[Bug c++/119034] Nested using-declaration doesn't do ADL or uses wrong associated namespace

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119034

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2025-02-27

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This is odd, doing this:
```
namespace foo
{
  struct X { };
  void func(X) { }
}

namespace bar
{
  int func() = delete;
  template<typename T>
    using type = decltype(func(T{})); // #2
}

template<typename, typename> constexpr bool is_same_v = false;
template<typename T> constexpr bool is_same_v<T, T> = true;

static_assert( is_same_v<bar::type<foo::X>, void> );
```

Works but if you add:
```
  template<bool>
    struct result
    {
      template<typename T>
        using type1 = type<T>; // #2
    };
```

After the type alias, GCC fails. even if result<arg>::type1 is unused.


That is this fails:
```
namespace foo
{
  struct X { };
  void func(X) { }
}

namespace bar
{
  int func() = delete;

  template<typename T>
    using type = decltype(func(T{})); // #2
  template<bool>
    struct result
    {
      template<typename T>
        using type1 = type<T>; // #2
    };
}

template<typename, typename> constexpr bool is_same_v = false;
template<typename T> constexpr bool is_same_v<T, T> = true;

static_assert( is_same_v<bar::type<foo::X>, void> );
```