[Bug regression/34973] New: Wno-strict-aliasing is not working

[Bug regression/34973] New: Wno-strict-aliasing is not working

[Christoph_vW at reactos dot org]

mingw32-g++ -c base/shell/explorer/shell/fatfs.cpp -o
obj-i386/base/shell/explorer/shell/fatfs_explorer.o
-Iobj-i386/base/shell/explorer -Ibase/shell/explorer -DUNICODE -DWIN32 -D_ROS_
-D_WIN32_IE=0x0600 -D_WIN32_WINNT=0x0501 -DWINVER=0x0500 -D__WINDRES__
-Iobj-i386/base/shell/explorer -mpreferred-stack-boundary=2
-Fno-strict-aliasing -Wno-strict-aliasing -Wpointer-arith -I. -Iinclude
-Iobj-i386/include -Iinclude/psdk -Iobj-i386/include/psdk -Iinclude/dxsdk
-Iinclude/crt -Iinclude/crt/mingw32 -Iinclude/ddk -Iinclude/GL -Iinclude/ndk
-Iinclude/reactos -Iobj-i386/include/reactos -Iinclude/reactos/libs
-D__REACTOS__ -D_M_IX86 -D_X86_ -D__i386__ -Iobj-i386/base/shell/explorer
-DDBG=1 -D_SEH_ENABLE_TRACE -Iobj-i386/base/shell/explorer -DKDBG=1
-Iobj-i386/base/shell/explorer -Os -ftracer -momit-leaf-frame-pointer -I.
-Iinclude -Iobj-i386/include -Iinclude/psdk -Iobj-i386/include/psdk
-Iinclude/dxsdk -Iinclude/crt -Iinclude/crt/mingw32 -Iinclude/ddk -Iinclude/GL
-Iinclude/ndk -Iinclude/reactos -Iobj-i386/include/reactos
-Iinclude/reactos/libs -Wall -march=pentium -mpreferred-stack-boundary=2
-Fno-strict-aliasing -Wno-strict-aliasing -Wpointer-arith -Os -ftracer
-momit-leaf-frame-pointer -g -pipe -fshort-wchar -fno-optimize-sibling-calls
base/shell/explorer/shell/fatfs.cpp: In function 'DEntry*
link_dir_entries(dirent*, Kette*, int)':
base/shell/explorer/shell/fatfs.cpp:42: warning: dereferencing type-punned
pointer will break strict-aliasing rules
base/shell/explorer/shell/fatfs.cpp:44: warning: dereferencing type-punned
pointer will break strict-aliasing rules
base/shell/explorer/shell/fatfs.cpp: In member function 'virtual void
FATDirectory::read_directory(int)':
base/shell/explorer/shell/fatfs.cpp:66: warning: dereferencing type-punned
pointer will break strict-aliasing rules
base/shell/explorer/shell/fatfs.cpp: In member function 'bool
FATDirectory::read_dir()':
base/shell/explorer/shell/fatfs.cpp:390: warning: dereferencing type-punned
pointer will break strict-aliasing rules


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           Summary: Wno-strict-aliasing is not working
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: regression
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: Christoph_vW at reactos dot org
 GCC build triplet: 4.3.0 20080118
  GCC host triplet: linux x86_64
GCC target triplet: mingw32


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34973

[Bug regression/34973] Wno-strict-aliasing is not working

[ian at airs dot com]

------- Comment #1 from ian at airs dot com  2008-01-25 18:56 -------
This was probably fixed by this patch:

2008-01-22  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>

        PR 32102
        * doc/invoke.texi (-Wall): -Wall enables -Wstrict-overflow=1.
        * flags.h (warn_strict_aliasing): Remove.
        (warn_strict_overflow): Remove.
        * opts.c (warn_strict_aliasing): Remove.
        (warn_strict_overflow): Remove.
        * c-opts.c (c_common_handle_option): -Wall only sets
        -Wstrict-aliasing or -Wstrict-overflow if they are uninitialized.
        (c_common_post_options): Give default values to -Wstrict-aliasing
        and -Wstrict-overflow if they are uninitialized.
        * common.opt (Wstrict-aliasing): Specify Var and Init.
        (Wstrict-overflow): Likewise.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34973

[Bug regression/34973] Wno-strict-aliasing is not working

[pinskia at gcc dot gnu dot org]

------- Comment #2 from pinskia at gcc dot gnu dot org  2008-01-25 18:57 -------
I don't think this is a bug.
We have -Wno-strict-aliasing -Wall, so we turn back on the warning via the
-Wall option.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34973

[Bug regression/34973] Wno-strict-aliasing is not working

[rguenth at gcc dot gnu dot org]

------- Comment #3 from rguenth at gcc dot gnu dot org  2008-01-25 20:17 -------
Even -Wall should not warn for strict-aliasing issues as we also see
-Fno-strict-aliasing (wrong caps?);  also we have another -Wno-strict-aliasing
after -Wall.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34973

[Bug regression/34973] Wno-strict-aliasing is not working

[rguenth at gcc dot gnu dot org]

------- Comment #4 from rguenth at gcc dot gnu dot org  2008-01-25 20:19 -------
Btw, a testcase would be nice.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34973

[Bug middle-end/34973] Wno-strict-aliasing is not working

[pinskia at gcc dot gnu dot org]

------- Comment #5 from pinskia at gcc dot gnu dot org  2008-01-25 22:13 -------
This is not a regression ...


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pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|regression                  |middle-end


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34973

[Bug middle-end/34973] Wno-strict-aliasing is not working

[Christoph_vW at reactos dot org]

------- Comment #6 from Christoph_vW at reactos dot org  2008-01-26 09:51 -------
I changed -Fno-strict-aliasing to -fno-strict-aliasing and the warning
disappeared.

But shouldn't -Wno-strict-aliasing suppress the warning?


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34973

[Bug middle-end/34973] Wno-strict-aliasing is not working

[rguenth at gcc dot gnu dot org]

------- Comment #7 from rguenth at gcc dot gnu dot org  2008-01-26 11:37 -------
Well, yes.  Which is why a testcase would be nice (like preprocessed source of
one file you see this error).


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34973

[Bug middle-end/34973] Wno-strict-aliasing is not working

[pinskia at gcc dot gnu dot org]

------- Comment #8 from pinskia at gcc dot gnu dot org  2008-01-26 12:11 -------
(In reply to comment #6)
> But shouldn't -Wno-strict-aliasing suppress the warning?

Yes if you actually have -Wno-strict-aliasing after -Wall.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34973

[Bug middle-end/34973] Wno-strict-aliasing is not working

[manu at gcc dot gnu dot org]

------- Comment #10 from manu at gcc dot gnu dot org  2008-01-28 10:51 -------
(In reply to comment #8)
> (In reply to comment #6)
> > But shouldn't -Wno-strict-aliasing suppress the warning?
> 
> Yes if you actually have -Wno-strict-aliasing after -Wall.

Andrew, note that this is not longer true in 4.2.3 and 4.3. -Wall won't
override -Wno-strict-aliasing and it won't override -Wstrict-aliasing=2 (and
the same for -Wstrict-overflow variants)


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34973

[Bug middle-end/34973] Wno-strict-aliasing is not working

[manu at gcc dot gnu dot org]

------- Comment #9 from manu at gcc dot gnu dot org  2008-01-28 10:45 -------
Christoph, we need a testcase to be able to reproduce the bug, otherwise, we
cannot fix it.


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manu at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |manu at gcc dot gnu dot org
             Status|UNCONFIRMED                 |WAITING


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34973

[Bug middle-end/34973] Wno-strict-aliasing is not working

[awalton at gnome dot org]

------- Comment #11 from awalton at gnome dot org  2008-05-03 11:26 -------
I believe we're running into this in Nautilus and GCC 4.3.x (confirmed on both
Ubuntu Intrepid Ibex/8.10's 4.3 toolchain and Arch Linux's toolchain [unsure of
the micro-version]). If anyone wants to walk me through the steps of what you
need to diagnose this bug, that would be very helpful. We're currently
considering just working around it entirely with -fno-strict-aliasing, but if
this bug can be fixed upstream, all the better. Thanks.

GNOME Bug: http://bugzilla.gnome.org/show_bug.cgi?id=528081


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awalton at gnome dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |awalton at gnome dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34973

[Bug middle-end/34973] Wno-strict-aliasing is not working

[rguenth at gcc dot gnu dot org]

------- Comment #12 from rguenth at gcc dot gnu dot org  2008-05-03 12:18 -------
We are still waiting for a testcase, which would be the preprocessed source of
the file triggering the warning.  You'll get preprocessed source by appending
'-save-temps' to the gcc commandline and the preprocessed file will be named
$SOURCE.i.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34973

[Bug middle-end/34973] Wno-strict-aliasing is not working

[awalton at gnome dot org]

------- Comment #13 from awalton at gnome dot org  2008-05-03 13:59 -------
Created an attachment (id=15569)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=15569&action=view)
preprocessor output (gzipped)

With "gcc (Ubuntu 4.3.0-3ubuntu4) 4.3.1 20080430 (prerelease)". This is what I
got from gcc -E fm-directory-view.c (huge list of includes omitted for sanity).
I couldn't quite get -save-temps working (it only output a 75 byte file, which
can't possibly be right). 

Anyways, the specific problem is coming from a macro
"EEL_ASSIGN_MUST_OVERRIDE_SIGNAL", which is defined as "#define
EEL_ASSIGN_MUST_OVERRIDE_SIGNAL(class_pointer, prefix, signal)
* (void (**)(void)) & (class_pointer)->signal =
prefix##_unimplemented_##signal". Fails to build with "-Wall
-Wmissing-declarations -Wmissing-prototypes -Wnested-externs -Wpointer-arith
-Wcast-align -Werror -Wno-strict-aliasing -Wno-pointer-sign"

I can include the original C file if it's needed as well. Hope this helps.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34973

[Bug middle-end/34973] Wno-strict-aliasing is not working

[rguenth at gcc dot gnu dot org]

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------- Comment #14 from rguenth at gcc dot gnu dot org  2008-05-03 14:05 -------
This doesn't lookk like the strict-aliasing warning though, but

gcc-4.3 -S t.i -o /dev/null -Wall -Wmissing-declarations -Wmissing-prototypes
-Wnested-externs -Wpointer-arith -Wcast-align -Werror -Wno-pointer-sign
-Wno-strict-aliasing -m64
cc1: warnings being treated as errors
fm-directory-view.c: In function ‘file_and_directory_hash’:
fm-directory-view.c:521: error: cast from pointer to integer of different size
fm-directory-view.c:521: error: cast from pointer to integer of different size
fm-directory-view.c: In function ‘remove_not_really_moved_files’:
fm-directory-view.c:2445: error: cast from pointer to integer of different size

(works fine for me without -m64 / with -m32).  You can use
-Wno-pointer-to-int-cast to disable this particular warning.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34973

[Bug middle-end/34973] Wno-strict-aliasing is not working

[rguenth at gcc dot gnu dot org]

------- Comment #15 from rguenth at gcc dot gnu dot org  2008-05-03 14:06 -------
Whoops.  I can reproduce the

fm-directory-view.c:8887: error: dereferencing type-punned pointer will break
strict-aliasing rules

errors with -O2.


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rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2008-05-03 14:06:17
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34973

[Bug middle-end/34973] Wno-strict-aliasing is not working

[rguenth at gcc dot gnu dot org]

------- Comment #16 from rguenth at gcc dot gnu dot org  2008-05-03 14:13 -------
Err, simple.  (-Wstrict-aliasing=0 works, but -Wno-strict-aliasing doesn't)

Index: opts.c
===================================================================
--- opts.c      (revision 134849)
+++ opts.c      (working copy)
@@ -1865,6 +1865,8 @@ set_Wstrict_aliasing (int onoff)
   gcc_assert (onoff == 0 || onoff == 1);
   if (onoff != 0)
     warn_strict_aliasing = 3;
+  else
+    warn_strict_aliasing = 0;
 }

 /* The following routines are useful in setting all the flags that


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rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |rguenth at gcc dot gnu dot
                   |dot org                     |org
             Status|NEW                         |ASSIGNED
           Keywords|                            |diagnostic
   Last reconfirmed|2008-05-03 14:06:17         |2008-05-03 14:13:53
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34973

[Bug middle-end/34973] Wno-strict-aliasing is not working

[awalton at gnome dot org]

------- Comment #17 from awalton at gnome dot org  2008-05-03 14:57 -------
(In reply to comment #15)
> Whoops.  I can reproduce the
> 
> fm-directory-view.c:8887: error: dereferencing type-punned pointer will break
> strict-aliasing rules
> 
> errors with -O2.
> 

Yes, of course, that's what we were seeing. I should have said I was using -O2,
sorry for not pointing that out and for your quick work on this!


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34973

[Bug middle-end/34973] Wno-strict-aliasing is not working

[rguenth at gcc dot gnu dot org]

------- Comment #18 from rguenth at gcc dot gnu dot org  2008-05-03 15:26 -------
Subject: Bug 34973

Author: rguenth
Date: Sat May  3 15:26:10 2008
New Revision: 134902

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=134902
Log:
2008-05-03  Richard Guenther  <rguenther@suse.de>

        PR middle-end/34973
        * opts.c (set_Wstrict_aliasing): Handle the turn-off case.

Modified:
    branches/gcc-4_3-branch/gcc/ChangeLog
    branches/gcc-4_3-branch/gcc/opts.c


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34973

[Bug middle-end/34973] Wno-strict-aliasing is not working

[rguenth at gcc dot gnu dot org]

------- Comment #19 from rguenth at gcc dot gnu dot org  2008-05-03 15:29 -------
Fixed.


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rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|---                         |4.3.1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34973

[Bug middle-end/34973] Wno-strict-aliasing is not working

[rguenth at gcc dot gnu dot org]

------- Comment #20 from rguenth at gcc dot gnu dot org  2008-05-03 15:29 -------
Subject: Bug 34973

Author: rguenth
Date: Sat May  3 15:28:57 2008
New Revision: 134903

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=134903
Log:
2008-05-03  Richard Guenther  <rguenther@suse.de>

        PR middle-end/34973
        * opts.c (set_Wstrict_aliasing): Handle the turn-off case.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/opts.c


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34973