module: exclude node:ffi from builtinModules when flag is disabled

[ljharb]

Module.builtinModules is supposed to only list modules that are accessible to user code. node:ffi requires --experimental-ffi to be required, so filter it out when the flag is not set, mirroring the existing handling for --experimental-quic.

Refs: #63137 (comment), #62072

[nodejs-github-bot]

Review requested:

• @nodejs/loaders

[github-actions]

Fast-track has been requested by @aduh95. Please 👍 to approve.

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/73210/

[aduh95]

Related failure to address:

=== release test-ffi-module ===
Path: ffi/test-ffi-module
Error: --- stderr ---
(node:87480) ExperimentalWarning: FFI is an experimental feature and might change at any time
(Use `node --trace-warnings ...` to show where the warning was created)
--- stdout ---
Test failure: 'ffi builtin is listed'
Location: test/ffi/test-ffi-module.js:34:1
AssertionError [ERR_ASSERTION]: Expected values to be strictly equal:

'false' !== 'true'

    at TestContext.<anonymous> (/home/runner/work/_temp/node-v27.0.0-nightly2026-05-069c7b977313-slim/test/ffi/test-ffi-module.js:42:10)
    at Test.runInAsyncScope (node:async_hooks:226:14)
    at Test.run (node:internal/test_runner/test:1306:25)
    at Test.processPendingSubtests (node:internal/test_runner/test:897:18)
    at Test.postRun (node:internal/test_runner/test:1447:19)
    at Test.run (node:internal/test_runner/test:1372:12)
    at async Test.processPendingSubtests (node:internal/test_runner/test:897:7) {
  generatedMessage: true,
  code: 'ERR_ASSERTION',
  actual: 'false',
  expected: 'true',
  operator: 'strictEqual',
  diff: 'simple'
}
Command: out/Release/node --experimental-ffi --test-reporter=./test/common/test-error-reporter.js --test-reporter-destination=stdout /home/runner/work/_temp/node-v27.0.0-nightly2026-05-069c7b977313-slim/test/ffi/test-ffi-module.js

===
=== 1 tests failed
===

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/73212/

[ljharb]

@aduh95 thanks, fixed!

[mcollina]

lgtm

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/73214/

[ljharb]

the CI failure looks spurious?

[aduh95]

It's a bit annoying that you force-pushed my commit out, it seems unlikely there will be time to include this PR in 26.1.0 now