[Bug c++/109621] New: GCC accepts invalid program with multiple using declarations

[jlame646 at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109621

            Bug ID: 109621
           Summary: GCC accepts invalid program with multiple using
                    declarations
           Product: gcc
           Version: 13.1.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jlame646 at gmail dot com
  Target Milestone: ---

The following invalid program(afaik) is accepted by gcc and msvc.
https://godbolt.org/z/1Tsx54ro5

```
namespace X 
{ 
    struct type {}; 
}
namespace Y 
{ 
    using type = int; 
}
using X::type;
using Y::type;
int main()
{
    auto i = sizeof(type); //gcc and msvc accepts this but clang rejects this
}
```