[Pthreads] Fix worker.js in ES6 module environments

ChangeLog.md

@@ -20,6 +20,10 @@ See docs/process.md for more on how version tagging works.
 
 3.1.52 (in development)
 -----------------------
+- Building with `pthreads+EXPORT_ES6` will now emit the worker file as
+  `NAME.worker.mjs` rather than `.js`. This is a necessary breaking change to
+  resolve other `pthreads+EXPORT_ES6` issues in Node.js (because Node.js is
+  affected by the suffix in some cases). (#21041)
 - Include paths added by ports (e.g. `-sUSE_SDL=2`) now use `-isystem` rather
   then `-I`.  This means that files in user-specified include directories will
   now take precedence over port includes. (#21014)

src/worker.js

@@ -18,6 +18,16 @@ var ENVIRONMENT_IS_NODE = typeof process == 'object' && typeof process.versions
 if (ENVIRONMENT_IS_NODE) {
   // Create as web-worker-like an environment as we can.
 
+  // See the parallel code in shell.js, but here we don't need the condition on
+  // multi-environment builds, as we do not have the need to interact with the
+  // modularization logic as shell.js must (see link.py:node_es6_imports and
+  // how that is used in link.py).
+#if EXPORT_ES6
+  const { createRequire } = await import('module');
+  /** @suppress{duplicate} */
+  var require = createRequire(import.meta.url);
+#endif
+
   var nodeWorkerThreads = require('worker_threads');
 
   var parentPort = nodeWorkerThreads.parentPort;
@@ -32,7 +42,13 @@ if (ENVIRONMENT_IS_NODE) {
     require,
     Module,
     location: {
-      href: __filename
+      // __filename is undefined in ES6 modules, and import.meta.url only in ES6
+      // modules.
+#if EXPORT_ES6
+      href: typeof __filename !== 'undefined' ? __filename : import.meta.url
+#else
+      href: typeof __filename
+#endif
     },
     Worker: nodeWorkerThreads.Worker,
     importScripts: (f) => vm.runInThisContext(fs.readFileSync(f, 'utf8'), {filename: f}),

test/test_other.py

@@ -343,10 +343,10 @@ def test_emcc_output_worker_mjs(self, args):
                       test_file('hello_world.c')] + args)
     src = read_file('subdir/hello_world.mjs')
     self.assertContained("new URL('hello_world.wasm', import.meta.url)", src)
-    self.assertContained("new Worker(new URL('hello_world.worker.js', import.meta.url), {type: 'module'})", src)
+    self.assertContained("new Worker(new URL('hello_world.worker.mjs', import.meta.url), {type: 'module'})", src)
     self.assertContained("new Worker(pthreadMainJs, {type: 'module'})", src)
     self.assertContained('export default Module;', src)
-    src = read_file('subdir/hello_world.worker.js')
+    src = read_file('subdir/hello_world.worker.mjs')
     self.assertContained("import('./hello_world.mjs')", src)
     self.assertContained('hello, world!', self.run_js('subdir/hello_world.mjs'))
 
@@ -358,7 +358,7 @@ def test_emcc_output_worker_mjs_single_file(self):
                       test_file('hello_world.c'), '-sSINGLE_FILE'])
     src = read_file('hello_world.mjs')
     self.assertNotContained("new URL('data:", src)
-    self.assertContained("new Worker(new URL('hello_world.worker.js', import.meta.url), {type: 'module'})", src)
+    self.assertContained("new Worker(new URL('hello_world.worker.mjs', import.meta.url), {type: 'module'})", src)
     self.assertContained("new Worker(pthreadMainJs, {type: 'module'})", src)
     self.assertContained('hello, world!', self.run_js('hello_world.mjs'))
 
@@ -400,11 +400,16 @@ def test_export_es6_allows_export_in_post_js(self):
     src = read_file('a.out.js')
     self.assertContained('export{doNothing};', src)
 
+  @parameterized({
+    '': (False,),
+    'package_json': (True,),
+  })
   @parameterized({
     '': ([],),
-    'pthreads': (['-pthread'],),
+    # load a worker before startup to check ES6 modules there as well
+    'pthreads': (['-pthread', '-sPTHREAD_POOL_SIZE=1'],),
   })
-  def test_export_es6(self, args):
+  def test_export_es6(self, args, package_json):
     self.run_process([EMCC, test_file('hello_world.c'), '-sEXPORT_ES6',
                       '-o', 'hello.mjs'] + args)
     # In ES6 mode we use MODULARIZE, so we must instantiate an instance of the
@@ -413,6 +418,12 @@ def test_export_es6(self, args):
       import Hello from "./hello.mjs";
       Hello();
     ''')
+
+    if package_json:
+      # This makes node load all files in the directory as ES6 modules,
+      # including the worker.js file.
+      create_file('package.json', '{"type":"module"}')
+
     self.assertContained('hello, world!', self.run_js('runner.mjs'))
 
   def test_emcc_out_file(self):

tools/link.py

@@ -513,6 +513,10 @@ def do_split_module(wasm_file, options):
   building.run_binaryen_command('wasm-split', wasm_file + '.orig', outfile=wasm_file, args=args)
 
 
+def get_worker_js_suffix():
+  return '.worker.mjs' if settings.EXPORT_ES6 else '.worker.js'
+
+
 def setup_pthreads(target):
   if settings.RELOCATABLE:
     # phtreads + dyanmic linking has certain limitations
@@ -569,7 +573,7 @@ def setup_pthreads(target):
   building.user_requested_exports.update(worker_imports)
 
   # set location of worker.js
-  settings.PTHREAD_WORKER_FILE = unsuffixed_basename(target) + '.worker.js'
+  settings.PTHREAD_WORKER_FILE = unsuffixed_basename(target) + get_worker_js_suffix()
 
   if settings.MINIMAL_RUNTIME:
     building.user_requested_exports.add('exit')
@@ -1999,12 +2003,27 @@ def phase_memory_initializer(memfile):
   final_js += '.mem.js'
 
 
+# Unmangle previously mangled `import.meta` and `await import` references in
+# both main code and libraries.
+# See also: `preprocess` in parseTools.js.
+def fix_es6_import_statements(js_file):
+  if not settings.EXPORT_ES6 or not settings.USE_ES6_IMPORT_META:
+    return
+
+  src = read_file(js_file)
+  write_file(js_file, src
+             .replace('EMSCRIPTEN$IMPORT$META', 'import.meta')
+             .replace('EMSCRIPTEN$AWAIT$IMPORT', 'await import'))
+
+
 def create_worker_file(input_file, target_dir, output_file):
   output_file = os.path.join(target_dir, output_file)
   input_file = utils.path_from_root(input_file)
   contents = shared.read_and_preprocess(input_file, expand_macros=True)
   write_file(output_file, contents)
 
+  fix_es6_import_statements(output_file)
+
   # Minify the worker JS file, if JS minification is enabled.
   if settings.MINIFY_WHITESPACE:
     contents = building.acorn_optimizer(output_file, ['minifyWhitespace'], return_output=True)
@@ -2045,17 +2064,8 @@ def phase_final_emitting(options, state, target, wasm_target, memfile):
     # mode)
     final_js = building.closure_compiler(final_js, advanced=False, extra_closure_args=options.closure_args)
 
-  # Unmangle previously mangled `import.meta` and `await import` references in
-  # both main code and libraries.
-  # See also: `preprocess` in parseTools.js.
-  if settings.EXPORT_ES6 and settings.USE_ES6_IMPORT_META:
-    src = read_file(final_js)
-    final_js += '.esmeta.js'
-    write_file(final_js, src
-               .replace('EMSCRIPTEN$IMPORT$META', 'import.meta')
-               .replace('EMSCRIPTEN$AWAIT$IMPORT', 'await import'))
-    shared.get_temp_files().note(final_js)
-    save_intermediate('es6-module')
+  fix_es6_import_statements(final_js)
+  save_intermediate('es6-module')
 
   # Apply pre and postjs files
   if options.extern_pre_js or options.extern_post_js:
@@ -2600,7 +2610,7 @@ def generate_worker_js(target, js_target, target_basename):
     proxy_worker_filename = get_subresource_location(js_target)
   else:
     # compiler output goes in .worker.js file
-    move_file(js_target, shared.replace_suffix(js_target, '.worker.js'))
+    move_file(js_target, shared.replace_suffix(js_target, get_worker_js_suffix()))
     worker_target_basename = target_basename + '.worker'
     proxy_worker_filename = (settings.PROXY_TO_WORKER_FILENAME or worker_target_basename) + '.js'