From 10b00bc2eaa5d6e49ed68eb5eb832abfdeff5f1a Mon Sep 17 00:00:00 2001
From: Danil Alexeev <danil@alexeev.xyz>
Date: Fri, 22 Sep 2023 10:10:22 +0300
Subject: [PATCH] GDScript: Prevent constructing and inheriting engine
 singletons

---
 modules/gdscript/gdscript_analyzer.cpp                 | 10 ++++++++++
 .../analyzer/errors/engine_singleton_instantiate.gd    |  2 ++
 .../analyzer/errors/engine_singleton_instantiate.out   |  2 ++
 .../scripts/analyzer/errors/extend_engine_singleton.gd |  6 ++++++
 .../analyzer/errors/extend_engine_singleton.out        |  2 ++
 5 files changed, 22 insertions(+)
 create mode 100644 modules/gdscript/tests/scripts/analyzer/errors/engine_singleton_instantiate.gd
 create mode 100644 modules/gdscript/tests/scripts/analyzer/errors/engine_singleton_instantiate.out
 create mode 100644 modules/gdscript/tests/scripts/analyzer/errors/extend_engine_singleton.gd
 create mode 100644 modules/gdscript/tests/scripts/analyzer/errors/extend_engine_singleton.out

diff --git a/modules/gdscript/gdscript_analyzer.cpp b/modules/gdscript/gdscript_analyzer.cpp
index 04c86d60a8c..92050154b59 100644
--- a/modules/gdscript/gdscript_analyzer.cpp
+++ b/modules/gdscript/gdscript_analyzer.cpp
@@ -459,6 +459,10 @@ Error GDScriptAnalyzer::resolve_class_inheritance(GDScriptParser::ClassNode *p_c
 				}
 				base = info_parser->get_parser()->head->get_datatype();
 			} else if (class_exists(name)) {
+				if (Engine::get_singleton()->has_singleton(name)) {
+					push_error(vformat(R"(Cannot inherit native class "%s" because it is an engine singleton.)", name), id);
+					return ERR_PARSE_ERROR;
+				}
 				base.kind = GDScriptParser::DataType::NATIVE;
 				base.native_type = name;
 			} else {
@@ -3203,6 +3207,12 @@ void GDScriptAnalyzer::reduce_call(GDScriptParser::CallNode *p_call, bool p_is_a
 
 	bool is_constructor = (base_type.is_meta_type || (p_call->callee && p_call->callee->type == GDScriptParser::Node::IDENTIFIER)) && p_call->function_name == SNAME("new");
 
+	if (is_constructor && Engine::get_singleton()->has_singleton(base_type.native_type)) {
+		push_error(vformat(R"(Cannot construct native class "%s" because it is an engine singleton.)", base_type.native_type), p_call);
+		p_call->set_datatype(call_type);
+		return;
+	}
+
 	if (get_function_signature(p_call, is_constructor, base_type, p_call->function_name, return_type, par_types, default_arg_count, method_flags)) {
 		// If the method is implemented in the class hierarchy, the virtual flag will not be set for that MethodInfo and the search stops there.
 		// Virtual check only possible for super() calls because class hierarchy is known. Node/Objects may have scripts attached we don't know of at compile-time.
diff --git a/modules/gdscript/tests/scripts/analyzer/errors/engine_singleton_instantiate.gd b/modules/gdscript/tests/scripts/analyzer/errors/engine_singleton_instantiate.gd
new file mode 100644
index 00000000000..7e1efb8d1b4
--- /dev/null
+++ b/modules/gdscript/tests/scripts/analyzer/errors/engine_singleton_instantiate.gd
@@ -0,0 +1,2 @@
+func test():
+	Time.new()
diff --git a/modules/gdscript/tests/scripts/analyzer/errors/engine_singleton_instantiate.out b/modules/gdscript/tests/scripts/analyzer/errors/engine_singleton_instantiate.out
new file mode 100644
index 00000000000..bc4875d908f
--- /dev/null
+++ b/modules/gdscript/tests/scripts/analyzer/errors/engine_singleton_instantiate.out
@@ -0,0 +1,2 @@
+GDTEST_ANALYZER_ERROR
+Cannot construct native class "Time" because it is an engine singleton.
diff --git a/modules/gdscript/tests/scripts/analyzer/errors/extend_engine_singleton.gd b/modules/gdscript/tests/scripts/analyzer/errors/extend_engine_singleton.gd
new file mode 100644
index 00000000000..a46b6d8658b
--- /dev/null
+++ b/modules/gdscript/tests/scripts/analyzer/errors/extend_engine_singleton.gd
@@ -0,0 +1,6 @@
+# GH-82081
+
+extends Time
+
+func test():
+	pass
diff --git a/modules/gdscript/tests/scripts/analyzer/errors/extend_engine_singleton.out b/modules/gdscript/tests/scripts/analyzer/errors/extend_engine_singleton.out
new file mode 100644
index 00000000000..7c26dea56ed
--- /dev/null
+++ b/modules/gdscript/tests/scripts/analyzer/errors/extend_engine_singleton.out
@@ -0,0 +1,2 @@
+GDTEST_ANALYZER_ERROR
+Cannot inherit native class "Time" because it is an engine singleton.