doc,lib,src: throw on missing WebAssembly or RX support by ShogunPanda · Pull Request #66533 · nodejs/node

ShogunPanda · 2026-10-05T14:36:54Z

Summary

When WebAssembly or RX memory are not available, eventually due to --jitless, a catchable error is now thrown.

In the docs is also clearly stated that if a feature requires one of the features above, Node.js guarantess no fallback.

Changes

Report ERR_WEBASSEMBLY_NOT_SUPPORTED for WASM module imports, including source-phase imports.
Introduce ERR_RX_MEMORY_NOT_SUPPORTED for otherwise eligible FFI Fast API functions when the executable-memory probe fails.
Diagnose missing RX support after libffi callback allocation fails, preserving platform-specific static trampolines and other FFI errors.
Decouple the RX capability probe from Fast API emitter availability.
Document capability requirements and fallback limitations, and add jitless and Linux seccomp regression coverage.

Notes

A Undici / Fetch similar change is deferred to a separate upstream change.

Assisted-By: OpenAI:GPT-6.1 Sol <openai/gpt-6.1-sol>

Signed-off-by: Paolo Insogna <paolo@cowtech.it>

nodejs-github-bot · 2026-10-05T14:37:50Z

aduh95

LGTM % linter failures

ShogunPanda · 2026-10-05T15:18:42Z

Undici PR: nodejs/undici#5966

mcollina

lgtm

codecov · 2026-10-05T16:52:37Z

Codecov Report

❌ Patch coverage is 68.96552% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.42%. Comparing base (bbd566d) to head (2b63e8c).
⚠️ Report is 64 commits behind head on main.

Files with missing lines	Patch %	Lines
src/ffi/fast.cc	57.14%	6 Missing ⚠️
src/node_ffi.cc	72.72%	1 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #66533      +/-   ##
==========================================
- Coverage   92.74%   90.42%   -2.32%     
==========================================
  Files         422      791     +369     
  Lines      193170   276531   +83361     
  Branches    29783    53097   +23314     
==========================================
+ Hits       179160   250064   +70904     
- Misses      13682    16856    +3174     
- Partials      328     9611    +9283

Files with missing lines	Coverage Δ
lib/internal/modules/esm/translators.js	`97.57% <100.00%> (+6.03%)`	⬆️
src/ffi/fast.h	`100.00% <ø> (ø)`
src/ffi/jit_memory.cc	`89.47% <ø> (ø)`
src/node_errors.h	`86.95% <ø> (ø)`
src/node_ffi.cc	`72.62% <72.72%> (ø)`
src/ffi/fast.cc	`69.95% <57.14%> (ø)`

... and 497 files with indirect coverage changes

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Signed-off-by: Paolo Insogna <paolo@cowtech.it>

nodejs-github-bot · 2026-10-06T11:21:06Z

CI: https://ci.nodejs.org/job/node-test-pull-request/78206/

aduh95 · 2026-10-06T13:33:24Z

What's the semverness of this change? IIUC there's already an error thrown, this change only improves the DX by throwing a proper one, so semver-minor PRs that contain new features and should be released in the next minor version. ?

ShogunPanda · 2026-10-06T14:26:45Z

@aduh95 Yes, I concur: minor.
The only possible candiate for a semver-major change could have been the intent change in the docs, but it's just an intent and it's not changing what's happening today.

nodejs-github-bot · 2026-10-06T14:28:12Z

CI: https://ci.nodejs.org/job/node-test-pull-request/78214/

nodejs-github-bot · 2026-10-06T20:35:54Z

CI: https://ci.nodejs.org/job/node-test-pull-request/78227/

Signed-off-by: Paolo Insogna <paolo@cowtech.it>

mcollina

lgtm

nodejs-github-bot · 2026-10-07T09:23:09Z

CI: https://ci.nodejs.org/job/node-test-pull-request/78237/

github-actions · 2026-10-08T11:23:26Z

Failed to start CI

   ℹ  Existing CI run found: https://ci.nodejs.org/job/node-test-pull-request/78237/
   ✖  Refusing to start a potentially duplicate CI job. Check the existing CI run in Jenkins and rebase the PR if needed. To start a new CI run manually: ncu-ci run https://github.com/nodejs/node/pull/66533

Full Auto Start CI output

�[36m⠋�[39m Getting reviews from nodejs/node/pull/66533
�[36m⠋�[39m Getting commits from nodejs/node/pull/66533
�[36m⠙�[39m Validating Jenkins credentials
�[36m⠙�[39m Validating Jenkins credentials
✔  Jenkins credentials valid
�[36m⠹�[39m Getting comments from nodejs/node/pull/66533
�[36m⠸�[39m Querying data for job/node-test-pull-request/78237/
�[36m⠸�[39m Querying data for job/node-test-pull-request/78237/
�[36m⠸�[39m Querying API for job/node-test-pull-request/78237/
✔  Build data downloaded
   ℹ  Existing CI run found: https://ci.nodejs.org/job/node-test-pull-request/78237/
   ✖  Refusing to start a potentially duplicate CI job. Check the existing CI run in Jenkins and rebase the PR if needed. To start a new CI run manually: ncu-ci run https://github.com/nodejs/node/pull/66533

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nodejs-github-bot · 2026-10-08T11:33:41Z

CI: https://ci.nodejs.org/job/node-test-pull-request/78252/

aduh95 · 2026-10-08T11:38:32Z

@ShogunPanda can you please refrain from cancelling top-level jobs? Not only the cancellation does not propagate to the lower jobs (the ones that are actually stuck), but it also removes the possibility to resume the CI.

In any case, launching a new CI is not going to help as long as the Windows CI is not available

ShogunPanda · 2026-10-08T11:41:10Z

@aduh95 Noted, didn't know about it. Sorry.
But I saw other job progressing. Do you mind clarifying the status of the CI at the moment?

aduh95 · 2026-10-08T11:44:46Z

I don't know, I'm not part of the Build WG, but looking at https://ci.nodejs.org/job/node-test-commit-windows-fanned/, the situation has not evolved. I'm not sure anyone has even opened an issue to nodejs/build, in which case this is not even being investigated in all likeliness, that should be the first step

doc,lib,src: throw on missing WebAssembly or RX support

3afc022

Signed-off-by: Paolo Insogna <paolo@cowtech.it>

ShogunPanda requested review from aduh95, joyeecheung and mcollina October 5, 2026 14:36

ShogunPanda mentioned this pull request Oct 5, 2026

src: do not use --allow-overwriting-for-next-flag #66524

Closed

nodejs-github-bot added c++ Issues and PRs that require attention from people who are familiar with C++. lib / src Issues and PRs involving general changes in the lib/ or src/ directories. needs-ci PRs that need a full CI run. labels Oct 5, 2026

aduh95 reviewed Oct 5, 2026

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Comment thread test/es-module/test-esm-wasm-jitless.mjs Outdated

aduh95 approved these changes Oct 5, 2026

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ShogunPanda mentioned this pull request Oct 5, 2026

feat: Throw an error when WebAssembly is not available. nodejs/undici#5966

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mcollina approved these changes Oct 5, 2026

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ronag approved these changes Oct 5, 2026

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addaleax approved these changes Oct 5, 2026

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TheOneTheOnlyJJ reviewed Oct 5, 2026

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Comment thread src/node_errors.h Outdated

MikeMcC399 mentioned this pull request Oct 5, 2026

Revert "deps,lib,tools: remove jitless and lite modes" #66516

Merged

fixup

0484eca

Signed-off-by: Paolo Insogna <paolo@cowtech.it>

ronag approved these changes Oct 6, 2026

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aduh95 added the semver-minor PRs that contain new features and should be released in the next minor version. label Oct 6, 2026

fixup

2b63e8c

Signed-off-by: Paolo Insogna <paolo@cowtech.it>

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ShogunPanda commented Oct 5, 2026

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