[Bug fortran/37420] New: [4.4 Regression] -Wunused-variable broken

[Bug fortran/37420] New: [4.4 Regression] -Wunused-variable broken

[janus at gcc dot gnu dot org]

Consider the following Fortran code:

subroutine s(x)
  real :: x
  integer :: i
end subroutine

Compiling this with "gfortran-4.3 -Wunused-variable" triggered two warnings:

Warning: Unused variable 'i' declared at (1)
Warning: Unused dummy argument 'x' at (1)

With recent trunk builds the first one is missing, and only the missing dummy
argument is detected. This seems to be a Fortran-specific problem, since unused
variables in C code are reported as expected.
Observed on x86_64-unknown-linux-gnu with rev. 140091.


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           Summary: [4.4 Regression] -Wunused-variable broken
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: janus at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37420

[Bug fortran/37420] [4.4 Regression] -Wunused-variable broken

[dfranke at gcc dot gnu dot org]

------- Comment #1 from dfranke at gcc dot gnu dot org  2008-09-08 09:26 -------
There used to be a message in fortran-format, not a middle end message.
See PR24784.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37420

[Bug fortran/37420] [4.4 Regression] -Wunused-variable broken

[tkoenig at gcc dot gnu dot org]

------- Comment #2 from tkoenig at gcc dot gnu dot org  2008-09-08 18:22 -------
Confirmed.


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tkoenig at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tkoenig at gcc dot gnu dot
                   |                            |org
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2008-09-08 18:22:54
               date|                            |
   Target Milestone|---                         |4.4.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37420

[Bug fortran/37420] [4.4 Regression] -Wunused-variable broken

[burnus at gcc dot gnu dot org]

------- Comment #3 from burnus at gcc dot gnu dot org  2008-09-08 20:16 -------
I saw it around 2008-02-28-r132751 / 2008-02-29-r132761, however, as the SVN
looks innocent, one should not rely one the exact date. Before that date, with
"-O  -Wunused-variable" one could get a message, afterwards it stopped.

Maybe one should do a proper regression search.


-- 

burnus at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |burnus at gcc dot gnu dot
                   |                            |org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37420

[Bug fortran/37420] [4.4 Regression] -Wunused-variable broken

[jakub at gcc dot gnu dot org]

-- 

jakub at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37420

[Bug fortran/37420] [4.4 Regression] -Wunused-variable broken

[burnus at gcc dot gnu dot org]

------- Comment #4 from burnus at gcc dot gnu dot org  2008-09-09 12:15 -------
That algorithm looks bogus:

generate_local_decl (gfc_symbol * sym)
{
  if (sym->attr.flavor == FL_VARIABLE)
    {
      /* Check for dependencies in the array specification and string
        length, adding the necessary declarations to the function.  We
        mark the symbol now, as well as in traverse_ns, to prevent
        getting stuck in a circular dependency.  */
      sym->mark = 1;
      [...]
      else if (warn_unused_variable
               && !(sym->attr.in_common || sym->attr.use_assoc || sym->mark))

It might be that sym->mark is somewhere reset, but I don't see where; if it is
not reset then it is clear that the message is not printed.


I think it got broken by Rev. 132756:
       else if (warn_unused_variable
-              && !(sym->attr.in_common || sym->attr.use_assoc))
+              && !(sym->attr.in_common || sym->attr.use_assoc || sym->mark))


+2008-02-28  Daniel Franke  <franke.daniel@gmail.com>
+
+       PR fortran/31463
+       PR fortran/33950
+       PR fortran/34296

See also:
http://gcc.gnu.org/viewcvs?view=rev&revision=132756


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37420

[Bug fortran/37420] [4.4 Regression] -Wunused-variable broken

[dfranke at gcc dot gnu dot org]

------- Comment #5 from dfranke at gcc dot gnu dot org  2008-09-09 13:23 -------
> I think it got broken by Rev. 132756

Confirmed :(

Further down in trans-decl.c (introduced in the same revision):
3547:     /* Prevents "Unused variable" warning for RESULT variables.  */
3548:     sym->mark = sym->result->mark = 1;


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37420

[Bug fortran/37420] [4.4 Regression] -Wunused-variable broken

[burnus at gcc dot gnu dot org]

------- Comment #6 from burnus at gcc dot gnu dot org  2008-09-09 17:24 -------
Mine


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burnus at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |burnus at gcc dot gnu dot
                   |dot org                     |org
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2008-09-08 18:22:54         |2008-09-09 17:24:35
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37420

[Bug fortran/37420] [4.4 Regression] -Wunused-variable broken

[burnus at gcc dot gnu dot org]

------- Comment #7 from burnus at gcc dot gnu dot org  2008-09-10 11:54 -------
FIXED on the trunk (4.4.0)


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burnus at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37420

[Bug fortran/37420] [4.4 Regression] -Wunused-variable broken

[burnus at gcc dot gnu dot org]

------- Comment #8 from burnus at gcc dot gnu dot org  2008-09-10 11:55 -------
Subject: Bug 37420

Author: burnus
Date: Wed Sep 10 11:54:08 2008
New Revision: 140229

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=140229
Log:
2008-09-10  Tobias Burnus  <burnus@net-b.de>

        PR fortran/37420
        * trans-decl.c (get_proc_pointer_decl): Fix -Wunused-variable.

2008-09-10  Tobias Burnus  <burnus@net-b.de>

        PR fortran/37420
        * gfortran.dg/warn_unused_var.f90: New test.
        * gfortran.dg/warn_unused_var.f90: Add cleanup-modules.


Added:
    trunk/gcc/testsuite/gfortran.dg/warn_unused_var.f90
Modified:
    trunk/gcc/fortran/ChangeLog
    trunk/gcc/fortran/trans-decl.c
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/gfortran.dg/implicit_12.f90


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37420