[Bug build/26647] New: [-Werror=array-parameter=] due to different declarations for __sigsetjmp

[Bug build/26647] New: [-Werror=array-parameter=] due to different declarations for __sigsetjmp

[vvinayag at arm dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=26647

            Bug ID: 26647
           Summary: [-Werror=array-parameter=] due to different
                    declarations for __sigsetjmp
           Product: glibc
           Version: unspecified
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: build
          Assignee: unassigned at sourceware dot org
          Reporter: vvinayag at arm dot com
                CC: carlos at redhat dot com
  Target Milestone: ---

After this patch [1], I am seeing this -Warray-parameter error when building
gcc:

In file included from ../include/pthread.h:1,
                 from ../sysdeps/nptl/thread_db.h:25,
                 from ../nptl/descr.h:32,
                 from ../sysdeps/aarch64/nptl/tls.h:44,
                 from ../include/errno.h:25,
                 from ../sysdeps/unix/sysv/linux/sysdep.h:23,
                 from ../sysdeps/unix/sysv/linux/generic/sysdep.h:22,
                 from ../sysdeps/unix/sysv/linux/aarch64/sysdep.h:24,
                 from <stdin>:1:
../sysdeps/nptl/pthread.h:734:47: error: argument 1 of type ‘struct
__jmp_buf_tag *’ declared as a pointer [-Werror=array-parameter=]
  734 | extern int __sigsetjmp (struct __jmp_buf_tag *__env, int __savemask)
__THROWNL;
      |                         ~~~~~~~~~~~~~~~~~~~~~~^~~~~
In file included from ../include/setjmp.h:2,
                 from ../nptl/descr.h:24,
                 from ../sysdeps/aarch64/nptl/tls.h:44,
                 from ../include/errno.h:25,
                 from ../sysdeps/unix/sysv/linux/sysdep.h:23,
                 from ../sysdeps/unix/sysv/linux/generic/sysdep.h:22,
                 from ../sysdeps/unix/sysv/linux/aarch64/sysdep.h:24,
                 from <stdin>:1:
../setjmp/setjmp.h:54:46: note: previously declared as an array ‘struct
__jmp_buf_tag[1]’
   54 | extern int __sigsetjmp (struct __jmp_buf_tag __env[1], int __savemask)
__THROWNL;
      |                         ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~
cc1: all warnings being treated as errors


The build/host/target setup is:
Build: x86_64-linux-gnu (Ubuntu 18.04)
Host: x86_64-linux-gnu
Target: aarch64-none-linux-gnu, aarch64_be-none-linux-gnu,
arm-none-linux-gnueabi, arm-none-linux-gnueabihf


This was mentioned in
https://gcc.gnu.org/pipermail/gcc-patches/2020-September/554415.html and it
seems like the warning might need to be suppressed in glibc.

[1]
https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=6450f07388f9fe575a489c9309c36012b17b88b0

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug build/26647] [-Werror=array-parameter=] due to different declarations for __sigsetjmp

[vvinayag at arm dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=26647

vvinayag at arm dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
              Build|                            |x86_64-linux-gnu
               Host|                            |x86_64-linux-gnu
             Target|                            |aarch64-none-linux-gnu,
                   |                            |arm-none-linux-gnueabi

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug build/26647] [-Werror=array-parameter=] due to different declarations for __sigsetjmp

[msc at linux dot ibm.com]

https://sourceware.org/bugzilla/show_bug.cgi?id=26647

Matheus Castanho <msc at linux dot ibm.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |msc at linux dot ibm.com

--- Comment #1 from Matheus Castanho <msc at linux dot ibm.com> ---
I also noticed this when building natively on ppc64le. It doesn't seem to be
target-specific.

I experimented adjusting the __sigsetjmp declaration in sysdeps/nptl/pthread.h
to match the one in setjmp/setjmp.h, but then it led to other failure:

../csu/libc-start.c: In function ‘generic_start_main.isra’:
../setjmp/setjmp.h:62:25: error: ‘_setjmp’ accessing 656 bytes in a region of
size 528 [-Werror=stringop-overflow=]
   62 | #define setjmp(env)     _setjmp (env)
      |                         ^~~~~~~~~~~~~
../csu/libc-start.c:301:20: note: in expansion of macro ‘setjmp’
  301 |   not_first_call = setjmp ((struct __jmp_buf_tag *)
unwind_buf.cancel_jmp_buf);
      |                    ^~~~~~
../setjmp/setjmp.h:62:25: note: referencing argument 1 of type ‘struct
__jmp_buf_tag *’
   62 | #define setjmp(env)     _setjmp (env)
      |                         ^~~~~~~~~~~~~
../csu/libc-start.c:301:20: note: in expansion of macro ‘setjmp’
  301 |   not_first_call = setjmp ((struct __jmp_buf_tag *)
unwind_buf.cancel_jmp_buf);
      |                    ^~~~~~



cancel_jmp_buf is defined in nptl/descr.h as:

struct pthread_unwind_buf
{
  struct
  {
    __jmp_buf jmp_buf;
    int mask_was_saved;
  } cancel_jmp_buf[1];

  <...>
}

On the line causing the warning above, the field is cast to 'struct
__jmp_buf_tag *' and passed to setjmp. But this last struct has an extra field
that cancel_jmp_buf doesn't:

struct __jmp_buf_tag
  {
    /* NOTE: The machine-dependent definitions of `__sigsetjmp'
       assume that a `jmp_buf' begins with a `__jmp_buf' and that
       `__mask_was_saved' follows it.  Do not move these members
       or add others before it.  */
    __jmp_buf __jmpbuf;         /* Calling environment.  */
    int __mask_was_saved;       /* Saved the signal mask?  */
    __sigset_t __saved_mask;    /* Saved signal mask.  */       <-------
  };


Could this be an actual invalid access and not just a false-positive after all
or was this by design?

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug build/26647] [-Werror=array-parameter=] due to different declarations for __sigsetjmp

[schwab@linux-m68k.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=26647

--- Comment #2 from Andreas Schwab <schwab@linux-m68k.org> ---
This depends on the fact that _setjmp never saves the signal mask and thus
never accesses the __saved_mask field (and neither does longjmp).

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug build/26647] [-Werror=array-parameter=] due to different declarations for __sigsetjmp

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=26647

--- Comment #3 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Joseph Myers <jsm28@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=19302b27bdacfe87e861ff46fc0fbad60dd6602d

commit 19302b27bdacfe87e861ff46fc0fbad60dd6602d
Author: Joseph Myers <joseph@codesourcery.com>
Date:   Mon Oct 5 16:46:46 2020 +0000

    Fix GCC 11 -Warray-parameter warning for __sigsetjmp (bug 26647)

    This patch fixes part of bug 26647 (-Werror=array-parameter error
    building with GCC 11 because of __sigsetjmp being declared using an
    array parameter in one header and a pointer parameter in another).

    The fix is to split the struct __jmp_buf_tag definition out to a
    separate bits/types/ header so it can be included in pthread.h, so
    that pthread.h can declare __sigsetjmp with the type contents visible,
    so can use an array (as in setjmp.h) rather than a pointer in the
    declaration.

    Note that several other build failures with GCC 11 remain.  This does
    not fix the jmp_buf-related -Wstringop-overflow errors (also discussed
    in bug 26647), or -Warray-parameter errors for other functions (bug
    26686), or -Warray-bounds errors (bug 26687).

    Tested, with older compilers, natively for x86_64 and with
    build-many-glibc.py for aarch64-linux-gnu.  Tested with
    build-many-glibcs.py with GCC mainline for aarch64-linux-gnu that this
    gets past the -Warray-parameter issue for __sigsetjmp (with the next
    build failure being the other one discussed in bug 26647).

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug build/26647] [-Werror=array-parameter=] due to different declarations for __sigsetjmp

[schwab@linux-m68k.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=26647

Andreas Schwab <schwab@linux-m68k.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |euloanty at live dot com

--- Comment #4 from Andreas Schwab <schwab@linux-m68k.org> ---
*** Bug 26709 has been marked as a duplicate of this bug. ***

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug build/26647] [-Werror=array-parameter=] due to different declarations for __sigsetjmp

[schwab@linux-m68k.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=26647

Andreas Schwab <schwab@linux-m68k.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |hjl.tools at gmail dot com

--- Comment #5 from Andreas Schwab <schwab@linux-m68k.org> ---
*** Bug 26750 has been marked as a duplicate of this bug. ***

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug build/26647] [-Werror=array-parameter=] due to different declarations for __sigsetjmp

[schwab@linux-m68k.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=26647

Andreas Schwab <schwab@linux-m68k.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |msebor at gmail dot com

--- Comment #6 from Andreas Schwab <schwab@linux-m68k.org> ---
*** Bug 26789 has been marked as a duplicate of this bug. ***

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug build/26647] [-Werror=array-parameter=] due to different declarations for __sigsetjmp

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=26647

--- Comment #7 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Joseph Myers <jsm28@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=2098d4034d398cbde6ccd4a2aaac52c518374698

commit 2098d4034d398cbde6ccd4a2aaac52c518374698
Author: Joseph Myers <joseph@codesourcery.com>
Date:   Fri Oct 30 21:38:31 2020 +0000

    Disable spurious -Wstringop-overflow for setjmp/longjmp (bug 26647)

    Building glibc with GCC 11 fails with (among other warnings) spurious
    -Wstringop-overflow warnings from calls to setjmp and longjmp with a
    pointer to a pthread_unwind_buf that is smaller than jmp_buf.  As
    discussed in bug 26647, the warning in libc-start.c is a false
    positive, because setjmp and longjmp do not access anything (the
    signal mask) beyond the common prefix of the two structures, so this
    patch disables the warning for that call to setjmp, as well as for two
    calls in NPTL code that produce the same warning and look like false
    positives for the same reason.

    Tested with build-many-glibcs.py for arm-linux-gnueabi, where this
    allows the build to get further.

    Reviewed-by: DJ Delorie <dj@redhat.com>

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug build/26647] [-Werror=array-parameter=] due to different declarations for __sigsetjmp

[jsm28 at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=26647

Joseph Myers <jsm28 at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
   Target Milestone|---                         |2.33
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #8 from Joseph Myers <jsm28 at gcc dot gnu.org> ---
Fixed for 2.33.

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug build/26647] [-Werror=array-parameter=] due to different declarations for __sigsetjmp

[bonzini at gnu dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=26647

Paolo Bonzini <bonzini at gnu dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bonzini at gnu dot org

--- Comment #9 from Paolo Bonzini <bonzini at gnu dot org> ---
The same error can occur with pthread_cleanup_push
(https://gitlab.com/qemu-project/qemu/-/issues/400).  Is it possible to include
the appropriate _Pragmas in the macro as well?

-- 
You are receiving this mail because:
You are on the CC list for the bug.