Fix TypeBuilder.DefineMethodOverride validation error

src/libraries/System.Private.CoreLib/src/System/Reflection/Emit/TypeBuilderInstantiation.cs

@@ -253,7 +253,8 @@ public override bool ContainsGenericParameters
 
         [RequiresUnreferencedCode("If some of the generic arguments are annotated (either with DynamicallyAccessedMembersAttribute, or generic constraints), trimming can't validate that the requirements of those annotations are met.")]
         public override Type MakeGenericType(params Type[] inst) { throw new InvalidOperationException(SR.Format(SR.Arg_NotGenericTypeDefinition, this)); }
-        public override bool IsAssignableFrom([NotNullWhen(true)] Type? c) { throw new NotSupportedException(); }
+
+        public override bool IsAssignableFrom([NotNullWhen(true)] Type? c) => this == c;
 
         public override bool IsSubclassOf(Type c)
         {

src/libraries/System.Reflection.Emit/tests/PersistedAssemblyBuilder/AssemblySaveTypeBuilderAPIsTests.cs

@@ -276,6 +276,32 @@ public void DefineMethodOverride_InterfaceImplementationWithByRefArrayTypes()
             implType.CreateType(); // succeeds
         }
 
+        public interface IConstructable<T>
+        {
+            static abstract T Create(int value);
+        }
+
+        [Fact]
+        public void DefineMethodOverride_ImplementStaticAbstractMethodOfGenericInterface()
+        {
+            PersistedAssemblyBuilder ab = AssemblySaveTools.PopulateAssemblyBuilderAndTypeBuilder(out TypeBuilder typeBuilder);
+            Type intfType = typeof(IConstructable<>).MakeGenericType(typeBuilder);
+            typeBuilder.AddInterfaceImplementation(intfType);
+            ConstructorBuilder ctor = typeBuilder.DefineConstructor(MethodAttributes.Public, CallingConventions.Standard, [typeof(int)]);
+            var il = ctor.GetILGenerator();
+            il.Emit(OpCodes.Ret);
+
+            MethodBuilder impl = typeBuilder.DefineMethod("Create", MethodAttributes.Public | MethodAttributes.Static, typeBuilder, [typeof(int)]);
+            il = impl.GetILGenerator();
+            il.Emit(OpCodes.Ldarg_0);
+            il.Emit(OpCodes.Call, ctor);
+            il.Emit(OpCodes.Ret);
+
+            MethodInfo intfMethod = TypeBuilder.GetMethod(intfType, typeof(IConstructable<>).GetMethod("Create")!)!;
+            typeBuilder.DefineMethodOverride(impl, intfMethod);
+            typeBuilder.CreateType(); // should succeed
+        }
+
         [Fact]
         public void TypeBuilderImplementsGenericInterfaceWithTypeBuilderGenericConstraint()
         {