Fix deserialization of implementations of interface T with a custom s…

…erializer

If the implementation is a pointer, and the pointer type
is not a named type but the pointed at type is, the
serialization layer incorrectly returns the interface type T
when deserializing the implementation of type T.

Fix the issue by keeping just enough type information
on the opaque types to be able to recreate the right type
at deser time.

types/inspect.go

@@ -302,6 +302,9 @@ func (t *Type) Format(s fmt.State, v rune) {
 		if name == "" {
 			name = fmt.Sprintf("<anon %s>", t.Kind())
 		}
+		if t.typ.Kind == coroutinev1.Kind_KIND_POINTER {
+			name = "*" + name
+		}
 		s.Write([]byte(name))
 		return
 	}

types/types.go

@@ -49,15 +49,22 @@ func (m *typemap) ToReflect(id typeid) reflect.Type {
 		panic(fmt.Sprintf("type %d not found", id))
 	}
 
-	if t.MemoryOffset != 0 {
-		return typeForOffset(namedTypeOffset(t.MemoryOffset))
-	}
-
 	if t.CustomSerializer > 0 {
+		if t.MemoryOffset != 0 {
+			et := typeForOffset(namedTypeOffset(t.MemoryOffset))
+			if t.Kind == coroutinev1.Kind_KIND_POINTER {
+				et = reflect.PointerTo(et)
+			}
+			return et
+		}
 		id := serdeid(t.CustomSerializer)
 		return m.serdes.serdeByID(id).typ
 	}
 
+	if t.MemoryOffset != 0 {
+		return typeForOffset(namedTypeOffset(t.MemoryOffset))
+	}
+
 	var x reflect.Type
 	switch t.Kind {
 	case coroutinev1.Kind_KIND_BOOL:
@@ -205,6 +212,14 @@ func (m *typemap) ToType(t reflect.Type) typeid {
 
 	// Types with custom serializers are opaque.
 	if s, ok := m.serdes.serdeByType(t); ok {
+		if t.Name() == "" && t.Kind() == reflect.Pointer {
+			if et := t.Elem(); et.Name() != "" {
+				ti.Kind = coroutinev1.Kind_KIND_POINTER
+				ti.MemoryOffset = uint64(offsetForType(et))
+				ti.Name = m.strings.Intern(et.Name())
+				ti.Package = m.strings.Intern(et.PkgPath())
+			}
+		}
 		ti.CustomSerializer = s.id
 		return id
 	}