GDScript: Treat enum values as int and enum types as dictionary

Since enums resolve to a dictionary at runtime, calling dictionary
methods on an enum type is a valid use case. This ensures this is true
by adding test cases. This also makes enum values be treated as ints
when used in operations.

modules/gdscript/gdscript_analyzer.cpp

@@ -108,7 +108,7 @@ static GDScriptParser::DataType make_native_enum_type(const StringName &p_native
 	GDScriptParser::DataType type;
 	type.type_source = GDScriptParser::DataType::ANNOTATED_EXPLICIT;
 	type.kind = GDScriptParser::DataType::ENUM;
-	type.builtin_type = Variant::OBJECT;
+	type.builtin_type = Variant::INT;
 	type.is_constant = true;
 	type.is_meta_type = true;
 
@@ -2416,6 +2416,11 @@ void GDScriptAnalyzer::reduce_call(GDScriptParser::CallNode *p_call, bool p_is_a
 		}
 		validate_call_arg(par_types, default_arg_count, is_vararg, p_call);
 
+		if (base_type.kind == GDScriptParser::DataType::ENUM && base_type.is_meta_type) {
+			// Enum type is treated as a dictionary value for function calls.
+			base_type.is_meta_type = false;
+		}
+
 		if (is_self && parser->current_function != nullptr && parser->current_function->is_static && !is_static) {
 			push_error(vformat(R"*(Cannot call non-static function "%s()" from static function "%s()".)*", p_call->function_name, parser->current_function->identifier->name), p_call->callee);
 		} else if (!is_self && base_type.is_meta_type && !is_static) {
@@ -2478,7 +2483,7 @@ void GDScriptAnalyzer::reduce_cast(GDScriptParser::CastNode *p_cast) {
 		return;
 	}
 
-	cast_type.is_meta_type = false; // The casted value won't be a type name.
+	cast_type = type_from_metatype(cast_type); // The casted value won't be a type name.
 	p_cast->set_datatype(cast_type);
 
 	if (!cast_type.is_variant()) {
@@ -2593,6 +2598,34 @@ void GDScriptAnalyzer::reduce_identifier_from_base(GDScriptParser::IdentifierNod
 
 	const StringName &name = p_identifier->name;
 
+	if (base.kind == GDScriptParser::DataType::ENUM) {
+		if (base.is_meta_type) {
+			if (base.enum_values.has(name)) {
+				p_identifier->is_constant = true;
+				p_identifier->reduced_value = base.enum_values[name];
+
+				GDScriptParser::DataType result;
+				result.type_source = GDScriptParser::DataType::ANNOTATED_EXPLICIT;
+				result.kind = GDScriptParser::DataType::ENUM;
+				result.is_constant = true;
+				result.builtin_type = Variant::INT;
+				result.native_type = base.native_type;
+				result.enum_type = base.enum_type;
+				p_identifier->set_datatype(result);
+				return;
+			} else {
+				// Consider as a Dictionary, so it can be anything.
+				// This will be evaluated in the next if block.
+				base.kind = GDScriptParser::DataType::BUILTIN;
+				base.builtin_type = Variant::DICTIONARY;
+				base.is_meta_type = false;
+			}
+		} else {
+			push_error(R"(Cannot get property from enum value.)", p_identifier);
+			return;
+		}
+	}
+
 	if (base.kind == GDScriptParser::DataType::BUILTIN) {
 		if (base.is_meta_type) {
 			bool valid = true;
@@ -2639,33 +2672,6 @@ void GDScriptAnalyzer::reduce_identifier_from_base(GDScriptParser::IdentifierNod
 		return;
 	}
 
-	if (base.kind == GDScriptParser::DataType::ENUM) {
-		if (base.is_meta_type) {
-			if (base.enum_values.has(name)) {
-				p_identifier->is_constant = true;
-				p_identifier->reduced_value = base.enum_values[name];
-
-				GDScriptParser::DataType result;
-				result.type_source = GDScriptParser::DataType::ANNOTATED_EXPLICIT;
-				result.kind = GDScriptParser::DataType::ENUM;
-				result.is_constant = true;
-				result.builtin_type = Variant::INT;
-				result.native_type = base.native_type;
-				result.enum_type = base.enum_type;
-				p_identifier->set_datatype(result);
-			} else {
-				// Consider as a Dictionary, so it can be anything.
-				GDScriptParser::DataType dummy;
-				dummy.type_source = GDScriptParser::DataType::UNDETECTED;
-				dummy.kind = GDScriptParser::DataType::VARIANT;
-				p_identifier->set_datatype(dummy);
-			}
-		} else {
-			push_error(R"(Cannot get property from enum value.)", p_identifier);
-		}
-		return;
-	}
-
 	GDScriptParser::ClassNode *base_class = base.class_type;
 
 	// TODO: Switch current class/function/suite here to avoid misrepresenting identifiers (in recursive reduce calls).
@@ -3501,6 +3507,9 @@ GDScriptParser::DataType GDScriptAnalyzer::type_from_metatype(const GDScriptPars
 	GDScriptParser::DataType result = p_meta_type;
 	result.is_meta_type = false;
 	result.is_constant = false;
+	if (p_meta_type.kind == GDScriptParser::DataType::ENUM) {
+		result.builtin_type = Variant::INT;
+	}
 	return result;
 }
 
@@ -3557,6 +3566,18 @@ bool GDScriptAnalyzer::get_function_signature(GDScriptParser::CallNode *p_source
 	r_default_arg_count = 0;
 	StringName function_name = p_function;
 
+	if (p_base_type.kind == GDScriptParser::DataType::ENUM) {
+		if (p_base_type.is_meta_type) {
+			// Enum type can be treated as a dictionary value.
+			p_base_type.kind = GDScriptParser::DataType::BUILTIN;
+			p_base_type.builtin_type = Variant::DICTIONARY;
+			p_base_type.is_meta_type = false;
+		} else {
+			push_error("Cannot call function on enum value.", p_source);
+			return false;
+		}
+	}
+
 	if (p_base_type.kind == GDScriptParser::DataType::BUILTIN) {
 		// Construct a base type to get methods.
 		Callable::CallError err;
@@ -3807,6 +3828,22 @@ GDScriptParser::DataType GDScriptAnalyzer::get_operation_type(Variant::Operator
 
 	Variant::Type a_type = p_a.builtin_type;
 	Variant::Type b_type = p_b.builtin_type;
+
+	if (p_a.kind == GDScriptParser::DataType::ENUM) {
+		if (p_a.is_meta_type) {
+			a_type = Variant::DICTIONARY;
+		} else {
+			a_type = Variant::INT;
+		}
+	}
+	if (p_b.kind == GDScriptParser::DataType::ENUM) {
+		if (p_b.is_meta_type) {
+			b_type = Variant::DICTIONARY;
+		} else {
+			b_type = Variant::INT;
+		}
+	}
+
 	Variant::ValidatedOperatorEvaluator op_eval = Variant::get_validated_operator_evaluator(p_operation, a_type, b_type);
 
 	bool hard_operation = p_a.is_hard_type() && p_b.is_hard_type();

modules/gdscript/gdscript_compiler.cpp

@@ -143,7 +143,11 @@ GDScriptDataType GDScriptCompiler::_gdtype_from_datatype(const GDScriptParser::D
 		case GDScriptParser::DataType::ENUM:
 			result.has_type = true;
 			result.kind = GDScriptDataType::BUILTIN;
+			if (p_datatype.is_meta_type) {
+				result.builtin_type = Variant::DICTIONARY;
+			} else {
 				result.builtin_type = Variant::INT;
+			}
 			break;
 		case GDScriptParser::DataType::UNRESOLVED: {
 			ERR_PRINT("Parser bug: converting unresolved type.");
@@ -468,7 +472,14 @@ GDScriptCodeGenerator::Address GDScriptCompiler::_parse_expression(CodeGen &code
 		} break;
 		case GDScriptParser::Node::CAST: {
 			const GDScriptParser::CastNode *cn = static_cast<const GDScriptParser::CastNode *>(p_expression);
-			GDScriptDataType cast_type = _gdtype_from_datatype(cn->cast_type->get_datatype());
+			GDScriptParser::DataType og_cast_type = cn->cast_type->get_datatype();
+			GDScriptDataType cast_type = _gdtype_from_datatype(og_cast_type);
+
+			if (og_cast_type.kind == GDScriptParser::DataType::ENUM) {
+				// Enum types are usually treated as dictionaries, but in this case we want to cast to an integer.
+				cast_type.kind = GDScriptDataType::BUILTIN;
+				cast_type.builtin_type = Variant::INT;
+			}
 
 			// Create temporary for result first since it will be deleted last.
 			GDScriptCodeGenerator::Address result = codegen.add_temporary(cast_type);

modules/gdscript/tests/scripts/analyzer/features/enum_is_treated_as_int.gd

@@ -0,0 +1,21 @@
+# Enum is equivalent to int for comparisons and operations.
+enum MyEnum {
+	ZERO,
+	ONE,
+	TWO,
+}
+
+enum OtherEnum {
+	ZERO,
+	ONE,
+	TWO,
+}
+
+func test():
+	print(MyEnum.ZERO == OtherEnum.ZERO)
+	print(MyEnum.ZERO == 1)
+	print(MyEnum.ZERO != OtherEnum.ONE)
+	print(MyEnum.ZERO != 0)
+
+	print(MyEnum.ONE + OtherEnum.TWO)
+	print(2 - MyEnum.ONE)

modules/gdscript/tests/scripts/analyzer/features/enum_is_treated_as_int.out

@@ -0,0 +1,7 @@
+GDTEST_OK
+true
+false
+true
+false
+3
+1

modules/gdscript/tests/scripts/analyzer/features/enum_type_is_treated_as_dictionary.gd

@@ -0,0 +1,13 @@
+enum MyEnum {
+	ZERO,
+	ONE,
+	TWO,
+}
+
+func test():
+	for key in MyEnum.keys():
+		prints(key, MyEnum[key])
+
+	# https://github.com/godotengine/godot/issues/55491
+	for key in MyEnum:
+		prints(key, MyEnum[key])

modules/gdscript/tests/scripts/analyzer/features/enum_type_is_treated_as_dictionary.out

@@ -0,0 +1,7 @@
+GDTEST_OK
+ZERO 0
+ONE 1
+TWO 2
+ZERO 0
+ONE 1
+TWO 2