lib,src: use Response URL as WebAssembly location

lib/internal/bootstrap/pre_execution.js

@@ -245,6 +245,10 @@ function setupFetch() {
         throw new ERR_WEBASSEMBLY_RESPONSE('body has already been used');
       }
 
+      if (response.url) {
+        streamState.setURL(response.url);
+      }
+
       // Pass all data from the response body to the WebAssembly compiler.
       for await (const chunk of response.body) {
         streamState.push(chunk);

src/node_wasm_web_api.cc

@@ -29,6 +29,7 @@ Local<Function> WasmStreamingObject::Initialize(Environment* env) {
   t->InstanceTemplate()->SetInternalFieldCount(
       WasmStreamingObject::kInternalFieldCount);
 
+  env->SetProtoMethod(t, "setURL", SetURL);
   env->SetProtoMethod(t, "push", Push);
   env->SetProtoMethod(t, "finish", Finish);
   env->SetProtoMethod(t, "abort", Abort);
@@ -75,6 +76,17 @@ void WasmStreamingObject::New(const FunctionCallbackInfo<Value>& args) {
   new WasmStreamingObject(env, args.This());
 }
 
+void WasmStreamingObject::SetURL(const FunctionCallbackInfo<Value>& args) {
+  WasmStreamingObject* obj;
+  ASSIGN_OR_RETURN_UNWRAP(&obj, args.Holder());
+  CHECK(obj->streaming_);
+
+  CHECK_EQ(args.Length(), 1);
+  CHECK(args[0]->IsString());
+  Utf8Value url(Environment::GetCurrent(args)->isolate(), args[0]);
+  obj->streaming_->SetUrl(url.out(), url.length());
+}
+
 void WasmStreamingObject::Push(const FunctionCallbackInfo<Value>& args) {
   WasmStreamingObject* obj;
   ASSIGN_OR_RETURN_UNWRAP(&obj, args.Holder());

src/node_wasm_web_api.h

@@ -33,6 +33,7 @@ class WasmStreamingObject final : public BaseObject {
 
  private:
   static void New(const v8::FunctionCallbackInfo<v8::Value>& args);
+  static void SetURL(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void Push(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void Finish(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void Abort(const v8::FunctionCallbackInfo<v8::Value>& args);

test/fixtures/crash.wat

@@ -0,0 +1 @@
+(module (func (export "crash") unreachable))

test/parallel/test-wasm-web-api.js

@@ -19,7 +19,7 @@ async function testRequest(handler) {
   const server = createServer((_, res) => handler(res)).unref().listen(0);
   await events.once(server, 'listening');
   const { port } = server.address();
-  return fetch(`http://127.0.0.1:${port}/`);
+  return fetch(`http://127.0.0.1:${port}/foo.wasm`);
 }
 
 // Runs the given function both with the promise itself and as a continuation
@@ -223,4 +223,25 @@ function testCompileStreamingRejectionUsingFetch(responseCallback, rejection) {
     name: 'TypeError',
     message: /terminated/
   });
+
+  // Test "Developer-Facing Display Conventions" described in the WebAssembly
+  // Web API specification.
+  await testCompileStreaming(() => testRequest((res) => {
+    // Respond with a WebAssembly module that only exports a single function,
+    // which only contains an 'unreachable' instruction.
+    res.setHeader('Content-Type', 'application/wasm');
+    res.end(fixtures.readSync('crash.wasm'));
+  }), async (modPromise) => {
+    // Call the WebAssembly function and check that the error stack contains the
+    // correct "WebAssembly location" as per the specification.
+    const mod = await modPromise;
+    const instance = new WebAssembly.Instance(mod);
+    assert.throws(() => instance.exports.crash(), (err) => {
+      const stack = err.stack.split(/\n/g);
+      assert.strictEqual(stack[0], 'RuntimeError: unreachable');
+      assert.match(stack[1],
+                   /^\s*at http:\/\/127\.0\.0\.1:\d+\/foo\.wasm:wasm-function\[0\]:0x22$/);
+      return true;
+    });
+  });
 })().then(common.mustCall());