Fixed creating generic type with abstract type when it is has a default constructor constraint

Author: Faolan-Rad

src/coreclr/nativeaot/System.Private.Reflection.Execution/src/Internal/Reflection/Execution/TypeLoader/ConstraintValidator.cs

@@ -38,7 +38,7 @@ private static bool SatisfiesConstraints(this Type genericVariable, SigTypeConte
 
             if ((attributes & GenericParameterAttributes.DefaultConstructorConstraint) != 0)
             {
-                if (!typeArg.HasExplicitOrImplicitPublicDefaultConstructor())
+                if (!typeArg.HasExplicitOrImplicitPublicDefaultConstructor() || typeArg.IsAbstract)
                     return false;
             }
 

src/coreclr/vm/typedesc.cpp

@@ -1464,7 +1464,7 @@ BOOL TypeVarTypeDesc::SatisfiesConstraints(SigTypeContext *pTypeContextOfConstra
 
         if ((specialConstraints & gpDefaultConstructorConstraint) != 0)
         {
-            if (thArg.IsTypeDesc() || (!thArg.AsMethodTable()->HasExplicitOrImplicitPublicDefaultConstructor()))
+            if (thArg.IsTypeDesc() || (!thArg.AsMethodTable()->HasExplicitOrImplicitPublicDefaultConstructor() || thArg.IsAbstract()))
                 return FALSE;
         }
 

src/libraries/System.ComponentModel.Composition/src/System/ComponentModel/Composition/ReflectionModel/GenericServices.cs

@@ -178,7 +178,7 @@ public static bool CanSpecialize(Type type, GenericParameterAttributes attribute
             if ((attributes & GenericParameterAttributes.DefaultConstructorConstraint) != 0)
             {
                 // value types always have default constructors
-                if (!type.IsValueType && (type.GetConstructor(Type.EmptyTypes) == null))
+                if (!type.IsValueType && ((type.GetConstructor(Type.EmptyTypes) == null) || type.IsAbstract))
                 {
                     return false;
                 }

src/mono/mono/metadata/verify.c

@@ -99,7 +99,7 @@ is_valid_generic_instantiation (MonoGenericContainer *gc, MonoGenericContext *co
 		if ((param_info->flags & GENERIC_PARAMETER_ATTRIBUTE_REFERENCE_TYPE_CONSTRAINT) && m_class_is_valuetype (paramClass))
 			return FALSE;
 
-		if ((param_info->flags & GENERIC_PARAMETER_ATTRIBUTE_CONSTRUCTOR_CONSTRAINT) && !m_class_is_valuetype (paramClass) && !mono_class_has_default_constructor (paramClass, TRUE))
+		if ((param_info->flags & GENERIC_PARAMETER_ATTRIBUTE_CONSTRUCTOR_CONSTRAINT) && !m_class_is_valuetype (paramClass) && (!mono_class_has_default_constructor (paramClass, TRUE) || mono_class_is_abstract(paramClass)))
 			return FALSE;
 
 		if (!param_info->constraints)