[Bug c++/63723] Narrowing conversion allowed in braced init list in SFINAE context

[tavianator at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63723

--- Comment #2 from Tavian Barnes <tavianator at gmail dot com> ---
It's decltype(requires_conversion<To2>({std::declval<From2>()})).  Not sure why
it says <missing>.