void test(a...)() {}

void main() {
        test!(a => 0);
        test!(mixin("a => 0"));
}


Notice the first one working, but then mixin the same code fails with

bug.d(5): Error: incomplete mixin type a => 0

on new dmd, used to work until very recently.

Up to      2.087.1: Success and no output
Since      2.088.0: Failure with output: onlineapp.d(5): Error: incomplete mixin type `a => 0`


still works on the ldc and gdc versions I have here on my computer.