add use counters for __defineGetter__ failing

We deviate from spec in that, in our implementation, __defineGetter__ on non-
configurable properties returns false instead of throwing a TypeError. This commit
adds a use counter to track how often we would be throwing an error we currently
avoid, to determine if we can change to align with spec or if the spec is not
implementable.

BUG=v8:5070

Review-Url: https://codereview.chromium.org/2089533002
Cr-Commit-Position: refs/heads/master@{#37259}

include/v8.h

@@ -5700,6 +5700,7 @@ class V8_EXPORT Isolate {
     kRegExpPrototypeOldFlagGetter = 31,
     kDecimalWithLeadingZeroInStrictMode = 32,
     kLegacyDateParser = 33,
+    kDefineGetterOrSetterWouldThrow = 34,
 
     // If you add new values here, you'll also need to update Chromium's:
     // UseCounter.h, V8PerIsolateData.cpp, histograms.xml

src/builtins.cc

@@ -1729,6 +1729,9 @@ Object* ObjectDefineAccessor(Isolate* isolate, Handle<Object> object,
   Maybe<bool> success = JSReceiver::DefineOwnProperty(
       isolate, receiver, name, &desc, Object::DONT_THROW);
   MAYBE_RETURN(success, isolate->heap()->exception());
+  if (!success.FromJust()) {
+    isolate->CountUsage(v8::Isolate::kDefineGetterOrSetterWouldThrow);
+  }
   // 6. Return undefined.
   return isolate->heap()->undefined_value();
 }

test/cctest/BUILD.gn

@@ -157,6 +157,7 @@ v8_executable("cctest") {
     "test-unboxed-doubles.cc",
     "test-unique.cc",
     "test-unscopables-hidden-prototype.cc",
+    "test-usecounters.cc",
     "test-utils.cc",
     "test-version.cc",
     "test-weakmaps.cc",

test/cctest/cctest.gyp

@@ -192,6 +192,7 @@
         'test-unboxed-doubles.cc',
         'test-unique.cc',
         'test-unscopables-hidden-prototype.cc',
+        'test-usecounters.cc',
         'test-utils.cc',
         'test-version.cc',
         'test-weakmaps.cc',

test/cctest/test-usecounters.cc

+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "src/v8.h"
+
+#include "test/cctest/cctest.h"
+
+namespace {
+
+int* global_use_counts = NULL;
+
+void MockUseCounterCallback(v8::Isolate* isolate,
+                            v8::Isolate::UseCounterFeature feature) {
+  ++global_use_counts[feature];
+}
+}
+
+TEST(DefineGetterSetterThrowUseCount) {
+  v8::Isolate* isolate = CcTest::isolate();
+  v8::HandleScope scope(isolate);
+  LocalContext env;
+  int use_counts[v8::Isolate::kUseCounterFeatureCount] = {};
+  global_use_counts = use_counts;
+  CcTest::isolate()->SetUseCounterCallback(MockUseCounterCallback);
+
+  // __defineGetter__ and __defineSetter__ do not increment
+  // kDefineGetterOrSetterWouldThrow on success
+  CompileRun(
+      "var a = {};"
+      "Object.defineProperty(a, 'b', { value: 0, configurable: true });"
+      "a.__defineGetter__('b', ()=>{});");
+  CHECK_EQ(0, use_counts[v8::Isolate::kDefineGetterOrSetterWouldThrow]);
+  CompileRun(
+      "var a = {};"
+      "Object.defineProperty(a, 'b', { value: 0, configurable: true });"
+      "a.__defineSetter__('b', ()=>{});");
+  CHECK_EQ(0, use_counts[v8::Isolate::kDefineGetterOrSetterWouldThrow]);
+
+  // __defineGetter__ and __defineSetter__ do not increment
+  // kDefineGetterOrSetterWouldThrow on other errors
+  v8::Local<v8::Value> resultProxyThrow = CompileRun(
+      "var exception;"
+      "try {"
+      "var a = new Proxy({}, { defineProperty: ()=>{throw new Error;} });"
+      "a.__defineGetter__('b', ()=>{});"
+      "} catch (e) { exception = e; }"
+      "exception");
+  CHECK_EQ(0, use_counts[v8::Isolate::kDefineGetterOrSetterWouldThrow]);
+  CHECK(resultProxyThrow->IsObject());
+  resultProxyThrow = CompileRun(
+      "var exception;"
+      "try {"
+      "var a = new Proxy({}, { defineProperty: ()=>{throw new Error;} });"
+      "a.__defineSetter__('b', ()=>{});"
+      "} catch (e) { exception = e; }"
+      "exception");
+  CHECK_EQ(0, use_counts[v8::Isolate::kDefineGetterOrSetterWouldThrow]);
+  CHECK(resultProxyThrow->IsObject());
+
+  // __defineGetter__ and __defineSetter__ increment
+  // kDefineGetterOrSetterWouldThrow when they would throw per spec (B.2.2.2)
+  CompileRun(
+      "var a = {};"
+      "Object.defineProperty(a, 'b', { value: 0, configurable: false });"
+      "a.__defineGetter__('b', ()=>{});");
+  CHECK_EQ(1, use_counts[v8::Isolate::kDefineGetterOrSetterWouldThrow]);
+  CompileRun(
+      "var a = {};"
+      "Object.defineProperty(a, 'b', { value: 0, configurable: false });"
+      "a.__defineSetter__('b', ()=>{});");
+  CHECK_EQ(2, use_counts[v8::Isolate::kDefineGetterOrSetterWouldThrow]);
+}