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From: "nicola at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug objc/45895] New: -Wunused-but-set-variable complains for almost all Objective-C objects
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D45895

           Summary: -Wunused-but-set-variable complains for almost all
                    Objective-C objects
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: objc
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: nicola@gcc.gnu.org


It seems that -Wunused-but-set-variable complains any time an Objective-C
object variable is set, and only used to invoke methods.  This is incorrect;
when a variable is used to invoke a method, it is used. :-)

(hence, compiling any Objective-C with -Wall generates lots of wrong warnin=
gs).

Here is a testcase --

#include <objc/objc.h>
#include <objc/Object.h>

int main (void)
{
  id o =3D nil;

  [o hash];

  return 0;
}

Here are what happens when you compile:

[nicola@lampone ~]$ gcc -Wall bug.m -lobjc -c
bug.m: In function =E2=80=98main=E2=80=99:
bug.m:6:6: warning: variable =E2=80=98o=E2=80=99 set but not used [-Wunused=
-but-set-variable]
[nicola@lampone ~]$=20

The warning is obviously incorrect because 'o' *is* used.  This is on a
i686-pc-linux-gnu.

Thanks