[Bug c++/111357] __integer_pack fails to work with values of dependent type convertible to integers in noexcept context

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111357

Andrew Pinski  changed:

   What|Removed |Added

   Last reconfirmed||2023-09-10
 Ever confirmed|0   |1
 Status|UNCONFIRMED |NEW

--- Comment #2 from Andrew Pinski  ---
Reduced slightly:
```
#include 

using std::integer_sequence;
using std::make_integer_sequence;

template
void g(integer_sequence)
{}

template
struct c1
{
  static constexpr int value = 1;
  constexpr operator int() { return value; } 
};
template
struct R
{
using S = make_integer_sequence{}>;

R() noexcept(noexcept(g(S(
{}
};
int main()
{
R();
}
```

The obvious workaround in this case (and the tuple_size case) is to use
`::value` (or tuple_size_v ).

[Bug c++/111357] __integer_pack fails to work with values of dependent type convertible to integers

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111357

--- Comment #1 from Andrew Pinski  ---
The front-end does:
  hi = instantiate_non_dependent_expr (hi, complain);
  hi = cxx_constant_value (hi, complain);
  int len = valid_constant_size_p (hi) ? tree_to_shwi (hi) : -1;