[Issue 20093] Error: cannot form tuple of tuples

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=20093

--- Comment #1 from Adam D. Ruppe <destructionator at gmail.com> ---
I'll also note that `@(Attr) void foo()` is perfectly acceptable D code; to
trigger this bug you do have to go through the mixin template or some other way
of creating a TypeTuple.

My expected behavior is that it expands the Attributes tuple inside the @()
just like it would anywhere else, even if it has that type arg instead of just
values.

--