[Bug c++/66934] New: Compiler accepting ill-formed program with extern variable declarations and using-declaration

[Bug c++/66934] New: Compiler accepting ill-formed program with extern variable declarations and using-declaration

[anders.granlund.0 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66934

            Bug ID: 66934
           Summary: Compiler accepting ill-formed program with extern
                    variable declarations and using-declaration
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: anders.granlund.0 at gmail dot com
  Target Milestone: ---

The following program is ill-formed since the two declarations in main are
conflicting.

  namespace N {
      extern int x;
  }

  int main() {
      using N::x;
      extern int x;
  }

GCC compiles with program without errors. The expected behaviour is to get a
compiler error.

[Bug c++/66934] Compiler accepting ill-formed program with extern variable declarations and using-declaration

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66934

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
I think we could combine most of your reports into one or two PRs since they're
all related and fixing them one by one would probably not be very efficient.

[Bug c++/66934] Compiler accepting ill-formed program with extern variable declarations and using-declaration

[anders.granlund.0 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66934

--- Comment #2 from Anders Granlund <anders.granlund.0 at gmail dot com> ---
(In reply to Jonathan Wakely from comment #1)
> I think we could combine most of your reports into one or two PRs since
> they're all related and fixing them one by one would probably not be very
> efficient.

What is a PR?

[Bug c++/66934] Compiler accepting ill-formed program with extern variable declarations and using-declaration

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66934

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Problem report i.e. bugzilla bug.

[Bug c++/66934] Compiler accepting ill-formed program with extern variable declarations and using-declaration

[anders.granlund.0 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66934

--- Comment #4 from Anders Granlund <anders.granlund.0 at gmail dot com> ---
I'm pulling in this test case from my related bug report.

  int x = 1;

  int main() {
      extern int x;
      using ::x;
  }

I this case the program is well-formed (the two declarations in main are not
conflicting), but error messages are still given:

  prog.cc: In function 'int main()':
  prog.cc:5:13: error: redeclaration of 'int x'
       using ::x;
               ^
  prog.cc:4:16: note: previous declaration 'int x'
       extern int x;
                  ^

[Bug c++/66934] Compiler accepting ill-formed program with extern variable declarations and using-declaration

[anders.granlund.0 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66934

--- Comment #5 from Anders Granlund <anders.granlund.0 at gmail dot com> ---
*** Bug 66935 has been marked as a duplicate of this bug. ***

[Bug c++/66934] Compiler accepting ill-formed program with extern variable declarations and using-declaration

[anders.granlund.0 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66934

--- Comment #6 from Anders Granlund <anders.granlund.0 at gmail dot com> ---
(In reply to Jonathan Wakely from comment #3)
> Problem report i.e. bugzilla bug.

Ok. Done.

[Bug c++/66934] Compiler accepting ill-formed program with extern variable declarations and using-declaration

[anders.granlund.0 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66934

--- Comment #7 from Anders Granlund <anders.granlund.0 at gmail dot com> ---
(In reply to Anders Granlund from comment #2)
> (In reply to Jonathan Wakely from comment #1)
> > I think we could combine most of your reports into one or two PRs since
> > they're all related and fixing them one by one would probably not be very
> > efficient.
> 
> What is a PR?

I have now pulled in 66935 into this report. I have also pulled in 66878 66888
66889 66901 into 66879. This reduces 7 of my bug reports to 2 bug reports.

I have currently 9 other bug reports open, but I think they are quite separate.

[Bug c++/66934] Compiler accepting ill-formed program with extern variable declarations and using-declaration

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66934

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=66878,
                   |                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=66888,
                   |                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=66889,
                   |                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=66901,
                   |                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=66935

--- Comment #8 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Anders Granlund from comment #0)
> The following program is ill-formed since the two declarations in main are
> conflicting.

This was fixed in GCC 8+.

[Bug c++/66934] Compiler accepting ill-formed program with extern variable declarations and using-declaration

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66934

--- Comment #9 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Anders Granlund from comment #4)
> I'm pulling in this test case from my related bug report.
> 
>   int x = 1;
> 
>   int main() {
>       extern int x;
>       using ::x;
>   }

This is unrelated to the first testcase though.

[Bug c++/66934] Compiler accepting ill-formed program with extern variable declarations and using-declaration

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66934

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to work|                            |8.1.0
   Last reconfirmed|                            |2021-12-03
      Known to fail|                            |7.5.0
   Target Milestone|---                         |8.0
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
           Keywords|rejects-valid               |needs-bisection

[Bug c++/66934] Compiler accepting ill-formed program with extern variable declarations and using-declaration

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66934

Martin Liška <marxin at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
                 CC|                            |marxin at gcc dot gnu.org
             Status|NEW                         |RESOLVED

--- Comment #10 from Martin Liška <marxin at gcc dot gnu.org> ---
Fixed with r8-872-g3a9cc6853ad1a188.