[2.24 PATCH 1/3] Add utility macros for clang detection, and deprecation with messages.

[Carlos O'Donell]

On 07/31/2016 04:09 PM, Zack Weinberg wrote:
> There are three new macros added to features.h and sys/cdefs.h:
> 
>  * __glibc_clang_prereq: just like __GNUC_PREREQ, but for clang.
>  * __glibc_clang_has_extension: wraps clang's intrinsic __has_extension.
>    Writing "#if defined __clang__ && __has_extension (...)" doesn't work,
>    because compilers other than clang will object to the unknown macro
>    __has_extension even though they don't need to evaluate it.
>    Instead, write "#if __glibc_clang_has_extension (...)".
> 
>  * __attribute_deprecated_msg__(msg): like __attribute_deprecated__, but
>    if possible, prints a message.
> 
> The first two are used to define the third.  The third will be used
> in subsequent patches.
> 
> ChangeLog:
> 	* include/features.h (__glibc_clang_prereq): New macro.
> 	* misc/sys/cdefs.h (__glibc_clang_has_extension)
> 	(__attribute_deprecated_msg__): New macros.

This looks good to me. I have no objections like Roland or Paul about
abstracting this into some generic infrastructure. These things should
grow organically based on need IMO.

-- 
Cheers,
Carlos.