newlib header breaks restricted pointers in C++

[Corinna Vinschen]

On Jul 25 19:46, Sebastian Huber wrote:
> On 25.07.23 19:35, Corinna Vinschen wrote:
> > 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?
> 
> I added a FreeBSD bug report:
> 
> https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=272723

Great, thanks!  Do we want to wait for a FreeBSD solution, or do
we want to change it now and, maybe, take the FreeBSD version later?

Does anybody want to provide a git compatible patch?


Thanks,
Corinna