Add override keywords for clang-3.6

Author: rudi-c

src/gc/collector.h

@@ -68,15 +68,14 @@ void startGCUnexpectedRegion();
 void endGCUnexpectedRegion();
 
 class GCVisitorNoRedundancy : public GCVisitor {
-    virtual void _visitRedundant(void** ptr_address) { visit(ptr_address); }
-    virtual void _visitRangeRedundant(void** start, void** end) { visitRange(start, end); }
+    void _visitRedundant(void** ptr_address) override { visit(ptr_address); }
+    void _visitRangeRedundant(void** start, void** end) override { visitRange(start, end); }
 
 public:
     virtual ~GCVisitorNoRedundancy() {}
 
-    virtual void visitPotentialRedundant(void* p) { visitPotential(p); }
-    virtual void visitPotentialRangeRedundant(void** start, void** end) { visitPotentialRange(start, end); }
-    virtual bool shouldVisitRedundants() { return true; }
+    void visitPotentialRedundant(void* p) override { visitPotential(p); }
+    void visitPotentialRangeRedundant(void** start, void** end) override { visitPotentialRange(start, end); }
 };
 
 //
@@ -85,18 +84,24 @@ class GCVisitorNoRedundancy : public GCVisitor {
 
 class ReferenceMapStack;
 
+#if MOVING_GC
+#define MOVING_OVERRIDE override
+#else
+#define MOVING_OVERRIDE
+#endif
+
 // Bulds the reference map, and also determine which objects cannot be moved.
 class GCVisitorPinning : public GCVisitorNoRedundancy {
 private:
     ReferenceMapStack* stack;
 
-    virtual void _visit(void** ptr_address);
+    void _visit(void** ptr_address) MOVING_OVERRIDE;
 
 public:
     GCVisitorPinning(ReferenceMapStack* stack) : stack(stack) {}
     virtual ~GCVisitorPinning() {}
 
-    virtual void visitPotential(void* p);
+    void visitPotential(void* p) MOVING_OVERRIDE;
 };
 
 // Visits the fields and replaces it with new_values if it was equal to old_value.
@@ -105,14 +110,14 @@ class GCVisitorReplacing : public GCVisitor {
     void* old_value;
     void* new_value;
 
-    virtual void _visit(void** p);
+    void _visit(void** p) MOVING_OVERRIDE;
 
 public:
     GCVisitorReplacing(void* old_value, void* new_value) : old_value(old_value), new_value(new_value) {}
     virtual ~GCVisitorReplacing() {}
 
-    virtual void visitPotential(void* p){};
-    virtual void visitPotentialRange(void** start, void** end){};
+    void visitPotential(void* p) MOVING_OVERRIDE{};
+    void visitPotentialRange(void** start, void** end) MOVING_OVERRIDE{};
 };
 
 class GCAllocation;