Index: src/Common/GC.h
===================================================================
--- src/Common/GC.h	(revision 68f9c43ecf1873cbb5f06aee682704b56612ed16)
+++ src/Common/GC.h	(revision 8d7bef249652cc2b9854c7090c758bcd9ad9f613)
@@ -66,5 +66,5 @@
 inline const GC& operator<< (const GC& gc, const T& x) { return gc; }
 
-inline void traceAll(const GC& gc) {}
+inline void traceAll(const GC&) {}
 
 /// Marks all arguments as live in current generation
@@ -94,10 +94,9 @@
 class GC_Traceable {
 	friend class GC;
-	friend class GcTracer;
+protected:
+	mutable bool mark;
 
-	mutable bool mark;
-protected:
 	/// override to trace any child objects
-	virtual void trace(const GC& gc) const {}
+	virtual void trace(const GC&) const {}
 };