source: CIVL/examples/omp/dataracebench-1.3.2/micro-benchmarks-fortran/DRB119-nestlock-orig-yes.f95

!!!~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~!!!
!!! Copyright (c) 2017-20, Lawrence Livermore National Security, LLC
!!! and DataRaceBench project contributors. See the DataRaceBench/COPYRIGHT file for details.
!!!
!!! SPDX-License-Identifier: (BSD-3-Clause)
!!!~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~!!!

!A nested lock can be locked several times. It doesn't unlock until you have unset
!it as many times as the number of calls to omp_set_nest_lock.
!incr_b is called at line 53 and line 58. So, it needs a nest_lock enclosing line 35
!Missing nest_lock will lead to race condition at line:35.
!Data Race Pairs, p%b@35:5 and p%b@35:5.

module DRB118
    use OMP_LIB, ONLY: OMP_NEST_LOCK_KIND
    type pair
        integer a
        integer b
        integer (OMP_NEST_LOCK_KIND) lck
    end type
end module

subroutine incr_a(p, a)
    use DRB118
    type(pair) :: p
    integer a
    p%a = p%a + 1
end subroutine

subroutine incr_b(p, b)
    use omp_lib
    use DRB118
    type(pair) :: p
    integer b
    p%b = p%b + 1
end subroutine

program DRB118_nestlock_orig_no
    use omp_lib
    use DRB118
    implicit none

    integer :: a, b

    type(pair) :: p
    p%a = 0
    p%b = 0
    call omp_init_nest_lock(p%lck);

    !$omp parallel sections
    !$omp section
        call omp_set_nest_lock(p%lck)
        call incr_b(p, a)
        call incr_a(p, b)
        call omp_unset_nest_lock(p%lck)

    !$omp section
        call incr_b(p, b);

    !$omp end parallel sections

    call omp_destroy_nest_lock(p%lck)

    print*,p%b

end program