Non-const macros may not return untyped lists.

releasenotes.md

@@ -18,6 +18,7 @@
 - Missing bounds check on upper bound with const ranges `foo[1:3]`.
 - Check up the hierarchy when considering if an interface cast is valid #2267.
 - Fix issue with labelled break inside of a $switch.
+- Non-const macros may not return untyped lists.
 
 ### Stdlib changes
 

src/compiler/sema_expr.c

@@ -2859,11 +2859,14 @@ EXIT:
 	}
 	sema_context_destroy(&macro_context);
 	call_expr->resolve_status = RESOLVE_DONE;
-	if (is_always_const && !expr_is_runtime_const(call_expr))
+	if (!expr_is_runtime_const(call_expr))
 	{
-		SEMA_ERROR(call_expr, "The macro failed to fold to a constant value, despite being '@const'.");
+		if (is_always_const)
-		SEMA_NOTE(decl, "The macro was declared here.");
+		{
-		return false;
+			SEMA_ERROR(call_expr, "The macro failed to fold to a constant value, despite being '@const'.");
+			SEMA_NOTE(decl, "The macro was declared here.");
+			return false;
+		}
 	}
 	return true;
 EXIT_FAIL:

test/test_suite/compile_time/compile_time_untyped.c3

@@ -0,0 +1,14 @@
+struct Test
+{
+    struct { int a; }
+}
+
+macro test(int x)
+{
+	return {{}};
+}
+fn int main()
+{
+	Test a = test(3);
+    return 0;
+}