[Patch, gfortran] PR26257 - Segmentation fault, on function call with assumed shape array parameter

[Paul Thomas <paulthomas2 at wanadoo dot fr>]

:ADDPATCH fortran:

With reference to the attached testcase, the seg fault due to the 
function being use associated - the segfault occurs via the route 
gfc_conv_intrinsic_size => gfc_conv_expr_descriptor => 
gfc_build_addr_expr, which is needed to calculate the potential offset 
between the full array and the actual argument of SIZE, which is assumed 
to be an array section.  However, seen from the main program, the 
address of a dummy argument of a module procedure is not the most 
readily available thing in the world - in fact, it has already gone out 
of scope.

Happily, SIZE does not need the offset or the data, come to that.  Thus 
a patch, in which we check that the symbol belongs to a namespace before 
trying to provoke a segfault, judiciously deposited in 
gfc_conv_expr_descriptor, does the job.  This patch is attached, 
together with a testsuite version of the reduced PR testcase.

Regtested on FC3/Athlon.

OK for mainline and 4.1, when reopened?

Paul

2006-02-29  Paul Thomas  <pault@gcc.gnu.org>

   PR fortran/26257
   * trans-array.c (gfc_conv_expr_descriptor): Exclude calculation of 
the offset
   for arrays without a namespace - ie. module procedure dummies.

2006-02-29  Paul Thomas  <pault@gcc.gnu.org>

   PR fortran/26257
   gfortran.dg/auto_char_len_3.f90: New test



Index: gcc/fortran/trans-array.c
===================================================================
*** gcc/fortran/trans-array.c	(revision 111450)
--- gcc/fortran/trans-array.c	(working copy)
*************** gfc_conv_expr_descriptor (gfc_se * se, g
*** 3789,3797 ****
--- 3789,3800 ----
    tree offset;
    int full;
    gfc_ref *ref;
+   gfc_symbol *sym;
  
    gcc_assert (ss != gfc_ss_terminator);
  
+   sym = expr->expr_type == EXPR_VARIABLE ? expr->symtree->n.sym : NULL;
+ 
    /* TODO: Pass constant array constructors without a temporary.  */
    /* Special case things we know we can pass easily.  */
    switch (expr->expr_type)
*************** gfc_conv_expr_descriptor (gfc_se * se, g
*** 4143,4154 ****
  	  dim++;
  	}
  
!       /* Point the data pointer at the first element in the section.  */
!       tmp = gfc_conv_array_data (desc);
!       tmp = build_fold_indirect_ref (tmp);
!       tmp = gfc_build_array_ref (tmp, offset);
!       offset = gfc_build_addr_expr (gfc_array_dataptr_type (desc), tmp);
!       gfc_conv_descriptor_data_set (&loop.pre, parm, offset);
  
        if (se->direct_byref)
  	{
--- 4146,4160 ----
  	  dim++;
  	}
  
!       if (!(sym && !sym->ns && !se->direct_byref))
! 	{
! 	  /* Point the data pointer at the first element in the section.  */
! 	  tmp = gfc_conv_array_data (desc);
! 	  tmp = build_fold_indirect_ref (tmp);
! 	  tmp = gfc_build_array_ref (tmp, offset);
! 	  offset = gfc_build_addr_expr (gfc_array_dataptr_type (desc), tmp);
! 	  gfc_conv_descriptor_data_set (&loop.pre, parm, offset);
! 	}
  
        if (se->direct_byref)
  	{

! { dg-do run }
! Test the fix for PR26257, in which the implicit reference to
! chararray in the main program call of chararray2string would
! cause a segfault in gfc_build_addr_expr.
!
! Based on the reduced testcase in the PR.
module chtest
contains
  function chararray2string(chararray) result(text)
    character(len=1), dimension(:) :: chararray    ! input
    character(len=size(chararray, 1)) :: text      ! output
    do i = 1,size(chararray,1)
      text(i:i) = chararray (i)
    end do
  end function chararray2string
end module chtest
program TestStringTools
  use chtest
  character(len=52)               :: txt
  character(len=1), dimension(52) :: chararr = &
        (/(char(i+64),char(i+96), i = 1,26)/)
  txt = chararray2string(chararr)
  if (txt .ne. "AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz") &
        call abort ()
end program TestStringTools