Bug 1149987 - Part 3: Give ErrorResult a move constructor and a move assignment operator; r=bzbarsky

dom/bindings/BindingUtils.cpp

@@ -13,6 +13,7 @@
 #include "mozilla/FloatingPoint.h"
 #include "mozilla/Assertions.h"
 #include "mozilla/Preferences.h"
+#include "mozilla/unused.h"
 
 #include "AccessCheck.h"
 #include "jsfriendapi.h"
@@ -327,6 +328,37 @@ ErrorResult::ReportNotEnoughArgsError(JSContext* cx,
   ThrowErrorMessage(cx, dom::MSG_MISSING_ARGUMENTS, errorMessage.get());
 }
 
+ErrorResult&
+ErrorResult::operator=(ErrorResult&& aRHS)
+{
+#ifdef DEBUG
+  mMightHaveUnreportedJSException = aRHS.mMightHaveUnreportedJSException;
+  aRHS.mMightHaveUnreportedJSException = false;
+#endif
+  if (aRHS.IsErrorWithMessage()) {
+    mMessage = aRHS.mMessage;
+    aRHS.mMessage = nullptr;
+  } else if (aRHS.IsJSException()) {
+    JSContext* cx = nsContentUtils::GetDefaultJSContextForThread();
+    MOZ_ASSERT(cx);
+    mJSException.setUndefined();
+    if (!js::AddRawValueRoot(cx, &mJSException, "ErrorResult::mJSException")) {
+      MOZ_CRASH("Could not root mJSException, we're about to OOM");
+    }
+    mJSException = aRHS.mJSException;
+    aRHS.mJSException.setUndefined();
+    js::RemoveRawValueRoot(cx, &aRHS.mJSException);
+  } else {
+    // Null out the union on both sides for hygiene purposes.
+    mMessage = aRHS.mMessage = nullptr;
+  }
+  // Note: It's important to do this last, since this affects the condition
+  // checks above!
+  mResult = aRHS.mResult;
+  aRHS.mResult = NS_OK;
+  return *this;
+}
+
 namespace dom {
 
 bool

dom/bindings/ErrorResult.h

@@ -17,6 +17,7 @@
 #include "nscore.h"
 #include "nsStringGlue.h"
 #include "mozilla/Assertions.h"
+#include "mozilla/Move.h"
 
 namespace IPC {
 class Message;
@@ -61,6 +62,12 @@ public:
   }
 #endif
 
+  ErrorResult(ErrorResult&& aRHS)
+  {
+    *this = Move(aRHS);
+  }
+  ErrorResult& operator=(ErrorResult&& aRHS);
+
   void Throw(nsresult rv) {
     MOZ_ASSERT(NS_FAILED(rv), "Please don't try throwing success");
     MOZ_ASSERT(rv != NS_ERROR_TYPE_ERR, "Use ThrowTypeError()");