Non-enumerable property fails to shadow inherited enumerable property…

… from for-in

https://bugs.webkit.org/show_bug.cgi?id=38970

Reviewed by Keith Miller.

JSTests:

* stress/arguments-bizarre-behaviour-disable-enumerability.js:
* stress/for-in-redefine-enumerable.js: Added.
* stress/for-in-shadow-non-enumerable.js: Added.
* test262/expectations.yaml: Mark 4 test cases as passing.

Source/JavaScriptCore:

While for/in was initially specified with notion of "shadowing", it wasn't clarified
until ES5 that [[Enumerable]] attributes are ignored when determining if a property
has already been processed. Recently, for/in spec was expanded [1] to pin down common
case enumeration as it's currently implemented by V8 and SpiderMonkey.

Since keeping track of DontEnum properties is a massive slowdown for uncached runs
(with any data structure used), this patch simply adds [[Enumerable]] check to
has_{indexed,structure,generic}_property bytecode ops and does renaming chores.

Common code is now shared between HasIndexedProperty (emitted for `0 in arr`) and
HasEnumerableIndexedProperty DFG nodes via passing different slow path ops rather
than having OpInfo with PropertySlot::InternalMethodType, which is a nice refactor.

While this change aligns common case for/in enumeration with the spec and other
engines, it also introduces a few observable discrepancies from V8 and SpiderMonkey,
which are permitted by the spec [2]:
a) properties that have been redefined as DontEnum within loop body are skipped,
   which matches the spec [3] and seems like expected behavior;
b) "shadowing" is broken if a DontEnum property of already visited object is
   added / deleted / redefined within loop body, which (pretty much) never happens.

This patch introduces a new invariant: all properties getOwn*PropertyNames() returns
in DontEnumPropertiesMode::Exclude should be reported as [[Enumerable]] by
getOwnPropertySlot(). JSCallbackObject and RuntimeArray are fixed to follow it.

for/in and Object.keys microbenchmarks are neutral. This change does not affect
JSPropertyNameEnumerator caching, nor fast paths of its bytecodes.

[1]: tc39/ecma262#1791
[2]: https://tc39.es/ecma262/#sec-enumerate-object-properties (last paragraph)
[3]: https://tc39.es/ecma262/#sec-%foriniteratorprototype%.next (step 7.b.iii)

* API/JSCallbackObjectFunctions.h:
(JSC::JSCallbackObject<Parent>::getOwnPropertySlot):
* API/tests/testapi.c:
* API/tests/testapiScripts/testapi.js:
* bytecode/BytecodeList.rb:
* bytecode/BytecodeUseDef.cpp:
(JSC::computeUsesForBytecodeIndexImpl):
(JSC::computeDefsForBytecodeIndexImpl):
* bytecode/CodeBlock.cpp:
(JSC::CodeBlock::finishCreation):
* bytecode/Opcode.h:
* bytecompiler/BytecodeGenerator.cpp:
(JSC::BytecodeGenerator::emitHasEnumerableIndexedProperty):
(JSC::BytecodeGenerator::emitHasEnumerableStructureProperty):
(JSC::BytecodeGenerator::emitHasEnumerableProperty):
(JSC::BytecodeGenerator::emitHasGenericProperty): Deleted.
(JSC::BytecodeGenerator::emitHasIndexedProperty): Deleted.
(JSC::BytecodeGenerator::emitHasStructureProperty): Deleted.
* bytecompiler/BytecodeGenerator.h:
* bytecompiler/NodesCodegen.cpp:
(JSC::ForInNode::emitBytecode):
* dfg/DFGAbstractInterpreterInlines.h:
(JSC::DFG::AbstractInterpreter<AbstractStateType>::executeEffects):
* dfg/DFGByteCodeParser.cpp:
(JSC::DFG::ByteCodeParser::parseBlock):
* dfg/DFGCapabilities.cpp:
(JSC::DFG::capabilityLevel):
* dfg/DFGClobberize.h:
(JSC::DFG::clobberize):
* dfg/DFGDoesGC.cpp:
(JSC::DFG::doesGC):
* dfg/DFGFixupPhase.cpp:
(JSC::DFG::FixupPhase::fixupNode):
(JSC::DFG::FixupPhase::convertToHasIndexedProperty):
* dfg/DFGNode.h:
(JSC::DFG::Node::hasArrayMode):
(JSC::DFG::Node::hasInternalMethodType const): Deleted.
(JSC::DFG::Node::internalMethodType const): Deleted.
(JSC::DFG::Node::setInternalMethodType): Deleted.
* dfg/DFGNodeType.h:
* dfg/DFGOperations.cpp:
(JSC::DFG::JSC_DEFINE_JIT_OPERATION):
* dfg/DFGOperations.h:
* dfg/DFGPredictionPropagationPhase.cpp:
* dfg/DFGSSALoweringPhase.cpp:
(JSC::DFG::SSALoweringPhase::handleNode):
* dfg/DFGSafeToExecute.h:
(JSC::DFG::safeToExecute):
* dfg/DFGSpeculativeJIT.cpp:
(JSC::DFG::SpeculativeJIT::compileHasEnumerableProperty):
(JSC::DFG::SpeculativeJIT::compileHasEnumerableStructureProperty):
(JSC::DFG::SpeculativeJIT::compileHasIndexedProperty):
(JSC::DFG::SpeculativeJIT::compileHasGenericProperty): Deleted.
(JSC::DFG::SpeculativeJIT::compileHasStructureProperty): Deleted.
* dfg/DFGSpeculativeJIT.h:
* dfg/DFGSpeculativeJIT32_64.cpp:
(JSC::DFG::SpeculativeJIT::compile):
* dfg/DFGSpeculativeJIT64.cpp:
(JSC::DFG::SpeculativeJIT::compile):
* ftl/FTLCapabilities.cpp:
(JSC::FTL::canCompile):
* ftl/FTLLowerDFGToB3.cpp:
(JSC::FTL::DFG::LowerDFGToB3::compileNode):
(JSC::FTL::DFG::LowerDFGToB3::compileHasIndexedProperty):
(JSC::FTL::DFG::LowerDFGToB3::compileHasEnumerableProperty):
(JSC::FTL::DFG::LowerDFGToB3::compileHasEnumerableStructureProperty):
(JSC::FTL::DFG::LowerDFGToB3::compileHasGenericProperty): Deleted.
(JSC::FTL::DFG::LowerDFGToB3::compileHasStructureProperty): Deleted.
* jit/JIT.cpp:
(JSC::JIT::privateCompileMainPass):
(JSC::JIT::privateCompileSlowCases):
* jit/JIT.h:
* jit/JITOpcodes.cpp:
(JSC::JIT::emit_op_has_enumerable_structure_property):
(JSC::JIT::emit_op_has_enumerable_indexed_property):
(JSC::JIT::emitSlow_op_has_enumerable_indexed_property):
(JSC::JIT::emit_op_has_structure_property): Deleted.
(JSC::JIT::emit_op_has_indexed_property): Deleted.
(JSC::JIT::emitSlow_op_has_indexed_property): Deleted.
* jit/JITOpcodes32_64.cpp:
(JSC::JIT::emit_op_has_enumerable_structure_property):
(JSC::JIT::emit_op_has_enumerable_indexed_property):
(JSC::JIT::emitSlow_op_has_enumerable_indexed_property):
(JSC::JIT::emit_op_has_structure_property): Deleted.
(JSC::JIT::emit_op_has_indexed_property): Deleted.
(JSC::JIT::emitSlow_op_has_indexed_property): Deleted.
* jit/JITOperations.cpp:
(JSC::JSC_DEFINE_JIT_OPERATION):
* jit/JITOperations.h:
* llint/LowLevelInterpreter.asm:
* llint/LowLevelInterpreter64.asm:
* runtime/CommonSlowPaths.cpp:
(JSC::JSC_DEFINE_COMMON_SLOW_PATH):
* runtime/CommonSlowPaths.h:
* runtime/JSObject.cpp:
(JSC::JSObject::hasProperty const):
(JSC::JSObject::hasEnumerableProperty const):
(JSC::JSObject::hasPropertyGeneric const): Deleted.
* runtime/JSObject.h:

Source/WebCore:

Report RuntimeArray indices as [[Enumerable]].

Test: platform/mac/fast/dom/wrapper-classes-objc.html

* bridge/runtime_array.cpp:
(JSC::RuntimeArray::getOwnPropertySlot):
(JSC::RuntimeArray::getOwnPropertySlotByIndex):

LayoutTests:

* platform/mac/fast/dom/wrapper-classes-objc-expected.txt:
* platform/mac/fast/dom/wrapper-classes-objc.html:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@270874 268f45cc-cd09-0410-ab3c-d52691b4dbfc

JSTests/ChangeLog

@@ -1,3 +1,15 @@
+2020-12-15  Alexey Shvayka  <[email protected]>
+
+        Non-enumerable property fails to shadow inherited enumerable property from for-in
+        https://bugs.webkit.org/show_bug.cgi?id=38970
+
+        Reviewed by Keith Miller.
+
+        * stress/arguments-bizarre-behaviour-disable-enumerability.js:
+        * stress/for-in-redefine-enumerable.js: Added.
+        * stress/for-in-shadow-non-enumerable.js: Added.
+        * test262/expectations.yaml: Mark 4 test cases as passing.
+
 2020-12-15  Yusuke Suzuki  <[email protected]>
 
         Suppress noise from JSTests/stress/lars-sab-workers.js

JSTests/stress/arguments-bizarre-behaviour-disable-enumerability.js

@@ -18,7 +18,7 @@ var array = [];
 for (var s in result[2])
     array.push(s);
 
-if (array.join(",") != "0")
+if (array.join(",") != "")
     throw new Error();
 
 if (Object.keys(result[2]).join(",") != "0")

JSTests/stress/for-in-redefine-enumerable.js

@@ -0,0 +1,107 @@
+function assert(x) {
+    if (!x)
+        throw new Error("Bad assertion!");
+}
+
+function shouldBe(actual, expected) {
+    if (actual !== expected)
+        throw new Error(`Bad value: ${actual}.`);
+}
+
+const enumDesc = { value: 0, writable: true, enumerable: true, configurable: true };
+const dontEnumDesc = { value: 0, writable: true, enumerable: false, configurable: true };
+
+// indexed property
+(() => {
+    function test() {
+        var arr = Object.defineProperties([0, 0, 0], { 1: dontEnumDesc });
+        for (var i in arr) {
+            assert(i in arr);
+            shouldBe(arr[i], 0);
+            ++arr[i];
+            if (i === "0")
+                Object.defineProperties(arr, { 1: enumDesc, 2: dontEnumDesc });
+        }
+        shouldBe(arr[0], 1);
+        shouldBe(arr[1], 0);
+        shouldBe(arr[2], 0);
+    }
+
+    for (var i = 0; i < 1e5; ++i)
+        test();
+})();
+
+// structure property
+(() => {
+    function test() {
+        var obj = Object.create(null, { a: enumDesc, b: enumDesc, c: dontEnumDesc });
+        for (var key in obj) {
+            assert(key in obj);
+            shouldBe(obj[key], 0);
+            ++obj[key];
+            if (key === "a")
+                Object.defineProperties(obj, { b: dontEnumDesc, c: enumDesc });
+        }
+        shouldBe(obj.a, 1);
+        shouldBe(obj.b, 0);
+        shouldBe(obj.c, 0);
+    }
+
+    for (var i = 0; i < 1e5; ++i)
+        test();
+})();
+
+// generic property (Proxy)
+(() => {
+    function test() {
+        var target = { a: 0, b: 0, c: 0 };
+        var enumMap = { a: true, b: true, c: false };
+        var proxy = new Proxy(target, {
+            getOwnPropertyDescriptor: (_, key) => {
+                return { value: target[key], writable: true, enumerable: enumMap[key], configurable: true };
+            },
+        });
+
+        for (var key in proxy) {
+            assert(key in proxy);
+            shouldBe(proxy[key], 0);
+            ++target[key];
+            if (key === "a") {
+                enumMap.b = false;
+                enumMap.c = true;
+            }
+        }
+        shouldBe(target.a, 1);
+        shouldBe(target.b, 0);
+        shouldBe(target.c, 0);
+    }
+
+    for (var i = 0; i < 1e5; ++i)
+        test();
+})();
+
+// generic property (in prototype)
+(() => {
+    function test() {
+        var seen = {};
+        var proto = Object.create(null, { b: enumDesc, c: dontEnumDesc, d: enumDesc, e: enumDesc });
+        var heir = Object.create(proto, { a: enumDesc, e: dontEnumDesc });
+        for (var key in heir) {
+            assert(key in heir);
+            shouldBe(heir[key], 0);
+            seen[key] = true;
+            if (key === "a")
+                Object.defineProperties(proto, { b: dontEnumDesc, c: enumDesc });
+            if (key === "d")
+                Object.defineProperties(heir, { e: enumDesc });
+        }
+        assert(seen.a);
+        assert(!seen.b);
+        assert(!seen.c);
+        assert(seen.d);
+        assert(seen.e);
+    }
+
+    for (var i = 0; i < 1e5; ++i)
+        test();
+})();

JSTests/stress/for-in-shadow-non-enumerable.js

@@ -0,0 +1,174 @@
+const dontEnumDesc = { value: 1, writable: true, enumerable: false, configurable: true };
+const testCases = [
+  {
+    name: "Object",
+    createObject: () => Object.create(null, { foo: dontEnumDesc, bar: dontEnumDesc }),
+    dontEnumKeys: ["foo", "bar"],
+  },
+  {
+    name: "Error",
+    createObject: () => new Error(),
+    dontEnumKeys: ["line", "column", "sourceURL", "stack"],
+  },
+  {
+    name: "Array (empty)",
+    createObject: () => [],
+    dontEnumKeys: ["length"],
+  },
+  {
+    name: "Array (sparse)",
+    createObject: () => Object.defineProperties([0, 1, 2], { 0: dontEnumDesc, 2: dontEnumDesc }),
+    dontEnumKeys: ["0", "2", "length"],
+  },
+  {
+    name: "Function (strict)",
+    createObject: () => function() { "use strict"; },
+    dontEnumKeys: ["length", "name", "prototype"],
+  },
+  {
+    name: "Function (non-strict)",
+    createObject: () => function() {},
+    dontEnumKeys: ["arguments", "caller", "length", "name", "prototype"],
+  },
+  {
+    name: "RegExp",
+    createObject: () => /(?:)/g,
+    dontEnumKeys: ["lastIndex"],
+  },
+  {
+    name: "String",
+    createObject: () => new String("foo"),
+    dontEnumKeys: ["length"],
+  },
+  {
+    name: "Arguments (strict)",
+    createObject: function(foo) { "use strict"; return arguments; },
+    dontEnumKeys: ["length", "callee"],
+  },
+  {
+    name: "Arguments (non-strict)",
+    createObject: function(foo) { return arguments; },
+    dontEnumKeys: ["length", "callee"],
+  },
+  {
+    name: "Reflect",
+    createObject: () => $vm.createGlobalObject().Reflect,
+    dontEnumKeys: ["apply", "get", "has", "set"],
+  },
+  {
+    name: "Date.prototype",
+    createObject: () => $vm.createGlobalObject().Date.prototype,
+    dontEnumKeys: ["toISOString", "getTime", "setYear"],
+  },
+];
+
+// basic tests
+for (const t of testCases) {
+  assert(!contains(forIn(t.createObject()), t.dontEnumKeys), t.name);
+  assert(!contains(Object.keys(t.createObject()), t.dontEnumKeys), t.name);
+
+  assert(contains(Object.getOwnPropertyNames(t.createObject()), t.dontEnumKeys), t.name);
+  assert(contains(Reflect.ownKeys(t.createObject()), t.dontEnumKeys), t.name);
+}
+
+// shadowing: DontEnum => Enum
+for (const t of testCases) {
+  assert(
+    !contains(
+      forIn(makePrototypeChain(t.createObject(), makeObject(t.dontEnumKeys))),
+      t.dontEnumKeys,
+    ),
+    t.name,
+  );
+}
+
+// shadowing: {} => DontEnum => {} => Enum
+for (const t of testCases) {
+  assert(
+    !contains(
+      forIn(makePrototypeChain({}, t.createObject(), {}, makeObject(t.dontEnumKeys))),
+      t.dontEnumKeys,
+    ),
+    t.name,
+  );
+}
+
+// shadowing: DontEnum => {} => Enum => {} => Enum
+for (const t of testCases) {
+  assert(
+    !contains(
+      forIn(makePrototypeChain(t.createObject(), {}, makeObject(t.dontEnumKeys), {}, makeObject(t.dontEnumKeys))),
+      t.dontEnumKeys,
+    ),
+    t.name,
+  );
+}
+
+// shadowing: {} => DontEnum (enumerable: true => false) => {} => Enum
+for (const t of testCases) {
+  const dontEnumObject = t.createObject();
+  const target = makePrototypeChain({}, dontEnumObject, {}, makeObject(t.dontEnumKeys));
+  assert(!contains(forIn(target), t.dontEnumKeys), t.name);
+
+  const enumKeys = t.dontEnumKeys.filter(key => Reflect.defineProperty(dontEnumObject, key, { enumerable: true }));
+  assert(contains(forIn(target), enumKeys), t.name);
+}
+
+// shadowing: {} => DontEnum (delete non-enumerable keys) => {} => Enum
+for (const t of testCases) {
+  const dontEnumObject = t.createObject();
+  const target = makePrototypeChain({}, dontEnumObject, {}, makeObject(t.dontEnumKeys));
+  assert(!contains(forIn(target), t.dontEnumKeys), t.name);
+
+  const enumKeys = t.dontEnumKeys.filter(key => Reflect.deleteProperty(dontEnumObject, key));
+  assert(contains(forIn(target), enumKeys), t.name);
+}
+
+// shadowing: {} => DontEnum (materialized) => {} => Enum
+for (const t of testCases) {
+  const dontEnumObject = t.createObject();
+  const target = makePrototypeChain({}, dontEnumObject, {}, makeObject(t.dontEnumKeys));
+  assert(!contains(forIn(target), t.dontEnumKeys), t.name);
+
+  const dontEnumKeys = t.dontEnumKeys.filter(key => {
+    const desc = Object.getOwnPropertyDescriptor(dontEnumObject, key);
+    if (!Reflect.deleteProperty(dontEnumObject, key)) return false;
+    Object.defineProperty(dontEnumObject, key, desc);
+    return true;
+  });
+
+  if (dontEnumKeys.length)
+    assert(!contains(forIn(target), dontEnumKeys), t.name);
+}
+
+// helpers
+function assert(value, name) {
+  if (!value)
+    throw new Error(`Bad value: ${value}. Test case: ${name}.`);
+}
+
+function contains(array, subarray) {
+  return subarray.every(item => array.includes(item));
+}
+
+function forIn(object) {
+  const keys = [];
+  for (const key in object)
+    keys.push(key);
+  return keys;
+}
+
+function makePrototypeChain(...objects) {
+  objects.reduce((object, prototype) => {
+    Object.setPrototypeOf(object, prototype);
+    return prototype;
+  });
+  return objects[0];
+}
+
+function makeObject(keys) {
+  const object = {};
+  for (const key of keys)
+    object[key] = key;
+  return object;
+}

JSTests/test262/expectations.yaml

@@ -1858,16 +1858,10 @@ test/language/statements/for-await-of/ticks-with-async-iter-resolved-promise-and
 test/language/statements/for-await-of/ticks-with-sync-iter-resolved-promise-and-constructor-lookup.js:
   default: 'Test262:AsyncTestFailure:Test262Error: Test262Error: Expected [pre, tick 1, constructor, constructor, tick 2, tick 3, loop, tick 4, constructor] and [pre, constructor, constructor, tick 1, tick 2, loop, constructor, tick 3, tick 4, post] to have the same contents. Ticks and constructor lookups'
   strict mode: 'Test262:AsyncTestFailure:Test262Error: Test262Error: Expected [pre, tick 1, constructor, constructor, tick 2, tick 3, loop, tick 4, constructor] and [pre, constructor, constructor, tick 1, tick 2, loop, constructor, tick 3, tick 4, post] to have the same contents. Ticks and constructor lookups'
-test/language/statements/for-in/12.6.4-2.js:
-  default: 'Test262Error: accessedProp Expected SameValue(«true», «false») to be true'
-  strict mode: 'Test262Error: accessedProp Expected SameValue(«true», «false») to be true'
 test/language/statements/for-in/head-lhs-let.js:
   default: "SyntaxError: Cannot use the keyword 'in' as a lexical variable name."
 test/language/statements/for-in/identifier-let-allowed-as-lefthandside-expression-not-strict.js:
   default: "SyntaxError: Cannot use the keyword 'in' as a lexical variable name."
-test/language/statements/for-in/order-enumerable-shadowed.js:
-  default: 'Test262Error: Expected [p1, p2] and [p1] to have the same contents. '
-  strict mode: 'Test262Error: Expected [p1, p2] and [p1] to have the same contents. '
 test/language/statements/for-in/scope-body-lex-open.js:
   default: 'Test262Error: Expected a ReferenceError to be thrown but no exception was thrown at all'
   strict mode: 'Test262Error: Expected a ReferenceError to be thrown but no exception was thrown at all'

LayoutTests/ChangeLog

@@ -1,3 +1,13 @@
+2020-12-15  Alexey Shvayka  <[email protected]>
+
+        Non-enumerable property fails to shadow inherited enumerable property from for-in
+        https://bugs.webkit.org/show_bug.cgi?id=38970
+
+        Reviewed by Keith Miller.
+
+        * platform/mac/fast/dom/wrapper-classes-objc-expected.txt:
+        * platform/mac/fast/dom/wrapper-classes-objc.html:
+
 2020-12-15  Alex Christensen  <[email protected]>
 
         REGRESSION: [macOS] http/tests/inspector/network/resource-response-service-worker.html is a flaky failure

LayoutTests/platform/mac/fast/dom/wrapper-classes-objc-expected.txt

@@ -189,6 +189,7 @@ PASS typeof objCObjectOfClass('NSCFString') is 'string'
 PASS typeof objCObjectOfClass('WebScriptObject') is 'object'
 PASS objCObjectOfClass('NSArray') instanceof Array is true
 PASS concatenateArray(objCArrayOfString()) is 'onetwothree'
+PASS objCArrayOfString().every((_, i, arr) => arr.propertyIsEnumerable(i)) is true
 PASS let arr = objCArrayOfString(); arr.length is 3
 PASS let arr = objCArrayOfString(); arr.length = 0 threw exception RangeError: Range error.
 PASS let arr = objCArrayOfString(); arr.length = 5 threw exception RangeError: Range error.

LayoutTests/platform/mac/fast/dom/wrapper-classes-objc.html

@@ -286,6 +286,7 @@
     shouldBeTrue("objCObjectOfClass('NSArray') instanceof Array");
 
     shouldBe("concatenateArray(objCArrayOfString())", "'onetwothree'");
+    shouldBeTrue("objCArrayOfString().every((_, i, arr) => arr.propertyIsEnumerable(i))");
 
     shouldBe("let arr = objCArrayOfString(); arr.length", "3");
     shouldThrow("let arr = objCArrayOfString(); arr.length = 0");