[Bug fortran/52370] Spurious "may be used uninitialized" warning for check of optional argument

[Bug fortran/52370] Spurious "may be used uninitialized" warning for check of optional argument

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52370

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |diagnostic

--- Comment #2 from Tobias Burnus <burnus at gcc dot gnu.org> 2012-02-24 14:05:32 UTC ---
(In reply to comment #1)
> The warning is not printed for the last line where one dereferences a pointer
> (line 8), but for the "b.0 =" assignment.

I have the impression that problem is rather line 8 - i.e. related to the
pointer dereference. The warning vanishes if one comments/moves the "a =" line
- unless "b" is volatile - or if one makes "a" a VALUE or a function result. I
assume that's because it is then simpler to merge the implicitly and the
explicitly created "if (present(b))" lines.

[Bug fortran/52370] Spurious "may be used uninitialized" warning for check of optional argument

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52370

--- Comment #3 from Tobias Burnus <burnus at gcc dot gnu.org> 2012-05-15 13:15:49 UTC ---
See also http://gcc.gnu.org/ml/fortran/2012-05/msg00066.html

[Bug fortran/52370] [4.7/4.8/4.9 Regression] Spurious "may be used uninitialized" warning for check of optional argument

[dominiq at lps dot ens.fr]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52370

Dominique d'Humieres <dominiq at lps dot ens.fr> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-12-14
            Summary|Spurious "may be used       |[4.7/4.8/4.9 Regression]
                   |uninitialized" warning for  |Spurious "may be used
                   |check of optional argument  |uninitialized" warning for
                   |                            |check of optional argument
     Ever confirmed|0                           |1

--- Comment #4 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
I get the warning with 4.6.4 up to trunk (r205944), but not for 4.5.4. The
change occurred between revisions r182107 (2011-12-08) and r182980
(2012-01-07).

> That the warning only shows up in 4.7 but not in 4.7.2 is probably due 
> to the patch for PR 50923. (The warning is only printed for -O1 but not 
> for -O2 or -O0.)

The fix for PR 50923 is in the above range.

[Bug fortran/52370] [4.7/4.8/4.9 Regression] Spurious "may be used uninitialized" warning for check of optional argument

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52370

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.7.4

[Bug fortran/52370] [4.7/4.8/4.9 Regression] Spurious "may be used uninitialized" warning for check of optional argument

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52370

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Until we get more fine-grained warning control, I believe the only way to fix
this is make sure TREE_NO_WARNING is set on Fortran optional argument related
variables (not just the data pointer (b.0 here), but I think the others too
(bounds, size, ...).

[Bug fortran/52370] [4.7/4.8/4.9 Regression] Spurious "may be used uninitialized" warning for check of optional argument

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52370

--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 32107
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=32107&action=edit
gcc49-pr52370.patch

So, how about this patch?

[Bug fortran/52370] [4.7/4.8 Regression] Spurious "may be used uninitialized" warning for check of optional argument

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52370

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |jakub at gcc dot gnu.org
            Summary|[4.7/4.8/4.9 Regression]    |[4.7/4.8 Regression]
                   |Spurious "may be used       |Spurious "may be used
                   |uninitialized" warning for  |uninitialized" warning for
                   |check of optional argument  |check of optional argument

--- Comment #9 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Fixed on the trunk so far.

[Bug fortran/52370] [4.7/4.8 Regression] Spurious "may be used uninitialized" warning for check of optional argument

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52370

--- Comment #10 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Author: jakub
Date: Thu Mar  6 08:00:49 2014
New Revision: 208367

URL: http://gcc.gnu.org/viewcvs?rev=208367&root=gcc&view=rev
Log:
    Backport from mainline
    2014-02-11  Jakub Jelinek  <jakub@redhat.com>

    PR fortran/52370
    * trans-decl.c (gfc_build_dummy_array_decl): Set TREE_NO_WARNING
    on decl if sym->attr.optional.

    * gfortran.dg/pr52370.f90: New test.

Added:
    branches/gcc-4_8-branch/gcc/testsuite/gfortran.dg/pr52370.f90
Modified:
    branches/gcc-4_8-branch/gcc/fortran/ChangeLog
    branches/gcc-4_8-branch/gcc/fortran/trans-decl.c
    branches/gcc-4_8-branch/gcc/testsuite/ChangeLog

[Bug fortran/52370] [4.7 Regression] Spurious "may be used uninitialized" warning for check of optional argument

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52370

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
      Known to work|                            |4.8.3
         Resolution|---                         |FIXED
   Target Milestone|4.7.4                       |4.8.3
      Known to fail|                            |4.7.4

--- Comment #12 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed for 4.8.3.