Re: Re: [PATCH v2] newlib: fix build with <gcc-5 versions

Interesting was not familiar with either of these
https://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html
https://gcc.gnu.org/onlinedocs/gcc/Integer-Overflow-Builtins.html

Eric Bresie
[email protected] (mailto:[email protected])

> On March 15, 2022 at 6:54:00 PM CDT, Mike Frysinger <[email protected] (mailto:[email protected])> wrote:
> On 15 Mar 2022 12:41, Richard Earnshaw wrote:
> > On 15/03/2022 03:25, Mike Frysinger wrote:
> > > __builtin_mul_overflow showed up with gcc-5, so stub it out for older
> > > versions.
> > > ---
> > > newlib/libc/include/sys/cdefs.h | 4 ++++
> > > 1 file changed, 4 insertions(+)
> > >
> > > diff --git a/newlib/libc/include/sys/cdefs.h b/newlib/libc/include/sys/cdefs.h
> > > index da729092185c..e51f7f4b873a 100644
> > > --- a/newlib/libc/include/sys/cdefs.h
> > > +++ b/newlib/libc/include/sys/cdefs.h
> > > @@ -416,6 +416,10 @@
> > > #define __unreachable() ((void)0)
> > > #endif
> > >
> > > +#if !__GNUC_PREREQ__(5, 0)
> > > +#define __builtin_mul_overflow(a, b, size) ({ *(size) = (a) * (b); 0; })
> >
> > Wouldn't
> > (*(size) = (a) * (b), 0)
> >
> > be more portable (avoiding the GNU statement expression extension)?
>
> sure, that works too, thanks
> -mike
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