Bug 1706404 - Change internal GetPropertyDescriptor to use Maybe and return holder object seperately. r=jandem

Depends on D112790

Differential Revision: https://phabricator.services.mozilla.com/D112917

js/src/jsapi.cpp

@@ -2037,7 +2037,19 @@ JS_PUBLIC_API bool JS_GetPropertyDescriptorById(
     JSContext* cx, HandleObject obj, HandleId id,
     MutableHandle<PropertyDescriptor> desc) {
   cx->check(obj, id);
-  return GetPropertyDescriptor(cx, obj, id, desc);
+
+  Rooted<Maybe<PropertyDescriptor>> desc_(cx);
+  RootedObject holder(cx);
+  if (!GetPropertyDescriptor(cx, obj, id, &desc_, &holder)) {
+    return false;
+  }
+
+  if (desc_.isNothing()) {
+    desc.object().set(nullptr);
+  } else {
+    desc.set(*desc_);
+  }
+  return true;
 }
 
 JS_PUBLIC_API bool JS_GetPropertyDescriptor(

js/src/vm/Iteration.cpp

@@ -1410,12 +1410,13 @@ static bool SuppressDeletedProperty(JSContext* cx, NativeIterator* ni,
           return false;
         }
 
-        Rooted<PropertyDescriptor> desc(cx);
-        if (!GetPropertyDescriptor(cx, proto, id, &desc)) {
+        Rooted<mozilla::Maybe<PropertyDescriptor>> desc(cx);
+        RootedObject holder(cx);
+        if (!GetPropertyDescriptor(cx, proto, id, &desc, &holder)) {
           return false;
         }
 
-        if (desc.object() && desc.enumerable()) {
+        if (desc.isSome() && desc->enumerable()) {
           continue;
         }
       }

js/src/vm/JSObject.cpp

@@ -2505,18 +2505,18 @@ bool js::SetImmutablePrototype(JSContext* cx, HandleObject obj,
   return true;
 }
 
-bool js::GetPropertyDescriptor(JSContext* cx, HandleObject obj, HandleId id,
-                               MutableHandle<PropertyDescriptor> desc) {
+bool js::GetPropertyDescriptor(
+    JSContext* cx, HandleObject obj, HandleId id,
+    MutableHandle<mozilla::Maybe<PropertyDescriptor>> desc,
+    MutableHandleObject holder) {
   RootedObject pobj(cx);
-
-  Rooted<Maybe<PropertyDescriptor>> desc_(cx);
   for (pobj = obj; pobj;) {
-    if (!GetOwnPropertyDescriptor(cx, pobj, id, &desc_)) {
+    if (!GetOwnPropertyDescriptor(cx, pobj, id, desc)) {
       return false;
     }
 
-    if (desc_.isSome()) {
-      desc.set(*desc_);
+    if (desc.isSome()) {
+      holder.set(desc->objectDoNotUse());
       return true;
     }
 
@@ -2525,7 +2525,8 @@ bool js::GetPropertyDescriptor(JSContext* cx, HandleObject obj, HandleId id,
     }
   }
 
-  MOZ_ASSERT(!desc.object());
+  MOZ_ASSERT(desc.isNothing());
+  MOZ_ASSERT(!holder);
   return true;
 }
 

js/src/vm/ObjectOperations.h

@@ -265,9 +265,15 @@ extern bool GetPrototypeIfOrdinary(JSContext* cx, JS::Handle<JSObject*> obj,
 extern bool SetImmutablePrototype(JSContext* cx, JS::Handle<JSObject*> obj,
                                   bool* succeeded);
 
-extern bool GetPropertyDescriptor(JSContext* cx, JS::Handle<JSObject*> obj,
-                                  JS::Handle<jsid> id,
-                                  MutableHandle<JS::PropertyDescriptor> desc);
+/*
+ * Deprecated. Finds a PropertyDescriptor somewhere along the prototype chain,
+ * similar to GetOwnPropertyDescriptor. |holder| indicates on which object the
+ * property was found.
+ */
+extern bool GetPropertyDescriptor(
+    JSContext* cx, JS::Handle<JSObject*> obj, JS::Handle<jsid> id,
+    MutableHandle<mozilla::Maybe<JS::PropertyDescriptor>> desc,
+    JS::MutableHandle<JSObject*> holder);
 
 /*
  * Deprecated. A version of HasProperty that also returns the object on which

js/src/wasm/AsmJS.cpp

@@ -21,6 +21,7 @@
 #include "mozilla/Attributes.h"
 #include "mozilla/Compression.h"
 #include "mozilla/MathAlgorithms.h"
+#include "mozilla/Maybe.h"
 #include "mozilla/ScopeExit.h"
 #include "mozilla/Sprintf.h"  // SprintfLiteral
 #include "mozilla/Unused.h"
@@ -6436,21 +6437,22 @@ static bool GetDataProperty(JSContext* cx, HandleValue objVal, HandleAtom field,
     return LinkFail(cx, "accessing property of a Proxy");
   }
 
-  Rooted<PropertyDescriptor> desc(cx);
   RootedId id(cx, AtomToId(field));
-  if (!GetPropertyDescriptor(cx, obj, id, &desc)) {
+  Rooted<mozilla::Maybe<PropertyDescriptor>> desc(cx);
+  RootedObject holder(cx);
+  if (!GetPropertyDescriptor(cx, obj, id, &desc, &holder)) {
     return false;
   }
 
-  if (!desc.object()) {
+  if (!desc.isSome()) {
     return LinkFail(cx, "property not present on object");
   }
 
-  if (!desc.isDataDescriptor()) {
+  if (!desc->isDataDescriptor()) {
     return LinkFail(cx, "property is not a data property");
   }
 
-  v.set(desc.value());
+  v.set(desc->value());
   return true;
 }