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-sEXPORT_ES6 and multithreading too old browsers. #25408

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Merged
merged 5 commits into from
Sep 29, 2025
Merged

-sEXPORT_ES6 and multithreading too old browsers. #25408

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02d750a
Abort build if attempting to target -sEXPORT_ES6 and multithreading w…
juj Sep 28, 2025
eadf19e
Demote error to warning
juj Sep 29, 2025
5a33a11
Add feature for Worker ES6 modules
juj Sep 29, 2025
a1ec7f7
ruff
juj Sep 29, 2025
ce7e3fe
Fix node
juj Sep 29, 2025
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9 changes: 9 additions & 0 deletions src/lib/libpthread.js
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Original file line number Diff line number Diff line change
Expand Up @@ -42,6 +42,15 @@ const pthreadWorkerScript = TARGET_JS_NAME;
// See https://github.com/emscripten-core/emscripten/issues/22394
const pthreadWorkerOptions = `{
#if EXPORT_ES6
#if MIN_FIREFOX_VERSION < 114
#error new Worker() supports ECMAScript module only starting from Firefox 114. Pass -sMIN_FIREFOX_VERSION=114 to target -sEXPORT_ES6 with -pthread. See https://caniuse.com/mdn-api_worker_worker_ecmascript_modules
#endif
#if MIN_CHROME_VERSION < 80
#error new Worker() supports ECMAScript module only starting from Chrome 80. Pass -sMIN_CHROME_VERSION=80 to target -sEXPORT_ES6 with -pthread. See https://caniuse.com/mdn-api_worker_worker_ecmascript_modules
#endif
#if MIN_SAFARI_VERSION < 150000
#error new Worker() supports ECMAScript module only starting from Safari 15. Pass -sMIN_SAFARI_VERSION=150000 to target -sEXPORT_ES6 with -pthread. See https://caniuse.com/mdn-api_worker_worker_ecmascript_modules
#endif
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It is even possible to hit these error now that the feature is added? i.e. -sEXPORT_ES6 + -pthreads will now force the correct versions or fail, right?

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I was pondering the same, so wanted to add these in to verify that won't be the case. Doesn't hurt to have them?

Or I could remove them - but seems like they're safe to have, they could trigger on possible refactors down the road.

'type': 'module',
#endif
#if ENVIRONMENT_MAY_BE_NODE
Expand Down
9 changes: 9 additions & 0 deletions src/lib/libwasm_worker.js
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Expand Up @@ -40,6 +40,15 @@
`;
const wasmWorkerOptions = `{
#if EXPORT_ES6
#if MIN_FIREFOX_VERSION < 114
#error new Worker() supports ECMAScript module only starting from Firefox 114. Pass -sMIN_FIREFOX_VERSION=114 to target -sEXPORT_ES6 with -sWASM_WORKERS. See https://caniuse.com/mdn-api_worker_worker_ecmascript_modules
#endif
#if MIN_CHROME_VERSION < 80
#error new Worker() supports ECMAScript module only starting from Chrome 80. Pass -sMIN_CHROME_VERSION=80 to target -sEXPORT_ES6 with -sWASM_WORKERS. See https://caniuse.com/mdn-api_worker_worker_ecmascript_modules
#endif
#if MIN_SAFARI_VERSION < 150000
#error new Worker() supports ECMAScript module only starting from Safari 15. Pass -sMIN_SAFARI_VERSION=150000 to target -sEXPORT_ES6 with -sWASM_WORKERS. See https://caniuse.com/mdn-api_worker_worker_ecmascript_modules
#endif
'type': 'module',
#endif
#if ENVIRONMENT_MAY_BE_NODE
Expand Down
13 changes: 13 additions & 0 deletions tools/feature_matrix.py
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Expand Up @@ -38,6 +38,7 @@ class Feature(IntEnum):
THREADS = auto()
PROMISE_ANY = auto()
MEMORY64 = auto()
WORKER_ES6_MODULES = auto()


disable_override_features = set()
Expand Down Expand Up @@ -86,6 +87,14 @@ class Feature(IntEnum):
'safari': UNSUPPORTED,
'node': 230000,
},
# https://caniuse.com/mdn-api_worker_worker_ecmascript_modules: The ability to
# call new Worker(url, { type: 'module' });
Feature.WORKER_ES6_MODULES: {
'chrome': 80,
'firefox': 114,
'safari': 150000,
'node': 0, # This is a browser only feature, no requirements on Node.js
},
}

# Static assertion to check that we actually need each of the above feature flags
Expand Down Expand Up @@ -173,3 +182,7 @@ def apply_min_browser_versions():
enable_feature(Feature.BULK_MEMORY, 'shared-mem')
if settings.MEMORY64 == 1:
enable_feature(Feature.MEMORY64, 'MEMORY64')
if settings.EXPORT_ES6 and settings.PTHREADS:
enable_feature(Feature.WORKER_ES6_MODULES, 'EXPORT_ES6 with -pthread')
if settings.EXPORT_ES6 and settings.WASM_WORKERS:
enable_feature(Feature.WORKER_ES6_MODULES, 'EXPORT_ES6 with -sWASM_WORKERS')