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

[George Dunlap <george.dunlap@eu.citrix.com>]

On 02/13/2014 11:24 AM, Tim Deegan wrote:
> George: ping.
>
> At 15:33 +0100 on 11 Feb (1392129226), Tim Deegan wrote:
>> At 14:24 +0000 on 11 Feb (1392125052), Julien Grall wrote:
>>> If it's possible I'd like this patch goes in Xen 4.4 to fix build with
>>> official version of clang (until 3.4).
>>>
>>> Clang 3.5 is still under development, so I don't think it's important to
>>> have support for it in Xen 4.4.
>> Fair enough.  In that case it needs a release ack from George.  It:
>>   - fixes a compile issue on some version s of clang;
>>   - might cause a regression with other compilers, but the regression
>>     is likely to be obvious (i.e. a compile-time failure).

So the main risk would be if stgarg.h contained something like the 
"__GNUC_PREREQ__(4, 5)" #ifdef-ery that we missed.  Without this patch, 
we know it doesn't compile on the latest version of clang.  I think 
that's probably worse than the risk of potentially not compiling on some 
compiler that doesn't end up being tested before the release:

Release-acked-by: George Dunlap <george.dunlap@eu.citrix.com>


>>
>> And it needs an ack from Keir, for changing common code.
>>
>> v2 is below, removing "-iwithprefix".  I've kept your tested-by; hope
>> that's OK.
>>
>> Cheers,
>>
>> Tim.
>>
>> commit 1d62fcb9ad8d2b409ac2cf0e8a3824e19ca3313f
>> 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>
>>      Tested-by: Julien Grall <julien.grall@linaro.org>
>>
>> diff --git a/xen/Rules.mk b/xen/Rules.mk
>> index df1428f..3a6cec5 100644
>> --- a/xen/Rules.mk
>> +++ b/xen/Rules.mk
>> @@ -44,10 +44,7 @@ ALL_OBJS-$(x86)          += $(BASEDIR)/crypto/built_in.o
>>   CFLAGS += -fno-builtin -fno-common
>>   CFLAGS += -Werror -Wredundant-decls -Wno-pointer-arith
>>   CFLAGS += -pipe -g -D__XEN__ -include $(BASEDIR)/include/xen/config.h
>> -# Solaris puts stdarg.h &c in the system include directory.
>> -ifneq ($(XEN_OS),SunOS)
>> -CFLAGS += -nostdinc -iwithprefix include
>> -endif
>> +CFLAGS += -nostdinc
>>   
>>   CFLAGS-$(XSM_ENABLE)    += -DXSM_ENABLE
>>   CFLAGS-$(FLASK_ENABLE)  += -DFLASK_ENABLE -DXSM_MAGIC=0xf97cff8c
>> 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__ */
>>
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