-sEXPORT_ES6 and multithreading too old browsers. (#25408)

~~Abort build if attempting to target -sEXPORT_ES6 and multithreading
with too old target browser versions.~~

Add ES6 Module Workers as feature in the feature matrix.

Author: juj

src/lib/libpthread.js

@@ -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
         'type': 'module',
 #endif
 #if ENVIRONMENT_MAY_BE_NODE

src/lib/libwasm_worker.js

@@ -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

tools/feature_matrix.py

@@ -38,6 +38,7 @@ class Feature(IntEnum):
   THREADS = auto()
   PROMISE_ANY = auto()
   MEMORY64 = auto()
+  WORKER_ES6_MODULES = auto()
 
 
 disable_override_features = set()
@@ -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
@@ -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')