Re: [RFC PATCH] compiler_attributes.h: Add 'fallthrough' pseudo keyword for switch/case use

[Peter Zijlstra]

On Wed, Jul 31, 2019 at 11:10:36PM -0700, hpa@xxxxxxxxx wrote:
> On July 31, 2019 4:55:47 PM PDT, Miguel Ojeda <miguel.ojeda.sandonis@xxxxxxxxx> wrote:
> >On Wed, Jul 31, 2019 at 11:01 PM <hpa@xxxxxxxxx> wrote:
> >>
> >> The standard is moving toward adding this as an attribute with the
> >[[fallthrough]] syntax; it is in C++17, not sure when it will be in C
> >be if it isn't already.
> >
> >Not yet, but it seems to be coming:
> >
> >  http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2268.pdf
> >
> >However, even if C2x gets it, it will be quite a while until the GCC
> >minimum version gets bumped up to that, so...
> >
> >Cheers,
> >Miguel
> 
> The point was that we should plan ahead in whatever we end up doing.

By reserving 'fallthrough' as a keyword we do exactly that. We can then
define it to whatever the compiler/tool at hand requires.

Once GCC gains support for that [[attribute]] nonsense, we can detector
that and use that over the __attribute__(())

[ Also the Cxx attribute syntax is an abomination -- just a lesser one
than reading actual comments :-) ]