Re: newlib header breaks restricted pointers in C++

[Corinna Vinschen <vinschen@redhat.com>]

Hi Bruno,

On Jul 24 22:23, Bruno De Fraine wrote:
> Hello,
> 
> As an extension, GCC and clang offer C99-style restricted pointers in C++ mode:
> https://gcc.gnu.org/onlinedocs/gcc/Restricted-Pointers.html
> 
> We notice that this extension is broken when including newlib headers: restricted pointers are treated as ordinary pointers.
> 
> We traced this to the following section of newlib/libc/include/sys/cdefs.h:
> 
>   /*
>    * GCC 2.95 provides `__restrict' as an extension to C90 to support the
>    * C99-specific `restrict' type qualifier.  We happen to use `__restrict' as
>    * a way to define the `restrict' type qualifier without disturbing older
>    * software that is unaware of C99 keywords.
>    */
>   #if !(__GNUC__ == 2 && __GNUC_MINOR__ == 95)
>   #if !defined(__STDC_VERSION__) || __STDC_VERSION__ < 199901
>   #define	__restrict
>   #else
>   #define	__restrict	restrict
>   #endif
>   #endif
> 
> While the GCC __restrict extension was indeed introduced in GCC 2.95, it is not limited to this version; the extension is also not limited to C90:
> https://gcc.gnu.org/gcc-2.95/c++features.html

Either way, the above has been taken from FreeBSD, and it is still,
as of today, the same expression as used in FreeBSDs sys/cdefs.h
file.

Seb, any input on this?


Corinna