[Bug c++/88355] [c++20] Placeholder non-type template argument type deduction fails with custom types

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88355

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
It was fixed by r273591 so maybe a dup of PR c++/90098 or PR c++/90099 or PR
c++/90101