[Bug c++/66834] [concepts] concept parameter kind mismatch causes hard error

[eric.niebler at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66834

--- Comment #6 from Eric Niebler <eric.niebler at gmail dot com> ---
Exhaustively overloading Constructible to avoid the kind mismatch and the
ambiguity runs into a different problem:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66841

I haven't filed an issue for the ambiguity/partial order problem. Should I, or
is that by design?

Either the kind mismatch problem needs to be fixed, or issue #66841. Right now
I don't seem to have a way to express what I'm trying to express.