[Bug c++/119316] [14/15 Regression] new expression incorrectly required to have constant expression size inside a requires constraint of a template function

[jason at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119316

--- Comment #3 from Jason Merrill <jason at gcc dot gnu.org> ---
We can see this without constraints in this adjusted testcase:

template <unsigned> struct A { };
template<typename T>
auto foo(unsigned n) -> A<sizeof(new T[n])>
{ return {}; }
int main() { foo<int>(5); }

The regression for the original testcase happened because mangling requirements
exposed this issue more.