[tsgen] Fix modularize definition for sync compilation. (#21766)

Fixes #21760

test/other/test_emit_tsd_sync.d.ts

@@ -0,0 +1,21 @@
+// TypeScript bindings for emscripten-generated code.  Automatically generated at compile time.
+declare namespace RuntimeExports {
+    let HEAPF64: any;
+    let HEAP_DATA_VIEW: any;
+    let HEAP8: any;
+    let HEAPU8: any;
+    let HEAP16: any;
+    let HEAPU16: any;
+    let HEAP32: any;
+    let HEAPU32: any;
+    let HEAP64: any;
+    let HEAPU64: any;
+}
+interface WasmModule {
+  _fooVoid(): void;
+  _fooInt(_0: number, _1: number): number;
+  _main(_0: number, _1: number): number;
+}
+
+export type MainModule = WasmModule & typeof RuntimeExports;
+export default function MainModuleFactory (options?: unknown): MainModule;

test/other/test_tsd_sync.ts

@@ -0,0 +1,5 @@
+import moduleFactory from './test_emit_tsd_sync.js'
+
+const module = moduleFactory();
+module._fooVoid();
+module._fooInt(7, 8);

test/test_other.py

@@ -3307,6 +3307,17 @@ def test_emit_tsd(self):
     cmd = shared.get_npm_cmd('tsc') + [test_file('other/test_tsd.ts'), '--noEmit']
     shared.check_call(cmd)
 
+  def test_emit_tsd_sync_compilation(self):
+    self.run_process([EMCC, test_file('other/test_emit_tsd.c'),
+                      '--emit-tsd', 'test_emit_tsd_sync.d.ts',
+                      '-sMODULARIZE', '-sWASM_ASYNC_COMPILATION=0',
+                      '-o', 'test_emit_tsd_sync.js'] +
+                     self.get_emcc_args())
+    self.assertFileContents(test_file('other/test_emit_tsd_sync.d.ts'), read_file('test_emit_tsd_sync.d.ts'))
+    # Test that the output compiles with a TS file that uses the defintions.
+    cmd = shared.get_npm_cmd('tsc') + [test_file('other/test_tsd_sync.ts'), '--noEmit']
+    shared.check_call(cmd)
+
   def test_emit_tsd_wasm_only(self):
     err = self.expect_fail([EMCC, test_file('other/test_emit_tsd.c'),
                             '--emit-tsd', 'test_emit_tsd_wasm_only.d.ts', '-o', 'out.wasm'])

tools/emscripten.py

@@ -664,7 +664,10 @@ def create_tsd(metadata, embind_tsd):
     export_interfaces += ' & EmbindModule'
   out += f'export type MainModule = {export_interfaces};\n'
   if settings.MODULARIZE:
-    out += 'export default function MainModuleFactory (options?: unknown): Promise<MainModule>;\n'
+    return_type = 'MainModule'
+    if settings.WASM_ASYNC_COMPILATION:
+      return_type = f'Promise<{return_type}>'
+    out += f'export default function MainModuleFactory (options?: unknown): {return_type};\n'
   return out