[Bug c/115587] New: Possible uninitialized variable (decl) in c_parser_omp_loop_nest

[Bug c/115587] New: Possible uninitialized variable (decl) in c_parser_omp_loop_nest

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115587

            Bug ID: 115587
           Summary: Possible uninitialized variable (decl) in
                    c_parser_omp_loop_nest
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Keywords: internal-improvement, openmp
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
  Target Milestone: ---

clang gives the following warning:
```
/home/worker/buildworker/tiber-gcc-clang/build/gcc/c/c-parser.cc:22585:12:
warning: variable 'decl' is used uninitialized whenever '&&' condition is false
[-Wsometimes-uninitialized]
/home/worker/buildworker/tiber-gcc-clang/build/gcc/c/c-parser.cc:22585:12:
warning: variable 'decl' is used uninitialized whenever 'if' condition is false
[-Wsometimes-uninitialized]
```
I looked into the code and it does look like decl could be used uninitialized.
It is a complex path to get there though so it is hard to tell.
It is also only on the error path and it does not look like it would cause any
issues to be used here uninitialized though since it is never accessed directly
on that path.

I think initializing it to null after error_init, will fix the warning and have
the same effect as right now.
But someone who knows this code better should look into it.

[Bug c/115587] [14/15 Regression] Possible uninitialized variable (decl) in c_parser_omp_loop_nest

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115587

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|Possible uninitialized      |[14/15 Regression] Possible
                   |variable (decl) in          |uninitialized variable
                   |c_parser_omp_loop_nest      |(decl) in
                   |                            |c_parser_omp_loop_nest
                 CC|                            |sandra at gcc dot gnu.org

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Function/bad code was introduced with r14-3489-g143151ac2013c2 .

[Bug c/115587] [14/15 Regression] Possible uninitialized variable (decl) in c_parser_omp_loop_nest

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115587

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |14.2

[Bug c/115587] [14/15 Regression] Possible uninitialized variable (decl) in c_parser_omp_loop_nest

[sandra at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115587

--- Comment #2 from sandra at gcc dot gnu.org ---
I'll take care of this.

[Bug c/115587] [14/15 Regression] Possible uninitialized variable (decl) in c_parser_omp_loop_nest since r14-3489-g143151ac2013c2

[sjames at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115587

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2024-06-23
     Ever confirmed|0                           |1
            Summary|[14/15 Regression] Possible |[14/15 Regression] Possible
                   |uninitialized variable      |uninitialized variable
                   |(decl) in                   |(decl) in
                   |c_parser_omp_loop_nest      |c_parser_omp_loop_nest
                   |                            |since
                   |                            |r14-3489-g143151ac2013c2

[Bug c/115587] [14/15 Regression] Possible uninitialized variable (decl) in c_parser_omp_loop_nest since r14-3489-g143151ac2013c2

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115587

--- Comment #3 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Sandra Loosemore <sandra@gcc.gnu.org>:

https://gcc.gnu.org/g:21f1073d388af8af207183b0ed592e1cc47d20ab

commit r15-1613-g21f1073d388af8af207183b0ed592e1cc47d20ab
Author: Sandra Loosemore <sloosemore@baylibre.com>
Date:   Tue Jun 25 13:54:43 2024 +0000

    Fix PR c/115587, uninitialized variable in c_parser_omp_loop_nest

    This function had a reference to an uninitialized variable on the
    error path.  The problem was diagnosed by clang but not gcc.  It seems
    the cleanest solution is to initialize all the loop-clause variables
    at the point of declaration rather than at different places in the
    code.

    The C++ front end didn't have this problem, but I've made similar
    changes there to keep the code in sync.

    gcc/c/ChangeLog:

            PR c/115587
            * c-parser.cc (c_parser_omp_loop_nest): Move initializations to
            point of declaration.

    gcc/cp/ChangeLog:

            PR c/115587
            * parser.cc (cp_parser_omp_loop_nest): Move initializations to
            point of declaration.

[Bug c/115587] [14/15 Regression] Possible uninitialized variable (decl) in c_parser_omp_loop_nest since r14-3489-g143151ac2013c2

[sandra at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115587

sandra at gcc dot gnu.org changed:

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

--- Comment #4 from sandra at gcc dot gnu.org ---
Patch pushed to the mainline as obvious.  I'll backport to the GCC 14 branch as
well since this was tagged as a regression on that branch.

[Bug c/115587] [14/15 Regression] Possible uninitialized variable (decl) in c_parser_omp_loop_nest since r14-3489-g143151ac2013c2

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115587

--- Comment #5 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-14 branch has been updated by Sandra Loosemore
<sandra@gcc.gnu.org>:

https://gcc.gnu.org/g:b383719aebe45bbe8cc3944e515ed7caa30e8744

commit r14-10346-gb383719aebe45bbe8cc3944e515ed7caa30e8744
Author: Sandra Loosemore <sloosemore@baylibre.com>
Date:   Tue Jun 25 13:54:43 2024 +0000

    Fix PR c/115587, uninitialized variable in c_parser_omp_loop_nest

    This function had a reference to an uninitialized variable on the
    error path.  The problem was diagnosed by clang but not gcc.  It seems
    the cleanest solution is to initialize all the loop-clause variables
    at the point of declaration rather than at different places in the
    code.

    The C++ front end didn't have this problem, but I've made similar
    changes there to keep the code in sync.

    gcc/c/ChangeLog:

            PR c/115587
            * c-parser.cc (c_parser_omp_loop_nest): Move initializations to
            point of declaration.

    gcc/cp/ChangeLog:

            PR c/115587
            * parser.cc (cp_parser_omp_loop_nest): Move initializations to
            point of declaration.

    (cherry picked from commit 21f1073d388af8af207183b0ed592e1cc47d20ab)