- Correctly errors when a generic module contains a self-generic type.

releasenotes.md

@@ -60,6 +60,7 @@
 - Incorrectly allowed getting pointer to a macro #2049.
 - &self not runtime null-checked in macro #1827.
 - Bug when printing a boolean value as an integer using printf.
+- Show error when a generic module contains a self-generic type.
 
 ### Stdlib changes
 - `new_*` functions in general moved to version without `new_` prefix.

src/compiler/sema_decls.c

@@ -4497,6 +4497,13 @@ Decl *sema_analyse_parameterized_identifier(SemaContext *c, Path *decl_path, con
 	Decl *alias = name_resolve.found;
 	ASSERT(alias);
 	Module *module = alias->unit->module;
+
+	if (c->unit->module->generic_module == module)
+	{
+		sema_error_at(c, span, "This identifier is recursively using %s.", module->name->module);
+		return poisoned_decl;
+	}
+
 	unsigned parameter_count = vec_size(module->parameters);
 	ASSERT(parameter_count > 0);
 	if (parameter_count != vec_size(params))

test/test_suite/generic/generic_self_ref.c3

@@ -0,0 +1,29 @@
+module gui::widget {Type};
+import gui::widget_types;
+import std::collections::list;
+import std::io;
+
+struct Widget
+{
+	int id;
+	Type type;
+	List {any} children;
+}
+
+fn void Widget{Label}.draw(Widget* self) // #error: This identifier is recursively using gui::widget
+{
+	io::printfn("Hello Label");
+}
+
+module gui::widget_types;
+import gui::widget;
+struct Label
+{
+	String text;
+}
+
+fn void main()
+{
+	Widget {int} y;
+	y.draw();
+}