dispatch:
 
+permissions: {}
+
 env:
   TZ: /usr/share/zoneinfo/America/Los_Angeles
 

ReactVersions.js

@@ -33,6 +33,7 @@ const canaryChannelLabel = 'canary';
 const rcNumber = 0;
 
 const stablePackages = {
+  'eslint-plugin-react-hooks': '5.2.0',
   'jest-react': '0.17.0',
   react: ReactVersion,
   'react-art': ReactVersion,

babel.config-react-compiler.js

@@ -0,0 +1,19 @@
+'use strict';
+
+/**
+ * HACK: @poteto React Compiler inlines Zod in its build artifact. Zod spreads values passed to .map
+ * which causes issues in @babel/plugin-transform-spread in loose mode, as it will result in
+ * {undefined: undefined} which fails to parse.
+ *
+ * [@babel/plugin-transform-block-scoping', {throwIfClosureRequired: true}] also causes issues with
+ * the built version of the compiler. The minimal set of plugins needed for this file is reexported
+ * from babel.config-ts.
+ *
+ * I will remove this hack later when we move eslint-plugin-react-hooks into the compiler directory.
+ **/
+
+const baseConfig = require('./babel.config-ts');
+
+module.exports = {
+  plugins: baseConfig.plugins,
+};

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

@@ -16,7 +16,7 @@
     "snap:build": "yarn workspace snap run build",
     "snap:ci": "yarn snap:build && yarn snap",
     "ts:analyze-trace": "scripts/ts-analyze-trace.sh",
-    "lint": "../../node_modules/eslint-v8/bin/eslint.js src",
+    "lint": "yarn eslint src",
     "watch": "yarn build --watch"
   },
   "dependencies": {
@@ -43,7 +43,7 @@
     "babel-jest": "^29.0.3",
     "babel-plugin-fbt": "^1.0.0",
     "babel-plugin-fbt-runtime": "^1.0.0",
-    "eslint-v8": "npm:eslint@^8.57.1",
+    "eslint": "^8.57.1",
     "invariant": "^2.2.4",
     "jest": "^29.0.3",
     "jest-environment-jsdom": "^29.0.3",

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

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

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

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

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

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

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

@@ -6,6 +6,7 @@
  */
 
 import type {SourceLocation} from './HIR';
+import {Err, Ok, Result} from './Utils/Result';
 import {assertExhaustive} from './Utils/utils';
 
 export enum ErrorSeverity {
@@ -224,6 +225,10 @@ export class CompilerError extends Error {
     return this.details.length > 0;
   }
 
+  asResult(): Result<void, CompilerError> {
+    return this.hasErrors() ? Err(this) : Ok(undefined);
+  }
+
   /*
    * An error is critical if it means the compiler has entered into a broken state and cannot
    * continue safely. Other expected errors such as Todos mean that we can skip over that component

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

@@ -100,8 +100,9 @@ import {propagateScopeDependenciesHIR} from '../HIR/PropagateScopeDependenciesHI
 import {outlineJSX} from '../Optimization/OutlineJsx';
 import {optimizePropsMethodCalls} from '../Optimization/OptimizePropsMethodCalls';
 import {transformFire} from '../Transform';
-import {validateNoImpureFunctionsInRender} from '../Validation/ValiateNoImpureFunctionsInRender';
+import {validateNoImpureFunctionsInRender} from '../Validation/ValidateNoImpureFunctionsInRender';
 import {CompilerError} from '..';
+import {validateStaticComponents} from '../Validation/ValidateStaticComponents';
 
 export type CompilerPipelineValue =
   | {kind: 'ast'; name: string; value: CodegenFunction}
@@ -161,7 +162,7 @@ function runWithEnvironment(
   log({kind: 'hir', name: 'PruneMaybeThrows', value: hir});
 
   validateContextVariableLValues(hir);
-  validateUseMemo(hir);
+  validateUseMemo(hir).unwrap();
 
   if (
     env.isInferredMemoEnabled &&
@@ -202,10 +203,10 @@ function runWithEnvironment(
 
   if (env.isInferredMemoEnabled) {
     if (env.config.validateHooksUsage) {
-      validateHooksUsage(hir);
+      validateHooksUsage(hir).unwrap();
     }
     if (env.config.validateNoCapitalizedCalls) {
-      validateNoCapitalizedCalls(hir);
+      validateNoCapitalizedCalls(hir).unwrap();
     }
   }
 
@@ -255,23 +256,23 @@ function runWithEnvironment(
     }
 
     if (env.config.validateRefAccessDuringRender) {
-      validateNoRefAccessInRender(hir);
+      validateNoRefAccessInRender(hir).unwrap();
     }
 
     if (env.config.validateNoSetStateInRender) {
-      validateNoSetStateInRender(hir);
+      validateNoSetStateInRender(hir).unwrap();
     }
 
     if (env.config.validateNoSetStateInPassiveEffects) {
-      validateNoSetStateInPassiveEffects(hir);
+      env.logErrors(validateNoSetStateInPassiveEffects(hir));
     }
 
     if (env.config.validateNoJSXInTryStatements) {
-      validateNoJSXInTryStatement(hir);
+      env.logErrors(validateNoJSXInTryStatement(hir));
     }
 
     if (env.config.validateNoImpureFunctionsInRender) {
-      validateNoImpureFunctionsInRender(hir);
+      validateNoImpureFunctionsInRender(hir).unwrap();
     }
   }
 
@@ -293,6 +294,10 @@ function runWithEnvironment(
   });
 
   if (env.isInferredMemoEnabled) {
+    if (env.config.validateStaticComponents) {
+      env.logErrors(validateStaticComponents(hir));
+    }
+
     /**
      * Only create reactive scopes (which directly map to generated memo blocks)
      * if inferred memoization is enabled. This makes all later passes which
@@ -509,14 +514,14 @@ function runWithEnvironment(
   });
 
   if (env.config.validateMemoizedEffectDependencies) {
-    validateMemoizedEffectDependencies(reactiveFunction);
+    validateMemoizedEffectDependencies(reactiveFunction).unwrap();
   }
 
   if (
     env.config.enablePreserveExistingMemoizationGuarantees ||
     env.config.validatePreserveExistingMemoizationGuarantees
   ) {
-    validatePreservedManualMemoization(reactiveFunction);
+    validatePreservedManualMemoization(reactiveFunction).unwrap();
   }
 
   const ast = codegenFunction(reactiveFunction, {

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

@@ -451,6 +451,12 @@ export function compileProgram(
             pass.code,
           ),
         };
+        if (
+          !compileResult.compiledFn.hasFireRewrite &&
+          !compileResult.compiledFn.hasLoweredContextAccess
+        ) {
+          return null;
+        }
       } catch (err) {
         // TODO: we might want to log error here, but this will also result in duplicate logging
         if (err instanceof CompilerError) {
@@ -1002,31 +1008,39 @@ function callsHooksOrCreatesJsx(
   return invokesHooks || createsJsx;
 }
 
+function isNonNode(node?: t.Expression | null): boolean {
+  if (!node) {
+    return true;
+  }
+  switch (node.type) {
+    case 'ObjectExpression':
+    case 'ArrowFunctionExpression':
+    case 'FunctionExpression':
+    case 'BigIntLiteral':
+    case 'ClassExpression':
+    case 'NewExpression': // technically `new Array()` is legit, but unlikely
+      return true;
+  }
+  return false;
+}
+
 function returnsNonNode(
   node: NodePath<
     t.FunctionDeclaration | t.ArrowFunctionExpression | t.FunctionExpression
   >,
 ): boolean {
-  let hasReturn = false;
   let returnsNonNode = false;
+  if (
+    // node.traverse#ArrowFunctionExpression isn't called for the root node
+    node.type === 'ArrowFunctionExpression' &&
+    node.node.body.type !== 'BlockStatement'
+  ) {
+    returnsNonNode = isNonNode(node.node.body);
+  }
 
   node.traverse({
     ReturnStatement(ret) {
-      hasReturn = true;
-      const argument = ret.node.argument;
-      if (argument == null) {
-        returnsNonNode = true;
-      } else {
-        switch (argument.type) {
-          case 'ObjectExpression':
-          case 'ArrowFunctionExpression':
-          case 'FunctionExpression':
-          case 'BigIntLiteral':
-          case 'ClassExpression':
-          case 'NewExpression': // technically `new Array()` is legit, but unlikely
-            returnsNonNode = true;
-        }
-      }
+      returnsNonNode = isNonNode(ret.node.argument);
     },
     // Skip traversing all nested functions and their return statements
     ArrowFunctionExpression: skipNestedFunctions(node),
@@ -1035,7 +1049,7 @@ function returnsNonNode(
     ObjectMethod: node => node.skip(),
   });
 
-  return !hasReturn || returnsNonNode;
+  return returnsNonNode;
 }
 
 /*

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

@@ -330,6 +330,11 @@ const EnvironmentConfigSchema = z.object({
    */
   validateNoJSXInTryStatements: z.boolean().default(false),
 
+  /**
+   * Validates against dynamically creating components during render.
+   */
+  validateStaticComponents: z.boolean().default(false),
+
   /**
    * Validates that the dependencies of all effect hooks are memoized. This helps ensure
    * that Forget does not introduce infinite renders caused by a dependency changing,
@@ -932,6 +937,19 @@ export class Environment {
     return makeScopeId(this.#nextScope++);
   }
 
+  logErrors(errors: Result<void, CompilerError>): void {
+    if (errors.isOk() || this.logger == null) {
+      return;
+    }
+    for (const error of errors.unwrapErr().details) {
+      this.logger.logEvent(this.filename, {
+        kind: 'CompileError',
+        detail: error,
+        fnLoc: null,
+      });
+    }
+  }
+
   isContextIdentifier(node: t.Identifier): boolean {
     return this.#contextIdentifiers.has(node);
   }

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

@@ -14,7 +14,7 @@ import {
   renameVariables,
 } from '.';
 import {CompilerError, ErrorSeverity} from '../CompilerError';
-import {Environment, EnvironmentConfig, ExternalFunction} from '../HIR';
+import {Environment, ExternalFunction} from '../HIR';
 import {
   ArrayPattern,
   BlockId,
@@ -156,7 +156,7 @@ export function codegenFunction(
   const compiled = compileResult.unwrap();
 
   const hookGuard = fn.env.config.enableEmitHookGuards;
-  if (hookGuard != null) {
+  if (hookGuard != null && fn.env.isInferredMemoEnabled) {
     compiled.body = t.blockStatement([
       createHookGuard(
         hookGuard,
@@ -250,7 +250,11 @@ export function codegenFunction(
   }
 
   const emitInstrumentForget = fn.env.config.enableEmitInstrumentForget;
-  if (emitInstrumentForget != null && fn.id != null) {
+  if (
+    emitInstrumentForget != null &&
+    fn.id != null &&
+    fn.env.isInferredMemoEnabled
+  ) {
     /*
      * Technically, this is a conditional hook call. However, we expect
      * __DEV__ and gating identifier to be runtime constants
@@ -548,7 +552,7 @@ function codegenBlockNoReset(
 }
 
 function wrapCacheDep(cx: Context, value: t.Expression): t.Expression {
-  if (cx.env.config.enableEmitFreeze != null) {
+  if (cx.env.config.enableEmitFreeze != null && cx.env.isInferredMemoEnabled) {
     // The import declaration for emitFreeze is inserted in the Babel plugin
     return t.conditionalExpression(
       t.identifier('__DEV__'),
@@ -1553,7 +1557,7 @@ function createHookGuard(
  * ```
  */
 function createCallExpression(
-  config: EnvironmentConfig,
+  env: Environment,
   callee: t.Expression,
   args: Array<t.Expression | t.SpreadElement>,
   loc: SourceLocation | null,
@@ -1564,8 +1568,8 @@ function createCallExpression(
     callExpr.loc = loc;
   }
 
-  const hookGuard = config.enableEmitHookGuards;
-  if (hookGuard != null && isHook) {
+  const hookGuard = env.config.enableEmitHookGuards;
+  if (hookGuard != null && isHook && env.isInferredMemoEnabled) {
     const iife = t.functionExpression(
       null,
       [],
@@ -1701,7 +1705,7 @@ function codegenInstructionValue(
       const callee = codegenPlaceToExpression(cx, instrValue.callee);
       const args = instrValue.args.map(arg => codegenArgument(cx, arg));
       value = createCallExpression(
-        cx.env.config,
+        cx.env,
         callee,
         args,
         instrValue.loc,
@@ -1791,7 +1795,7 @@ function codegenInstructionValue(
       );
       const args = instrValue.args.map(arg => codegenArgument(cx, arg));
       value = createCallExpression(
-        cx.env.config,
+        cx.env,
         memberExpr,
         args,
         instrValue.loc,

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

@@ -26,6 +26,7 @@ import {
   eachTerminalOperand,
 } from '../HIR/visitors';
 import {assertExhaustive} from '../Utils/utils';
+import {Result} from '../Utils/Result';
 
 /**
  * Represents the possible kinds of value which may be stored at a given Place during
@@ -87,7 +88,9 @@ function joinKinds(a: Kind, b: Kind): Kind {
  *   may not appear as the callee of a conditional call.
  *   See the note for Kind.PotentialHook for sources of potential hooks
  */
-export function validateHooksUsage(fn: HIRFunction): void {
+export function validateHooksUsage(
+  fn: HIRFunction,
+): Result<void, CompilerError> {
   const unconditionalBlocks = computeUnconditionalBlocks(fn);
 
   const errors = new CompilerError();
@@ -423,9 +426,7 @@ export function validateHooksUsage(fn: HIRFunction): void {
   for (const [, error] of errorsByPlace) {
     errors.push(error);
   }
-  if (errors.hasErrors()) {
-    throw errors;
-  }
+  return errors.asResult();
 }
 
 function visitFunctionExpression(errors: CompilerError, fn: HIRFunction): void {

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

@@ -22,6 +22,7 @@ import {
   ReactiveFunctionVisitor,
   visitReactiveFunction,
 } from '../ReactiveScopes/visitors';
+import {Result} from '../Utils/Result';
 
 /**
  * Validates that all known effect dependencies are memoized. The algorithm checks two things:
@@ -47,12 +48,12 @@ import {
  * mutate(object); // ... mutable range ends here after this mutation
  * ```
  */
-export function validateMemoizedEffectDependencies(fn: ReactiveFunction): void {
+export function validateMemoizedEffectDependencies(
+  fn: ReactiveFunction,
+): Result<void, CompilerError> {
   const errors = new CompilerError();
   visitReactiveFunction(fn, new Visitor(), errors);
-  if (errors.hasErrors()) {
-    throw errors;
-  }
+  return errors.asResult();
 }
 
 class Visitor extends ReactiveFunctionVisitor<CompilerError> {

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

@@ -4,11 +4,14 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  */
-import {CompilerError, EnvironmentConfig} from '..';
+import {CompilerError, EnvironmentConfig, ErrorSeverity} from '..';
 import {HIRFunction, IdentifierId} from '../HIR';
 import {DEFAULT_GLOBALS} from '../HIR/Globals';
+import {Result} from '../Utils/Result';
 
-export function validateNoCapitalizedCalls(fn: HIRFunction): void {
+export function validateNoCapitalizedCalls(
+  fn: HIRFunction,
+): Result<void, CompilerError> {
   const envConfig: EnvironmentConfig = fn.env.config;
   const ALLOW_LIST = new Set([
     ...DEFAULT_GLOBALS.keys(),
@@ -26,6 +29,7 @@ export function validateNoCapitalizedCalls(fn: HIRFunction): void {
     );
   };
 
+  const errors = new CompilerError();
   const capitalLoadGlobals = new Map<IdentifierId, string>();
   const capitalizedProperties = new Map<IdentifierId, string>();
   const reason =
@@ -73,7 +77,8 @@ export function validateNoCapitalizedCalls(fn: HIRFunction): void {
           const propertyIdentifier = value.property.identifier.id;
           const propertyName = capitalizedProperties.get(propertyIdentifier);
           if (propertyName != null) {
-            CompilerError.throwInvalidReact({
+            errors.push({
+              severity: ErrorSeverity.InvalidReact,
               reason,
               description: `${propertyName} may be a component.`,
               loc: value.loc,
@@ -85,4 +90,5 @@ export function validateNoCapitalizedCalls(fn: HIRFunction): void {
       }
     }
   }
+  return errors.asResult();
 }

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

@@ -8,6 +8,7 @@
 import {CompilerError, ErrorSeverity} from '..';
 import {HIRFunction} from '../HIR';
 import {getFunctionCallSignature} from '../Inference/InferReferenceEffects';
+import {Result} from '../Utils/Result';
 
 /**
  * Checks that known-impure functions are not called during render. Examples of invalid functions to
@@ -18,7 +19,9 @@ import {getFunctionCallSignature} from '../Inference/InferReferenceEffects';
  * this in several of our validation passes and should unify those analyses into a reusable helper
  * and use it here.
  */
-export function validateNoImpureFunctionsInRender(fn: HIRFunction): void {
+export function validateNoImpureFunctionsInRender(
+  fn: HIRFunction,
+): Result<void, CompilerError> {
   const errors = new CompilerError();
   for (const [, block] of fn.body.blocks) {
     for (const instr of block.instructions) {
@@ -46,7 +49,5 @@ export function validateNoImpureFunctionsInRender(fn: HIRFunction): void {
       }
     }
   }
-  if (errors.hasErrors()) {
-    throw errors;
-  }
+  return errors.asResult();
 }

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

@@ -7,6 +7,7 @@
 
 import {CompilerError, ErrorSeverity} from '..';
 import {BlockId, HIRFunction} from '../HIR';
+import {Result} from '../Utils/Result';
 import {retainWhere} from '../Utils/utils';
 
 /**
@@ -19,7 +20,9 @@ import {retainWhere} from '../Utils/utils';
  * created within a try block. JSX is allowed within a catch statement, unless that catch
  * is itself nested inside an outer try.
  */
-export function validateNoJSXInTryStatement(fn: HIRFunction): void {
+export function validateNoJSXInTryStatement(
+  fn: HIRFunction,
+): Result<void, CompilerError> {
   const activeTryBlocks: Array<BlockId> = [];
   const errors = new CompilerError();
   for (const [, block] of fn.body.blocks) {
@@ -46,7 +49,5 @@ export function validateNoJSXInTryStatement(fn: HIRFunction): void {
       activeTryBlocks.push(block.terminal.handler);
     }
   }
-  if (errors.hasErrors()) {
-    throw errors;
-  }
+  return errors.asResult();
 }

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

@@ -99,9 +99,11 @@ class Env extends Map<IdentifierId, RefAccessType> {
   }
 }
 
-export function validateNoRefAccessInRender(fn: HIRFunction): void {
+export function validateNoRefAccessInRender(
+  fn: HIRFunction,
+): Result<void, CompilerError> {
   const env = new Env();
-  validateNoRefAccessInRenderImpl(fn, env).unwrap();
+  return validateNoRefAccessInRenderImpl(fn, env).map(_ => undefined);
 }
 
 function refTypeOfType(place: Place): RefAccessType {

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

@@ -14,6 +14,7 @@ import {
   Place,
 } from '../HIR';
 import {eachInstructionValueOperand} from '../HIR/visitors';
+import {Result} from '../Utils/Result';
 
 /**
  * Validates against calling setState in the body of a *passive* effect (useEffect),
@@ -23,7 +24,9 @@ import {eachInstructionValueOperand} from '../HIR/visitors';
  * often bad for performance and frequently has more efficient and straightforward
  * alternatives. See https://react.dev/learn/you-might-not-need-an-effect for examples.
  */
-export function validateNoSetStateInPassiveEffects(fn: HIRFunction): void {
+export function validateNoSetStateInPassiveEffects(
+  fn: HIRFunction,
+): Result<void, CompilerError> {
   const setStateFunctions: Map<IdentifierId, Place> = new Map();
   const errors = new CompilerError();
   for (const [, block] of fn.body.blocks) {
@@ -98,9 +101,7 @@ export function validateNoSetStateInPassiveEffects(fn: HIRFunction): void {
     }
   }
 
-  if (errors.hasErrors()) {
-    throw errors;
-  }
+  return errors.asResult();
 }
 
 function getSetStateCall(

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

@@ -9,7 +9,7 @@ import {CompilerError, ErrorSeverity} from '../CompilerError';
 import {HIRFunction, IdentifierId, isSetStateType} from '../HIR';
 import {computeUnconditionalBlocks} from '../HIR/ComputeUnconditionalBlocks';
 import {eachInstructionValueOperand} from '../HIR/visitors';
-import {Err, Ok, Result} from '../Utils/Result';
+import {Result} from '../Utils/Result';
 
 /**
  * Validates that the given function does not have an infinite update loop
@@ -39,9 +39,11 @@ import {Err, Ok, Result} from '../Utils/Result';
  * y();
  * ```
  */
-export function validateNoSetStateInRender(fn: HIRFunction): void {
+export function validateNoSetStateInRender(
+  fn: HIRFunction,
+): Result<void, CompilerError> {
   const unconditionalSetStateFunctions: Set<IdentifierId> = new Set();
-  validateNoSetStateInRenderImpl(fn, unconditionalSetStateFunctions).unwrap();
+  return validateNoSetStateInRenderImpl(fn, unconditionalSetStateFunctions);
 }
 
 function validateNoSetStateInRenderImpl(
@@ -145,9 +147,5 @@ function validateNoSetStateInRenderImpl(
     }
   }
 
-  if (errors.hasErrors()) {
-    return Err(errors);
-  } else {
-    return Ok(undefined);
-  }
+  return errors.asResult();
 }

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

@@ -5,9 +5,10 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {CompilerError, Effect, ErrorSeverity} from '..';
+import {CompilerError, ErrorSeverity} from '../CompilerError';
 import {
   DeclarationId,
+  Effect,
   GeneratedSource,
   Identifier,
   IdentifierId,
@@ -30,6 +31,7 @@ import {
   ReactiveFunctionVisitor,
   visitReactiveFunction,
 } from '../ReactiveScopes/visitors';
+import {Result} from '../Utils/Result';
 import {getOrInsertDefault} from '../Utils/utils';
 
 /**
@@ -39,15 +41,15 @@ import {getOrInsertDefault} from '../Utils/utils';
  * This can occur if a value's mutable range somehow extended to include a hook and
  * was pruned.
  */
-export function validatePreservedManualMemoization(fn: ReactiveFunction): void {
+export function validatePreservedManualMemoization(
+  fn: ReactiveFunction,
+): Result<void, CompilerError> {
   const state = {
     errors: new CompilerError(),
     manualMemoState: null,
   };
   visitReactiveFunction(fn, new Visitor(), state);
-  if (state.errors.hasErrors()) {
-    throw state.errors;
-  }
+  return state.errors.asResult();
 }
 
 const DEBUG = false;

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

@@ -0,0 +1,83 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {CompilerError, ErrorSeverity} from '../CompilerError';
+import {HIRFunction, IdentifierId, SourceLocation} from '../HIR';
+import {Result} from '../Utils/Result';
+
+/**
+ * Validates against components that are created dynamically and whose identity is not guaranteed
+ * to be stable (which would cause the component to reset on each re-render).
+ */
+export function validateStaticComponents(
+  fn: HIRFunction,
+): Result<void, CompilerError> {
+  const error = new CompilerError();
+  const knownDynamicComponents = new Map<IdentifierId, SourceLocation>();
+  for (const block of fn.body.blocks.values()) {
+    phis: for (const phi of block.phis) {
+      for (const operand of phi.operands.values()) {
+        const loc = knownDynamicComponents.get(operand.identifier.id);
+        if (loc != null) {
+          knownDynamicComponents.set(phi.place.identifier.id, loc);
+          continue phis;
+        }
+      }
+    }
+    for (const instr of block.instructions) {
+      const {lvalue, value} = instr;
+      switch (value.kind) {
+        case 'FunctionExpression':
+        case 'NewExpression':
+        case 'MethodCall':
+        case 'CallExpression': {
+          knownDynamicComponents.set(lvalue.identifier.id, value.loc);
+          break;
+        }
+        case 'LoadLocal': {
+          const loc = knownDynamicComponents.get(value.place.identifier.id);
+          if (loc != null) {
+            knownDynamicComponents.set(lvalue.identifier.id, loc);
+          }
+          break;
+        }
+        case 'StoreLocal': {
+          const loc = knownDynamicComponents.get(value.value.identifier.id);
+          if (loc != null) {
+            knownDynamicComponents.set(lvalue.identifier.id, loc);
+            knownDynamicComponents.set(value.lvalue.place.identifier.id, loc);
+          }
+          break;
+        }
+        case 'JsxExpression': {
+          if (value.tag.kind === 'Identifier') {
+            const location = knownDynamicComponents.get(
+              value.tag.identifier.id,
+            );
+            if (location != null) {
+              error.push({
+                reason: `Components created during render will reset their state each time they are created. Declare components outside of render. `,
+                severity: ErrorSeverity.InvalidReact,
+                loc: value.tag.loc,
+                description: null,
+                suggestions: null,
+              });
+              error.push({
+                reason: `The component may be created during render`,
+                severity: ErrorSeverity.InvalidReact,
+                loc: location,
+                description: null,
+                suggestions: null,
+              });
+            }
+          }
+        }
+      }
+    }
+  }
+  return error.asResult();
+}

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

@@ -5,10 +5,12 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {CompilerError} from '..';
+import {CompilerError, ErrorSeverity} from '..';
 import {FunctionExpression, HIRFunction, IdentifierId} from '../HIR';
+import {Result} from '../Utils/Result';
 
-export function validateUseMemo(fn: HIRFunction): void {
+export function validateUseMemo(fn: HIRFunction): Result<void, CompilerError> {
+  const errors = new CompilerError();
   const useMemos = new Set<IdentifierId>();
   const react = new Set<IdentifierId>();
   const functions = new Map<IdentifierId, FunctionExpression>();
@@ -61,7 +63,8 @@ export function validateUseMemo(fn: HIRFunction): void {
           }
 
           if (body.loweredFunc.func.params.length > 0) {
-            CompilerError.throwInvalidReact({
+            errors.push({
+              severity: ErrorSeverity.InvalidReact,
               reason: 'useMemo callbacks may not accept any arguments',
               description: null,
               loc: body.loc,
@@ -70,7 +73,8 @@ export function validateUseMemo(fn: HIRFunction): void {
           }
 
           if (body.loweredFunc.func.async || body.loweredFunc.func.generator) {
-            CompilerError.throwInvalidReact({
+            errors.push({
+              severity: ErrorSeverity.InvalidReact,
               reason:
                 'useMemo callbacks may not be async or generator functions',
               description: null,
@@ -84,4 +88,5 @@ export function validateUseMemo(fn: HIRFunction): void {
       }
     }
   }
+  return errors.asResult();
 }

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

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

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

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

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

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

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

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

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

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

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-jsx-in-catch-in-outer-try-with-catch.expect.md

@@ -1,38 +0,0 @@
-
-## Input
-
-```javascript
-// @validateNoJSXInTryStatements
-import {identity} from 'shared-runtime';
-
-function Component(props) {
-  let el;
-  try {
-    let value;
-    try {
-      value = identity(props.foo);
-    } catch {
-      el = <div value={value} />;
-    }
-  } catch {
-    return null;
-  }
-  return el;
-}
-
-```
-
-
-## Error
-
-```
-   9 |       value = identity(props.foo);
-  10 |     } catch {
-> 11 |       el = <div value={value} />;
-     |            ^^^^^^^^^^^^^^^^^^^^^ InvalidReact: Unexpected JSX element within a try statement. To catch errors in rendering a given component, wrap that component in an error boundary. (https://react.dev/reference/react/Component#catching-rendering-errors-with-an-error-boundary) (11:11)
-  12 |     }
-  13 |   } catch {
-  14 |     return null;
-```
-          
-      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-jsx-in-try-with-catch.expect.md

@@ -1,31 +0,0 @@
-
-## Input
-
-```javascript
-// @validateNoJSXInTryStatements
-function Component(props) {
-  let el;
-  try {
-    el = <div />;
-  } catch {
-    return null;
-  }
-  return el;
-}
-
-```
-
-
-## Error
-
-```
-  3 |   let el;
-  4 |   try {
-> 5 |     el = <div />;
-    |          ^^^^^^^ InvalidReact: Unexpected JSX element within a try statement. To catch errors in rendering a given component, wrap that component in an error boundary. (https://react.dev/reference/react/Component#catching-rendering-errors-with-an-error-boundary) (5:5)
-  6 |   } catch {
-  7 |     return null;
-  8 |   }
-```
-          
-      

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

@@ -1,37 +0,0 @@
-
-## Input
-
-```javascript
-// @validateNoSetStateInPassiveEffects
-import {useEffect, useState} from 'react';
-
-function Component() {
-  const [state, setState] = useState(0);
-  const f = () => {
-    setState(s => s + 1);
-  };
-  const g = () => {
-    f();
-  };
-  useEffect(() => {
-    g();
-  });
-  return state;
-}
-
-```
-
-
-## Error
-
-```
-  11 |   };
-  12 |   useEffect(() => {
-> 13 |     g();
-     |     ^ InvalidReact: Calling setState directly within a useEffect causes cascading renders and is not recommended. Consider alternatives to useEffect. (https://react.dev/learn/you-might-not-need-an-effect) (13:13)
-  14 |   });
-  15 |   return state;
-  16 | }
-```
-          
-      

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

@@ -1,31 +0,0 @@
-
-## Input
-
-```javascript
-// @validateNoSetStateInPassiveEffects
-import {useEffect, useState} from 'react';
-
-function Component() {
-  const [state, setState] = useState(0);
-  useEffect(() => {
-    setState(s => s + 1);
-  });
-  return state;
-}
-
-```
-
-
-## Error
-
-```
-   5 |   const [state, setState] = useState(0);
-   6 |   useEffect(() => {
->  7 |     setState(s => s + 1);
-     |     ^^^^^^^^ InvalidReact: Calling setState directly within a useEffect causes cascading renders and is not recommended. Consider alternatives to useEffect. (https://react.dev/learn/you-might-not-need-an-effect) (7:7)
-   8 |   });
-   9 |   return state;
-  10 | }
-```
-          
-      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/invalid-jsx-in-catch-in-outer-try-with-catch.expect.md

@@ -0,0 +1,73 @@
+
+## Input
+
+```javascript
+// @logger @validateNoJSXInTryStatements
+import {identity} from 'shared-runtime';
+
+function Component(props) {
+  let el;
+  try {
+    let value;
+    try {
+      value = identity(props.foo);
+    } catch {
+      el = <div value={value} />;
+    }
+  } catch {
+    return null;
+  }
+  return el;
+}
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @logger @validateNoJSXInTryStatements
+import { identity } from "shared-runtime";
+
+function Component(props) {
+  const $ = _c(4);
+  let el;
+  try {
+    let value;
+    try {
+      let t0;
+      if ($[0] !== props.foo) {
+        t0 = identity(props.foo);
+        $[0] = props.foo;
+        $[1] = t0;
+      } else {
+        t0 = $[1];
+      }
+      value = t0;
+    } catch {
+      let t0;
+      if ($[2] !== value) {
+        t0 = <div value={value} />;
+        $[2] = value;
+        $[3] = t0;
+      } else {
+        t0 = $[3];
+      }
+      el = t0;
+    }
+  } catch {
+    return null;
+  }
+  return el;
+}
+
+```
+
+## Logs
+
+```
+{"kind":"CompileError","detail":{"options":{"reason":"Unexpected JSX element within a try statement. To catch errors in rendering a given component, wrap that component in an error boundary. (https://react.dev/reference/react/Component#catching-rendering-errors-with-an-error-boundary)","description":null,"severity":"InvalidReact","loc":{"start":{"line":11,"column":11,"index":214},"end":{"line":11,"column":32,"index":235},"filename":"invalid-jsx-in-catch-in-outer-try-with-catch.ts"}}},"fnLoc":null}
+{"kind":"CompileSuccess","fnLoc":{"start":{"line":4,"column":0,"index":83},"end":{"line":17,"column":1,"index":290},"filename":"invalid-jsx-in-catch-in-outer-try-with-catch.ts"},"fnName":"Component","memoSlots":4,"memoBlocks":2,"memoValues":2,"prunedMemoBlocks":0,"prunedMemoValues":0}
+```
+      
+### Eval output
+(kind: exception) Fixture not implemented

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/invalid-jsx-in-catch-in-outer-try-with-catch.js

@@ -1,4 +1,4 @@
-// @validateNoJSXInTryStatements
+// @logger @validateNoJSXInTryStatements
 import {identity} from 'shared-runtime';
 
 function Component(props) {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/invalid-jsx-in-try-with-catch.expect.md

@@ -0,0 +1,50 @@
+
+## Input
+
+```javascript
+// @logger @validateNoJSXInTryStatements
+function Component(props) {
+  let el;
+  try {
+    el = <div />;
+  } catch {
+    return null;
+  }
+  return el;
+}
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @logger @validateNoJSXInTryStatements
+function Component(props) {
+  const $ = _c(1);
+  let el;
+  try {
+    let t0;
+    if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+      t0 = <div />;
+      $[0] = t0;
+    } else {
+      t0 = $[0];
+    }
+    el = t0;
+  } catch {
+    return null;
+  }
+  return el;
+}
+
+```
+
+## Logs
+
+```
+{"kind":"CompileError","detail":{"options":{"reason":"Unexpected JSX element within a try statement. To catch errors in rendering a given component, wrap that component in an error boundary. (https://react.dev/reference/react/Component#catching-rendering-errors-with-an-error-boundary)","description":null,"severity":"InvalidReact","loc":{"start":{"line":5,"column":9,"index":96},"end":{"line":5,"column":16,"index":103},"filename":"invalid-jsx-in-try-with-catch.ts"}}},"fnLoc":null}
+{"kind":"CompileSuccess","fnLoc":{"start":{"line":2,"column":0,"index":41},"end":{"line":10,"column":1,"index":152},"filename":"invalid-jsx-in-try-with-catch.ts"},"fnName":"Component","memoSlots":1,"memoBlocks":1,"memoValues":1,"prunedMemoBlocks":0,"prunedMemoValues":0}
+```
+      
+### Eval output
+(kind: exception) Fixture not implemented

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/invalid-jsx-in-try-with-catch.js

@@ -1,4 +1,4 @@
-// @validateNoJSXInTryStatements
+// @logger @validateNoJSXInTryStatements
 function Component(props) {
   let el;
   try {

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

@@ -0,0 +1,73 @@
+
+## Input
+
+```javascript
+// @logger @validateNoSetStateInPassiveEffects
+import {useEffect, useState} from 'react';
+
+function Component() {
+  const [state, setState] = useState(0);
+  const f = () => {
+    setState(s => s + 1);
+  };
+  const g = () => {
+    f();
+  };
+  useEffect(() => {
+    g();
+  });
+  return state;
+}
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @logger @validateNoSetStateInPassiveEffects
+import { useEffect, useState } from "react";
+
+function Component() {
+  const $ = _c(2);
+  const [state, setState] = useState(0);
+  let t0;
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+    const f = () => {
+      setState(_temp);
+    };
+
+    t0 = () => {
+      f();
+    };
+    $[0] = t0;
+  } else {
+    t0 = $[0];
+  }
+  const g = t0;
+  let t1;
+  if ($[1] === Symbol.for("react.memo_cache_sentinel")) {
+    t1 = () => {
+      g();
+    };
+    $[1] = t1;
+  } else {
+    t1 = $[1];
+  }
+  useEffect(t1);
+  return state;
+}
+function _temp(s) {
+  return s + 1;
+}
+
+```
+
+## Logs
+
+```
+{"kind":"CompileError","detail":{"options":{"reason":"Calling setState directly within a useEffect causes cascading renders and is not recommended. Consider alternatives to useEffect. (https://react.dev/learn/you-might-not-need-an-effect)","description":null,"severity":"InvalidReact","suggestions":null,"loc":{"start":{"line":13,"column":4,"index":264},"end":{"line":13,"column":5,"index":265},"filename":"invalid-setState-in-useEffect-transitive.ts","identifierName":"g"}}},"fnLoc":null}
+{"kind":"CompileSuccess","fnLoc":{"start":{"line":4,"column":0,"index":91},"end":{"line":16,"column":1,"index":292},"filename":"invalid-setState-in-useEffect-transitive.ts"},"fnName":"Component","memoSlots":2,"memoBlocks":2,"memoValues":2,"prunedMemoBlocks":0,"prunedMemoValues":0}
+```
+      
+### Eval output
+(kind: exception) Fixture not implemented

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

@@ -1,4 +1,4 @@
-// @validateNoSetStateInPassiveEffects
+// @logger @validateNoSetStateInPassiveEffects
 import {useEffect, useState} from 'react';
 
 function Component() {

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

@@ -0,0 +1,53 @@
+
+## Input
+
+```javascript
+// @logger @validateNoSetStateInPassiveEffects
+import {useEffect, useState} from 'react';
+
+function Component() {
+  const [state, setState] = useState(0);
+  useEffect(() => {
+    setState(s => s + 1);
+  });
+  return state;
+}
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @logger @validateNoSetStateInPassiveEffects
+import { useEffect, useState } from "react";
+
+function Component() {
+  const $ = _c(1);
+  const [state, setState] = useState(0);
+  let t0;
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+    t0 = () => {
+      setState(_temp);
+    };
+    $[0] = t0;
+  } else {
+    t0 = $[0];
+  }
+  useEffect(t0);
+  return state;
+}
+function _temp(s) {
+  return s + 1;
+}
+
+```
+
+## Logs
+
+```
+{"kind":"CompileError","detail":{"options":{"reason":"Calling setState directly within a useEffect causes cascading renders and is not recommended. Consider alternatives to useEffect. (https://react.dev/learn/you-might-not-need-an-effect)","description":null,"severity":"InvalidReact","suggestions":null,"loc":{"start":{"line":7,"column":4,"index":179},"end":{"line":7,"column":12,"index":187},"filename":"invalid-setState-in-useEffect.ts","identifierName":"setState"}}},"fnLoc":null}
+{"kind":"CompileSuccess","fnLoc":{"start":{"line":4,"column":0,"index":91},"end":{"line":10,"column":1,"index":224},"filename":"invalid-setState-in-useEffect.ts"},"fnName":"Component","memoSlots":1,"memoBlocks":1,"memoValues":1,"prunedMemoBlocks":0,"prunedMemoValues":0}
+```
+      
+### Eval output
+(kind: exception) Fixture not implemented

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

@@ -1,4 +1,4 @@
-// @validateNoSetStateInPassiveEffects
+// @logger @validateNoSetStateInPassiveEffects
 import {useEffect, useState} from 'react';
 
 function Component() {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/repro-dont-add-hook-guards-on-retry.expect.md

@@ -0,0 +1,27 @@
+
+## Input
+
+```javascript
+// @flow @enableEmitHookGuards @panicThreshold(none) @enableFire
+
+component Foo(useDynamicHook) {
+  useDynamicHook();
+  return <div>hello world</div>;
+}
+
+```
+
+## Code
+
+```javascript
+function Foo({
+  useDynamicHook,
+}: $ReadOnly<{ useDynamicHook: any }>): React.Node {
+  useDynamicHook();
+  return <div>hello world</div>;
+}
+
+```
+      
+### Eval output
+(kind: exception) Fixture not implemented

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/repro-dont-add-hook-guards-on-retry.js

@@ -0,0 +1,6 @@
+// @flow @enableEmitHookGuards @panicThreshold(none) @enableFire
+
+component Foo(useDynamicHook) {
+  useDynamicHook();
+  return <div>hello world</div>;
+}

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/static-components/invalid-conditionally-assigned-dynamically-constructed-component-in-render.expect.md

@@ -0,0 +1,59 @@
+
+## Input
+
+```javascript
+// @logger @validateStaticComponents
+function Example(props) {
+  let Component;
+  if (props.cond) {
+    Component = createComponent();
+  } else {
+    Component = DefaultComponent;
+  }
+  return <Component />;
+}
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @logger @validateStaticComponents
+function Example(props) {
+  const $ = _c(3);
+  let Component;
+  if (props.cond) {
+    let t0;
+    if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+      t0 = createComponent();
+      $[0] = t0;
+    } else {
+      t0 = $[0];
+    }
+    Component = t0;
+  } else {
+    Component = DefaultComponent;
+  }
+  let t0;
+  if ($[1] !== Component) {
+    t0 = <Component />;
+    $[1] = Component;
+    $[2] = t0;
+  } else {
+    t0 = $[2];
+  }
+  return t0;
+}
+
+```
+
+## Logs
+
+```
+{"kind":"CompileError","detail":{"options":{"reason":"Components created during render will reset their state each time they are created. Declare components outside of render. ","description":null,"severity":"InvalidReact","suggestions":null,"loc":{"start":{"line":9,"column":10,"index":194},"end":{"line":9,"column":19,"index":203},"filename":"invalid-conditionally-assigned-dynamically-constructed-component-in-render.ts"}}},"fnLoc":null}
+{"kind":"CompileError","detail":{"options":{"reason":"The component may be created during render","description":null,"severity":"InvalidReact","suggestions":null,"loc":{"start":{"line":5,"column":16,"index":116},"end":{"line":5,"column":33,"index":133},"filename":"invalid-conditionally-assigned-dynamically-constructed-component-in-render.ts"}}},"fnLoc":null}
+{"kind":"CompileSuccess","fnLoc":{"start":{"line":2,"column":0,"index":37},"end":{"line":10,"column":1,"index":209},"filename":"invalid-conditionally-assigned-dynamically-constructed-component-in-render.ts"},"fnName":"Example","memoSlots":3,"memoBlocks":2,"memoValues":2,"prunedMemoBlocks":0,"prunedMemoValues":0}
+```
+      
+### Eval output
+(kind: exception) Fixture not implemented

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/static-components/invalid-conditionally-assigned-dynamically-constructed-component-in-render.js

@@ -0,0 +1,10 @@
+// @logger @validateStaticComponents
+function Example(props) {
+  let Component;
+  if (props.cond) {
+    Component = createComponent();
+  } else {
+    Component = DefaultComponent;
+  }
+  return <Component />;
+}

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/static-components/invalid-dynamically-construct-component-in-render.expect.md

@@ -0,0 +1,41 @@
+
+## Input
+
+```javascript
+// @logger @validateStaticComponents
+function Example(props) {
+  const Component = createComponent();
+  return <Component />;
+}
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @logger @validateStaticComponents
+function Example(props) {
+  const $ = _c(1);
+  let t0;
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+    const Component = createComponent();
+    t0 = <Component />;
+    $[0] = t0;
+  } else {
+    t0 = $[0];
+  }
+  return t0;
+}
+
+```
+
+## Logs
+
+```
+{"kind":"CompileError","detail":{"options":{"reason":"Components created during render will reset their state each time they are created. Declare components outside of render. ","description":null,"severity":"InvalidReact","suggestions":null,"loc":{"start":{"line":4,"column":10,"index":112},"end":{"line":4,"column":19,"index":121},"filename":"invalid-dynamically-construct-component-in-render.ts"}}},"fnLoc":null}
+{"kind":"CompileError","detail":{"options":{"reason":"The component may be created during render","description":null,"severity":"InvalidReact","suggestions":null,"loc":{"start":{"line":3,"column":20,"index":83},"end":{"line":3,"column":37,"index":100},"filename":"invalid-dynamically-construct-component-in-render.ts"}}},"fnLoc":null}
+{"kind":"CompileSuccess","fnLoc":{"start":{"line":2,"column":0,"index":37},"end":{"line":5,"column":1,"index":127},"filename":"invalid-dynamically-construct-component-in-render.ts"},"fnName":"Example","memoSlots":1,"memoBlocks":1,"memoValues":1,"prunedMemoBlocks":0,"prunedMemoValues":0}
+```
+      
+### Eval output
+(kind: exception) Fixture not implemented

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/static-components/invalid-dynamically-construct-component-in-render.js

@@ -0,0 +1,5 @@
+// @logger @validateStaticComponents
+function Example(props) {
+  const Component = createComponent();
+  return <Component />;
+}

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/static-components/invalid-dynamically-constructed-component-function.expect.md

@@ -0,0 +1,46 @@
+
+## Input
+
+```javascript
+// @logger @validateStaticComponents
+function Example(props) {
+  function Component() {
+    return <div />;
+  }
+  return <Component />;
+}
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @logger @validateStaticComponents
+function Example(props) {
+  const $ = _c(1);
+  let t0;
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+    const Component = function Component() {
+      return <div />;
+    };
+
+    t0 = <Component />;
+    $[0] = t0;
+  } else {
+    t0 = $[0];
+  }
+  return t0;
+}
+
+```
+
+## Logs
+
+```
+{"kind":"CompileError","detail":{"options":{"reason":"Components created during render will reset their state each time they are created. Declare components outside of render. ","description":null,"severity":"InvalidReact","suggestions":null,"loc":{"start":{"line":6,"column":10,"index":122},"end":{"line":6,"column":19,"index":131},"filename":"invalid-dynamically-constructed-component-function.ts"}}},"fnLoc":null}
+{"kind":"CompileError","detail":{"options":{"reason":"The component may be created during render","description":null,"severity":"InvalidReact","suggestions":null,"loc":{"start":{"line":3,"column":2,"index":65},"end":{"line":5,"column":3,"index":111},"filename":"invalid-dynamically-constructed-component-function.ts"}}},"fnLoc":null}
+{"kind":"CompileSuccess","fnLoc":{"start":{"line":2,"column":0,"index":37},"end":{"line":7,"column":1,"index":137},"filename":"invalid-dynamically-constructed-component-function.ts"},"fnName":"Example","memoSlots":1,"memoBlocks":1,"memoValues":1,"prunedMemoBlocks":0,"prunedMemoValues":0}
+```
+      
+### Eval output
+(kind: exception) Fixture not implemented

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/static-components/invalid-dynamically-constructed-component-function.js

@@ -0,0 +1,7 @@
+// @logger @validateStaticComponents
+function Example(props) {
+  function Component() {
+    return <div />;
+  }
+  return <Component />;
+}

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/static-components/invalid-dynamically-constructed-component-method-call.expect.md

@@ -0,0 +1,50 @@
+
+## Input
+
+```javascript
+// @logger @validateStaticComponents
+function Example(props) {
+  const Component = props.foo.bar();
+  return <Component />;
+}
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @logger @validateStaticComponents
+function Example(props) {
+  const $ = _c(4);
+  let t0;
+  if ($[0] !== props.foo) {
+    t0 = props.foo.bar();
+    $[0] = props.foo;
+    $[1] = t0;
+  } else {
+    t0 = $[1];
+  }
+  const Component = t0;
+  let t1;
+  if ($[2] !== Component) {
+    t1 = <Component />;
+    $[2] = Component;
+    $[3] = t1;
+  } else {
+    t1 = $[3];
+  }
+  return t1;
+}
+
+```
+
+## Logs
+
+```
+{"kind":"CompileError","detail":{"options":{"reason":"Components created during render will reset their state each time they are created. Declare components outside of render. ","description":null,"severity":"InvalidReact","suggestions":null,"loc":{"start":{"line":4,"column":10,"index":110},"end":{"line":4,"column":19,"index":119},"filename":"invalid-dynamically-constructed-component-method-call.ts"}}},"fnLoc":null}
+{"kind":"CompileError","detail":{"options":{"reason":"The component may be created during render","description":null,"severity":"InvalidReact","suggestions":null,"loc":{"start":{"line":3,"column":20,"index":83},"end":{"line":3,"column":35,"index":98},"filename":"invalid-dynamically-constructed-component-method-call.ts"}}},"fnLoc":null}
+{"kind":"CompileSuccess","fnLoc":{"start":{"line":2,"column":0,"index":37},"end":{"line":5,"column":1,"index":125},"filename":"invalid-dynamically-constructed-component-method-call.ts"},"fnName":"Example","memoSlots":4,"memoBlocks":2,"memoValues":2,"prunedMemoBlocks":0,"prunedMemoValues":0}
+```
+      
+### Eval output
+(kind: exception) Fixture not implemented

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/static-components/invalid-dynamically-constructed-component-method-call.js

@@ -0,0 +1,5 @@
+// @logger @validateStaticComponents
+function Example(props) {
+  const Component = props.foo.bar();
+  return <Component />;
+}

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/static-components/invalid-dynamically-constructed-component-new.expect.md

@@ -0,0 +1,41 @@
+
+## Input
+
+```javascript
+// @logger @validateStaticComponents
+function Example(props) {
+  const Component = new ComponentFactory();
+  return <Component />;
+}
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @logger @validateStaticComponents
+function Example(props) {
+  const $ = _c(1);
+  let t0;
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+    const Component = new ComponentFactory();
+    t0 = <Component />;
+    $[0] = t0;
+  } else {
+    t0 = $[0];
+  }
+  return t0;
+}
+
+```
+
+## Logs
+
+```
+{"kind":"CompileError","detail":{"options":{"reason":"Components created during render will reset their state each time they are created. Declare components outside of render. ","description":null,"severity":"InvalidReact","suggestions":null,"loc":{"start":{"line":4,"column":10,"index":117},"end":{"line":4,"column":19,"index":126},"filename":"invalid-dynamically-constructed-component-new.ts"}}},"fnLoc":null}
+{"kind":"CompileError","detail":{"options":{"reason":"The component may be created during render","description":null,"severity":"InvalidReact","suggestions":null,"loc":{"start":{"line":3,"column":20,"index":83},"end":{"line":3,"column":42,"index":105},"filename":"invalid-dynamically-constructed-component-new.ts"}}},"fnLoc":null}
+{"kind":"CompileSuccess","fnLoc":{"start":{"line":2,"column":0,"index":37},"end":{"line":5,"column":1,"index":132},"filename":"invalid-dynamically-constructed-component-new.ts"},"fnName":"Example","memoSlots":1,"memoBlocks":1,"memoValues":1,"prunedMemoBlocks":0,"prunedMemoValues":0}
+```
+      
+### Eval output
+(kind: exception) Fixture not implemented

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/static-components/invalid-dynamically-constructed-component-new.js

@@ -0,0 +1,5 @@
+// @logger @validateStaticComponents
+function Example(props) {
+  const Component = new ComponentFactory();
+  return <Component />;
+}

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/transform-fire/repro-dont-add-hook-guards-on-retry.expect.md

@@ -0,0 +1,49 @@
+
+## Input
+
+```javascript
+// @flow @enableEmitHookGuards @panicThreshold(none) @enableFire
+import {useEffect, fire} from 'react';
+
+function Component(props, useDynamicHook) {
+  'use memo';
+  useDynamicHook();
+  const foo = props => {
+    console.log(props);
+  };
+  useEffect(() => {
+    fire(foo(props));
+  });
+
+  return <div>hello world</div>;
+}
+
+```
+
+## Code
+
+```javascript
+import { $dispatcherGuard } from "react-compiler-runtime";
+import { useFire } from "react/compiler-runtime";
+import { useEffect, fire } from "react";
+
+function Component(props, useDynamicHook) {
+  "use memo";
+
+  useDynamicHook();
+  const foo = _temp;
+  const t0 = useFire(foo);
+
+  useEffect(() => {
+    t0(props);
+  });
+  return <div>hello world</div>;
+}
+function _temp(props_0) {
+  console.log(props_0);
+}
+
+```
+      
+### Eval output
+(kind: exception) Fixture not implemented

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/transform-fire/repro-dont-add-hook-guards-on-retry.js

@@ -0,0 +1,15 @@
+// @flow @enableEmitHookGuards @panicThreshold(none) @enableFire
+import {useEffect, fire} from 'react';
+
+function Component(props, useDynamicHook) {
+  'use memo';
+  useDynamicHook();
+  const foo = props => {
+    console.log(props);
+  };
+  useEffect(() => {
+    fire(foo(props));
+  });
+
+  return <div>hello world</div>;
+}

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

@@ -26,7 +26,7 @@
     "@types/eslint": "^8.56.12",
     "@types/node": "^20.2.5",
     "babel-jest": "^29.0.3",
-    "eslint-v8": "npm:eslint@^8.57.1",
+    "eslint": "8.57.0",
     "hermes-eslint": "^0.25.1",
     "jest": "^29.5.0"
   },

compiler/packages/eslint-plugin-react-hooks/babel.config.js

@@ -1,15 +0,0 @@
-/**
- * Copyright (c) Meta Platforms, Inc. and affiliates.
- *
- * This source code is licensed under the MIT license found in the
- * LICENSE file in the root directory of this source tree.
- */
-
-module.exports = {
-  presets: ['@babel/preset-env', '@babel/preset-typescript'],
-  plugins: [
-    ['@babel/plugin-transform-private-property-in-object', {loose: true}],
-    ['@babel/plugin-transform-class-properties', {loose: true}],
-    ['@babel/plugin-transform-private-methods', {loose: true}],
-  ],
-};

compiler/packages/eslint-plugin-react-hooks/tsup.config.ts

@@ -1,36 +0,0 @@
-import {defineConfig} from 'tsup';
-
-export default defineConfig({
-  entry: ['./src/index.ts'],
-  outDir: './dist',
-  external: [
-    '@babel/core',
-    '@babel/parser',
-    '@babel/plugin-proposal-private-methods',
-    'hermes-parser',
-    'zod',
-    'zod-validation-error',
-  ],
-  splitting: false,
-  sourcemap: false,
-  dts: false,
-  bundle: true,
-  format: 'cjs',
-  platform: 'node',
-  banner: {
-    js: `/**
- * Copyright (c) Meta Platforms, Inc. and affiliates.
- *
- * This source code is licensed under the MIT license found in the
- * LICENSE file in the root directory of this source tree.
- *
- * @lightSyntaxTransform
- * @noflow
- * @nolint
- * @preventMunge
- * @preserve-invariant-messages
- */
-
-"use no memo";`,
-  },
-});

compiler/scripts/release/shared/packages.js

@@ -1,7 +1,6 @@
 const PUBLISHABLE_PACKAGES = [
   'babel-plugin-react-compiler',
   'eslint-plugin-react-compiler',
-  'eslint-plugin-react-hooks',
   'react-compiler-healthcheck',
   'react-compiler-runtime',
 ];

fixtures/owner-stacks/.gitignore

@@ -0,0 +1,23 @@
+# See https://help.github.com/articles/ignoring-files/ for more about ignoring files.
+
+# dependencies
+/node_modules
+/.pnp
+.pnp.js
+
+# testing
+/coverage
+
+# production
+/build
+
+# misc
+.DS_Store
+.env.local
+.env.development.local
+.env.test.local
+.env.production.local
+
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*

fixtures/owner-stacks/README.md

@@ -0,0 +1,70 @@
+# Getting Started with Create React App
+
+This project was bootstrapped with [Create React App](https://github.com/facebook/create-react-app).
+
+## Available Scripts
+
+In the project directory, you can run:
+
+### `yarn start`
+
+Runs the app in the development mode.\
+Open [http://localhost:3000](http://localhost:3000) to view it in your browser.
+
+The page will reload when you make changes.\
+You may also see any lint errors in the console.
+
+### `yarn test`
+
+Launches the test runner in the interactive watch mode.\
+See the section about [running tests](https://facebook.github.io/create-react-app/docs/running-tests) for more information.
+
+### `yarn build`
+
+Builds the app for production to the `build` folder.\
+It correctly bundles React in production mode and optimizes the build for the best performance.
+
+The build is minified and the filenames include the hashes.\
+Your app is ready to be deployed!
+
+See the section about [deployment](https://facebook.github.io/create-react-app/docs/deployment) for more information.
+
+### `yarn eject`
+
+**Note: this is a one-way operation. Once you `eject`, you can't go back!**
+
+If you aren't satisfied with the build tool and configuration choices, you can `eject` at any time. This command will remove the single build dependency from your project.
+
+Instead, it will copy all the configuration files and the transitive dependencies (webpack, Babel, ESLint, etc) right into your project so you have full control over them. All of the commands except `eject` will still work, but they will point to the copied scripts so you can tweak them. At this point you're on your own.
+
+You don't have to ever use `eject`. The curated feature set is suitable for small and middle deployments, and you shouldn't feel obligated to use this feature. However we understand that this tool wouldn't be useful if you couldn't customize it when you are ready for it.
+
+## Learn More
+
+You can learn more in the [Create React App documentation](https://facebook.github.io/create-react-app/docs/getting-started).
+
+To learn React, check out the [React documentation](https://reactjs.org/).
+
+### Code Splitting
+
+This section has moved here: [https://facebook.github.io/create-react-app/docs/code-splitting](https://facebook.github.io/create-react-app/docs/code-splitting)
+
+### Analyzing the Bundle Size
+
+This section has moved here: [https://facebook.github.io/create-react-app/docs/analyzing-the-bundle-size](https://facebook.github.io/create-react-app/docs/analyzing-the-bundle-size)
+
+### Making a Progressive Web App
+
+This section has moved here: [https://facebook.github.io/create-react-app/docs/making-a-progressive-web-app](https://facebook.github.io/create-react-app/docs/making-a-progressive-web-app)
+
+### Advanced Configuration
+
+This section has moved here: [https://facebook.github.io/create-react-app/docs/advanced-configuration](https://facebook.github.io/create-react-app/docs/advanced-configuration)
+
+### Deployment
+
+This section has moved here: [https://facebook.github.io/create-react-app/docs/deployment](https://facebook.github.io/create-react-app/docs/deployment)
+
+### `yarn build` fails to minify
+
+This section has moved here: [https://facebook.github.io/create-react-app/docs/troubleshooting#npm-run-build-fails-to-minify](https://facebook.github.io/create-react-app/docs/troubleshooting#npm-run-build-fails-to-minify)

fixtures/owner-stacks/package.json

@@ -0,0 +1,36 @@
+{
+  "name": "owner-stacks",
+  "version": "0.1.0",
+  "private": true,
+  "dependencies": {
+    "react": "experimental",
+    "react-dom": "experimental",
+    "react-scripts": "5.0.1",
+    "web-vitals": "^2.1.0"
+  },
+  "scripts": {
+    "prestart": "cp -a ../../build/oss-experimental/. node_modules",
+    "start": "react-scripts start",
+    "build": "react-scripts build",
+    "test": "react-scripts test",
+    "eject": "react-scripts eject"
+  },
+  "eslintConfig": {
+    "extends": [
+      "react-app",
+      "react-app/jest"
+    ]
+  },
+  "browserslist": {
+    "production": [
+      ">0.2%",
+      "not dead",
+      "not op_mini all"
+    ],
+    "development": [
+      "last 1 chrome version",
+      "last 1 firefox version",
+      "last 1 safari version"
+    ]
+  }
+}

fixtures/owner-stacks/public/index.html

@@ -0,0 +1,43 @@
+<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8" />
+    <link rel="icon" href="%PUBLIC_URL%/favicon.ico" />
+    <meta name="viewport" content="width=device-width, initial-scale=1" />
+    <meta name="theme-color" content="#000000" />
+    <meta
+      name="description"
+      content="Web site created using create-react-app"
+    />
+    <link rel="apple-touch-icon" href="%PUBLIC_URL%/logo192.png" />
+    <!--
+      manifest.json provides metadata used when your web app is installed on a
+      user's mobile device or desktop. See https://developers.google.com/web/fundamentals/web-app-manifest/
+    -->
+    <link rel="manifest" href="%PUBLIC_URL%/manifest.json" />
+    <!--
+      Notice the use of %PUBLIC_URL% in the tags above.
+      It will be replaced with the URL of the `public` folder during the build.
+      Only files inside the `public` folder can be referenced from the HTML.
+
+      Unlike "/favicon.ico" or "favicon.ico", "%PUBLIC_URL%/favicon.ico" will
+      work correctly both with client-side routing and a non-root public URL.
+      Learn how to configure a non-root public URL by running `npm run build`.
+    -->
+    <title>React App</title>
+  </head>
+  <body>
+    <noscript>You need to enable JavaScript to run this app.</noscript>
+    <div id="root"></div>
+    <!--
+      This HTML file is a template.
+      If you open it directly in the browser, you will see an empty page.
+
+      You can add webfonts, meta tags, or analytics to this file.
+      The build step will place the bundled scripts into the <body> tag.
+
+      To begin the development, run `npm start` or `yarn start`.
+      To create a production bundle, use `npm run build` or `yarn build`.
+    -->
+  </body>
+</html>

fixtures/owner-stacks/public/manifest.json

@@ -0,0 +1,25 @@
+{
+  "short_name": "React App",
+  "name": "Create React App Sample",
+  "icons": [
+    {
+      "src": "favicon.ico",
+      "sizes": "64x64 32x32 24x24 16x16",
+      "type": "image/x-icon"
+    },
+    {
+      "src": "logo192.png",
+      "type": "image/png",
+      "sizes": "192x192"
+    },
+    {
+      "src": "logo512.png",
+      "type": "image/png",
+      "sizes": "512x512"
+    }
+  ],
+  "start_url": ".",
+  "display": "standalone",
+  "theme_color": "#000000",
+  "background_color": "#ffffff"
+}

fixtures/owner-stacks/public/robots.txt

@@ -0,0 +1,3 @@
+# https://www.robotstxt.org/robotstxt.html
+User-agent: *
+Disallow:

fixtures/owner-stacks/src/App.css

@@ -0,0 +1,62 @@
+.App-header {
+  background-color: #282c34;
+  min-height: 10vh;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  font-size: calc(10px + 2vmin);
+  color: white;
+}
+
+.page {
+  display: flex;
+  height: 90vh;
+}
+
+.content {
+  flex: 4;
+  background-color: #f0f0f0;
+  padding: 20px;
+  display: flex;
+  flex-direction: column;
+  text-align: left;
+}
+
+.content.highlight {
+  background-color: yellow;
+}
+
+.sidebar {
+  flex: 1;
+  background-color: #d0d0d0;
+  padding: 20px;
+}
+
+.line-number {
+  display: inline-block;
+  width: 30px;
+  text-align: right;
+  margin-right: 10px;
+  color: #888;
+}
+
+.text-symbol {
+  position: relative;
+  display: inline-block;
+}
+
+.hovercard {
+  display: none;
+  position: absolute;
+  top: -40px;
+  left: 0;
+  background-color: white;
+  border: 1px solid #ccc;
+  padding: 5px;
+  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.2);
+  z-index: 10;
+}
+
+.text-symbol:hover .hovercard {
+  display: block;
+}

fixtures/owner-stacks/src/App.js

@@ -0,0 +1,143 @@
+import {useState} from 'react';
+import {flushSync} from 'react-dom';
+import './App.css';
+
+const text = `
+  Lorem ipsum dolor sit amet, consectetur adipiscing elit.
+  Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+  Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
+  Lorem ipsum dolor sit amet, consectetur adipiscing elit.
+  Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+  Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
+  Lorem ipsum dolor sit amet, consectetur adipiscing elit.
+  Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+  Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
+  Lorem ipsum dolor sit amet, consectetur adipiscing elit.
+  Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+  Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
+  Lorem ipsum dolor sit amet, consectetur adipiscing elit.
+  Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+  Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
+  Lorem ipsum dolor sit amet, consectetur adipiscing elit.
+  Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+  Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
+  Lorem ipsum dolor sit amet, consectetur adipiscing elit.
+  Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+  Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
+  Lorem ipsum dolor sit amet, consectetur adipiscing elit.
+  Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+  Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
+  Lorem ipsum dolor sit amet, consectetur adipiscing elit.
+  Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+  Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
+  Lorem ipsum dolor sit amet, consectetur adipiscing elit.
+  Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+  Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
+  Lorem ipsum dolor sit amet, consectetur adipiscing elit.
+  Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+  Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
+ Lorem ipsum dolor sit amet, consectetur adipiscing elit.
+  Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+  Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
+  Lorem ipsum dolor sit amet, consectetur adipiscing elit.
+  Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+  Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
+  Lorem ipsum dolor sit amet, consectetur adipiscing elit.
+  Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+  Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
+  Lorem ipsum dolor sit amet, consectetur adipiscing elit.
+  Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+  Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
+  Lorem ipsum dolor sit amet, consectetur adipiscing elit.
+  Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+  Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
+  Lorem ipsum dolor sit amet, consectetur adipiscing elit.
+  Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+  Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
+  Lorem ipsum dolor sit amet, consectetur adipiscing elit.
+  Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+  Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
+  Lorem ipsum dolor sit amet, consectetur adipiscing elit.
+  Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+  Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
+  Lorem ipsum dolor sit amet, consectetur adipiscing elit.
+  Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+  Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
+  Lorem ipsum dolor sit amet, consectetur adipiscing elit.
+  Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+  Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
+  Lorem ipsum dolor sit amet, consectetur adipiscing elit.
+  Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+  Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
+  `;
+
+const loremIpsum = text + text;
+
+function TextSymbol({char, highlight}) {
+  const randomColor = highlight
+    ? `#${Math.floor(Math.random() * 16777215).toString(16)}`
+    : 'transparent';
+  return (
+    <span className="text-symbol" style={{backgroundColor: randomColor}}>
+      {char}
+      <div className="hovercard">
+        <p>Character: {char}</p>
+        <p>Color: {randomColor}</p>
+      </div>
+    </span>
+  );
+}
+
+function TextLine({sentence, highlight, lineNumber}) {
+  const randomColor = highlight
+    ? `#${Math.floor(Math.random() * 16777215).toString(16)}`
+    : 'transparent';
+  return (
+    <div style={{backgroundColor: randomColor}}>
+      <span className="line-number">{lineNumber}</span>
+      {sentence.split('').map((char, index) => (
+        <TextSymbol key={index} char={char} highlight={highlight} />
+      ))}
+    </div>
+  );
+}
+
+function App() {
+  const [highlight, setHighlight] = useState(false);
+
+  const toggleHighlight = () => {
+    console.time('toggleHighlight');
+    flushSync(() => {
+      setHighlight(!highlight);
+    });
+    console.timeEnd('toggleHighlight');
+  };
+
+  return (
+    <div className="App">
+      <header className="App-header">Owner Stacks Stress Test</header>
+      <div className="page">
+        <div className={`content ${highlight ? 'highlight' : ''}`}>
+          {loremIpsum
+            .trim()
+            .split('\n')
+            .map((sentence, index) => (
+              <TextLine
+                key={index}
+                sentence={sentence.trim()}
+                highlight={highlight}
+                lineNumber={index + 1}
+              />
+            ))}
+        </div>
+        <div className="sidebar">
+          <button onClick={toggleHighlight}>
+            {highlight ? 'Remove Highlight' : 'Highlight Content'}
+          </button>
+        </div>
+      </div>
+    </div>
+  );
+}
+
+export default App;

fixtures/owner-stacks/src/index.css

@@ -0,0 +1,13 @@
+body {
+  margin: 0;
+  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen',
+    'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue',
+    sans-serif;
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
+}
+
+code {
+  font-family: source-code-pro, Menlo, Monaco, Consolas, 'Courier New',
+    monospace;
+}

fixtures/owner-stacks/src/index.js

@@ -0,0 +1,17 @@
+import React from 'react';
+import ReactDOM from 'react-dom/client';
+import './index.css';
+import App from './App';
+import reportWebVitals from './reportWebVitals';
+
+const root = ReactDOM.createRoot(document.getElementById('root'));
+root.render(
+  <React.StrictMode>
+    <App />
+  </React.StrictMode>
+);
+
+// If you want to start measuring performance in your app, pass a function
+// to log results (for example: reportWebVitals(console.log))
+// or send to an analytics endpoint. Learn more: https://bit.ly/CRA-vitals
+reportWebVitals();

fixtures/owner-stacks/src/logo.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 841.9 595.3"><g fill="#61DAFB"><path d="M666.3 296.5c0-32.5-40.7-63.3-103.1-82.4 14.4-63.6 8-114.2-20.2-130.4-6.5-3.8-14.1-5.6-22.4-5.6v22.3c4.6 0 8.3.9 11.4 2.6 13.6 7.8 19.5 37.5 14.9 75.7-1.1 9.4-2.9 19.3-5.1 29.4-19.6-4.8-41-8.5-63.5-10.9-13.5-18.5-27.5-35.3-41.6-50 32.6-30.3 63.2-46.9 84-46.9V78c-27.5 0-63.5 19.6-99.9 53.6-36.4-33.8-72.4-53.2-99.9-53.2v22.3c20.7 0 51.4 16.5 84 46.6-14 14.7-28 31.4-41.3 49.9-22.6 2.4-44 6.1-63.6 11-2.3-10-4-19.7-5.2-29-4.7-38.2 1.1-67.9 14.6-75.8 3-1.8 6.9-2.6 11.5-2.6V78.5c-8.4 0-16 1.8-22.6 5.6-28.1 16.2-34.4 66.7-19.9 130.1-62.2 19.2-102.7 49.9-102.7 82.3 0 32.5 40.7 63.3 103.1 82.4-14.4 63.6-8 114.2 20.2 130.4 6.5 3.8 14.1 5.6 22.5 5.6 27.5 0 63.5-19.6 99.9-53.6 36.4 33.8 72.4 53.2 99.9 53.2 8.4 0 16-1.8 22.6-5.6 28.1-16.2 34.4-66.7 19.9-130.1 62-19.1 102.5-49.9 102.5-82.3zm-130.2-66.7c-3.7 12.9-8.3 26.2-13.5 39.5-4.1-8-8.4-16-13.1-24-4.6-8-9.5-15.8-14.4-23.4 14.2 2.1 27.9 4.7 41 7.9zm-45.8 106.5c-7.8 13.5-15.8 26.3-24.1 38.2-14.9 1.3-30 2-45.2 2-15.1 0-30.2-.7-45-1.9-8.3-11.9-16.4-24.6-24.2-38-7.6-13.1-14.5-26.4-20.8-39.8 6.2-13.4 13.2-26.8 20.7-39.9 7.8-13.5 15.8-26.3 24.1-38.2 14.9-1.3 30-2 45.2-2 15.1 0 30.2.7 45 1.9 8.3 11.9 16.4 24.6 24.2 38 7.6 13.1 14.5 26.4 20.8 39.8-6.3 13.4-13.2 26.8-20.7 39.9zm32.3-13c5.4 13.4 10 26.8 13.8 39.8-13.1 3.2-26.9 5.9-41.2 8 4.9-7.7 9.8-15.6 14.4-23.7 4.6-8 8.9-16.1 13-24.1zM421.2 430c-9.3-9.6-18.6-20.3-27.8-32 9 .4 18.2.7 27.5.7 9.4 0 18.7-.2 27.8-.7-9 11.7-18.3 22.4-27.5 32zm-74.4-58.9c-14.2-2.1-27.9-4.7-41-7.9 3.7-12.9 8.3-26.2 13.5-39.5 4.1 8 8.4 16 13.1 24 4.7 8 9.5 15.8 14.4 23.4zM420.7 163c9.3 9.6 18.6 20.3 27.8 32-9-.4-18.2-.7-27.5-.7-9.4 0-18.7.2-27.8.7 9-11.7 18.3-22.4 27.5-32zm-74 58.9c-4.9 7.7-9.8 15.6-14.4 23.7-4.6 8-8.9 16-13 24-5.4-13.4-10-26.8-13.8-39.8 13.1-3.1 26.9-5.8 41.2-7.9zm-90.5 125.2c-35.4-15.1-58.3-34.9-58.3-50.6 0-15.7 22.9-35.6 58.3-50.6 8.6-3.7 18-7 27.7-10.1 5.7 19.6 13.2 40 22.5 60.9-9.2 20.8-16.6 41.1-22.2 60.6-9.9-3.1-19.3-6.5-28-10.2zM310 490c-13.6-7.8-19.5-37.5-14.9-75.7 1.1-9.4 2.9-19.3 5.1-29.4 19.6 4.8 41 8.5 63.5 10.9 13.5 18.5 27.5 35.3 41.6 50-32.6 30.3-63.2 46.9-84 46.9-4.5-.1-8.3-1-11.3-2.7zm237.2-76.2c4.7 38.2-1.1 67.9-14.6 75.8-3 1.8-6.9 2.6-11.5 2.6-20.7 0-51.4-16.5-84-46.6 14-14.7 28-31.4 41.3-49.9 22.6-2.4 44-6.1 63.6-11 2.3 10.1 4.1 19.8 5.2 29.1zm38.5-66.7c-8.6 3.7-18 7-27.7 10.1-5.7-19.6-13.2-40-22.5-60.9 9.2-20.8 16.6-41.1 22.2-60.6 9.9 3.1 19.3 6.5 28.1 10.2 35.4 15.1 58.3 34.9 58.3 50.6-.1 15.7-23 35.6-58.4 50.6zM320.8 78.4z"/><circle cx="420.9" cy="296.5" r="45.7"/><path d="M520.5 78.1z"/></g></svg>

fixtures/owner-stacks/src/reportWebVitals.js

@@ -0,0 +1,13 @@
+const reportWebVitals = onPerfEntry => {
+  if (onPerfEntry && onPerfEntry instanceof Function) {
+    import('web-vitals').then(({getCLS, getFID, getFCP, getLCP, getTTFB}) => {
+      getCLS(onPerfEntry);
+      getFID(onPerfEntry);
+      getFCP(onPerfEntry);
+      getLCP(onPerfEntry);
+      getTTFB(onPerfEntry);
+    });
+  }
+};
+
+export default reportWebVitals;