return-type deduction failure for lambda inside decltype. #168249
Description
This fails to compile on clang-trunk.
template<int I> using X = decltype( []{ if constexpr(I == 0) return int{}; else return char{}; }() ); template<int I> inline constexpr auto Y = X<I>{}; static_assert(Y<1> == char{});Need to inject a template-param () for it to work.
Works on gcc. Godbolt: https://godbolt.org/z/3Ydv8b866.