Re: [PATCH] xen: Don't use -nostdinc flags with CLANG

[Julien Grall <julien.grall@linaro.org>]

On 11/02/14 12:59, Tim Deegan wrote:
> At 12:36 +0000 on 11 Feb (1392118581), Julien Grall wrote:
>>
>>
>> On 11/02/14 12:35, Tim Deegan wrote:
>>> At 12:30 +0000 on 11 Feb (1392118227), Julien Grall wrote:
>>>>
>>>>
>>>> On 11/02/14 08:53, Tim Deegan wrote:
>>>>> At 23:29 +0000 on 10 Feb (1392071374), Julien Grall wrote:
>>>>>> Commit 06a9c7e "xen: move -nostdinc into common Rules.mk." breaks
>>>>>> compilation with clang:
>>>>>>
>>>>>> In file included from sched_sedf.c:8:
>>>>>> In file included from /home/julieng/works/xen/xen/include/xen/lib.h:5:
>>>>>> /home/julieng/works/xen/xen/include/xen/stdarg.h:20:12: error: 'stdarg.h' file
>>>>>> not found with <angled> include; use "quotes" instead
>>>>>>               ^~~~~~~~~~
>>>>>>               "stdarg.h"
>>>>>
>>>>> Looks like on your system stdarg.h doesn't live in a compiler-specific
>>>>> path, like we have for the BSDs.  I think we should just go to using
>>>>> our own definitions for stdarg/stdbool everywhere; trying to chase the
>>>>> compiler-specific versions around is a PITA, and the pieces we
>>>>> actually need are trivial.
>>>>
>>>> For BSDs, we are using our own stdargs/stdbool.  So we don't include the
>>>> system <stdarg.h>.
>>>>
>>>> Linux is using $(CC) -print-file-name=include to get the right path. It
>>>> works with both gcc and clang on Linux distos, but not on FreeBSD.
>>>
>>> Wait - is the error message you posted from clang on FreeBSD?
>>> That's surprising; on FreeBSD xen/stdarg.h shouldn't be trying to
>>> include <stdarg.h> at all.  Is __FreeBSD__ not being defined?
>>
>>
>> No it's from Linux (Debian Wheezy and Fedora). I just gave a try to the
>> "-print-file-name" solution on FreeBSD.
>
> Oh, OK.  Yeah, we knew that didn't work there, because on *BSD the
> compiler-specific headers like stdarg.h actually live in /usr/include
> and can themselves include other system headers.  That's why we have
> our own implementation of the bits we need, that we use on BSD.
>
> Are you using a very old version of clang?  As 06a9c7e points out,
> our current runes didn't work before clang v3.0.
>
> If not, rather than chasing this around any further, I think we should
> abandon trying to use the compiler-provided headers even on linux.
> Does this patch fix your build issue?
>
> commit e7003f174e0df9192dde6fa8d33b0a20f99ce053
> Author: Tim Deegan <tim@xen.org>
> Date:   Tue Feb 11 12:44:09 2014 +0000
>
>      xen: stop trying to use the system <stdarg.h> and <stdbool.h>
>
>      We already have our own versions of the stdarg/stdbool definitions, for
>      systems where those headers are installed in /usr/include.
>
>      On linux, they're typically installed in compiler-specific paths, but
>      finding them has proved unreliable.  Drop that and use our own versions
>      everywhere.
>
>      Signed-off-by: Tim Deegan <tim@xen.org>
>
> diff --git a/xen/include/xen/stdarg.h b/xen/include/xen/stdarg.h
> index d1b2540..0283f06 100644
> --- a/xen/include/xen/stdarg.h
> +++ b/xen/include/xen/stdarg.h
> @@ -1,23 +1,21 @@
>   #ifndef __XEN_STDARG_H__
>   #define __XEN_STDARG_H__
>
> -#if defined(__OpenBSD__) || defined(__NetBSD__) || defined(__FreeBSD__)
> -   typedef __builtin_va_list va_list;
> -#  ifdef __GNUC__
> -#    define __GNUC_PREREQ__(x, y)                                       \
> -        ((__GNUC__ == (x) && __GNUC_MINOR__ >= (y)) ||                  \
> -         (__GNUC__ > (x)))
> -#  else
> -#    define __GNUC_PREREQ__(x, y)   0
> -#  endif
> -#  if !__GNUC_PREREQ__(4, 5)
> -#    define __builtin_va_start(ap, last)    __builtin_stdarg_start((ap), (last))
> -#  endif
> -#  define va_start(ap, last)    __builtin_va_start((ap), (last))
> -#  define va_end(ap)            __builtin_va_end(ap)
> -#  define va_arg                __builtin_va_arg
> +#ifdef __GNUC__
> +#  define __GNUC_PREREQ__(x, y)                                       \
> +      ((__GNUC__ == (x) && __GNUC_MINOR__ >= (y)) ||                  \
> +       (__GNUC__ > (x)))
>   #else
> -#  include <stdarg.h>
> +#  define __GNUC_PREREQ__(x, y)   0
>   #endif
>
> +#if !__GNUC_PREREQ__(4, 5)
> +#  define __builtin_va_start(ap, last)    __builtin_stdarg_start((ap), (last))
> +#endif
> +
> +typedef __builtin_va_list va_list;
> +#define va_start(ap, last)    __builtin_va_start((ap), (last))
> +#define va_end(ap)            __builtin_va_end(ap)
> +#define va_arg                __builtin_va_arg
> +
>   #endif /* __XEN_STDARG_H__ */
> diff --git a/xen/include/xen/stdbool.h b/xen/include/xen/stdbool.h
> index f0faedf..b0947a6 100644
> --- a/xen/include/xen/stdbool.h
> +++ b/xen/include/xen/stdbool.h
> @@ -1,13 +1,9 @@
>   #ifndef __XEN_STDBOOL_H__
>   #define __XEN_STDBOOL_H__
>
> -#if defined(__OpenBSD__) || defined(__NetBSD__) || defined(__FreeBSD__)
> -#  define bool _Bool
> -#  define true 1
> -#  define false 0
> -#  define __bool_true_false_are_defined   1
> -#else
> -#  include <stdbool.h>
> -#endif
> +#define bool _Bool
> +#define true 1
> +#define false 0
> +#define __bool_true_false_are_defined   1
>
>   #endif /* __XEN_STDBOOL_H__ */
>

-- 
Julien Grall