[Bug c++/90731] [9/10 Regression] noexcept broken for forward declarations with decltype

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90731

--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
This test using using should compile in c++17:

using T = void() noexcept(true);
T t;
void t() noexcept(true);