[Bug c++/65906] New: using-declaration allowed for non-direct base class

[Bug c++/65906] New: using-declaration allowed for non-direct base class

[danregister at poczta dot fm]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65906

            Bug ID: 65906
           Summary: using-declaration allowed for non-direct base class
           Product: gcc
           Version: 4.8.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: danregister at poczta dot fm
  Target Milestone: ---

GCC compiles without complaining the following code, which contains
using-declaration which brings constructor of non-direct base class:

----------------------------------------------------------------
#include <iostream>
void log(std::string msg) { std::cout << msg << std::endl; }

struct Base
{
        Base() { log(__func__); }
        Base(int, int) { log(__func__); }
};
struct D1 : Base
{
        D1() { log(__func__); }
};
struct D2 : D1
{
        D2() { log(__func__); }
        using Base::Base;
};

int main()
{
        D2 d(1, 2);
}
----------------------------------------------------------------

The output:

----------------------------------------------------------------
Base
D1
----------------------------------------------------------------

The same code compiled with clang produces: error: 'Base' is not a direct base
of 'D2', cannot inherit constructors

Possible duplicate: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=32039

[Bug c++/65906] using-declaration allowed for non-direct base class

[danregister at poczta dot fm]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65906

--- Comment #1 from Daniel Adamski <danregister at poczta dot fm> ---
Just to clarify, it is "Base()" that's being called, not "Base(int, int)" (I
should have used something else than "__func__").

[Bug c++/65906] using-declaration allowed for non-direct base class

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65906

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |accepts-invalid
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2015-04-27
     Ever confirmed|0                           |1

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Daniel Adamski from comment #0)
> Possible duplicate: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=32039

Maybe, but there is a specific rule regarding inheriting constructors that
applies here and not for 32039, in [namespace.udecl]/3:

    If such a using-declaration names a constructor, the nested-name-specifier
    shall name a direct base class of the class being defined;

[Bug c++/65906] using-declaration allowed for non-direct base class

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65906

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED
   Target Milestone|---                         |7.0

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This was fixed with r7-4255: Implement P0136R1, Rewording inheriting
constructors.

Which makes sense.