[iterator-helpers] Remove IsCallable check

In this CL, we remove IsCallable check from GetIteratorDirect. This
change is based on
tc39/proposal-iterator-helpers#274 and
discussion on May 2023 TC39.

Bug: v8:13558
Change-Id: I33f952391d49e3d4aa2e24e71897d3b97c252e44
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/4545191
Reviewed-by: Shu-yu Guo <syg@chromium.org>
Commit-Queue: Rezvan Mahdavi Hezaveh <rezvan@chromium.org>
Cr-Commit-Position: refs/heads/main@{#87741}

src/builtins/iterator-helpers.tq

@@ -18,15 +18,11 @@ macro MarkIteratorHelperAsExhausted(helper: JSIteratorHelper): void {
 transitioning macro GetIteratorDirect(implicit context: Context)(
     obj: JSReceiver): IteratorRecord {
   // 1. Let nextMethod be ? Get(obj, "next").
-  const nextProp = GetProperty(obj, kNextString);
+  const nextMethod = GetProperty(obj, kNextString);
 
-  // 2. If IsCallable(nextMethod) is false, throw a TypeError exception.
-  const nextMethod = Cast<Callable>(nextProp)
-      otherwise ThrowTypeError(MessageTemplate::kCalledNonCallable, 'next');
-
-  // 3. Let iteratorRecord be Record { [[Iterator]]: obj, [[NextMethod]]:
+  // 2. Let iteratorRecord be Record { [[Iterator]]: obj, [[NextMethod]]:
   //    nextMethod, [[Done]]: false }.
-  // 4. Return iteratorRecord.
+  // 3. Return iteratorRecord.
   return IteratorRecord{object: obj, next: nextMethod};
 }
 

test/mjsunit/harmony/iterator-helpers.js

@@ -182,6 +182,26 @@ function TestHelperPrototypeSurface(helper) {
   assertEquals({value: undefined, done: true}, mapIter.next());
 })();
 
+(function TestMapNotCallableNext() {
+  const iterator = {
+    i: 1,
+    next() {
+      undefined;
+    },
+    return () {
+      return {};
+    },
+  };
+
+  Object.setPrototypeOf(iterator, Iterator.prototype);
+  const mapIter = iterator.map((x, i) => {
+    return x;
+  });
+  assertThrows(() => {
+    mapIter.next();
+  });
+})();
+
 // --- Test filter helper
 
 (function TestFilter() {

tools/v8heapconst.py

@@ -580,32 +580,32 @@
   ("old_space", 0x04d69): "StringSplitCache",
   ("old_space", 0x05171): "RegExpMultipleCache",
   ("old_space", 0x05579): "BuiltinsConstantsTable",
-  ("old_space", 0x05add): "AsyncFunctionAwaitRejectSharedFun",
-  ("old_space", 0x05b01): "AsyncFunctionAwaitResolveSharedFun",
-  ("old_space", 0x05b25): "AsyncGeneratorAwaitRejectSharedFun",
-  ("old_space", 0x05b49): "AsyncGeneratorAwaitResolveSharedFun",
-  ("old_space", 0x05b6d): "AsyncGeneratorYieldWithAwaitResolveSharedFun",
-  ("old_space", 0x05b91): "AsyncGeneratorReturnResolveSharedFun",
-  ("old_space", 0x05bb5): "AsyncGeneratorReturnClosedRejectSharedFun",
-  ("old_space", 0x05bd9): "AsyncGeneratorReturnClosedResolveSharedFun",
-  ("old_space", 0x05bfd): "AsyncIteratorValueUnwrapSharedFun",
-  ("old_space", 0x05c21): "ErrorStackGetterSharedFun",
-  ("old_space", 0x05c69): "ErrorStackSetterSharedFun",
-  ("old_space", 0x05cb1): "PromiseAllResolveElementSharedFun",
-  ("old_space", 0x05cd5): "PromiseAllSettledResolveElementSharedFun",
-  ("old_space", 0x05cf9): "PromiseAllSettledRejectElementSharedFun",
-  ("old_space", 0x05d1d): "PromiseAnyRejectElementSharedFun",
-  ("old_space", 0x05d41): "PromiseCapabilityDefaultRejectSharedFun",
-  ("old_space", 0x05d65): "PromiseCapabilityDefaultResolveSharedFun",
-  ("old_space", 0x05d89): "PromiseCatchFinallySharedFun",
-  ("old_space", 0x05dad): "PromiseGetCapabilitiesExecutorSharedFun",
-  ("old_space", 0x05dd1): "PromiseThenFinallySharedFun",
-  ("old_space", 0x05df5): "PromiseThrowerFinallySharedFun",
-  ("old_space", 0x05e19): "PromiseValueThunkFinallySharedFun",
-  ("old_space", 0x05e3d): "ProxyRevokeSharedFun",
-  ("old_space", 0x05e61): "ShadowRealmImportValueFulfilledSFI",
-  ("old_space", 0x05e85): "SourceTextModuleExecuteAsyncModuleFulfilledSFI",
-  ("old_space", 0x05ea9): "SourceTextModuleExecuteAsyncModuleRejectedSFI",
+  ("old_space", 0x05ad9): "AsyncFunctionAwaitRejectSharedFun",
+  ("old_space", 0x05afd): "AsyncFunctionAwaitResolveSharedFun",
+  ("old_space", 0x05b21): "AsyncGeneratorAwaitRejectSharedFun",
+  ("old_space", 0x05b45): "AsyncGeneratorAwaitResolveSharedFun",
+  ("old_space", 0x05b69): "AsyncGeneratorYieldWithAwaitResolveSharedFun",
+  ("old_space", 0x05b8d): "AsyncGeneratorReturnResolveSharedFun",
+  ("old_space", 0x05bb1): "AsyncGeneratorReturnClosedRejectSharedFun",
+  ("old_space", 0x05bd5): "AsyncGeneratorReturnClosedResolveSharedFun",
+  ("old_space", 0x05bf9): "AsyncIteratorValueUnwrapSharedFun",
+  ("old_space", 0x05c1d): "ErrorStackGetterSharedFun",
+  ("old_space", 0x05c65): "ErrorStackSetterSharedFun",
+  ("old_space", 0x05cad): "PromiseAllResolveElementSharedFun",
+  ("old_space", 0x05cd1): "PromiseAllSettledResolveElementSharedFun",
+  ("old_space", 0x05cf5): "PromiseAllSettledRejectElementSharedFun",
+  ("old_space", 0x05d19): "PromiseAnyRejectElementSharedFun",
+  ("old_space", 0x05d3d): "PromiseCapabilityDefaultRejectSharedFun",
+  ("old_space", 0x05d61): "PromiseCapabilityDefaultResolveSharedFun",
+  ("old_space", 0x05d85): "PromiseCatchFinallySharedFun",
+  ("old_space", 0x05da9): "PromiseGetCapabilitiesExecutorSharedFun",
+  ("old_space", 0x05dcd): "PromiseThenFinallySharedFun",
+  ("old_space", 0x05df1): "PromiseThrowerFinallySharedFun",
+  ("old_space", 0x05e15): "PromiseValueThunkFinallySharedFun",
+  ("old_space", 0x05e39): "ProxyRevokeSharedFun",
+  ("old_space", 0x05e5d): "ShadowRealmImportValueFulfilledSFI",
+  ("old_space", 0x05e81): "SourceTextModuleExecuteAsyncModuleFulfilledSFI",
+  ("old_space", 0x05ea5): "SourceTextModuleExecuteAsyncModuleRejectedSFI",
 }
 
 # Lower 32 bits of first page addresses for various heap spaces.