[tsgen] Support JSPI when emitting TypeScript definitions.

- Adds a Promise<T> wrapper around the return type for async embind functions.
- Disables JSPI while generating the definitions, since it's not needed.

Fixes emscripten-core#23272

src/embind/embind_gen.js

@@ -83,7 +83,11 @@ var LibraryEmbind = {
       if (this.isNonnullReturn && this.returnType instanceof PointerDefinition) {
         returnType = this.returnType.classType;
       }
-      out.push(`): ${nameMap(returnType, true)}`);
+      returnType = nameMap(returnType, true);
+      if (this.isAsync) {
+        returnType = `Promise<${returnType}>`;
+      }
+      out.push(`): ${returnType}`);
     }
 
     printFunction(nameMap, out) {

test/other/embind_tsgen_jspi.cpp

@@ -0,0 +1,9 @@
+#include <emscripten/bind.h>
+
+using namespace emscripten;
+
+void sleep() {}
+
+EMSCRIPTEN_BINDINGS(Test) {
+  function("sleep", &sleep, async());
+}

test/other/embind_tsgen_jspi.d.ts

@@ -0,0 +1,22 @@
+// TypeScript bindings for emscripten-generated code.  Automatically generated at compile time.
+declare namespace RuntimeExports {
+    let HEAPF32: any;
+    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 {
+}
+
+interface EmbindModule {
+  sleep(): Promise<void>;
+}
+
+export type MainModule = WasmModule & typeof RuntimeExports & EmbindModule;

test/test_other.py

@@ -3527,6 +3527,13 @@ def test_embind_tsgen_memory64(self):
                      self.get_emcc_args())
     self.assertFileContents(test_file('other/embind_tsgen_memory64.d.ts'), read_file('embind_tsgen_memory64.d.ts'))
 
+  @requires_jspi
+  def test_embind_tsgen_jspi(self):
+    self.run_process([EMXX, test_file('other/embind_tsgen_jspi.cpp'),
+                      '-lembind', '--emit-tsd', 'embind_tsgen_jspi.d.ts', '-sJSPI'] +
+                     self.get_emcc_args())
+    self.assertFileContents(test_file('other/embind_tsgen_jspi.d.ts'), read_file('embind_tsgen_jspi.d.ts'))
+
   @parameterized({
     '': [0],
     'wasm_exnref': [1]

tools/link.py

@@ -2001,6 +2001,11 @@ def run_embind_gen(wasm_target, js_syms, extra_settings, linker_inputs):
   setup_environment_settings()
   # Use a separate Wasm file so the JS does not need to be modified after emscripten.emscript.
   settings.SINGLE_FILE = False
+  if settings.JSPI:
+    # JSPI is not needed to generate the definitions.
+    # TODO: when the emsdk node version supports JSPI, it probably makes more sense
+    # to enable it in node than disabling the setting here.
+    settings.ASYNCIFY = 0
   # Embind may be included multiple times, de-duplicate the list first.
   settings.JS_LIBRARIES = dedup_list(settings.JS_LIBRARIES)
   # Replace embind with the TypeScript generation version.