On Thu, Jul 19, 2018 at 01:39:04PM +0200, Florian Weimer wrote:
> On 07/19/2018 01:33 PM, Jakub Jelinek wrote:
> > On Thu, Jul 19, 2018 at 04:21:26AM -0700, H.J. Lu wrote:
> > > The new indirect_return attribute is intended to mark swapcontext in
> > > <ucontext.h>. This patch defines __HAVE_INDIRECT_RETURN_ATTRIBUTE__
> > > so that it can be used checked before using indirect_return attribute
> > > in <ucontext.h>. It works when the indirect_return attribute is
> > > backported to GCC 8.
> > >
> > > OK for trunk?
> >
> > No. Use
> > #ifdef __has_attribute
> > #if __has_attribute (indirect_return)
> > ...
> > #endif
> > #endif
> > instead, like for any other attribute.
>
> That doesn't work because indirect_return is not in the implementation
> namespace and expanded in this context. I assume that __has_attribute
> (__indirect_return__) would work, though.
>
> Could we add:
>
> #ifdef __has_attribute
> # define __glibc_has_attribute(attr) __has_attribute (attr)
> #else
> # define __glibc_has_attribute 0
# define __glibc_has_attribute(attr) 0
instead, otherwise you get errors.
> #endif
>
> And then use this:
>
> #if __glibc_has_attribute (__indirect_return__)
>
> Would that still work?
Sure, you can do this.
Jakub
