Bug 967364: Use every already_AddRefed. r=bsmedberg

content/media/MediaStreamGraph.cpp

@@ -5,6 +5,7 @@
 
 #include "MediaStreamGraphImpl.h"
 #include "mozilla/LinkedList.h"
+#include "mozilla/unused.h"
 
 #include "AudioSegment.h"
 #include "VideoSegment.h"
@@ -24,6 +25,7 @@
 #include <algorithm>
 #include "DOMMediaStream.h"
 #include "GeckoProfiler.h"
+#include "mozilla/unused.h"
 
 using namespace mozilla::layers;
 using namespace mozilla::dom;
@@ -2387,7 +2389,7 @@ ProcessedMediaStream::AllocateInputPort(MediaStream* aStream, uint32_t aFlags,
       mPort->Init();
       // The graph holds its reference implicitly
       mPort->GraphImpl()->SetStreamOrderDirty();
-      mPort.forget();
+      unused << mPort.forget();
     }
     virtual void RunDuringShutdown()
     {

content/svg/content/src/nsSVGElement.cpp

@@ -5,6 +5,7 @@
 
 #include "mozilla/ArrayUtils.h"
 #include "mozilla/DebugOnly.h"
+#include "mozilla/unused.h"
 
 #include "nsSVGElement.h"
 
@@ -49,6 +50,7 @@
 #include "nsAttrValueOrString.h"
 #include "nsSMILAnimationController.h"
 #include "mozilla/dom/SVGElementBinding.h"
+#include "mozilla/unused.h"
 
 using namespace mozilla;
 using namespace mozilla::dom;
@@ -1363,7 +1365,7 @@ nsSVGElement::UpdateAnimatedContentStyleRule()
                   SMIL_MAPPED_ATTR_STYLERULE_ATOM,
                   animContentStyleRule.get(),
                   ReleaseStyleRule);
-    animContentStyleRule.forget();
+    unused << animContentStyleRule.forget();
     NS_ABORT_IF_FALSE(rv == NS_OK,
                       "SetProperty failed (or overwrote something)");
   }

dom/base/nsGlobalWindow.cpp

@@ -48,6 +48,7 @@
 #include "ScriptSettings.h"
 #include "mozilla/Preferences.h"
 #include "mozilla/Likely.h"
+#include "mozilla/unused.h"
 
 // Other Classes
 #include "nsEventListenerManager.h"
@@ -11667,7 +11668,7 @@ nsGlobalWindow::SetTimeoutOrInterval(nsIScriptTimeoutHandler *aHandler,
     }
 
     // The timeout is now also held in the timer's closure.
-    copy.forget();
+    unused << copy.forget();
   } else {
     // If we are frozen, however, then we instead simply set
     // timeout->mTimeRemaining to be the "time remaining" in the timeout (i.e.,

ipc/glue/BackgroundImpl.cpp

@@ -9,6 +9,7 @@
 #include "mozilla/DebugOnly.h"
 #include "mozilla/Services.h"
 #include "mozilla/StaticPtr.h"
+#include "mozilla/unused.h"
 #include "mozilla/dom/ContentChild.h"
 #include "mozilla/dom/ContentParent.h"
 #include "mozilla/ipc/ProtocolTypes.h"
@@ -677,7 +678,7 @@ private:
   {
     if (mTransport) {
       CRASH_IN_CHILD_PROCESS("Leaking transport!");
-      mTransport.forget();
+      unused << mTransport.forget();
     }
   }
 
@@ -1533,7 +1534,7 @@ ChildImpl::CreateCallbackRunnable::~CreateCallbackRunnable()
 {
   if (mActor) {
     CRASH_IN_CHILD_PROCESS("Leaking actor!");
-    mActor.forget();
+    unused << mActor.forget();
   }
 }
 
@@ -1676,7 +1677,7 @@ ChildImpl::OpenMainProcessActorRunnable::Run()
   }
 
   // Now that Open() has succeeded transfer the ownership of the actors to IPDL.
-  parentActor.forget();
+  unused << parentActor.forget();
 
   auto threadLocalInfo =
     static_cast<ThreadLocalInfo*>(PR_GetThreadPrivate(sThreadLocalIndex));

layout/forms/nsComboboxControlFrame.cpp

@@ -38,6 +38,7 @@
 #include "nsTextNode.h"
 #include "mozilla/LookAndFeel.h"
 #include "mozilla/MouseEvents.h"
+#include "mozilla/unused.h"
 
 using namespace mozilla;
 
@@ -803,7 +804,7 @@ nsComboboxControlFrame::Reflow(nsPresContext*          aPresContext,
   if (NS_SUCCEEDED(aPresContext->PresShell()->PostReflowCallback(resize))) {
     // The reflow callback queue doesn't AddRef so we keep it alive until
     // it's released in its ReflowFinished / ReflowCallbackCanceled.
-    resize.forget();
+    unused << resize.forget();
   }
 
   // Get the width of the vertical scrollbar.  That will be the width of the

netwerk/protocol/http/nsHttpConnectionMgr.cpp

@@ -31,6 +31,7 @@
 #include <algorithm>
 #include "Http2Compression.h"
 #include "mozilla/ChaosMode.h"
+#include "mozilla/unused.h"
 
 // defined by the socket transport service while active
 extern PRThread *gSocketThread;
@@ -333,7 +334,7 @@ nsHttpConnectionMgr::DoShiftReloadConnectionCleanup(nsHttpConnectionInfo *aCI)
     nsresult rv = PostEvent(&nsHttpConnectionMgr::OnMsgDoShiftReloadConnectionCleanup,
                             0, connInfo);
     if (NS_SUCCEEDED(rv))
-        connInfo.forget();
+        unused << connInfo.forget();
     return rv;
 }
 
@@ -408,7 +409,7 @@ nsHttpConnectionMgr::SpeculativeConnect(nsHttpConnectionInfo *ci,
     nsresult rv =
         PostEvent(&nsHttpConnectionMgr::OnMsgSpeculativeConnect, 0, args);
     if (NS_SUCCEEDED(rv))
-        args.forget();
+        unused << args.forget();
     return rv;
 }
 
@@ -505,7 +506,7 @@ nsHttpConnectionMgr::UpdateRequestTokenBucket(EventTokenBucket *aBucket)
     nsresult rv = PostEvent(&nsHttpConnectionMgr::OnMsgUpdateRequestTokenBucket,
                             0, bucket);
     if (NS_SUCCEEDED(rv))
-        bucket.forget();
+        unused << bucket.forget();
     return rv;
 }
 

netwerk/protocol/wyciwyg/nsWyciwygChannel.cpp

@@ -24,6 +24,7 @@
 #include "nsIProgressEventSink.h"
 #include "nsIURI.h"
 #include "mozilla/DebugOnly.h"
+#include "mozilla/unused.h"
 
 typedef mozilla::net::LoadContextInfo LoadContextInfo;
 
@@ -38,7 +39,7 @@ public:
     NS_WARN_IF_FALSE(thread, "Couldn't get the main thread!");
     if (thread) {
       nsIWyciwygChannel *chan = static_cast<nsIWyciwygChannel *>(mChannel);
-      mChannel.forget();
+      mozilla::unused << mChannel.forget();
       NS_ProxyRelease(thread, chan);
     }
   }

parser/html/nsHtml5Atom.cpp

@@ -4,6 +4,7 @@
 
 #include "nsHtml5Atom.h"
 #include "nsAutoPtr.h"
+#include "mozilla/unused.h"
 
 nsHtml5Atom::nsHtml5Atom(const nsAString& aString)
 {
@@ -24,7 +25,7 @@ nsHtml5Atom::nsHtml5Atom(const nsAString& aString)
   NS_ASSERTION(Equals(aString), "correct data");
 
   // Take ownership of buffer
-  buf.forget();
+  mozilla::unused << buf.forget();
 }
 
 nsHtml5Atom::~nsHtml5Atom()

uriloader/prefetch/nsOfflineCacheUpdateService.cpp

@@ -48,6 +48,7 @@
 #include "nsIAsyncVerifyRedirectCallback.h"
 #include "mozilla/Preferences.h"
 #include "mozilla/Attributes.h"
+#include "mozilla/unused.h"
 #include "nsIDiskSpaceWatcher.h"
 #include "nsIDocShell.h"
 #include "nsIDocShellTreeItem.h"
@@ -55,6 +56,7 @@
 #include "mozilla/dom/TabChild.h"
 #include "mozilla/dom/PermissionMessageUtils.h"
 #include "nsContentUtils.h"
+#include "mozilla/unused.h"
 
 using namespace mozilla;
 using namespace mozilla::dom;
@@ -405,7 +407,7 @@ nsOfflineCacheUpdateService::ScheduleOnDocumentStop(nsIURI *aManifestURI,
     NS_ENSURE_SUCCESS(rv, rv);
 
     // The update will release when it has scheduled itself.
-    update.forget();
+    unused << update.forget();
 
     return NS_OK;
 }

widget/xpwidgets/nsBaseWidget.cpp

@@ -36,12 +36,14 @@
 #include "prdtoa.h"
 #include "prenv.h"
 #include "mozilla/Attributes.h"
+#include "mozilla/unused.h"
 #include "nsContentUtils.h"
 #include "gfxPrefs.h"
 #include "mozilla/gfx/2D.h"
 #include "mozilla/MouseEvents.h"
 #include "GLConsts.h"
 #include "LayerScope.h"
+#include "mozilla/unused.h"
 
 #ifdef ACCESSIBILITY
 #include "nsAccessibilityService.h"
@@ -189,8 +191,8 @@ void nsBaseWidget::DestroyCompositor()
                                    mCompositorChild));
     // The DestroyCompositor task we just added to the MessageLoop will handle
     // releasing mCompositorParent and mCompositorChild.
-    mCompositorParent.forget();
-    mCompositorChild.forget();
+    unused << mCompositorParent.forget();
+    unused << mCompositorChild.forget();
   }
 }
 

xpcom/ds/nsAtomTable.cpp

@@ -10,6 +10,7 @@
 #include "mozilla/HashFunctions.h"
 #include "mozilla/MemoryReporting.h"
 #include "mozilla/DebugOnly.h"
+#include "mozilla/unused.h"
 
 #include "nsAtomTable.h"
 #include "nsStaticAtom.h"
@@ -344,7 +345,7 @@ AtomImpl::AtomImpl(const nsAString& aString, uint32_t aHash)
   NS_ASSERTION(Equals(aString), "correct data");
 
   // Take ownership of buffer
-  buf.forget();
+  mozilla::unused << buf.forget();
 }
 
 AtomImpl::AtomImpl(nsStringBuffer* aStringBuffer, uint32_t aLength,

xpcom/glue/nsCOMPtr.h

@@ -118,6 +118,12 @@
   #define NSCAP_LOG_RELEASE(this, ptr)
 #endif
 
+namespace mozilla {
+
+struct unused_t;
+
+} // namespace mozilla
+
 template <class T>
 struct already_AddRefed
     /*
@@ -156,7 +162,33 @@ struct already_AddRefed
       // nothing else to do here
     }
 
-    T* take() const { return mRawPtr; }
+    already_AddRefed(const already_AddRefed<T>& aOther)
+      : mRawPtr(aOther.take())
+    {
+      // nothing else to do here
+    }
+
+    ~already_AddRefed()
+    {
+      MOZ_ASSERT(!mRawPtr);
+    }
+
+    // Specialize the unused operator<< for already_AddRefed, to allow
+    // nsCOMPtr<nsIFoo> foo;
+    // unused << foo.forget();
+    friend void operator<<(const mozilla::unused_t& unused,
+                                         const already_AddRefed<T>& rhs)
+    {
+      auto mutableAlreadyAddRefed = const_cast<already_AddRefed<T>*>(&rhs);
+      unused << mutableAlreadyAddRefed->take();
+    }
+
+    T* take()
+    {
+      T* rawPtr = mRawPtr;
+      mRawPtr = nullptr;
+      return rawPtr;
+    }
 
     /**
      * This helper is useful in cases like