From c4adf5736e4e41cc4eaa15c6137735a7002df6d8 Mon Sep 17 00:00:00 2001
From: Andrew McCreight <amccreight@mozilla.com>
Date: Wed, 15 Feb 2012 15:28:42 -0800
Subject: [PATCH] Bug 727313 - avoid warnings, add case for skippable CC
 macros. r=smaug

---
 xpcom/glue/nsCycleCollectionParticipant.h | 25 +++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/xpcom/glue/nsCycleCollectionParticipant.h b/xpcom/glue/nsCycleCollectionParticipant.h
index 7bcefbebd335..50a55f8da968 100644
--- a/xpcom/glue/nsCycleCollectionParticipant.h
+++ b/xpcom/glue/nsCycleCollectionParticipant.h
@@ -299,6 +299,10 @@ public:
 #define NS_CYCLE_COLLECTION_UPCAST(obj, clazz)                                 \
   NS_CYCLE_COLLECTION_CLASSNAME(clazz)::Upcast(obj)
 
+///////////////////////////////////////////////////////////////////////////////
+// Helpers for implementing CanSkip methods
+///////////////////////////////////////////////////////////////////////////////
+
 #define NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_BEGIN(_class)                        \
   NS_IMETHODIMP_(bool)                                                         \
   NS_CYCLE_COLLECTION_CLASSNAME(_class)::CanSkipReal(void *p,                  \
@@ -310,6 +314,7 @@ public:
     _class *tmp = Downcast(s);
 
 #define NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_END                                  \
+    (void)tmp;                                                                 \
     return false;                                                              \
   }
 
@@ -323,6 +328,7 @@ public:
     _class *tmp = Downcast(s);
 
 #define NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_IN_CC_END                            \
+    (void)tmp;                                                                 \
     return false;                                                              \
   }
 
@@ -336,6 +342,7 @@ public:
     _class *tmp = Downcast(s);
 
 #define NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_THIS_END                             \
+    (void)tmp;                                                                 \
     return false;                                                              \
   }
 
@@ -614,6 +621,24 @@ NS_CYCLE_COLLECTION_PARTICIPANT_INSTANCE
 #define NS_DECL_CYCLE_COLLECTION_CLASS(_class)                                 \
   NS_DECL_CYCLE_COLLECTION_CLASS_AMBIGUOUS(_class, _class)
 
+// Cycle collector helper for ambiguous classes that can sometimes be skipped.
+#define NS_DECL_CYCLE_COLLECTION_SKIPPABLE_CLASS_AMBIGUOUS(_class, _base)        \
+class NS_CYCLE_COLLECTION_INNERCLASS                                             \
+ : public nsXPCOMCycleCollectionParticipant                                      \
+{                                                                                \
+public:                                                                          \
+  NS_CYCLE_COLLECTION_INNERCLASS () : nsXPCOMCycleCollectionParticipant(true) {} \
+  NS_DECL_CYCLE_COLLECTION_CLASS_BODY(_class, _base)                             \
+protected:                                                                       \
+  NS_IMETHOD_(bool) CanSkipReal(void *p, bool aRemovingAllowed);                 \
+  NS_IMETHOD_(bool) CanSkipInCCReal(void *p);                                    \
+  NS_IMETHOD_(bool) CanSkipThisReal(void *p);                                    \
+};                                                                               \
+NS_CYCLE_COLLECTION_PARTICIPANT_INSTANCE
+
+#define NS_DECL_CYCLE_COLLECTION_SKIPPABLE_CLASS(_class)                       \
+        NS_DECL_CYCLE_COLLECTION_SKIPPABLE_CLASS_AMBIGUOUS(_class, _class)
+
 // Cycle collector helper for classes that don't want to unlink anything.
 // Note: if this is used a lot it might make sense to have a base class that
 //       doesn't do anything in Root/Unlink/Unroot.