Various fixes for generics

- Fix handling of generic types and instances in several locations.
- Fix access to MethodSpec_Index.
- Add missing handling of MethodSpec in ldtoken instruction.
- Fix field iteration in NewGenericInstanceObject.

Author: josesimoes

src/CLR/Core/CLR_RT_HeapBlock.cpp

@@ -351,6 +351,7 @@ HRESULT CLR_RT_HeapBlock::SetGenericInstanceObject(const CLR_RT_TypeSpec_Index &
 
     m_data.genericInstance.genericType = genericType;
     m_data.genericInstance.ptr = nullptr;
+    m_id.raw = CLR_RT_HEAPBLOCK_RAW_ID(DATATYPE_GENERICINST, 0, 1);
 
     NANOCLR_NOCLEANUP();
 }

src/CLR/Core/Execution.cpp

@@ -91,7 +91,7 @@ HRESULT CLR_RT_ExecutionEngine::ExecutionEngine_Initialize()
                                                     // CLR_RT_Thread*                      m_cctorThread;
                                                     //
 #if !defined(NANOCLR_APPDOMAINS)
-    m_globalLock = nullptr;  // CLR_RT_HeapBlock*                  m_globalLock;
+    m_globalLock = nullptr;           // CLR_RT_HeapBlock*                  m_globalLock;
     m_outOfMemoryException = nullptr; // CLR_RT_HeapBlock*                   m_outOfMemoryException;
 #endif
 
@@ -2262,27 +2262,31 @@ HRESULT CLR_RT_ExecutionEngine::NewGenericInstanceObject(
     const CLR_RECORD_FIELDDEF *target = nullptr;
     CLR_RT_Assembly *assm = nullptr;
     CLR_RT_TypeDef_Instance instSub = instance;
+    CLR_RT_HeapBlock_GenericInstance *giHeader = nullptr;
+    CLR_RT_HeapBlock *fieldCursor = nullptr;
 
     reference.SetObjectReference(nullptr);
 
     int clsFields = instance.target->instanceFieldsCount;
     int totFields = instance.CrossReference().totalFields + CLR_RT_HeapBlock::HB_Object_Fields_Offset;
 
-    CLR_RT_HeapBlock_GenericInstance *genericInst;
+    giHeader = (CLR_RT_HeapBlock_GenericInstance *)ExtractHeapBlocksForGenericInstance(0, genericInstance, totFields);
+    CHECK_ALLOCATION(giHeader);
 
-    genericInst =
-        (CLR_RT_HeapBlock_GenericInstance *)ExtractHeapBlocksForGenericInstance(0, genericInstance, totFields);
-    CHECK_ALLOCATION(genericInst);
+    reference.SetObjectReference(giHeader);
 
-    reference.SetObjectReference(genericInst);
+    // Associate the instance with its declaring type for reflection & casting utilities.
+    giHeader->SetObjectCls(instance);
 
     //
     // Initialize field types, from last to first.
     //
     // We do the decrement BEFORE the comparison because we want to stop short of the first field, the
     // object descriptor (already initialized).
     //
-    genericInst += totFields;
+
+    fieldCursor = reinterpret_cast<CLR_RT_HeapBlock *>(giHeader) + totFields;
+
     while (--totFields > 0)
     {
         while (clsFields == 0)
@@ -2302,11 +2306,11 @@ HRESULT CLR_RT_ExecutionEngine::NewGenericInstanceObject(
             target = assm->GetFieldDef(instSub.target->firstInstanceField + clsFields);
         }
 
-        genericInst--;
+        fieldCursor--;
         target--;
         clsFields--;
 
-        NANOCLR_CHECK_HRESULT(InitializeReference(*genericInst, target, assm));
+        NANOCLR_CHECK_HRESULT(InitializeReference(*fieldCursor, target, assm));
     }
 
     if (instance.HasFinalizer())

src/CLR/Core/Interpreter.cpp

@@ -2548,6 +2548,7 @@ HRESULT CLR_RT_Thread::Execute_IL(CLR_RT_StackFrame &stackArg)
                     {
                         case DATATYPE_CLASS:
                         case DATATYPE_VALUETYPE:
+                        case DATATYPE_GENERICINST:
                             evalPos[0].Assign(obj[fieldInst.CrossReference().offset]);
                             goto Execute_LoadAndPromote;
                         case DATATYPE_DATETIME:
@@ -2600,13 +2601,17 @@ HRESULT CLR_RT_Thread::Execute_IL(CLR_RT_StackFrame &stackArg)
 #if defined(NANOCLR_APPDOMAINS)
                     _ASSERTE(dt != DATATYPE_TRANSPARENT_PROXY);
 #endif
-                    if (dt == DATATYPE_CLASS || dt == DATATYPE_VALUETYPE)
+                    if (dt == DATATYPE_CLASS || dt == DATATYPE_VALUETYPE || dt == DATATYPE_GENERICINST)
                     {
+                        // This is a reference to the field.
+                        // We need to make sure that the object is not a transparent proxy.
                         evalPos[0].SetReference(obj[fieldInst.CrossReference().offset]);
                     }
-                    else if (dt == DATATYPE_DATETIME || dt == DATATYPE_TIMESPAN) // Special case.
+                    // Special case.
+                    else if (dt == DATATYPE_DATETIME || dt == DATATYPE_TIMESPAN)
                     {
-                        NANOCLR_SET_AND_LEAVE(CLR_E_WRONG_TYPE); // NOT SUPPORTED.
+                        // NOT SUPPORTED.
+                        NANOCLR_SET_AND_LEAVE(CLR_E_WRONG_TYPE);
                     }
                     else
                     {
@@ -3212,6 +3217,17 @@ HRESULT CLR_RT_Thread::Execute_IL(CLR_RT_StackFrame &stackArg)
                         }
                         break;
 
+                        case TBL_MethodSpec:
+                        {
+                            CLR_RT_MethodDef_Instance method{};
+                            if (!method.ResolveToken(arg, assm))
+                            {
+                                NANOCLR_SET_AND_LEAVE(CLR_E_WRONG_TYPE);
+                            }
+
+                            evalPos[0].SetReflection(method);
+                        }
+
                         default:
                             NANOCLR_SET_AND_LEAVE(CLR_E_WRONG_TYPE);
                             break;

src/CLR/Include/nanoCLR_Runtime.h

@@ -712,7 +712,7 @@ struct CLR_RT_MethodSpec_Index
 
     CLR_INDEX Method() const
     {
-        return (data & 0x7FFF);
+        return (CLR_INDEX)data;
     }
 };
 

src/CLR/Include/nanoCLR_Runtime__HeapBlock.h

@@ -1187,6 +1187,7 @@ struct CLR_RT_HeapBlock
     {
         m_id.raw = CLR_RT_HEAPBLOCK_RAW_ID(DATATYPE_GENERICINST, 0, 1);
         m_data.genericInstance.genericType.data = genericType.data;
+        m_data.genericInstance.ptr = nullptr; 
     }
 
     const CLR_RT_TypeSpec_Index &ObjectGenericType() const