[Bug c++/115809] paramater packed of function argument inside decltype of trailing return type is rejected

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115809

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|Gcc can't parse code where  |paramater packed of
                   |the decltype is written,    |function argument inside
                   |which depends on the        |decltype of trailing return
                   |runtime arguments passed to |type is rejected
                   |the function.               |

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Note it is the decltype for the trailing return type that is causing the issue.

That is this works just fine:
```
template <int...>
void Foo() {};

template<typename ...T>
void Foo3(T... is) {
  return (decltype(Foo<is...>()))0;
};
void f()
{
  Foo3();
}
```