[Patch, fortran] PR83344 - Use of uninitialized memory with ASSOCIATE and strings

[Paul Richard Thomas]

Hi Janne and Thomas,

1) The patch is attached now - sorry!

2) The commented out part of associate_22.f90 is not yet fixed. I am
working on it.

3) I will take a look at PR83975 tomorrow night.

Paul


On 18 February 2018 at 16:08, Janne Blomqvist <blomqvist.janne@gmail.com> wrote:
> On Sun, Feb 18, 2018 at 5:48 PM, Paul Richard Thomas
> <paul.richard.thomas@gmail.com> wrote:
>> Bootstraps and regtests on FC27/x86_64 - OK for trunk?
>
> Hi,
>
> thanks for looking into this!
>
> 1. The patch itself is missing...
>
> 2. Could you uncomment the commented out part of associate_22.f90 and
> check that the tree-original dump is sensible.
>
> 3. Same for the testcases posted to PR 83975. I suspect (err, hope)
> that this patch would fix those as well. If so, please add that PR to
> the ChangeLog entries as well.
>
>>
>> Paul
>>
>> 2018-02-18  Paul Thomas  <pault@gcc.gnu.org>
>>
>>     PR fortran/83344
>>     * resolve.c (resolve_assoc_var): Character associate names that
>>     have no length expression that have variable targets and are
>>     not deferred length have assumed length.
>>     * trans-decl.c (gfc_get_symbol_decl): Set 'length' to
>>     gfc_index_zero_node for character associate names, whose string
>>     length is a PARM_DECL.
>>
>> 2018-02-18  Paul Thomas  <pault@gcc.gnu.org>
>>
>>     PR fortran/83344
>>     * gfortran.dg/associate_36.f90: New test.
>
>
>
> --
> Janne Blomqvist



-- 
"If you can't explain it simply, you don't understand it well enough"
- Albert Einstein
-------------- next part --------------
Index: gcc/fortran/resolve.c
===================================================================
*** gcc/fortran/resolve.c	(revision 257787)
--- gcc/fortran/resolve.c	(working copy)
*************** resolve_assoc_var (gfc_symbol* sym, bool
*** 8656,8662 ****
  	    sym->ts.u.cl->length =
  	      gfc_get_int_expr (gfc_charlen_int_kind, NULL,
  				target->value.character.length);
! 	  else
  	    gfc_error ("Not Implemented: Associate target with type character"
  		       " and non-constant length at %L", &target->where);
  	}
--- 8656,8663 ----
  	    sym->ts.u.cl->length =
  	      gfc_get_int_expr (gfc_charlen_int_kind, NULL,
  				target->value.character.length);
! 	  /* If the target is a variable, it is an assumed length dummy.  */
! 	  else if (target->expr_type != EXPR_VARIABLE)
  	    gfc_error ("Not Implemented: Associate target with type character"
  		       " and non-constant length at %L", &target->where);
  	}
Index: gcc/fortran/trans-decl.c
===================================================================
*** gcc/fortran/trans-decl.c	(revision 257787)
--- gcc/fortran/trans-decl.c	(working copy)
*************** gfc_get_symbol_decl (gfc_symbol * sym)
*** 1712,1718 ****
  
        if (sym->attr.associate_var
  	  && sym->ts.u.cl->backend_decl
! 	  && VAR_P (sym->ts.u.cl->backend_decl))
  	length = gfc_index_zero_node;
        else
  	length = gfc_create_string_length (sym);
--- 1712,1719 ----
  
        if (sym->attr.associate_var
  	  && sym->ts.u.cl->backend_decl
! 	  && (VAR_P (sym->ts.u.cl->backend_decl)
! 	      || TREE_CODE (sym->ts.u.cl->backend_decl) == PARM_DECL))
  	length = gfc_index_zero_node;
        else
  	length = gfc_create_string_length (sym);
Index: gcc/testsuite/gfortran.dg/associate_36.f90
===================================================================
*** gcc/testsuite/gfortran.dg/associate_36.f90	(nonexistent)
--- gcc/testsuite/gfortran.dg/associate_36.f90	(working copy)
***************
*** 0 ****
--- 1,28 ----
+ ! { dg-do run }
+ !
+ ! Test the fix for PR83344.
+ !
+ ! Contributed by <Janne Blomqvist  <jb@gcc.gnu.org>
+ !
+ program foo
+    implicit none
+    character(len=1) a
+    character(len=2) b
+    character(len=3) c
+    a = 'a'
+    call bah(a, len (a))
+    b = 'bb'
+    call bah(b, len (b))
+    c = 'ccc'
+    call bah(c, len (c))
+    contains
+       subroutine bah(x, clen)
+          implicit none
+          integer :: clen
+          character(len=*), intent(in) :: x
+          associate(y => x)
+             if (len(y) .ne. clen) stop 1
+             if (y .ne. x) stop 2
+          end associate
+       end subroutine bah
+ end program foo