[Bug c++/127373] ICE when instantiating conversion to pointer to function for generic lambda

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127373

Drea Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |c++-lambda

--- Comment #2 from Drea Pinski <pinskia at gcc dot gnu.org> ---
>I assume the reason is that gcc does not apply constraints (requires
clauses/concepts)

It does. Because if you used int rather than float, it is accepted.


So it looks like it is lambda related because if I emulate it; things work:
```

#include <concepts>
template <typename T>
using a = T(*)();

struct s2
{
template <std::integral T>
static constexpr  T f(){return 0;}
template <std::integral T>
  constexpr operator a<T> ()
  {
    return f;
  }
};

struct s3
{
template <std::floating_point T>
static constexpr  T f(){return 1;}
template <std::floating_point T>
  constexpr operator a<T> ()
  {
    return f;
  }
};

struct foo1: s2, s3 {};
constexpr float(*pfn2)() = foo1{};
static_assert(pfn2() == 1);
constexpr int(*pfn3)() = foo1{};
static_assert(pfn3() == 0);
```