[Bug middle-end/95506] New: [OpenMP] omp target – private clause and allocatables – unallocated or reallocation

[burnus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95506

            Bug ID: 95506
           Summary: [OpenMP] omp target  – private clause and allocatables
                    – unallocated or reallocation
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Keywords: openmp
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: burnus at gcc dot gnu.org
                CC: jakub at gcc dot gnu.org
  Target Milestone: ---

Found when playing around with PR95499 – which is about ICEs.

The following program fails at run time – the actual argument is not allocated
– hence, 'str = "a"' will allocate str on assignment
            if (*str != 0B) goto L.1;
            *str = (character(kind=1)[1:*_str] *) __builtin_malloc (1);
            goto L.2;
However, if '*str == NULL' the code crashes, likewise, if the 'str' is
allocated to a different length (e.g. 'my_str = "ab"' + 'str = "a"' + change
'len=5' to 'len=:').

As 'str' is private, I think the (re)allocation of 'str' should be fine,
shouldn't it?

program main
  implicit none
  character(len=5), allocatable :: my_str
  ! my_str = "b"  ! << commented, i.e. unallocated
  call bar_str(my_str)
contains
  subroutine bar_str(str)
    integer :: i
    character(len=5), allocatable :: str

    !$omp target private(str)
    str = "a"
    print *, str
    !$omp end target
  end
end