Re: [PATCH][BZ #21326] Ensure C99 and C11 interfaces are available for C++

[Jonathan Wakely <jwakely at redhat dot com>]

On 22/09/17 17:59 +0000, Joseph Myers wrote:
> On Fri, 22 Sep 2017, Jonathan Wakely wrote:
>
> > +#ifdef __cplusplus
> > +/* This is to enable compatibility for ISO C++17.  */
> > +#if __cplusplus >= 201703L
> > +# define __USE_ISOCXX17	1
> > +# define __USE_ISOC11	1
> > +#endif
> > /* This is to enable compatibility for ISO C++11.
> > -
> > -   So far g++ does not provide a macro.  Check the temporary macro for
> > -   now, too.  */
> > -#if ((defined __cplusplus && __cplusplus >= 201103L)
> > \
> > -     || defined __GXX_EXPERIMENTAL_CXX0X__)
> > +   Check the temporary macro for now, too.  */
> > +#if __cplusplus >= 201103L || defined __GXX_EXPERIMENTAL_CXX0X__
> > # define __USE_ISOCXX11	1
>
> There is a comment listing all the __USE_ macros at the top of features.h.
> It should be updated to add __USE_ISOCXX17.  (Actually, it needs
> __USE_ISOCXX11 added as well, but that's a preexisting condition.  And I'm
> not sure __USE_ISOCXX17 should be added at all until there is something to
> condition on it.)

Good point. If there was reason to add it without anything using it
then there should be a __USE_ISOCXX14 as well. But since nothing needs
them, they can be left out.

> The existing __USE_* macros are also undefined in features.h before being
> possibly defined, including __USE_ISOCXX11.  If a new __USE_ISOCXX17 is
> added, it should be added to that #undef sequence as well.

Here's a new patch without __USE_ISOCXX17 and listing __USE_ISOCXX11
in the comment at the top.

Tested x86_64-linux.

Attachment: 0001-BZ-21326-Ensure-C99-and-C11-interfaces-are-available.patch
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