Bug 1797724 - Part 5: Use consistent error messages when iterator method returns a non-object. r=mgaudet

This ensures `Array.fromAsync` uses the same error message as `Array.from` and
normal iteration (`for-of` and `for-await-of`).

This let's us also remove the `GetIterator` self-hosted function.

Also renamed `asyncIterator` to `iterator`, because the returned iterator isn't
an async iterator.

Depends on D160478

Differential Revision: https://phabricator.services.mozilla.com/D160479

js/src/builtin/Array.js

@@ -871,17 +871,27 @@ function ArrayFromAsync(asyncItems, mapfn = undefined, thisArg = undefined) {
     // Step 3.h. If usingAsyncIterator is not undefined, then
     if (usingAsyncIterator !== undefined) {
       //     Step 3.h.i. Set iteratorRecord to ? GetIterator(asyncItems, async, usingAsyncIterator).
-      iteratorRecord = GetIterator(asyncItems, "async", usingAsyncIterator);
+      let iterator = callContentFunction(usingAsyncIterator, asyncItems);
+
+      if (!IsObject(iterator)) {
+        ThrowTypeError(JSMSG_GET_ASYNC_ITER_RETURNED_PRIMITIVE);
+      }
+
+      iteratorRecord = { iterator, nextMethod: iterator.next };
     } else if (usingSyncIterator !== undefined) {
       // Step 3.i. Else if usingSyncIterator is not undefined, then
       //     Step 3.i.i. Set iteratorRecord to ? CreateAsyncFromSyncIterator(GetIterator(asyncItems, sync, usingSyncIterator)).
-      let asyncIterator = GetIterator(asyncItems, "sync", usingSyncIterator);
+      let iterator = callContentFunction(usingSyncIterator, asyncItems);
+
+      if (!IsObject(iterator)) {
+        ThrowTypeError(JSMSG_GET_ITER_RETURNED_PRIMITIVE);
+      }
 
       // SpiderMonkey's CreateAsyncFromSyncIterator doesn't return an iterator record
       // with named slots; so we need to create our own iterator record.
       let asyncFromSyncIteratorObject = CreateAsyncFromSyncIterator(
-        asyncIterator.iterator,
-        asyncIterator.nextMethod
+        iterator,
+        iterator.next
       );
 
       iteratorRecord = {

js/src/builtin/Iterator.js

@@ -43,61 +43,6 @@ function IteratorClose(iteratorRecord, value) {
   return value;
 }
 
-/**
- * ES2022 draft rev c5f683e61d5dce703650f1c90d2309c46f8c157a
- *
- * GetIterator ( obj [ , hint [ , method ] ] )
- * https://tc39.es/ecma262/#sec-getiterator
- *
- */
-function GetIterator(obj, hint = undefined, method = undefined) {
-  // Step 1. If hint is not present, set hint to sync.
-  if (hint === undefined) {
-    hint = "sync";
-  }
-
-  // Step 2. If method is not present, then
-  if (method === undefined) {
-    // Step 2.a. If hint is async, then
-    if (hint === "async") {
-      // Step 2.a.i. Set method to ? GetMethod(obj, @@asyncIterator).
-      method = GetMethod(obj, GetBuiltinSymbol("asyncIterator"));
-      // Step 2.a.ii. If method is undefined, then
-      if (method === undefined) {
-        // Step 2.a.ii.1. Let syncMethod be ? GetMethod(obj, @@iterator).
-        let syncMethod = GetMethod(obj, GetBuiltinSymbol("iterator"));
-        // Step 2.a.ii.2. Let syncIteratorRecord be ? GetIterator(obj, sync, syncMethod).
-        let syncIteratorRecord = GetIterator(obj, "sync", syncMethod);
-        // Step 2.a.ii.3. Return CreateAsyncFromSyncIterator(syncIteratorRecord).
-        // (SpiderMonkey extracts the contents of the iterator record for this call.)
-        return CreateAsyncFromSyncIterator(
-          syncIteratorRecord.iterator,
-          syncIteratorRecord.nextMethod
-        );
-      }
-    } else {
-      // Step 2.b. Otherwise, set method to ? GetMethod(obj, @@iterator).
-      method = GetMethod(obj, GetBuiltinSymbol("iterator"));
-    }
-  }
-
-  // Step 3. Let iterator be ? Call(method, obj).
-  let iterator = callContentFunction(method, obj);
-  // Step 4. If iterator is not an Object, throw a TypeError exception.
-  if (!IsObject(iterator)) {
-    ThrowTypeError(JSMSG_OBJECT_REQUIRED, iterator);
-  }
-
-  // Step 5. Let nextMethod be ? GetV(iterator, "next").
-  let nextMethod = iterator.next;
-
-  // Step 6. Let iteratorRecord be the Iterator Record { [[Iterator]]: iterator, [[NextMethod]]: nextMethod, [[Done]]: false }.
-  let iteratorRecord = { iterator, nextMethod, done: false };
-
-  // Step 7. Return iteratorRecord.
-  return iteratorRecord;
-}
-
 /**
  * ES2022 draft rev c5f683e61d5dce703650f1c90d2309c46f8c157a
  *

js/src/tests/non262/Array/from_async.js

@@ -133,5 +133,46 @@ assertEq(done, true);
 })();
 
 drainJobQueue();
+
+(async function() {
+  var badSyncIterator = {
+    [Symbol.iterator](){
+      return null;
+    }
+  };
+
+  var badAsyncIterator = {
+    [Symbol.asyncIterator](){
+      return null;
+    }
+  };
+
+  async function errorMessage(fn) {
+    try {
+      await fn();
+    } catch (e) {
+      return e.message;
+    }
+    throw new Error("missing error");
+  }
+
+  // Ensure Array.from and Array.fromAsync use consistent error reporting.
+  var expected = await errorMessage(() => Array.from(badSyncIterator));
+  var actual = await errorMessage(() => Array.fromAsync(badSyncIterator));
+  assertEq(actual, expected);
+
+  // Ensure for-of iteration and Array.fromAsync use consistent error reporting.
+  var expected = await errorMessage(() => { for (var _ of badSyncIterator); });
+  var actual = await errorMessage(() => Array.fromAsync(badSyncIterator));
+  assertEq(actual, expected);
+
+  // Ensure await for-of iteration and Array.fromAsync use consistent error reporting.
+  var expected = await errorMessage(async () => { for await (var _ of badAsyncIterator); });
+  var actual = await errorMessage(() => Array.fromAsync(badAsyncIterator));
+  assertEq(actual, expected);
+})();
+
+drainJobQueue();
+
 if (typeof reportCompare === 'function')
     reportCompare(true, true);