[Bug fortran/118690] New: [OpenMP] declare_variant - multiple use for same procedure not diagnosed

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118690

            Bug ID: 118690
           Summary: [OpenMP] declare_variant - multiple use for same
                    procedure not diagnosed
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Keywords: accepts-invalid, openmp
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: burnus at gcc dot gnu.org
  Target Milestone: ---

The following cases are accepted but shouldn't:

! (A) Self reference:

subroutine sub()
  !$omp declare variant(sub) match(user={condition(.true.)})
end


! (B) having the multiple 'declare variant' in the same scope
!
! → this is accepted to for C for '#include <header_file.h>'
!   following by identical version
!   the same selector par is checked for in omp_mark_declare_variant

subroutine var1(); end

subroutine b1()
  !$omp declare variant(var1) match(user={condition(.true.)})
  !$omp declare variant(var1) match(user={condition(.true.)})
end


! (C) Same issue

subroutine var2(); end

subroutine b2(x)
  use iso_c_binding
  type(c_ptr) :: x
  !$omp declare variant(var2) match(construct={dispatch}) &
  !$omp&                      adjust_args(need_device_ptr: x)
  !$omp declare variant(var2) match(construct={dispatch}) &
  !$omp&                      adjust_args(need_device_ptr: x)
                              ! ---OR---  nothing : x
end


! (D) Same as (B), but differently written - might not yet be accepted
! syntax wise:

subroutine var3(); end

subroutine bar()
  interface
    subroutine b3()
      !$omp declare variant(var2) match(user={condition(.true.)})
    end
  end interface
 !$omp declare variant(b2 : var2) match(user={condition(.true.)})
end


! (E) The following is also wrong - similar code required to
!     omp_mark_declare_variant - or extend it?
!     i.e. check both adjust_args and append_args.
!
! [not quite sure whether it can occur for Fortran or not.]


void f(int *);
#pragma omp declare variant(f) adjust_args(nothing: x) \
            match(construct={dispatch})
void g(int *x);

// …
#pragma omp declare variant(f) adjust_args(need_device_ptr: x) \
            match(construct={dispatch})
void g(int *x)
{ /* … */ }