[Bug c++/88095] class nontype template parameter UDL string literals doesn't accepts deduction placeholder

[tom at honermann dot net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88095

--- Comment #2 from Tom Honermann <tom at honermann dot net> ---
I confirmed that Jeff's patch, applied to gcc 9.1.0, suffices to address both
Hana's test case and the code in the "Emulate C++17 u8 literals" section of
P1423R2
(http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1423r2.html#emulate)
if the declaration of operator <=> is commented out (since gcc doesn't yet
support operator <=>).