[Bug fortran/107508] New: Invalid bounds due to bogus reallocation on assignment with KIND=4 characters

[Bug fortran/107508] New: Invalid bounds due to bogus reallocation on assignment with KIND=4 characters

[burnus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107508

            Bug ID: 107508
           Summary: Invalid bounds due to bogus reallocation on assignment
                    with KIND=4 characters
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: burnus at gcc dot gnu.org
  Target Milestone: ---

In the following code, the bounds change during the assignment
but I believe the RHS and the LHS have the same shape and length parameters.

As it works with kind=4, I assume that there is a missing '*4' in the size
calculation.

! ------------------

implicit none
character(len=:,kind=4), allocatable :: a4str(:), a4str2
allocate(character(len=7,kind=4) :: a4str(-2:3))

if (lbound(a4str,1) /= -2) error stop
if (ubound(a4str,1) /= 3) error stop

a4str = [4_"sf456aq", 4_"3dtzu24", 4_"_4fh7sm", 4_"=ff85s7", 4_"j=8af4d",
4_".,A%Fsz"]

print *, lbound(a4str), ubound(a4str)  ! expected (-2:3) - actually: (1:6)

if (lbound(a4str,1) /= -2) error stop
if (ubound(a4str,1) /= 3) error stop
end

[Bug fortran/107508] Invalid bounds due to bogus reallocation on assignment with KIND=4 characters

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107508

--- Comment #1 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Tobias Burnus <burnus@gcc.gnu.org>:

https://gcc.gnu.org/g:071d00e0faabbd45449d2e83f207fca0f8e8ef68

commit r13-3751-g071d00e0faabbd45449d2e83f207fca0f8e8ef68
Author: Tobias Burnus <tobias@codesourcery.com>
Date:   Mon Nov 7 11:32:33 2022 +0100

    Fortran: Fix reallocation on assignment for kind=4 strings [PR107508]

    The check whether reallocation on assignment was required did not handle
    kind=4 characters correctly such that there was always a reallocation,
    implying issues with pointer addresses and lower bounds.  Additionally,
    with all deferred strings, the old memory was not freed on reallocation.
    And, finally, inside the block which was only executed if string lengths
    or bounds or dynamic types changed, was a subcheck of the same, which
    was effectively a no op but still confusing and at least added with -O0
    extra instructions to the binary.

            PR fortran/107508

    gcc/fortran/ChangeLog:

            * trans-array.cc (gfc_alloc_allocatable_for_assignment): Fix
            string-length check, plug memory leak, and avoid generation of
            effectively no-op code.
            * trans-expr.cc (alloc_scalar_allocatable_for_assignment): Extend
            comment; minor cleanup.

    gcc/testsuite/ChangeLog:

            * gfortran.dg/widechar_11.f90: New test.

[Bug fortran/107508] Invalid bounds due to bogus reallocation on assignment with KIND=4 characters

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107508

anlauf at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |WAITING
   Last reconfirmed|                            |2023-01-12
     Ever confirmed|0                           |1

--- Comment #2 from anlauf at gcc dot gnu.org ---
So fixed for gcc-13?