[Bug c/52600] New: OpenMP: declaration as structured block

[Bug c/52600] New: OpenMP: declaration as structured block

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52600

             Bug #: 52600
           Summary: OpenMP: declaration as structured block
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Keywords: openmp, rejects-valid
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: burnus@gcc.gnu.org


Found at
http://openmp.org/forum/viewtopic.php?f=10&t=1329&sid=58cf62c9cbfc7fee81768f053e079615

... and there believed to be valid. GCC rejects the following:

    #pragma omp task
    int x = foo();

with
  error: expected expression before ‘int’

While the following, syntactically identical (?), is accepted:

  #pragma omp task
  { int x = foo(); }

[Bug c/52600] OpenMP: declaration as structured block

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52600

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

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

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-03-26 10:17:02 UTC ---
In C++ we accept this, in C we don't (we call c_parser_statement, but
declarations aren't handled by that, due to the allowing/disallowing of mixing
of declarations and statements in C99 vs. C90).
I guess we could move the loop body from c_parser_compound_statement_nostart
to a new function and use it there as well as in c_parser_omp_structured_block,
c_parser_omp_{parallel,task} and c_parser_omp_sections_scope.

It is very ugly to allow there declarations though, that means code behaves
very differently between -fopenmp and -fno-openmp - in the former case the
declared var would go out of scope immediately, in the latter would be around
until closing }.

[Bug c/52600] OpenMP: declaration as structured block

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52600

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2021-12-12
     Ever confirmed|0                           |1

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
hmm, clang also rejects it for the C case.

Though it would be interesting because we now allow:
int foo1(void);
void foo()
{
 a:  int x = foo1();
}

But still reject:
int foo1(void);
void foo()
{
    #pragma omp task
 a:  int x = foo1();
}

While clang accepts the case with labels.