[Bug c/100450] New: Missing ' ' space for '-E' preprocessing output, works with direct compilation

[Bug c/100450] New: Missing ' ' space for '-E' preprocessing output, works with direct compilation

[burnus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100450

            Bug ID: 100450
           Summary: Missing ' ' space for '-E' preprocessing output, works
                    with direct compilation
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: burnus at gcc dot gnu.org
  Target Milestone: ---

The following code compiles with
  -c -fopenmp -Wall test.c

But the output with -E + compilation shows:
  warning: ignoring ‘#pragma omp forreduction’ [-Wunknown-pragmas]

as the -E preprocessor outputs:
  #pragma omp forreduction(+:red)
instead of the expected
  #pragma omp for reduction(+:red)
-----------------^

Testcase:
-----------------------------------
#define TEST(T) { \
     {T} \
}
#define CLAUSES reduction(+:red)
#define PARALLEL_FOR(X) TEST({ \
_Pragma("omp for CLAUSES") \
X \
})

void foo()
{
  int red = 0;
  int A[3] = {};
  #pragma omp parallel shared(red)
  PARALLEL_FOR( for(int i=0; i < 3; i++) red += A[i]; )
}

[Bug c/100450] Missing ' ' space for '-E' preprocessing output, works with direct compilation

[burnus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100450

--- Comment #1 from Tobias Burnus <burnus at gcc dot gnu.org> ---
Likewise with g++ - nonsurprising as it is common code
in  c-ppoutput.c's  token_streamer::stream. First called with
  token->type == CPP_PRAGMA
        fprintf (print.outf, "%s %s", space, name);
is the proper '#pragma omp for'. Then comes a CPP_PADDING followed by CPP_NAME.
There is some 'Subtle logic to output a space if and only if necessary.' at the
top of that file - and that seems to break here.

[Bug c/100450] Missing ' ' space for '-E' preprocessing output, works with direct compilation

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100450

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

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

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
I think it started with my
https://gcc.gnu.org/legacy-ml/gcc-patches/2008-02/msg01329.html
Before that we weren't expanding those CLAUSES at all during preprocessing,
neither for _Pragma nor for #pragma.  But #pragma omp for CLAUSES works fine.

[Bug c/100450] Missing ' ' space for '-E' preprocessing output, works with direct compilation

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100450

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |jakub at gcc dot gnu.org
   Last reconfirmed|                            |2021-05-06
     Ever confirmed|0                           |1

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
I guess would should in libcpp/lex.c (cpp_avoid_paste) handle
case CPP_PRAGMA: like case CPP_NAME:
cpp_avoid_paste is called only from token_streamer::stream and from Fortran
scan_translation_unit, so I think we should be ok.
What we print for CPP_PRAGMA is always #pragma name or #pragma space name
where name is some identifier.

[Bug c/100450] Missing ' ' space for '-E' preprocessing output, works with direct compilation

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100450

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 50769
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=50769&action=edit
gcc12-pr100450.patch

Untested fix.

[Bug c/100450] Missing ' ' space for '-E' preprocessing output, works with direct compilation

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100450

--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:170c850e4bd46745e2a5130b5eb09f9fceb98416

commit r12-616-g170c850e4bd46745e2a5130b5eb09f9fceb98416
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Fri May 7 17:48:37 2021 +0200

    libcpp: Fix up pragma preprocessing [PR100450]

    Since the r0-85991-ga25a8f3be322fe0f838947b679f73d6efc2a412c
    https://gcc.gnu.org/legacy-ml/gcc-patches/2008-02/msg01329.html
    changes, so that we handle macros inside of pragmas that should expand
    macros, during preprocessing we print those pragmas token by token,
    with CPP_PRAGMA printed as
          fputs ("#pragma ", print.outf);
          if (space)
            fprintf (print.outf, "%s %s", space, name);
          else
            fprintf (print.outf, "%s", name);
    where name is some identifier (so e.g. print
     #pragma omp parallel
    or
     #pragma omp for
    etc.).  Because it ends in an identifier, we need to handle it like
    an identifier (i.e. CPP_NAME) for the decision whether a space needs
    to be emitted in between that #pragma whatever or #pragma whatever whatever
    and following token, otherwise the attached testcase is preprocessed as
     #pragma omp forreduction(+:red)
    rather than
     #pragma omp for reduction(+:red)
    The cpp_avoid_paste function is only called for this purpose.

    2021-05-07  Jakub Jelinek  <jakub@redhat.com>

            PR c/100450
            * lex.c (cpp_avoid_paste): Handle token1 CPP_PRAGMA like CPP_NAME.

            * c-c++-common/gomp/pr100450.c: New test.

[Bug c/100450] Missing ' ' space for '-E' preprocessing output, works with direct compilation

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100450

--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:8482ed658ca77bfd7fc119cd62afd5b70a024500

commit r11-8371-g8482ed658ca77bfd7fc119cd62afd5b70a024500
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Fri May 7 17:48:37 2021 +0200

    libcpp: Fix up pragma preprocessing [PR100450]

    Since the r0-85991-ga25a8f3be322fe0f838947b679f73d6efc2a412c
    https://gcc.gnu.org/legacy-ml/gcc-patches/2008-02/msg01329.html
    changes, so that we handle macros inside of pragmas that should expand
    macros, during preprocessing we print those pragmas token by token,
    with CPP_PRAGMA printed as
          fputs ("#pragma ", print.outf);
          if (space)
            fprintf (print.outf, "%s %s", space, name);
          else
            fprintf (print.outf, "%s", name);
    where name is some identifier (so e.g. print
     #pragma omp parallel
    or
     #pragma omp for
    etc.).  Because it ends in an identifier, we need to handle it like
    an identifier (i.e. CPP_NAME) for the decision whether a space needs
    to be emitted in between that #pragma whatever or #pragma whatever whatever
    and following token, otherwise the attached testcase is preprocessed as
     #pragma omp forreduction(+:red)
    rather than
     #pragma omp for reduction(+:red)
    The cpp_avoid_paste function is only called for this purpose.

    2021-05-07  Jakub Jelinek  <jakub@redhat.com>

            PR c/100450
            * lex.c (cpp_avoid_paste): Handle token1 CPP_PRAGMA like CPP_NAME.

            * c-c++-common/gomp/pr100450.c: New test.

    (cherry picked from commit 170c850e4bd46745e2a5130b5eb09f9fceb98416)

[Bug c/100450] Missing ' ' space for '-E' preprocessing output, works with direct compilation

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100450

--- Comment #7 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:d7c8e6261532e7b2d16221becd5db11ded03e059

commit r10-9810-gd7c8e6261532e7b2d16221becd5db11ded03e059
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Fri May 7 17:48:37 2021 +0200

    libcpp: Fix up pragma preprocessing [PR100450]

    Since the r0-85991-ga25a8f3be322fe0f838947b679f73d6efc2a412c
    https://gcc.gnu.org/legacy-ml/gcc-patches/2008-02/msg01329.html
    changes, so that we handle macros inside of pragmas that should expand
    macros, during preprocessing we print those pragmas token by token,
    with CPP_PRAGMA printed as
          fputs ("#pragma ", print.outf);
          if (space)
            fprintf (print.outf, "%s %s", space, name);
          else
            fprintf (print.outf, "%s", name);
    where name is some identifier (so e.g. print
     #pragma omp parallel
    or
     #pragma omp for
    etc.).  Because it ends in an identifier, we need to handle it like
    an identifier (i.e. CPP_NAME) for the decision whether a space needs
    to be emitted in between that #pragma whatever or #pragma whatever whatever
    and following token, otherwise the attached testcase is preprocessed as
     #pragma omp forreduction(+:red)
    rather than
     #pragma omp for reduction(+:red)
    The cpp_avoid_paste function is only called for this purpose.

    2021-05-07  Jakub Jelinek  <jakub@redhat.com>

            PR c/100450
            * lex.c (cpp_avoid_paste): Handle token1 CPP_PRAGMA like CPP_NAME.

            * c-c++-common/gomp/pr100450.c: New test.

    (cherry picked from commit 170c850e4bd46745e2a5130b5eb09f9fceb98416)

[Bug c/100450] Missing ' ' space for '-E' preprocessing output, works with direct compilation

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100450

--- Comment #8 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-9 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:ec910efa1f70e3903091b23e80c5c554b4db6c9b

commit r9-9521-gec910efa1f70e3903091b23e80c5c554b4db6c9b
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Fri May 7 17:48:37 2021 +0200

    libcpp: Fix up pragma preprocessing [PR100450]

    Since the r0-85991-ga25a8f3be322fe0f838947b679f73d6efc2a412c
    https://gcc.gnu.org/legacy-ml/gcc-patches/2008-02/msg01329.html
    changes, so that we handle macros inside of pragmas that should expand
    macros, during preprocessing we print those pragmas token by token,
    with CPP_PRAGMA printed as
          fputs ("#pragma ", print.outf);
          if (space)
            fprintf (print.outf, "%s %s", space, name);
          else
            fprintf (print.outf, "%s", name);
    where name is some identifier (so e.g. print
     #pragma omp parallel
    or
     #pragma omp for
    etc.).  Because it ends in an identifier, we need to handle it like
    an identifier (i.e. CPP_NAME) for the decision whether a space needs
    to be emitted in between that #pragma whatever or #pragma whatever whatever
    and following token, otherwise the attached testcase is preprocessed as
     #pragma omp forreduction(+:red)
    rather than
     #pragma omp for reduction(+:red)
    The cpp_avoid_paste function is only called for this purpose.

    2021-05-07  Jakub Jelinek  <jakub@redhat.com>

            PR c/100450
            * lex.c (cpp_avoid_paste): Handle token1 CPP_PRAGMA like CPP_NAME.

            * c-c++-common/gomp/pr100450.c: New test.

    (cherry picked from commit 170c850e4bd46745e2a5130b5eb09f9fceb98416)

[Bug c/100450] Missing ' ' space for '-E' preprocessing output, works with direct compilation

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100450

--- Comment #9 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-8 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:e2979f8687f590461bef9f87bd997390af67312e

commit r8-10958-ge2979f8687f590461bef9f87bd997390af67312e
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Fri May 7 17:48:37 2021 +0200

    libcpp: Fix up pragma preprocessing [PR100450]

    Since the r0-85991-ga25a8f3be322fe0f838947b679f73d6efc2a412c
    https://gcc.gnu.org/legacy-ml/gcc-patches/2008-02/msg01329.html
    changes, so that we handle macros inside of pragmas that should expand
    macros, during preprocessing we print those pragmas token by token,
    with CPP_PRAGMA printed as
          fputs ("#pragma ", print.outf);
          if (space)
            fprintf (print.outf, "%s %s", space, name);
          else
            fprintf (print.outf, "%s", name);
    where name is some identifier (so e.g. print
     #pragma omp parallel
    or
     #pragma omp for
    etc.).  Because it ends in an identifier, we need to handle it like
    an identifier (i.e. CPP_NAME) for the decision whether a space needs
    to be emitted in between that #pragma whatever or #pragma whatever whatever
    and following token, otherwise the attached testcase is preprocessed as
     #pragma omp forreduction(+:red)
    rather than
     #pragma omp for reduction(+:red)
    The cpp_avoid_paste function is only called for this purpose.

    2021-05-07  Jakub Jelinek  <jakub@redhat.com>

            PR c/100450
            * lex.c (cpp_avoid_paste): Handle token1 CPP_PRAGMA like CPP_NAME.

            * c-c++-common/gomp/pr100450.c: New test.

    (cherry picked from commit 170c850e4bd46745e2a5130b5eb09f9fceb98416)