Fix _scriptDir for node.js + USE_PTHREADS + MODULARIZE (#9875)

node.js doesn't have document.currentScript.src, so use __filename instead.

emcc.py

@@ -3166,6 +3166,7 @@ def modularize():
       # document.currentScript, so a simple export declaration is enough.
       src = 'var %s=%s' % (shared.Settings.EXPORT_NAME, src)
     else:
+      script_url_node = ""
       # When MODULARIZE this JS may be executed later,
       # after document.currentScript is gone, so we save it.
       # (when MODULARIZE_INSTANCE, an instance is created
@@ -3176,15 +3177,19 @@ def modularize():
         script_url = "import.meta.url"
       else:
         script_url = "typeof document !== 'undefined' && document.currentScript ? document.currentScript.src : undefined"
+        if shared.Settings.target_environment_may_be('node'):
+          script_url_node = "if (typeof __filename !== 'undefined') _scriptDir = _scriptDir || __filename;"
       src = '''
 var %(EXPORT_NAME)s = (function() {
   var _scriptDir = %(script_url)s;
+  %(script_url_node)s
   return (%(src)s);
 })();
 ''' % {
         'EXPORT_NAME': shared.Settings.EXPORT_NAME,
-        'src': src,
-        'script_url': script_url
+        'script_url': script_url,
+        'script_url_node': script_url_node,
+        'src': src
       }
   else:
     # Create the MODULARIZE_INSTANCE instance

tests/test_other.py

@@ -8992,6 +8992,28 @@ def test_node_js_run_from_different_directory(self):
     ret = run_process(NODE_JS + [os.path.join('subdir', 'a.js')], stdout=PIPE).stdout
     self.assertContained('hello, world!', ret)
 
+  # Tests that a pthreads + modularize build can be run in node js
+  @no_fastcomp('node pthreads only supported on wasm backend')
+  def test_node_js_pthread_module(self):
+    # create module loader script
+    moduleLoader = 'moduleLoader.js'
+    moduleLoaderContents = '''
+const test_module = require("./module");
+test_module().then((test_module_instance) => {
+  test_module_instance._main();
+  process.exit(0);
+});
+'''
+    os.makedirs('subdir', exist_ok=True)
+    create_test_file(os.path.join('subdir', moduleLoader), moduleLoaderContents)
+
+    # build hello_world.c
+    run_process([PYTHON, EMCC, path_from_root('tests', 'hello_world.c'), '-o', os.path.join('subdir', 'module.js'), '-s', 'USE_PTHREADS=1', '-s', 'PTHREAD_POOL_SIZE=2', '-s', 'MODULARIZE=1', '-s', 'EXPORT_NAME=test_module', '-s', 'ENVIRONMENT=worker,node'])
+
+    # run the module
+    ret = run_process(NODE_JS + ['--experimental-wasm-threads'] + [os.path.join('subdir', moduleLoader)], stdout=PIPE).stdout
+    self.assertContained('hello, world!', ret)
+
   def test_is_bitcode(self):
     fname = 'tmp.o'