cgen: fix alias of map clone() (fix #18384) (#18386)

Author: yuyi98

vlib/v/gen/c/fn.v

@@ -1277,7 +1277,7 @@ fn (mut g Gen) method_call(node ast.CallExpr) {
 		g.get_free_method(rec_type)
 	}
 	mut has_cast := false
-	if left_sym.kind == .map && node.name in ['clone', 'move'] {
+	if final_left_sym.kind == .map && node.name in ['clone', 'move'] {
 		receiver_type_name = 'map'
 	}
 	if final_left_sym.kind == .array && !(left_sym.kind == .alias && left_sym.has_method(node.name))

vlib/v/tests/alias_map_clone_test.v

@@ -0,0 +1,13 @@
+type Fields = map[string]string
+
+fn test_alias_map_clone() {
+	f := Fields({
+		's': 'a'
+	})
+
+	s := f.clone()
+	println(s)
+	assert s == {
+		's': 'a'
+	}
+}