[Bug fortran/50619] New: Surprising interaction between -finit-real=NAN and the associate construct

[Bug fortran/50619] New: Surprising interaction between -finit-real=NAN and the associate construct

[fkrogh#gcc at mathalacarte dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50619

             Bug #: 50619
           Summary: Surprising interaction between  -finit-real=NAN and
                    the associate construct
    Classification: Unclassified
           Product: gcc
           Version: 4.6.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: fkrogh#gcc@mathalacarte.com


With a real variable defined in a derived type and referenced in an associate
construct the value is redefined as a NaN when using the compilier flag
-finit-real=NAN.  The following two short routines illustrate the problem.


program testa1
  use testa2
  type(test_ty) :: e
  call test(e)
  stop
end program testa1

module testa2
type, public ::  test_ty ! Values that can be set or looked at by the user.
  real :: rmult = 1.0e0 ! Multiplies reals using default format.
end type test_ty

contains
  subroutine test(e)
    type(test_ty) :: e
    print '("No associate: e%rmult =", es15.6)', e%rmult
    associate (rmult=>e%rmult)
      print '("Associate: %rmult =", es15.6)', e%rmult
    end associate
  end subroutine test
end module testa2

compile with

gfortran  -ggdb -finit-real=NAN  -o testa1 testa2.f90 testa1.f90

and get

No associate: e%rmult =   1.000000E+00
Associate: %rmult =            NaN

[Bug fortran/50619] Surprising interaction between -finit-real=NAN and the associate construct

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50619

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |wrong-code
                 CC|                            |burnus at gcc dot gnu.org,
                   |                            |janus at gcc dot gnu.org

--- Comment #1 from Tobias Burnus <burnus at gcc dot gnu.org> 2011-10-05 08:25:21 UTC ---
This seems to be an ordering problem - from -fdump-tree-original:

test (struct test_ty & restrict e)
{
  {
    real(kind=4) * rmult;
    {
       I/O before ASSOCIATE ...
    }
    rmult = &e->rmult;
    *rmult =  Nan;
    {
       I/O in ASSOCIATE ...
    }

The "*rmult = NaN" line should be before "rmult = &e->rmult". I don't quite see
whether that's a problem of inserting the NAN or of the ASSOCIATE assignment.

[Bug fortran/50619] Surprising interaction between -finit-real=NAN and the associate construct

[bdavis at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50619

Bud Davis <bdavis at gcc dot gnu.org> changed:

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

--- Comment #2 from Bud Davis <bdavis at gcc dot gnu.org> 2011-11-30 21:30:30 UTC ---
Reduced a bit more, for those that like it simple....


  real :: rmult = 1.0e0 
  real :: e
  print*,'No Associate',rmult
  associate (rmult=>e)
  print*,'   Associate',e
  end associate
  end

[Bug fortran/50619] Surprising interaction between -finit-real=NAN and the associate construct

[gcc.10.dimsea at spamgourmet dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50619

Stephan Weller <gcc.10.dimsea at spamgourmet dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |gcc.10.dimsea at
                   |                            |spamgourmet dot org

--- Comment #3 from Stephan Weller <gcc.10.dimsea at spamgourmet dot org> 2012-06-04 09:44:06 UTC ---
I can confirm this behaviour in gcc-4.6.2, 4.7.0, and 4.8.0 (20120530)
development version. Since this renders -finit-real=NAN unusable for me, I
would consider this a serious bug.

[Bug fortran/50619] Surprising interaction between -finit-real=NAN and the associate construct

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50619

--- Comment #4 from Tobias Burnus <burnus at gcc dot gnu.org> 2012-06-04 12:32:20 UTC ---
(In reply to comment #3)
> I can confirm this behaviour in gcc-4.6.2, 4.7.0, and 4.8.0 (20120530)
> development version. Since this renders -finit-real=NAN unusable for me, I
> would consider this a serious bug.

I concur that it is a bad wrong-code bug, but it only occurs with the
nondefault flag -finit-real=* - and it is not a regression -, thus, I think it
is bad but not serious.

Unfortunately, the number of active gfortran developers is not that high, which
in turn means that bugs aren't fixed and features not implemented as quickly as
everyone would like. (Note: 99% of the Fortran-frontend development is done in
the spare time!) Thus, if you are interested in contributing to gfortran - or
if you know someone who is ...

 * * *

Regarding this bugreport: I think the following patch should fix it. I will
test it and submit it.

--- a/gcc/fortran/resolve.c
+++ b/gcc/fortran/resolve.c
@@ -10105,3 +10105,4 @@ build_default_init_expr (gfc_symbol *sym)
       || sym->attr.cray_pointee
-      || sym->attr.cray_pointer)
+      || sym->attr.cray_pointer
+      || sym->assoc)
     return NULL;

[Bug fortran/50619] Surprising interaction between -finit-real=NAN and the associate construct

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50619

--- Comment #5 from Tobias Burnus <burnus at gcc dot gnu.org> 2012-06-04 21:01:05 UTC ---
Author: burnus
Date: Mon Jun  4 21:01:02 2012
New Revision: 188208

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=188208
Log:
2012-06-04  Tobias Burnus  <burnus@net-b.de>

        PR fortran/50619
        * resolve.c (build_default_init_expr): Don't initialize
        ASSOCIATE names.

2012-06-04  Tobias Burnus  <burnus@net-b.de>

        PR fortran/50619
        * gfortran.dg/init_flag_10.f90: New.


Added:
    trunk/gcc/testsuite/gfortran.dg/init_flag_10.f90
Modified:
    trunk/gcc/fortran/ChangeLog
    trunk/gcc/fortran/resolve.c
    trunk/gcc/testsuite/ChangeLog

[Bug fortran/50619] Surprising interaction between -finit-real=NAN and the associate construct

[gcc.10.dimsea at spamgourmet dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50619

--- Comment #6 from Stephan Weller <gcc.10.dimsea at spamgourmet dot org> 2012-06-05 11:56:59 UTC ---
Great, this fixes the problem for me. In current svn revision, -finit-real=NAN
works as expected. Thanks for keeping up the good work!

[Bug fortran/50619] Surprising interaction between -finit-real=NAN and the associate construct

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50619

--- Comment #7 from Tobias Burnus <burnus at gcc dot gnu.org> 2012-06-05 13:05:38 UTC ---
Author: burnus
Date: Tue Jun  5 13:05:31 2012
New Revision: 188237

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=188237
Log:
2012-06-05  Tobias Burnus  <burnus@net-b.de>

        PR fortran/50619
        * resolve.c (build_default_init_expr): Don't initialize
        ASSOCIATE names.

2012-06-05  Tobias Burnus  <burnus@net-b.de>

        PR fortran/50619
        * gfortran.dg/init_flag_10.f90: New.


Added:
    branches/gcc-4_6-branch/gcc/testsuite/gfortran.dg/init_flag_10.f90
Modified:
    branches/gcc-4_6-branch/gcc/fortran/ChangeLog
    branches/gcc-4_6-branch/gcc/fortran/resolve.c
    branches/gcc-4_6-branch/gcc/testsuite/ChangeLog

[Bug fortran/50619] Surprising interaction between -finit-real=NAN and the associate construct

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50619

--- Comment #8 from Tobias Burnus <burnus at gcc dot gnu.org> 2012-06-14 13:04:57 UTC ---
Author: burnus
Date: Thu Jun 14 13:04:43 2012
New Revision: 188617

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=188617
Log:
2012-06-14  Tobias Burnus  <burnus@net-b.de>

        Backport from mainline
        2012-06-04  Tobias Burnus  <burnus@net-b.de>

        PR fortran/50619
        * resolve.c (build_default_init_expr): Don't initialize
        ASSOCIATE names.

2012-06-14  Tobias Burnus  <burnus@net-b.de>

        Backport from mainline
        2012-06-04  Tobias Burnus  <burnus@net-b.de>

        PR fortran/50619
        * gfortran.dg/init_flag_10.f90: New.


Added:
    branches/gcc-4_7-branch/gcc/testsuite/gfortran.dg/init_flag_10.f90
Modified:
    branches/gcc-4_7-branch/gcc/fortran/ChangeLog
    branches/gcc-4_7-branch/gcc/fortran/resolve.c
    branches/gcc-4_7-branch/gcc/testsuite/ChangeLog

[Bug fortran/50619] Surprising interaction between -finit-real=NAN and the associate construct

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50619

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

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

--- Comment #9 from Tobias Burnus <burnus at gcc dot gnu.org> 2012-06-14 13:06:54 UTC ---
FIXED on all affected branches: On the (4.8) trunk and the 4.6 and the 4.7
branches. (Note that the patch came too late for the 4.7.1 release.)