[Bug fortran/50570] New: Incorrect error for assignment to intent(in) pointer

[Bug fortran/50570] New: Incorrect error for assignment to intent(in) pointer

[longb at cray dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50570

             Bug #: 50570
           Summary: Incorrect error for assignment to intent(in) pointer
    Classification: Unclassified
           Product: gcc
           Version: 4.6.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: longb@cray.com


> cat test.f90
program bots_sparselu_pointer_intent_in
! derived from Fortran trans of BOTS sparselu

  implicit none
  integer, pointer :: array(:)

  allocate(array(4))
  array = 0
  call sub(array)
  write (*,*) SUM(array)

contains

  subroutine sub(dummy)
     integer, pointer, intent(in) :: dummy(:)
     dummy(1) = 1 ! note that gfortran 4.6.1 accepts "dummy = 1"
  end subroutine sub

end program bots_sparselu_pointer_intent_in

> gfortran -c test.f90
test.f90:16.5:

     dummy(1) = 1 ! note that gfortran 4.6.1 accepts "dummy = 1"
     1
Error: Dummy argument 'dummy' with INTENT(IN) in variable definition context
(assignment) at (1)



This should compile.  In the case of a POINTER dummy, the INTENT(IN) applies to
the pointer association status, not definition of the target.

Appears to be a regression, as 4.5.3 was OK.

[Bug fortran/50570] [4.6/4.7 Regression] Incorrect error for assignment to intent(in) pointer

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50570

Tobias Burnus <burnus at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
           Keywords|                            |rejects-valid
   Last reconfirmed|                            |2011-09-30
                 CC|                            |burnus at gcc dot gnu.org,
                   |                            |domob at gcc dot gnu.org
     Ever Confirmed|0                           |1
            Summary|Incorrect error for         |[4.6/4.7 Regression]
                   |assignment to intent(in)    |Incorrect error for
                   |pointer                     |assignment to intent(in)
                   |                            |pointer
   Target Milestone|---                         |4.6.2

--- Comment #1 from Tobias Burnus <burnus at gcc dot gnu.org> 2011-09-30 06:25:40 UTC ---
Working: 2010-09-09-r164046
Failing: 2010-09-28-r164677

Possible culprit:

r164550 | domob | 2010-09-23 10:37:54 +0200
http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=164550

2010-09-23  Daniel Kraft  <d@domob.eu>

        PR fortran/38936
        PR fortran/44044
        PR fortran/45474

        * expr.c (gfc_check_assign): Remove INTENT(IN) check here.
        (gfc_check_pointer_assign): Ditto (and other checks removed).
        (gfc_check_vardef_context): New method.


In expr.c's gfc_check_vardef_context, the problem is that for

4547          sym = e->value.function.esym ? e->value.function.esym :
e->symtree->n.sym;
4550      attr = gfc_expr_attr (e);

(gdb) p sym->attr.pointer
$3 = 1
(gdb) p attr.pointer
$1 = 0

Here, gfc_expr_attr() takes the array reference into account such that
"dummy(1)" is not pointer ...

[Bug fortran/50570] [4.6/4.7 Regression] Incorrect error for assignment to intent(in) pointer

[msteghofer at cistib dot upf.edu]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50570

--- Comment #2 from msteghofer at cistib dot upf.edu 2011-10-03 10:15:09 UTC ---
Created attachment 25403
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25403
Code to reproduce the behaviour

Subroutine POINTER_INTENT_IN_BUG_FAILING contains the failing code.
Subroutien POINTER_INTENT_IN_BUG_WORKING contains an alternative code that does
the same thing, but compiles (to show that the behaviour of gfortran doesn't
make sense as protection, either).

[Bug fortran/50570] [4.6/4.7 Regression] Incorrect error for assignment to intent(in) pointer

[msteghofer at cistib dot upf.edu]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50570

msteghofer at cistib dot upf.edu changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |msteghofer at cistib dot
                   |                            |upf.edu

--- Comment #3 from msteghofer at cistib dot upf.edu 2011-10-03 10:16:51 UTC ---
I've got a very similar problem (attachment above). The difference is that I'm
not using assignments to write something inside the intent(in) pointer, but I'm
calling the function move_alloc with something inside the intent(in) pointer as
actual argument.

Please see the attached code above for details. The error message (gfortran
4.6.1) is the following:

bug.f90:22.20:
    CALL MOVE_ALLOC(POINTER_INTENT_IN_VARIABLE%VALUE, LOCAL_VALUE)
                    1
Error: 'from' argument of 'move_alloc' intrinsic at (1) cannot be INTENT(IN)

As the error message is different from the one posted before, I'm not sure, if
this is the same bug, please check. If it's not, I will post a new report - I
just want to avoid duplicates.

Also I'm not sure about what the Fortran standard says, but I don't think that
giving this error is a desired behaviour because:
* According to documentation of other compilers the code should compile:
http://publib.boulder.ibm.com/infocenter/comphelp/v111v131/topic/com.ibm.xlf131.aix.doc/language_ref/intent.html
(section "Rules", subsection about pointer dummy arguments)
* If INTENT(IN) really tries to protect the *members* (not the pointer itself)
of the derived type from being changed (that's the only scenario in which this
behaviour would make sense), then it's not doing its job: Copying the pointer
to a local variable I'm able to change them, as the example
"POINTER_INTENT_IN_BUG_WORKING" in the attached code shows.

[Bug fortran/50570] [4.6/4.7 Regression] Incorrect error for assignment to intent(in) pointer

[janus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50570

janus at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |janus at gcc dot gnu.org

--- Comment #4 from janus at gcc dot gnu.org 2011-10-09 20:31:34 UTC ---
How about this?


Index: gcc/fortran/expr.c
===================================================================
--- gcc/fortran/expr.c  (revision 179723)
+++ gcc/fortran/expr.c  (working copy)
@@ -4635,7 +4635,7 @@ gfc_check_vardef_context (gfc_expr* e, bool pointe
                       sym->name, context, &e->where);
          return FAILURE;
        }
-      if (!pointer && !is_pointer)
+      if (!pointer && !sym->attr.pointer)
        {
          if (context)
            gfc_error ("Dummy argument '%s' with INTENT(IN) in variable"

[Bug fortran/50570] [4.6/4.7 Regression] Incorrect error for assignment to intent(in) pointer

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50570

--- Comment #5 from Tobias Burnus <burnus at gcc dot gnu.org> 2011-10-09 20:39:47 UTC ---
(In reply to comment #4)
> How about this?

Looks as if should work (for comment 0).

(I think the test case in comment 2 is a completely different issue, which
needs a separate fix.)

[Bug fortran/50570] [4.6/4.7 Regression] Incorrect error for assignment to intent(in) pointer

[janus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50570

janus at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
         AssignedTo|unassigned at gcc dot       |janus at gcc dot gnu.org
                   |gnu.org                     |

--- Comment #6 from janus at gcc dot gnu.org 2011-10-09 21:15:20 UTC ---
(In reply to comment #5)
> > How about this?
> 
> Looks as if should work (for comment 0).

It does. I'll check for regressions.



> (I think the test case in comment 2 is a completely different issue, which
> needs a separate fix.)

Agreed. Separate, though related. I think the error message is a bug indeed. A
way to fix it might be:

Index: gcc/fortran/check.c
===================================================================
--- gcc/fortran/check.c (revision 179722)
+++ gcc/fortran/check.c (working copy)
@@ -458,7 +458,8 @@ variable_check (gfc_expr *e, int n, bool allow_pro
   if (e->expr_type == EXPR_VARIABLE
       && e->symtree->n.sym->attr.intent == INTENT_IN
       && (gfc_current_intrinsic_arg[n]->intent == INTENT_OUT
-         || gfc_current_intrinsic_arg[n]->intent == INTENT_INOUT))
+         || gfc_current_intrinsic_arg[n]->intent == INTENT_INOUT)
+      && !(e->symtree->n.sym->attr.pointer && e->ref))
     {
       gfc_error ("'%s' argument of '%s' intrinsic at %L cannot be INTENT(IN)",
                 gfc_current_intrinsic_arg[n]->name, gfc_current_intrinsic,

[Bug fortran/50570] [4.6/4.7 Regression] Incorrect error for assignment to intent(in) pointer

[janus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50570

--- Comment #7 from janus at gcc dot gnu.org 2011-10-09 23:08:04 UTC ---
(In reply to comment #6)
> (In reply to comment #5)
> > > How about this?
> > 
> > Looks as if should work (for comment 0).
> 
> It does. I'll check for regressions.

Unfortunately it fails on:

FAIL: gfortran.dg/pointer_intent_1.f90  -O0  (test for excess errors)
FAIL: gfortran.dg/pointer_intent_3.f90  -O  (test for excess errors)
FAIL: gfortran.dg/pointer_intent_4.f90  -O0  (test for excess errors)

[Bug fortran/50570] [4.6/4.7 Regression] Incorrect error for assignment to intent(in) pointer

[janus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50570

--- Comment #8 from janus at gcc dot gnu.org 2011-10-09 23:26:45 UTC ---
(In reply to comment #7)
> > > > How about this?
> > > 
> > > Looks as if should work (for comment 0).
> > 
> > It does. I'll check for regressions.
> 
> Unfortunately it fails on:
> 
> FAIL: gfortran.dg/pointer_intent_1.f90  -O0  (test for excess errors)
> FAIL: gfortran.dg/pointer_intent_3.f90  -O  (test for excess errors)
> FAIL: gfortran.dg/pointer_intent_4.f90  -O0  (test for excess errors)

The following variant avoids these regressions:

Index: gcc/fortran/expr.c
===================================================================
--- gcc/fortran/expr.c  (revision 179729)
+++ gcc/fortran/expr.c  (working copy)
@@ -4635,7 +4635,7 @@ gfc_check_vardef_context (gfc_expr* e, bool pointe
                       sym->name, context, &e->where);
          return FAILURE;
        }
-      if (!pointer && !is_pointer)
+      if (!pointer && !is_pointer && !sym->attr.pointer)
        {
          if (context)
            gfc_error ("Dummy argument '%s' with INTENT(IN) in variable"

[Bug fortran/50570] [4.6/4.7 Regression] Incorrect error for assignment to intent(in) pointer

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50570

--- Comment #9 from Tobias Burnus <burnus at gcc dot gnu.org> 2011-10-10 06:58:27 UTC ---
(In reply to comment #6)
> Agreed. Separate, though related. I think the error message is a bug indeed. A
> way to fix it might be:

That won't work for:

 type(t), intent(in) :: dt
 call move_alloc(dt%allocatable, ...)

That's invalid as dt%allocatable is intent(in); it would be valid for, e.g.,
  call move_alloc(dt%dt2%ptr%allocatable, ...)
One really needs to walk the expression.

[Bug fortran/50570] [4.6/4.7 Regression] Incorrect error for assignment to intent(in) pointer

[msteghofer at cistib dot upf.edu]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50570

--- Comment #10 from Martin Steghöfer <msteghofer at cistib dot upf.edu> 2011-10-10 09:43:30 UTC ---
Do you want me to commit a new bug report for my issue then or are you going to
fix both issues using this one (although they need separate fixes)?

[Bug fortran/50570] [4.6/4.7 Regression] Incorrect error for assignment to intent(in) pointer

[janus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50570

--- Comment #11 from janus at gcc dot gnu.org 2011-10-10 11:45:30 UTC ---
Martin,

> Do you want me to commit a new bug report for my issue

yes, I think that would be a good idea.

Thanks,
Janus

[Bug fortran/50570] [4.6/4.7 Regression] Incorrect error for assignment to intent(in) pointer

[msteghofer at cistib dot upf.edu]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50570

--- Comment #12 from Martin Steghöfer <msteghofer at cistib dot upf.edu> 2011-10-10 13:24:24 UTC ---
OK, created bug 50684.

[Bug fortran/50570] [4.6/4.7 Regression] Incorrect error for assignment to intent(in) pointer

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50570

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P4

[Bug fortran/50570] [4.6/4.7 Regression] Incorrect error for assignment to intent(in) pointer

[janus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50570

--- Comment #13 from janus at gcc dot gnu.org 2011-10-14 17:59:36 UTC ---
Author: janus
Date: Fri Oct 14 17:59:29 2011
New Revision: 180000

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=180000
Log:
2011-10-14  Janus Weil  <janus@gcc.gnu.org>

    PR fortran/50570
    * expr.c (gfc_check_vardef_context): Don't throw an error on
    non-pointer assignments involving an intent(in) pointer dummy.


2011-10-14  Janus Weil  <janus@gcc.gnu.org>

    PR fortran/50570
    * gfortran.dg/pointer_intent_5.f90: New.

Added:
    trunk/gcc/testsuite/gfortran.dg/pointer_intent_5.f90
Modified:
    trunk/gcc/fortran/ChangeLog
    trunk/gcc/fortran/expr.c
    trunk/gcc/testsuite/ChangeLog

[Bug fortran/50570] [4.6/4.7 Regression] Incorrect error for assignment to intent(in) pointer

[janus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50570

--- Comment #14 from janus at gcc dot gnu.org 2011-10-15 13:30:13 UTC ---
Author: janus
Date: Sat Oct 15 13:30:07 2011
New Revision: 180037

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=180037
Log:
2011-10-15  Janus Weil  <janus@gcc.gnu.org>

    PR fortran/50570
    * expr.c (gfc_check_vardef_context): Don't throw an error on
    non-pointer assignments involving an intent(in) pointer dummy.


2011-10-15  Janus Weil  <janus@gcc.gnu.org>

    PR fortran/50570
    * gfortran.dg/pointer_intent_5.f90: New.

Added:
    branches/gcc-4_6-branch/gcc/testsuite/gfortran.dg/pointer_intent_5.f90
Modified:
    branches/gcc-4_6-branch/gcc/fortran/ChangeLog
    branches/gcc-4_6-branch/gcc/fortran/expr.c
    branches/gcc-4_6-branch/gcc/testsuite/ChangeLog

[Bug fortran/50570] [4.6/4.7 Regression] Incorrect error for assignment to intent(in) pointer

[janus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50570

janus at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED

--- Comment #15 from janus at gcc dot gnu.org 2011-10-15 13:31:51 UTC ---
Fixed on 4.6 and trunk. Closing.

Thanks for the report!