fix backcompat issue for standalone GC (#117793)

#116310 breaks the backward compatibility for the standalone GC - it can no longer work with previous versions of the runtime on both windows and linux. this is easily reproducible by just loading a standalone GC dll built from main with say 8.0 runtime because it will fail as soon as it hits FinalizeLoad when coreclr is trying to load the standalone dll.

both msvc and clang put the 2 methods, both named IsPromoted next to each other instead of maintaining the order as declared. renaming the new one to IsPromoted2 worked. but I also just made IsPromoted2 on IGCHeapInternal instead since it's only used by the GC side.

Author: Maoni0

src/coreclr/gc/gc.cpp

@@ -49779,10 +49779,10 @@ HRESULT GCHeap::Initialize()
 // GC callback functions
 bool GCHeap::IsPromoted(Object* object)
 {
-    return IsPromoted(object, true);
+    return IsPromoted2(object, true);
 }
 
-bool GCHeap::IsPromoted(Object* object, bool bVerifyNextHeader)
+bool GCHeap::IsPromoted2(Object* object, bool bVerifyNextHeader)
 {
     uint8_t* o = (uint8_t*)object;
 

src/coreclr/gc/gc.h

@@ -285,11 +285,16 @@ struct alloc_context : gc_alloc_context
 #endif // FEATURE_SVR_GC
 };
 
+// NOTE!
+// Do not add overloaded methods, always use a different name, different from any methods declared here or
+// on the IGCHeap interface.
 class IGCHeapInternal : public IGCHeap {
 public:
     virtual int GetNumberOfHeaps () PURE_VIRTUAL
     virtual int GetHomeHeapNumber () PURE_VIRTUAL
     virtual size_t GetPromotedBytes(int heap_index) PURE_VIRTUAL
+    // Used by the bridge code.
+    virtual bool IsPromoted2(Object* object, bool bVerifyNextHeader) PURE_VIRTUAL
 
     unsigned GetMaxGeneration()
     {

src/coreclr/gc/gcbridge.cpp

@@ -666,7 +666,7 @@ static bool PushObject(Object* obj, void* unused)
     }
 
     // We only care about dead objects
-    if (!data && g_theGCHeap->IsPromoted(obj, false))
+    if (!data && g_theGCHeap->IsPromoted2(obj, false))
     {
 #if DUMP_GRAPH
         printf ("alive\n");

src/coreclr/gc/gcimpl.h

@@ -126,7 +126,7 @@ class GCHeap : public IGCHeapInternal
     // Check if an argument is promoted (ONLY CALL DURING
     // THE PROMOTIONSGRANTED CALLBACK.)
     bool IsPromoted (Object *object);
-    bool IsPromoted (Object *object, bool bVerifyNextHeader);
+    bool IsPromoted2 (Object *object, bool bVerifyNextHeader);
 
     size_t GetPromotedBytes (int heap_index);
 

src/coreclr/gc/gcinterface.h

@@ -644,6 +644,9 @@ enum class GCConfigurationType
 using ConfigurationValueFunc = void (*)(void* context, void* name, void* publicKey, GCConfigurationType type, int64_t data);
 
 // IGCHeap is the interface that the VM will use when interacting with the GC.
+// NOTE!
+// Only add methods to the end.
+// Do not add overloaded methods. Always use a different name.
 class IGCHeap {
 public:
     /*
@@ -1065,9 +1068,6 @@ class IGCHeap {
     virtual void DiagWalkHeapWithACHandling(walk_fn fn, void* context, int gen_number, bool walk_large_object_heap_p) PURE_VIRTUAL
 
     virtual void NullBridgeObjectsWeakRefs(size_t length, void* unreachableObjectHandles) PURE_VIRTUAL;
-
-    // Returns whether nor this GC was promoted by the last GC.
-    virtual bool IsPromoted(Object* object, bool bVerifyNextHeader) PURE_VIRTUAL
 };
 
 #ifdef WRITE_BARRIER_CHECK