[Bug c++/113873] New: false warning about #pragma once

[Bug c++/113873] New: false warning about #pragma once

[jadexradex at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113873

            Bug ID: 113873
           Summary: false warning about #pragma once
           Product: gcc
           Version: 12.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jadexradex at gmail dot com
  Target Milestone: ---

If you create an empty file with C/C++ extension and write "#pragma once", it
will show warning "#pragma once in main file".

However, this file does not have any code or entry point. So this message may
be misleading.

[Bug c++/113873] false warning about #pragma once

[sjames at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113873

Sam James <sjames at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |sjames at gcc dot gnu.org

--- Comment #1 from Sam James <sjames at gcc dot gnu.org> ---
(In reply to Jadex Radex from comment #0)
> If you create an empty file with C/C++ extension and write "#pragma once",
> it will show warning "#pragma once in main file".
> 

What is "it" here? Is it "g++ foo.cxx', or is it 'g++ -c foo.cxx', or something
else?

[Bug preprocessor/113873] false warning about #pragma once

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113873

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |diagnostic
          Component|c++                         |preprocessor

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Can you provide an exact commands you used to compile?
Main here is pointing to the main source file that is being compiled.
Maybe the warning could be slightly clearer but it is basically saying you
can't use it outside of a header file that is being `#include`d.

[Bug preprocessor/113873] false warning about #pragma once

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113873

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |DUPLICATE
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Oh it is basically a dup of bug 89808.

*** This bug has been marked as a duplicate of bug 89808 ***

[Bug preprocessor/113873] false warning about #pragma once

[jadexradex at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113873

--- Comment #4 from Jadex Radex <jadexradex at gmail dot com> ---
(In reply to Sam James from comment #1)
> (In reply to Jadex Radex from comment #0)
> > If you create an empty file with C/C++ extension and write "#pragma once",
> > it will show warning "#pragma once in main file".
> > 
> 
> What is "it" here? Is it "g++ foo.cxx', or is it 'g++ -c foo.cxx', or
> something else?

Sorry for my ambiguous explanation. I meant the warning inside a code editor
(micro in my case). It doesn't appears at compilation stage.