[Bug c++/126345] ICE when using contract with empty parameter pack

[hello at nathanbaggs dot co.uk via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126345

--- Comment #1 from hello at nathanbaggs dot co.uk ---
Just checked and it also happens with free functions

template <class... Args>
auto go(Args &&...args) -> void
    pre(true)
{
}

int main()
{
    go();
}