Runtime-async continuation object reading with Cordb

src/coreclr/debug/daccess/dacdbiimpl.cpp

@@ -2315,6 +2315,7 @@ void DacDbiInterfaceImpl::GetClassTypeInfo(TypeHandle                      typeH
                                            DebuggerIPCE_ExpandedTypeData * pTypeInfo,
                                            AppDomain *                     pAppDomain)
 {
+    typeHandle = typeHandle.UpCastTypeIfNeeded();
     Module * pModule = typeHandle.GetModule();
 
     if (typeHandle.HasInstantiation()) // the type handle represents a generic instantiation
@@ -2402,9 +2403,10 @@ void DacDbiInterfaceImpl::TypeHandleToBasicTypeInfo(TypeHandle
         case ELEMENT_TYPE_CLASS:
         case ELEMENT_TYPE_VALUETYPE:
         {
-            Module * pModule = typeHandle.GetModule();
+            typeHandle = typeHandle.UpCastTypeIfNeeded();
 
-            if (typeHandle.HasInstantiation())   // only set if instantiated
+            Module * pModule = typeHandle.GetModule();
+            if (typeHandle.HasInstantiation()) // only set if instantiated
             {
                 pTypeInfo->vmTypeHandle.SetDacTargetPtr(typeHandle.AsTAddr());
             }

src/coreclr/debug/ee/debugger.cpp

@@ -11657,6 +11657,7 @@ void Debugger::TypeHandleToBasicTypeInfo(AppDomain *pAppDomain, TypeHandle th, D
     case ELEMENT_TYPE_CLASS:
     case ELEMENT_TYPE_VALUETYPE:
         {
+            th = th.UpCastTypeIfNeeded();
             res->vmTypeHandle = th.HasInstantiation() ? WrapTypeHandle(th) : VMPTR_TypeHandle::NullPtr();
                                                                              // only set if instantiated
             res->metadataToken = th.GetCl();
@@ -11739,6 +11740,7 @@ void Debugger::TypeHandleToExpandedTypeInfo(AreValueTypesBoxed boxed,
     case ELEMENT_TYPE_CLASS:
         {
 treatAllValuesAsBoxed:
+            th = th.UpCastTypeIfNeeded();
             res->ClassTypeData.typeHandle = th.HasInstantiation() ? WrapTypeHandle(th) : VMPTR_TypeHandle::NullPtr(); // only set if instantiated
             res->ClassTypeData.metadataToken = th.GetCl();
             DebuggerModule * pModule = LookupOrCreateModule(th.GetModule());

src/coreclr/vm/typehandle.h

@@ -386,6 +386,7 @@ class TypeHandle
     // And some types (like ByRef or generic type parameters) have no
     // method table and this function returns NULL for them.
     inline PTR_MethodTable GetMethodTable() const;
+    inline TypeHandle UpCastTypeIfNeeded() const;
 
     // Returns the type which should be used for visibility checking.
     inline MethodTable* GetMethodTableOfRootTypeParam() const;

src/coreclr/vm/typehandle.inl

@@ -27,6 +27,24 @@ inline PTR_MethodTable TypeHandle::GetMethodTable() const
         return AsMethodTable();
 }
 
+// This method allows you to get the "upcasted" type handle. Currently we need this
+// because continuation types for runtime-async methods are dynamically created subtypes of a
+// parent continuation class that have no metadata of their own. This way, when we need to get
+// the TypeHandle to retrieve metadata, we are able to get a reasonable approximation.
+// If we need to handle more such types in the future we can add them here.
+inline TypeHandle TypeHandle::UpCastTypeIfNeeded() const
+{
+    LIMITED_METHOD_DAC_CONTRACT;
+
+    if (IsTypeDesc())
+        return *this;
+    if (AsMethodTable()->IsContinuation())
+    {
+        return TypeHandle(g_pContinuationClassIfSubTypeCreated);
+    }
+    return *this;
+}
+
 inline void TypeHandle::SetIsFullyLoaded()
 {
     LIMITED_METHOD_CONTRACT;