feat: add React Compiler support for ActionMenu

[joshblack]

Closes N/A

Changelog

New

N/A

Changed

• Enabled React Compiler support for ActionMenu.
• Updated ActionMenu tests to render compiled JSX helpers as components and keep the external-anchor replacement assertion compiler-safe.
• Added a patch changeset for the rendering performance improvement.

Removed

N/A

Rollout strategy

• Patch release
• Minor release
• Major release; if selected, include a written rollout or migration plan
• None; if selected, include a brief description as to why

Testing & Reviewing

• npx eslint --no-cache packages/react/src/ActionMenu/**/*.{ts,tsx}
• npm test -- --run packages/react/src/ActionMenu/ActionMenu.test.tsx packages/react/src/__tests__/deprecated/ActionMenu.test.tsx packages/react/src/AnchoredOverlay/AnchoredOverlay.test.tsx
• npm run build && npm test -- --run && npm run type-check && npm run lint && npm run lint:css && npm run format:diff
• Storybook started and responded locally at http://localhost:6006.

Merge checklist

• Added/updated tests (not needed; existing coverage validated)
• Added/updated documentation (not needed)
• Added/updated previews (not needed)
• Changes are SSR compatible
• Tested in Chrome
• Tested in Firefox
• Tested in Safari
• Tested in Edge
• (GitHub staff only) Integration tests pass at github/github-ui (Learn more about how to run integration tests)

[changeset-bot]

🦋 Changeset detected

Latest commit: c457dd8

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@primer/react	Patch

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Click here if you're a maintainer who wants to add another changeset to this PR

[github-actions]

⚠️ Action required

👋 Hi, this pull request contains changes to the source code that github/github-ui depends on. If you are GitHub staff, test these changes with github/github-ui using the integration workflow. If this doesn't work, you can also use the original workflow here. Check the integration testing docs for step-by-step instructions. Or, apply the integration-tests: skipped manually label to skip these checks.

To publish a canary release for integration testing, apply the Canary Release label to this PR.

[Copilot]

Pull request overview

Enables React Compiler support for ActionMenu by removing it from the compiler “unsupported” list and updating ActionMenu tests to be compatible with compiled output expectations.

Changes:

• Allow src/ActionMenu/**/*.tsx to be treated as React Compiler-supported.
• Refactor ActionMenu tooltip-v2 test helpers to be rendered as components (compiler-friendly).
• Stabilize the “replaceable anchor” assertion by waiting for the computed anchor-name / position-anchor linkage, and add a patch changeset noting the perf improvement.

Show a summary per file

File	Description
packages/react/src/ActionMenu/ActionMenu.test.tsx	Updates test helpers and assertions to be React Compiler-safe.
packages/react/script/react-compiler.mjs	Removes ActionMenu from the unsupported patterns list, enabling compilation support.
.changeset/react-compiler-action-menu.md	Adds a patch changeset for the consumer-facing rendering performance improvement.

Copilot's findings

• Files reviewed: 3/3 changed files
• Comments generated: 2