[Bug fortran/56138] Deferred-length character RESULT: ICE in gfc_add_modify_loc

["pault at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56138

Paul Thomas <pault at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-01-30
         AssignedTo|unassigned at gcc dot       |pault at gcc dot gnu.org
                   |gnu.org                     |
     Ever Confirmed|0                           |1

--- Comment #1 from Paul Thomas <pault at gcc dot gnu.org> 2013-01-30 06:10:59 UTC ---
Created attachment 29305
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=29305
Fix for testcase in comment #0

Whilst the patch fixes the testcase and allows John Reid's version of
iso_varying_string (ISO/IEC JTC1/SC22/WG5 N1913) to compile, the test programme
does not, for the lack of deferred character length components in gfortran. 
Note that ifort correctly compiles both.

Bootstraps and regtests OK with:

! { dg-do run }
! Checks the fix for PR56138.
!
! Taken from ISO/IEC JTC1/SC22/WG5 N1913 by John Reid
! Reported by Tobias Burnus  <burnus@gcc.gnu.org>
!
  character(Len = :), allocatable :: bar
  bar = "bar"
  if (LEN (s_to_c ("foo"//bar)) .ne. 6) call abort
  If (s_to_c (bar//"foo") .ne. "barfoo") call abort
contains
 PURE FUNCTION s_to_c (string)
  CHARACTER(LEN=*), INTENT(IN)  :: string
  CHARACTER(LEN=:), ALLOCATABLE :: s_to_c
  s_to_c = string
 ENDFUNCTION s_to_c
end

This PR, therefore becomes one to fix deferred character length components.