Thanks!

Any chance you could also make the (new'ish) weak event handler machinery in event_target use this? (It's the other place I know in the code that uses FinalizationRegistry and WeakRef).

I wouldn't expect this to work yet. WeakRef can still be disabled with a V8 flag (--no-harmony-weak-refs) so they are not available while bootstrapping.

I might just go change that, moving the error snapshot use instead of creation.

FWIW, Node.js already fails to start when the --no-harmony-weak-refs flag is used...

root@DESKTOP-5KK9VIR:~/node/node# ./node --no-harmony-weak-refs
node:internal/util/iterable_weak_map:14
  class SafeFinalizationRegistry extends globalThis.FinalizationRegistry {}
                                                    ^

TypeError: Class extends value undefined is not a constructor or null
    at node:internal/util/iterable_weak_map:14:53
    at NativeModule.compileForInternalLoader (node:internal/bootstrap/loaders:283:7)
    at nativeModuleRequire (node:internal/bootstrap/loaders:312:14)
    at node:internal/source_map/source_map_cache:28:29
    at NativeModule.compileForInternalLoader (node:internal/bootstrap/loaders:283:7)
    at nativeModuleRequire (node:internal/bootstrap/loaders:312:14)
    at node:internal/modules/cjs/loader:78:5
    at NativeModule.compileForInternalLoader (node:internal/bootstrap/loaders:283:7)
    at nativeModuleRequire (node:internal/bootstrap/loaders:312:14)
    at node:internal/modules/esm/loader:4:1

@jasnell the issue is that V8 disables flagged globals during snapshot, regardless of whether you expect them to be available later or not.

I'v e submitted https://chromium-review.googlesource.com/c/v8/v8/+/2741582/ to unblock this.

@aduh95 cloudflare uses that flag for workers, probably can't land.

I'd like to talk to the V8 team about a new flag system which allows them to be snapshotted, but they don't seem to care at all about our design constraints or maintaining contact with us so it's been delayed.

Flag has been removed upstream, I've opened #38162 to test if that makes the tests pass.

Tests are passing :) @ExE-Boss I've forced-pushed to your branch to include the V8 patch, please have a look in case I did something wrong (oh and I added f98f3b551cc5433ba2224178e6f1a03f0af32769, I hope that's OK; if you disagree of course feel free to revert).

CI: https://ci.nodejs.org/job/node-test-pull-request/37337/

CI: https://ci.nodejs.org/job/node-test-pull-request/37380/

CI: https://ci.nodejs.org/job/node-test-pull-request/37416/

CI: https://ci.nodejs.org/job/node-test-pull-request/37421/

CI: https://ci.nodejs.org/job/node-test-pull-request/37424/

Landed in 78343bb