[Bug c++/60927] New: Ambiguity not caught when name introduced through using-directive conflicts with previously declared entity

[Bug c++/60927] New: Ambiguity not caught when name introduced through using-directive conflicts with previously declared entity

[filip.roseen at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60927

            Bug ID: 60927
           Summary: Ambiguity not caught when name introduced through
                    using-directive conflicts with previously declared
                    entity
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: filip.roseen at gmail dot com

Created attachment 32656
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=32656&action=edit
testcase.cpp

namespace N {
  namespace A {
    int x = 1;
  }
}

struct A {
  static int x;
};

int main () {
  using namespace N;

  A::x = 123;
}

----------------------------------------------------

`gcc` accepts the above even though there's an ambiguity between `N::A::x` and
`A::x` when referenced as `A::x` in `main`.

------------------------------------------------------

[ note: `gcc` treats the `A::x` as referring to `N::A::x`. ]

[ note: `clang` shows the correct behaviour and issues a diagnostic saying that
`A::x` is ambiguous. ]

[Bug c++/60927] Ambiguity not caught when name introduced through using-directive conflicts with previously declared entity

[mbos at google dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60927

Maurice Bos <mbos at google dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mbos at google dot com

--- Comment #1 from Maurice Bos <mbos at google dot com> ---
Some interesting related test cases:

namespace N { struct A {}; }
namespace A {}
using namespace N;
A * x;
int main() {}

G++ correctly complains about ambiguity. When the two lines with 'N' are
removed, it complains that A is not a type. (As expected.)

Very similar test case:

#include <memory>
namespace N { struct A {}; }
namespace A {}
using namespace N;
std::unique_ptr<A> x; // Only this line is different.
int main() {}

G++ does not complain about ambiguity, but gives the same error as when the two
lines with 'N' are removed.

[Bug c++/60927] Ambiguity not caught when name introduced through using-directive conflicts with previously declared entity

[ville.voutilainen at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60927

Ville Voutilainen <ville.voutilainen at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2014-12-14
                 CC|                            |ville.voutilainen at gmail dot com
     Ever confirmed|0                           |1
      Known to fail|                            |4.8.2, 4.9.1, 5.0