[Bug c++/87075] [7/8/9 Regression] ICE when compiling the test suite of GLM 0.9.9.0

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87075

--- Comment #4 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Reduced:

template <typename T>
struct vec
{
  struct { T y; };
  vec() = default;
};

template <typename T>
struct S
{
  vec<T> value[2];
  template<typename U>
  constexpr S(const U&);
};

template<typename T>
template<typename X>
constexpr S<T>::S(const X&)
{
  value[0] = vec<T>();
}

S<float>m(0);