[Bug fortran/109911] New: [OpenMP] 'declare reduction' not USE associated

[Bug fortran/109911] New: [OpenMP] 'declare reduction' not USE associated

[burnus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109911

            Bug ID: 109911
           Summary: [OpenMP] 'declare reduction' not USE associated
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Keywords: openmp, rejects-valid
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: burnus at gcc dot gnu.org
  Target Milestone: ---

Found via OpenMP Spec Pull Request #3629 for Issue #3595.

The following program fails with:
  Error: !$OMP DECLARE REDUCTION add not found at (1)

But it works when moving or copying the declare line into the main program.

[Side remark: It is unclear (see PR above) whether the code is supposed to work
with 'private'.]

Note that the spec states:
"If a _directive_ appears in the specification part of a module then the
behavior is as if that _directive_ appears in the specification part of any
_compilation-unit_ that references the module with a *USE* statement unless
otherwise specified."


module m
  !  private
  !$omp declare reduction (Add : integer : myadd(omp_in, omp_out))
contains
  subroutine myadd(in, out)
    integer :: in, out
  end
end module

use m
implicit none (type,external)
integer :: x
!$omp parallel reduction(Add: x)
  ! ...
!$omp end parallel
end