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Re: _NEWLIB_VERSION exposure through sys/cdefs.h
- From: Jeff Johnston <jjohnstn at redhat dot com>
- To: Jonathan Roelofs <jonathan at codesourcery dot com>
- Cc: newlib at sourceware dot org, Corinna Vinschen <vinschen at redhat dot com>, Dan Albert <danalbert at google dot com>, JF Bastien <jfb at chromium dot org>
- Date: Wed, 17 Sep 2014 17:47:49 -0400 (EDT)
- Subject: Re: _NEWLIB_VERSION exposure through sys/cdefs.h
- Authentication-results: sourceware.org; auth=none
- References: <5419F88C dot 70905 at codesourcery dot com>
----- Original Message -----
> From: "Jonathan Roelofs" <email@example.com>
> To: firstname.lastname@example.org, "Corinna Vinschen" <email@example.com>
> Cc: "Dan Albert" <firstname.lastname@example.org>, "JF Bastien" <email@example.com>
> Sent: Wednesday, September 17, 2014 5:09:32 PM
> Subject: _NEWLIB_VERSION exposure through sys/cdefs.h
> In libc++, we'd like to be able to tell when the underlying libc is Newlib.
> the moment, that requires us to do things like this:
> #if defined(__has_include) && __has_include(<newlib.h>)
> #include <newlib.h>
> #if defined(_NEWLIB_VERSION)
> The problem with that strategy is that it does not work when using gcc, as it
> doesn't have __has_include support yet. It came up in discussion that
> sys/cdefs.h might be the right place for that, as that's where glibc puts
> Would there be an objection to #include <newlib.h> from sys/cdefs.h? Is
> there a
> better way to detect Newlib that I've overlooked?
Corinna is on vacation until Oct 8th.
My version of glibc has __GLIBC__ defined in features.h which in glibc is
included by sys/cdefs.h.
I wouldn't have a problem with simply adding a __NEWLIB__ macro in newlib's
features.h. I also wouldn't have a real problem with including newlib.h from sys/cdefs.h
though I notice one of the newlib.h macros is missing an underscore and needs to be fixed.
A way of solving your problem now would be to look for:
that is set by <machine/_default_types.h> which is a newlib-specific header
that is included by sys/cdefs.h. I don't see any platform overriding sys/cdefs.h
except for x86-linux and it eventually includes <machine/_default_types.h> as
-- Jeff J.
> Jon Roelofs
> CodeSourcery / Mentor Embedded