[Bug fortran/128476] New: [OpenMP] Implicit 'private' for loop variables rejects valid, bogus code with 'target teams map(...)'

[burnus at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=128476

            Bug ID: 128476
           Summary: [OpenMP] Implicit 'private' for loop variables rejects
                    valid, bogus code with 'target teams map(...)'
           Product: gcc
           Version: 17.0
            Status: UNCONFIRMED
          Keywords: diagnostic, rejects-valid
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: burnus at gcc dot gnu.org
  Target Milestone: ---

Cf. https://github.com/OpenMP-Validation-and-Verification/OpenMP_VV/pull/919

  !$omp target teams map(j)
    !$omp loop
       do j = 1, 2
       end do
    !$omp end loop
  !$omp end target teams
  end

This code currently gives:
  Error: Symbol ‘j’ present on multiple clauses at (1)

The reason is that an implicit 'private(j)' is added due to:

> 7.1.1 Variables Referenced in a Construct
> ...
>  * Loop-iteration variables inside task-generating constructs are private in 
> the innermost such construct that encloses the loop.

However, IMHO this only applies to 'teams' and not to 'target teams' - and the
problem occurs because it is added to the latter, clashing with 'map(j)'.


EXPECTED: The code is accepted but a warning is printed that the
implicit 'private' makes the 'map' clause pointless.

As we have eventually to support 'private( teams : j)', this could be added
once this feature is implemented.

For the test case discussed, either 'map(j)' or 'shared(j)' makes the code
sensible.