[Nullable] Allow the configuration of the detection of assigning the …

…result of a function that returns void to a variable.

doc/classes/ProjectSettings.xml

@@ -553,6 +553,10 @@
 		<member name="debug/gdscript/warnings/return_value_discarded" type="int" setter="" getter="" default="0">
 			When set to [code]warn[/code] or [code]error[/code], produces a warning or an error respectively when calling a function without using its return value (by assigning it to a variable or using it as a function argument). These return values are sometimes used to indicate possible errors using the [enum Error] enum.
 		</member>
+		<member name="debug/gdscript/warnings/return_value_void" type="int" setter="" getter="" default="0">
+			When set to [code]warn[/code] or [code]error[/code], produces a warning or an error respectively when trying to assign the result of a function that returns void.
+			When set to [code]ignore[/code] neither the editor nor the debug export will detect this kind of assignment when running the game.
+		</member>
 		<member name="debug/gdscript/warnings/shadowed_global_identifier" type="int" setter="" getter="" default="1">
 			When set to [code]warn[/code] or [code]error[/code], produces a warning or an error respectively when defining a local or member variable, signal, or enum that would have the same name as a built-in function or global class name, thus shadowing it.
 		</member>

modules/gdscript/gdscript_analyzer.cpp

@@ -1917,7 +1917,14 @@ void GDScriptAnalyzer::resolve_assignable(GDScriptParser::AssignableNode *p_assi
 			if (!initializer_type.is_set() || initializer_type.has_no_type() || !initializer_type.is_hard_type()) {
 				push_error(vformat(R"(Cannot infer the type of "%s" %s because the value doesn't have a set type.)", p_assignable->identifier->name, p_kind), p_assignable->initializer);
 			} else if (initializer_type.kind == GDScriptParser::DataType::BUILTIN && initializer_type.builtin_type == Variant::NIL && !is_constant) {
-				push_error(vformat(R"(Cannot infer the type of "%s" %s because the value is "null".)", p_assignable->identifier->name, p_kind), p_assignable->initializer);
+#ifdef DEBUG_ENABLED
+				GDScriptWarning::WarnLevel return_value_void_warn_level = GDScriptWarning::get_project_warning_level(GDScriptWarning::RETURN_VALUE_VOID);
+				if (return_value_void_warn_level == GDScriptWarning::WarnLevel::IGNORE) {
+					parser->push_warning(p_assignable, GDScriptWarning::INFERENCE_ON_VARIANT, p_kind);
+				} else {
+					push_error(vformat(R"(Cannot infer the type of "%s" %s because the value is "null".)", p_assignable->identifier->name, p_kind), p_assignable->initializer);
+				}
+#endif
 			}
 #ifdef DEBUG_ENABLED
 			if (initializer_type.is_hard_type() && initializer_type.is_variant()) {
@@ -3182,7 +3189,12 @@ void GDScriptAnalyzer::reduce_call(GDScriptParser::CallNode *p_call, bool p_is_a
 			MethodInfo function_info = GDScriptUtilityFunctions::get_function_info(function_name);
 
 			if (!p_is_root && !p_is_await && function_info.return_val.type == Variant::NIL && ((function_info.return_val.usage & PROPERTY_USAGE_NIL_IS_VARIANT) == 0)) {
-				push_error(vformat(R"*(Cannot get return value of call to "%s()" because it returns "void".)*", function_name), p_call);
+#ifdef DEBUG_ENABLED
+				GDScriptWarning::WarnLevel return_value_void_warn_level = GDScriptWarning::get_project_warning_level(GDScriptWarning::RETURN_VALUE_VOID);
+				if (return_value_void_warn_level != GDScriptWarning::WarnLevel::IGNORE) {
+					parser->push_warning(p_call, GDScriptWarning::RETURN_VALUE_VOID, function_name);
+				}
+#endif
 			}
 
 			if (all_is_constant && GDScriptUtilityFunctions::is_function_constant(function_name)) {
@@ -3233,7 +3245,12 @@ void GDScriptAnalyzer::reduce_call(GDScriptParser::CallNode *p_call, bool p_is_a
 			MethodInfo function_info = info_from_utility_func(function_name);
 
 			if (!p_is_root && !p_is_await && function_info.return_val.type == Variant::NIL && ((function_info.return_val.usage & PROPERTY_USAGE_NIL_IS_VARIANT) == 0)) {
-				push_error(vformat(R"*(Cannot get return value of call to "%s()" because it returns "void".)*", function_name), p_call);
+#ifdef DEBUG_ENABLED
+				GDScriptWarning::WarnLevel return_value_void_warn_level = GDScriptWarning::get_project_warning_level(GDScriptWarning::RETURN_VALUE_VOID);
+				if (return_value_void_warn_level != GDScriptWarning::WarnLevel::IGNORE) {
+					parser->push_warning(p_call, GDScriptWarning::RETURN_VALUE_VOID, function_name);
+				}
+#endif
 			}
 
 			if (all_is_constant && Variant::get_utility_function_type(function_name) == Variant::UTILITY_FUNC_TYPE_MATH) {
@@ -3395,7 +3412,12 @@ void GDScriptAnalyzer::reduce_call(GDScriptParser::CallNode *p_call, bool p_is_a
 		}
 
 		if (!p_is_root && !p_is_await && return_type.is_hard_type() && return_type.kind == GDScriptParser::DataType::BUILTIN && return_type.builtin_type == Variant::NIL) {
-			push_error(vformat(R"*(Cannot get return value of call to "%s()" because it returns "void".)*", p_call->function_name), p_call);
+#ifdef DEBUG_ENABLED
+			GDScriptWarning::WarnLevel return_value_void_warn_level = GDScriptWarning::get_project_warning_level(GDScriptWarning::RETURN_VALUE_VOID);
+			if (return_value_void_warn_level != GDScriptWarning::WarnLevel::IGNORE) {
+				parser->push_warning(p_call, GDScriptWarning::RETURN_VALUE_VOID, p_call->function_name);
+			}
+#endif
 		}
 
 #ifdef DEBUG_ENABLED

modules/gdscript/gdscript_vm.cpp

@@ -36,6 +36,8 @@
 
 #ifdef DEBUG_ENABLED
 
+#include "gdscript_warning.h"
+
 static bool _profile_count_as_native(const Object *p_base_obj, const StringName &p_methodname) {
 	if (!p_base_obj) {
 		return false;
@@ -1736,7 +1738,7 @@ Variant GDScriptFunction::call(GDScriptInstance *p_instance, const Variant **p_a
 					GET_INSTRUCTION_ARG(ret, argc + 1);
 					base->callp(*methodname, (const Variant **)argptrs, argc, *ret, err);
 #ifdef DEBUG_ENABLED
-					if (ret->get_type() == Variant::NIL) {
+					if (ret->get_type() == Variant::NIL && GDScriptWarning::get_project_warning_level(GDScriptWarning::RETURN_VALUE_VOID) == GDScriptWarning::ERROR) {
 						if (base_type == Variant::OBJECT) {
 							if (base_obj) {
 								MethodBind *method = ClassDB::get_method(base_class, *methodname);

modules/gdscript/gdscript_warning.cpp

@@ -34,6 +34,8 @@
 
 #ifdef DEBUG_ENABLED
 
+#include "core/config/project_settings.h"
+
 String GDScriptWarning::get_message() const {
 #define CHECK_SYMBOLS(m_amount) ERR_FAIL_COND_V(symbols.size() < m_amount, String());
 
@@ -163,6 +165,8 @@ String GDScriptWarning::get_message() const {
 		case FUNCTION_USED_AS_PROPERTY: // This is valid, returns `Callable`.
 			break;
 #endif
+		case RETURN_VALUE_VOID:
+			return vformat(R"*(Cannot get return value of call to "%s()" because it returns "void".)*", symbols[0]);
 		case WARNING_MAX:
 			break; // Can't happen, but silences warning.
 	}
@@ -240,6 +244,7 @@ String GDScriptWarning::get_name_from_code(Code p_code) {
 		"CONSTANT_USED_AS_FUNCTION",
 		"FUNCTION_USED_AS_PROPERTY",
 #endif
+		"RETURN_VALUE_VOID",
 	};
 
 	static_assert((sizeof(names) / sizeof(*names)) == WARNING_MAX, "Amount of warning types don't match the amount of warning names.");
@@ -261,4 +266,8 @@ GDScriptWarning::Code GDScriptWarning::get_code_from_name(const String &p_name)
 	return WARNING_MAX;
 }
 
+GDScriptWarning::WarnLevel GDScriptWarning::get_project_warning_level(Code p_code) {
+	return (GDScriptWarning::WarnLevel)(int)GLOBAL_GET(GDScriptWarning::get_settings_path_from_code(p_code));
+}
+
 #endif // DEBUG_ENABLED

modules/gdscript/gdscript_warning.h

@@ -94,6 +94,7 @@ class GDScriptWarning {
 		CONSTANT_USED_AS_FUNCTION, // Function not found, but there's a constant with the same name.
 		FUNCTION_USED_AS_PROPERTY, // Property not found, but there's a function with the same name.
 #endif
+		RETURN_VALUE_VOID, // Functions that return void cannot have their return value stored.
 		WARNING_MAX,
 	};
 
@@ -146,6 +147,7 @@ class GDScriptWarning {
 		WARN, // CONSTANT_USED_AS_FUNCTION
 		WARN, // FUNCTION_USED_AS_PROPERTY
 #endif
+		IGNORE, // RETURN_VALUE_VOID
 	};
 
 	static_assert((sizeof(default_warning_levels) / sizeof(default_warning_levels[0])) == WARNING_MAX, "Amount of default levels does not match the amount of warnings.");
@@ -162,6 +164,7 @@ class GDScriptWarning {
 	static String get_name_from_code(Code p_code);
 	static String get_settings_path_from_code(Code p_code);
 	static Code get_code_from_name(const String &p_name);
+	static GDScriptWarning::WarnLevel get_project_warning_level(Code p_code);
 };
 
 #endif // DEBUG_ENABLED

modules/gdscript/tests/scripts/analyzer/errors/use_value_of_void_function_builtin_method.out

@@ -1,2 +1,6 @@
-GDTEST_ANALYZER_ERROR
-Cannot get return value of call to "reverse()" because it returns "void".
+GDTEST_OK
+>> WARNING
+>> Line: 3
+>> RETURN_VALUE_VOID
+>> Cannot get return value of call to "reverse()" because it returns "void".
+<null>

modules/gdscript/tests/scripts/analyzer/errors/use_value_of_void_function_custom_method.out

@@ -1,2 +1,6 @@
-GDTEST_ANALYZER_ERROR
-Cannot get return value of call to "foo()" because it returns "void".
+GDTEST_OK
+>> WARNING
+>> Line: 5
+>> RETURN_VALUE_VOID
+>> Cannot get return value of call to "foo()" because it returns "void".
+<null>

modules/gdscript/tests/scripts/analyzer/errors/use_value_of_void_function_gd_utility.out

@@ -1,2 +1,7 @@
-GDTEST_ANALYZER_ERROR
-Cannot get return value of call to "print_debug()" because it returns "void".
+GDTEST_OK
+>> WARNING
+>> Line: 2
+>> RETURN_VALUE_VOID
+>> Cannot get return value of call to "print_debug()" because it returns "void".
+
+<null>

modules/gdscript/tests/scripts/analyzer/errors/use_value_of_void_function_native_method.out

@@ -1,2 +1,6 @@
-GDTEST_ANALYZER_ERROR
-Cannot get return value of call to "free()" because it returns "void".
+GDTEST_OK
+>> WARNING
+>> Line: 3
+>> RETURN_VALUE_VOID
+>> Cannot get return value of call to "free()" because it returns "void".
+<null>

modules/gdscript/tests/scripts/analyzer/errors/use_value_of_void_function_utility.out

@@ -1,2 +1,7 @@
-GDTEST_ANALYZER_ERROR
-Cannot get return value of call to "print()" because it returns "void".
+GDTEST_OK
+>> WARNING
+>> Line: 2
+>> RETURN_VALUE_VOID
+>> Cannot get return value of call to "print()" because it returns "void".
+
+<null>

modules/gdscript/tests/scripts/runtime/errors/use_return_value_of_free_call.gd

@@ -1,4 +1,3 @@
 func test():
-	var obj
-	obj = Node.new()
+	var obj := Node.new()
 	print(obj.free())

modules/gdscript/tests/scripts/runtime/errors/use_return_value_of_free_call.out

@@ -1,6 +1,6 @@
-GDTEST_RUNTIME_ERROR
->> SCRIPT ERROR
->> on function: test()
->> runtime/errors/use_return_value_of_free_call.gd
->> 4
->> Trying to get a return value of a method that returns "void"
+GDTEST_OK
+>> WARNING
+>> Line: 3
+>> RETURN_VALUE_VOID
+>> Cannot get return value of call to "free()" because it returns "void".
+<null>

modules/gdscript/tests/scripts/runtime/errors/use_return_value_of_void_builtin_method_call.gd

@@ -1,4 +1,3 @@
 func test():
-	var value
-	value = []
+	var value := []
 	print(value.reverse())

modules/gdscript/tests/scripts/runtime/errors/use_return_value_of_void_builtin_method_call.out

@@ -1,6 +1,6 @@
-GDTEST_RUNTIME_ERROR
->> SCRIPT ERROR
->> on function: test()
->> runtime/errors/use_return_value_of_void_builtin_method_call.gd
->> 4
->> Trying to get a return value of a method that returns "void"
+GDTEST_OK
+>> WARNING
+>> Line: 3
+>> RETURN_VALUE_VOID
+>> Cannot get return value of call to "reverse()" because it returns "void".
+<null>

modules/gdscript/tests/scripts/runtime/errors/use_return_value_of_void_native_method_call.gd

@@ -1,4 +1,3 @@
 func test():
-	var obj
-	obj = RefCounted.new()
+	var obj := RefCounted.new()
 	print(obj.notify_property_list_changed())

modules/gdscript/tests/scripts/runtime/errors/use_return_value_of_void_native_method_call.out

@@ -1,6 +1,6 @@
-GDTEST_RUNTIME_ERROR
->> SCRIPT ERROR
->> on function: test()
->> runtime/errors/use_return_value_of_void_native_method_call.gd
->> 4
->> Trying to get a return value of a method that returns "void"
+GDTEST_OK
+>> WARNING
+>> Line: 3
+>> RETURN_VALUE_VOID
+>> Cannot get return value of call to "notify_property_list_changed()" because it returns "void".
+<null>