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).
  

Ping.  This patch 
<https://sourceware.org/pipermail/libc-alpha/2020-October/118237.html> is 
pending review.
  

On 01/10/2020 19:47, Joseph Myers wrote:
> 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).

As a side note I am checking on bz#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).

LGTM, thanks.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

> 
> diff --git a/include/bits/types/struct___jmp_buf_tag.h b/include/bits/types/struct___jmp_buf_tag.h
> new file mode 100644
> index 0000000000..e3250150da
> --- /dev/null
> +++ b/include/bits/types/struct___jmp_buf_tag.h
> @@ -0,0 +1 @@
> +#include <setjmp/bits/types/struct___jmp_buf_tag.h>
> diff --git a/setjmp/Makefile b/setjmp/Makefile
> index dcac56932d..603f61d76e 100644
> --- a/setjmp/Makefile
> +++ b/setjmp/Makefile
> @@ -22,7 +22,8 @@ subdir	:= setjmp
>  
>  include ../Makeconfig
>  
> -headers	:= setjmp.h bits/setjmp.h bits/setjmp2.h
> +headers	:= setjmp.h bits/setjmp.h bits/setjmp2.h \
> +	   bits/types/struct___jmp_buf_tag.h
>  
>  routines	:= setjmp sigjmp bsd-setjmp bsd-_setjmp \
>  		   longjmp __longjmp jmp-unwind

Ok.

> diff --git a/setjmp/bits/types/struct___jmp_buf_tag.h b/setjmp/bits/types/struct___jmp_buf_tag.h
> new file mode 100644
> index 0000000000..9d8634f1e4
> --- /dev/null
> +++ b/setjmp/bits/types/struct___jmp_buf_tag.h
> @@ -0,0 +1,37 @@
> +/* Define struct __jmp_buf_tag.
> +   Copyright (C) 1991-2020 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#ifndef	__jmp_buf_tag_defined
> +#define	__jmp_buf_tag_defined 1> +
> +#include <bits/setjmp.h>		/* Get `__jmp_buf'.  */
> +#include <bits/types/__sigset_t.h>
> +
> +/* Calling environment, plus possibly a saved signal mask.  */
> +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.  */
> +  };
> +
> +#endif

Ok.

> diff --git a/setjmp/setjmp.h b/setjmp/setjmp.h
> index 4e3443c37e..c6c59f4094 100644
> --- a/setjmp/setjmp.h
> +++ b/setjmp/setjmp.h
> @@ -27,20 +27,7 @@
>  __BEGIN_DECLS
>  
>  #include <bits/setjmp.h>		/* Get `__jmp_buf'.  */
> -#include <bits/types/__sigset_t.h>
> -
> -/* Calling environment, plus possibly a saved signal mask.  */
> -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.  */
> -  };
> -
> +#include <bits/types/struct___jmp_buf_tag.h>
>  
>  typedef struct __jmp_buf_tag jmp_buf[1];
>  

Ok.

> diff --git a/sysdeps/nptl/pthread.h b/sysdeps/nptl/pthread.h
> index 8a403cbf36..d4194da776 100644
> --- a/sysdeps/nptl/pthread.h
> +++ b/sysdeps/nptl/pthread.h
> @@ -28,6 +28,7 @@
>  #include <bits/wordsize.h>
>  #include <bits/types/struct_timespec.h>
>  #include <bits/types/__sigset_t.h>
> +#include <bits/types/struct___jmp_buf_tag.h>
>  
>  
>  /* Detach state.  */
> @@ -730,8 +731,8 @@ extern void __pthread_unwind_next (__pthread_unwind_buf_t *__buf)
>  #endif
>  
>  /* Function used in the macros.  */
> -struct __jmp_buf_tag;
> -extern int __sigsetjmp (struct __jmp_buf_tag *__env, int __savemask) __THROWNL;
> +extern int __sigsetjmp (struct __jmp_buf_tag __env[1],
> +			int __savemask) __THROWNL;
>  
>  
>  /* Mutex handling.  */
> 

Ok.