Support explicit values in flag properties, add C# flags support

- Add support for explicit values in properties using `PROPERTY_HINT_FLAGS`
that works the same way it does for enums.
- Fix enums and flags in VisualScriptEditor (it wasn't considering the
explicit value).
- Use `PROPERTY_HINT_FLAGS` for C# enums with the FlagsAttribute instead
of `PROPERTY_HINT_ENUM`.

6 files changed, 21 insertions, 2 deletions

diff --git a/modules/mono/csharp_script.cpp b/modules/mono/csharp_script.cpp
index bee4e0e1fb..622838b308 100644
--- a/modules/mono/csharp_script.cpp
+++ b/modules/mono/csharp_script.cpp
@@ -2807,7 +2807,8 @@ int CSharpScript::_try_get_member_export_hint(IMonoClassMember *p_member, Manage
 	GD_MONO_ASSERT_THREAD_ATTACHED;
 
 	if (p_variant_type == Variant::INT && p_type.type_encoding == MONO_TYPE_VALUETYPE && mono_class_is_enum(p_type.type_class->get_mono_ptr())) {
-		r_hint = PROPERTY_HINT_ENUM;
+		MonoReflectionType *reftype = mono_type_get_object(mono_domain_get(), p_type.type_class->get_mono_type());
+		r_hint = GDMonoUtils::Marshal::type_has_flags_attribute(reftype) ? PROPERTY_HINT_FLAGS : PROPERTY_HINT_ENUM;
 
 		Vector<MonoClassField *> fields = p_type.type_class->get_enum_fields();
 
@@ -2844,7 +2845,8 @@ int CSharpScript::_try_get_member_export_hint(IMonoClassMember *p_member, Manage
 			uint64_t val = GDMonoUtils::unbox_enum_value(val_obj, enum_basetype, r_error);
 			ERR_FAIL_COND_V_MSG(r_error, -1, "Failed to unbox '" + enum_field_name + "' constant enum value.");
 
-			if (val != (unsigned int)i) {
+			unsigned int expected_val = r_hint == PROPERTY_HINT_FLAGS ? 1 << i : i;
+			if (val != expected_val) {
 				uses_default_values = false;
 			}
 
diff --git a/modules/mono/glue/GodotSharp/GodotSharp/Core/MarshalUtils.cs b/modules/mono/glue/GodotSharp/GodotSharp/Core/MarshalUtils.cs
index ee4d0eed08..50ae2eb112 100644
--- a/modules/mono/glue/GodotSharp/GodotSharp/Core/MarshalUtils.cs
+++ b/modules/mono/glue/GodotSharp/GodotSharp/Core/MarshalUtils.cs
@@ -80,6 +80,11 @@ namespace Godot
         private static bool TypeIsGenericIDictionary(Type type) => type.GetGenericTypeDefinition() == typeof(IDictionary<,>);
 
         /// <summary>
+        /// Returns <see langword="true"/> if the <see cref="FlagsAttribute"/> is applied to the given type.
+        /// </summary>
+        private static bool TypeHasFlagsAttribute(Type type) => type.IsDefined(typeof(FlagsAttribute), false);
+
+        /// <summary>
         /// Returns the generic type definition of <paramref name="type"/>.
         /// </summary>
         /// <exception cref="InvalidOperationException">
diff --git a/modules/mono/mono_gd/gd_mono_cache.cpp b/modules/mono/mono_gd/gd_mono_cache.cpp
index d8fd244067..44a8e26b8f 100644
--- a/modules/mono/mono_gd/gd_mono_cache.cpp
+++ b/modules/mono/mono_gd/gd_mono_cache.cpp
@@ -176,6 +176,7 @@ void CachedData::clear_godot_api_cache() {
 	methodthunk_MarshalUtils_TypeIsGenericIEnumerable.nullify();
 	methodthunk_MarshalUtils_TypeIsGenericICollection.nullify();
 	methodthunk_MarshalUtils_TypeIsGenericIDictionary.nullify();
+	methodthunk_MarshalUtils_TypeHasFlagsAttribute.nullify();
 
 	methodthunk_MarshalUtils_GetGenericTypeDefinition.nullify();
 
@@ -300,6 +301,7 @@ void update_godot_api_cache() {
 	CACHE_METHOD_THUNK_AND_CHECK(MarshalUtils, TypeIsGenericIEnumerable, GODOT_API_CLASS(MarshalUtils)->get_method("TypeIsGenericIEnumerable", 1));
 	CACHE_METHOD_THUNK_AND_CHECK(MarshalUtils, TypeIsGenericICollection, GODOT_API_CLASS(MarshalUtils)->get_method("TypeIsGenericICollection", 1));
 	CACHE_METHOD_THUNK_AND_CHECK(MarshalUtils, TypeIsGenericIDictionary, GODOT_API_CLASS(MarshalUtils)->get_method("TypeIsGenericIDictionary", 1));
+	CACHE_METHOD_THUNK_AND_CHECK(MarshalUtils, TypeHasFlagsAttribute, GODOT_API_CLASS(MarshalUtils)->get_method("TypeHasFlagsAttribute", 1));
 
 	CACHE_METHOD_THUNK_AND_CHECK(MarshalUtils, GetGenericTypeDefinition, GODOT_API_CLASS(MarshalUtils)->get_method("GetGenericTypeDefinition", 2));
 
diff --git a/modules/mono/mono_gd/gd_mono_cache.h b/modules/mono/mono_gd/gd_mono_cache.h
index 4000342c94..92136e1f41 100644
--- a/modules/mono/mono_gd/gd_mono_cache.h
+++ b/modules/mono/mono_gd/gd_mono_cache.h
@@ -147,6 +147,7 @@ struct CachedData {
 	GDMonoMethodThunkR<MonoBoolean, MonoReflectionType *> methodthunk_MarshalUtils_TypeIsGenericIEnumerable;
 	GDMonoMethodThunkR<MonoBoolean, MonoReflectionType *> methodthunk_MarshalUtils_TypeIsGenericICollection;
 	GDMonoMethodThunkR<MonoBoolean, MonoReflectionType *> methodthunk_MarshalUtils_TypeIsGenericIDictionary;
+	GDMonoMethodThunkR<MonoBoolean, MonoReflectionType *> methodthunk_MarshalUtils_TypeHasFlagsAttribute;
 
 	GDMonoMethodThunk<MonoReflectionType *, MonoReflectionType **> methodthunk_MarshalUtils_GetGenericTypeDefinition;
 
diff --git a/modules/mono/mono_gd/gd_mono_utils.cpp b/modules/mono/mono_gd/gd_mono_utils.cpp
index 25678be624..1983d6ebe2 100644
--- a/modules/mono/mono_gd/gd_mono_utils.cpp
+++ b/modules/mono/mono_gd/gd_mono_utils.cpp
@@ -614,6 +614,14 @@ bool type_is_generic_idictionary(MonoReflectionType *p_reftype) {
 	return (bool)res;
 }
 
+bool type_has_flags_attribute(MonoReflectionType *p_reftype) {
+	NO_GLUE_RET(false);
+	MonoException *exc = nullptr;
+	MonoBoolean res = CACHED_METHOD_THUNK(MarshalUtils, TypeHasFlagsAttribute).invoke(p_reftype, &exc);
+	UNHANDLED_EXCEPTION(exc);
+	return (bool)res;
+}
+
 void get_generic_type_definition(MonoReflectionType *p_reftype, MonoReflectionType **r_generic_reftype) {
 	MonoException *exc = nullptr;
 	CACHED_METHOD_THUNK(MarshalUtils, GetGenericTypeDefinition).invoke(p_reftype, r_generic_reftype, &exc);
diff --git a/modules/mono/mono_gd/gd_mono_utils.h b/modules/mono/mono_gd/gd_mono_utils.h
index 4c2c2c93c2..246a1cd31e 100644
--- a/modules/mono/mono_gd/gd_mono_utils.h
+++ b/modules/mono/mono_gd/gd_mono_utils.h
@@ -61,6 +61,7 @@ bool type_is_system_generic_dictionary(MonoReflectionType *p_reftype);
 bool type_is_generic_ienumerable(MonoReflectionType *p_reftype);
 bool type_is_generic_icollection(MonoReflectionType *p_reftype);
 bool type_is_generic_idictionary(MonoReflectionType *p_reftype);
+bool type_has_flags_attribute(MonoReflectionType *p_reftype);
 
 void get_generic_type_definition(MonoReflectionType *p_reftype, MonoReflectionType **r_generic_reftype);