[Bug fortran/46581] New: [4.6 Regression] [OOP] segfault in SELECT TYPE with associate-name

[Bug fortran/46581] New: [4.6 Regression] [OOP] segfault in SELECT TYPE with associate-name

[janus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46581

           Summary: [4.6 Regression] [OOP] segfault in SELECT TYPE with
                    associate-name
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: janus@gcc.gnu.org


Reported by Salvatore at http://gcc.gnu.org/ml/fortran/2010-11/msg00290.html.

Reduced test case:


program bug23
  implicit none

  type :: t1
    integer, allocatable :: ja(:)
  end type

  class(t1), allocatable  :: a 

  allocate(a)

  select type (aa=>a)
  type is (t1)
    write(*,*) 'Allocation status: ',allocated(aa%ja)
  end select

end program bug23


This compiles, but fails at runtime with a segfault.

It was working at r166401 (and r166825?), but fails at r166914. Possibly a
regression of r166480.

Note: With 4.5 it fails at runtime with a 'double free' error, after correctly
printing "Allocation status:  F".

[Bug fortran/46581] [4.6 Regression] [OOP] segfault in SELECT TYPE with associate-name

[dominiq at lps dot ens.fr]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46581

--- Comment #1 from Dominique d'Humieres <dominiq at lps dot ens.fr> 2010-11-20 16:45:08 UTC ---
> This compiles, but fails at runtime with a segfault.

On x86_64-apple-darwin10 (for both r166533 and r16697) it gives the wrong
result:

 Allocation status:  T

[Bug fortran/46581] [4.6 Regression] [OOP] segfault in SELECT TYPE with associate-name

[janus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46581

--- Comment #2 from janus at gcc dot gnu.org 2010-11-20 17:04:17 UTC ---
(In reply to comment #0)
> It was working at r166401 (and r166825?), but fails at r166914. Possibly a
> regression of r166480.

I just checked: It's indeed due to my r166480.

[Bug fortran/46581] [4.6 Regression] [OOP] segfault in SELECT TYPE with associate-name

[janus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46581

janus at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |d at domob dot eu

--- Comment #3 from janus at gcc dot gnu.org 2010-11-21 16:32:23 UTC ---
(In reply to comment #2)
> I just checked: It's indeed due to my r166480.

Well, at least this commit is the direct cause of the regression, because it
changed the names of the temporaries. However, there is nothing wrong with that
patch, and I think it rather uncovered a latent bug of Daniel's patch for
SELECT TYPE with associate-name:

http://gcc.gnu.org/viewcvs?view=revision&revision=163572

Namely, it does not handle correctly nested ASSOCIATE statements, which is how
SELECT TYPE is implemented: There is an outer BLOCK namespace for the whole
SELECT TYPE statement, with the selector as associate-name. And then there are
inner BLOCK namespaces for each TYPE IS/CLASS IS case with a temporary as
associate-name.

Right now all the temporaries (and the selector) are initialized in the outer
ns, though they should be initialized in their respective inner ns. So it can
happen that by accident the temps get initialized before the selector, which
causes the error.

I have a draft patch which fixes this (regtesting now).

[Bug fortran/46581] [4.6 Regression] [OOP] segfault in SELECT TYPE with associate-name

[janus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46581

janus at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2010.11.21 18:15:45
         AssignedTo|unassigned at gcc dot       |janus at gcc dot gnu.org
                   |gnu.org                     |
     Ever Confirmed|0                           |1

[Bug fortran/46581] [4.6 Regression] [OOP] segfault in SELECT TYPE with associate-name

[janus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46581

--- Comment #4 from janus at gcc dot gnu.org 2010-11-25 22:05:06 UTC ---
Author: janus
Date: Thu Nov 25 22:04:59 2010
New Revision: 167154

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=167154
Log:
2010-11-25  Janus Weil  <janus@gcc.gnu.org>

    PR fortran/46581
    * trans.h (gfc_process_block_locals): Removed second argument.
    * trans-decl.c (trans_associate_var): Moved to trans-stmt.c.
    (gfc_trans_deferred_vars): Skip ASSOCIATE variables.
    (gfc_process_block_locals): Don't mark associate names to be
    initialized.
    * trans-stmt.c (trans_associate_var): Moved here from trans-decl.c.
    (gfc_trans_block_construct): Call 'trans_associate_var' from here
    to make sure SELECT TYPE with associate-name is treated correctly.

2010-11-25  Janus Weil  <janus@gcc.gnu.org>

    PR fortran/46581
    * gfortran.dg/select_type_19.f03: New.

Added:
    trunk/gcc/testsuite/gfortran.dg/select_type_19.f03
Modified:
    trunk/gcc/fortran/ChangeLog
    trunk/gcc/fortran/trans-decl.c
    trunk/gcc/fortran/trans-stmt.c
    trunk/gcc/fortran/trans.h
    trunk/gcc/testsuite/ChangeLog

[Bug fortran/46581] [4.6 Regression] [OOP] segfault in SELECT TYPE with associate-name

[janus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46581

janus at gcc dot gnu.org changed:

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

--- Comment #5 from janus at gcc dot gnu.org 2010-11-25 22:07:25 UTC ---
Fixed with r167154. Closing.