[Bug preprocessor/90400] _Pragma not always expanded in the right location within macros

[Bug preprocessor/90400] _Pragma not always expanded in the right location within macros

[burnus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90400

Tobias Burnus <burnus at gcc dot gnu.org> changed:

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

--- Comment #4 from Tobias Burnus <burnus at gcc dot gnu.org> ---
If I look at the 'gcc -E' output, the order is reverted:

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wall"
#pragma GCC diagnostic pop
  else { b--; ; ; a--; ; }

this should be instead:

  else { b--;
#pragma GCC diagnostic push
;
#pragma GCC diagnostic ignored "-Wall"
; a--;
#pragma GCC diagnostic pop
; }


I did observe the same in PR102409 – see analysis there. But contrary to the
issue in the other PR, the patch there does not solve the issue in this PR.

Additionally, for 'GCC diagnostic' there might be a column issue as discussed
in PR91669 comment 3.

[Bug preprocessor/90400] _Pragma not always expanded in the right location within macros

[burnus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90400

--- Comment #5 from Tobias Burnus <burnus at gcc dot gnu.org> ---
The problem is that the pragma is not known/registered. In that case, when
calling
libcpp/directives.c's do_pragma, the result is  p == NULL

and thus:

  if (p)
    ...
  else if (pfile->cb.def_pragma)
    ...
    pfile->cb.def_pragma (pfile, pfile->directive_line);

the latter immediately prints the '#pragma ...'

I think what needs to be done is if (p == NULL && pfile->state.in_directive) to
create a new pragma on the fly and store it in pfile->directive_result to use
it later.

 * * *

Side note: For 'gcc -E c-c++-common/gomp/pragma-1.c' the same issue occurs, but
if one adds  -fopenmp, p != NULL and everything is fine.

[Bug preprocessor/90400] _Pragma not always expanded in the right location within macros

[burnus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90400

--- Comment #6 from Tobias Burnus <burnus at gcc dot gnu.org> ---
Created attachment 51700
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=51700&action=edit
Draft patch for the 'gcc -E' / 'gcc -save-temps' issue

This solves the -E / -save-temps preprocessing issue.

For the non -E issue, it could be the issue described at PR 91669.

[Bug preprocessor/90400] _Pragma not always expanded in the right location within macros

[burnus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90400

--- Comment #7 from Tobias Burnus <burnus at gcc dot gnu.org> ---
(In reply to Tobias Burnus from comment #6)
> Created attachment 51700 [details]
> Draft patch for the 'gcc -E' / 'gcc -save-temps' issue
> 
> This solves the -E / -save-temps preprocessing issue.
> 
> For the non -E issue, it could be the issue described at PR 91669.

Regarding "-E": Actually, looking at PR103165 comment 2, I note that for the
example there 'clang -E' outputs:

"hello; \"\" _Pragma(\"GCC diagnostic pop\") world;"

that is: While the macros are replaced, the (unknown) _Pragma remains as
_Pragma - such that it is then later only processed when running the compiler.

No idea whether that makes sense or not not - just as observation.

[Bug preprocessor/90400] _Pragma not always expanded in the right location within macros

[lhyatt at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90400

Lewis Hyatt <lhyatt at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2023-08-25
                 CC|                            |lhyatt at gcc dot gnu.org
     Ever confirmed|0                           |1
           See Also|                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=103165,
                   |                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=102409

--- Comment #8 from Lewis Hyatt <lhyatt at gcc dot gnu.org> ---
(In reply to Tobias Burnus from comment #7)
> Regarding "-E": Actually, looking at PR103165 comment 2, I note that for the
> example there 'clang -E' outputs:
> 
> "hello; \"\" _Pragma(\"GCC diagnostic pop\") world;"
> 
> that is: While the macros are replaced, the (unknown) _Pragma remains as
> _Pragma - such that it is then later only processed when running the
> compiler.
> 
> No idea whether that makes sense or not not - just as observation.

This issue was indeed fixed by r12-5454, the fix for PR103165.

I will get a testcase added and then close this one. The testcase will be a
tweaked version of the original one from this PR. It needs to use a different
_Pragma, because nowadays, '#pragma GCC diagnostic' is recognized by the
preprocessor. The existing c-c++-common/gomp/pragma-2.c provides coverage for
that case. '#pragma GCC unroll' is a useful new testcase, being another pragma
that is explicitly ignored during preprocess-only modes.

[Bug preprocessor/90400] _Pragma not always expanded in the right location within macros

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90400

--- Comment #9 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Lewis Hyatt <lhyatt@gcc.gnu.org>:

https://gcc.gnu.org/g:d8e08ba9396b1f7da50011468f260250b7afaab7

commit r14-4186-gd8e08ba9396b1f7da50011468f260250b7afaab7
Author: Lewis Hyatt <lhyatt@gmail.com>
Date:   Fri Aug 25 15:57:19 2023 -0400

    testsuite: Add test for already-fixed issue with _Pragma expansion
[PR90400]

    The PR was fixed by r12-5454. Since the fix was somewhat incidental,
    although related, add a testcase from PR90400 too before closing it out.

    gcc/testsuite/ChangeLog:

            PR preprocessor/90400
            * c-c++-common/cpp/pr90400.c: New test.

[Bug preprocessor/90400] _Pragma not always expanded in the right location within macros

[lhyatt at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90400

Lewis Hyatt <lhyatt at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #10 from Lewis Hyatt <lhyatt at gcc dot gnu.org> ---
Marking it fixed now that the testcase is added.

[Bug preprocessor/90400] _Pragma not always expanded in the right location within macros

[lhyatt at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90400

Lewis Hyatt <lhyatt at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |paboyle at ph dot ed.ac.uk

--- Comment #11 from Lewis Hyatt <lhyatt at gcc dot gnu.org> ---
*** Bug 91517 has been marked as a duplicate of this bug. ***