[cfe-dev] Newlib v2.5.0 and LibC++ locale support BROKEN

[James Y Knight via cfe-dev]

You should define _GNU_SOURCE, in order to get the vasprintf definition
(newlib will set __GNU_VISIBLE based on it)

While _GNU_SOURCE is "theoretically" supposed to be for end-users to
define, to request extra nonstandard functions from standard headers, in
practice, it's set effectively always for C++ code, because the C++
standard libraries need it. (see how clang sets it by default for a number
of targets in clang/lib/Basic/Targets.cpp).


On Fri, Jan 13, 2017 at 10:17 AM, Martin J. O'Riordan via cfe-dev <
cfe-dev at lists.llvm.org> wrote:

> I have a partial fix for these issues.
>
>
>
> The first is a group of errors that are due to Newlib v2.5.0 providing a
> richer Locale support than previous releases (Newlib’s ‘locale.h’), and
> this is turn results in conflicts for all the definitions contained in
> LibC++’s source ‘include/support/newlib/xlocale.h’ I have changed:
>
>
>
> #include <support/xlocale/__nop_locale_mgmt.h>
>
> to:
>
> #if defined(__NEWLIB__) && (__NEWLIB__ == 2) \
>
>      && defined(__NEWLIB_MINOR__) && (__NEWLIB_MINOR__ >= 5) \
>
>      && (!defined(__POSIX_VISIBLE) || (__POSIX_VISIBLE < 200809))
>
> #include <support/xlocale/__nop_locale_mgmt.h>
>
> #endif
>
>
>
> I think that  this is a reasonably portable resolution, though I will have
> to examine intermediate versions of Newlib after v2.2.0-20150423 and before
> v2.5.0 to see when the relevant changes occurred, so the exclusion check
> may need to be refined.
>
>
>
> However, I am not sure what to do about ‘vasprintf’.  I tried excluding
> the function ‘__libcpp_asprintf_l’ if ‘__STRICT_ANSI__’ is defined, but
> this had knock-on consequences because this function is used elsewhere in
> the C++ headers, so it is a more complex issue to resolve.
>
>
>
> Thanks,
>
>
>
>             MartinO
>
>
>
> *From:* Martin J. O'Riordan [mailto:martin.oriordan at movidius.com]
> *Sent:* 12 January 2017 15:58
> *To:* 'cfe-dev' <cfe-dev at lists.llvm.org>
> *Subject:* Newlib v2.5.0 and LibC++ locale support
>
>
>
> I am in the process of updating from using Newlib v2.2.0-20150423 for our
> common C library with LLVM to v2.5.0 and this is breaking LibC++.  Both
> LibC++ v3.9 and what is currently at head are affected.
>
>
>
> There are some general problems with Locales, and in particular the
> definition of the type ‘locale_t’ which is defined in Newlib’s ‘
> sys/_locale.h’ as:
>
>
>
> typedef struct __locale_t *locale_t;
>
>
>
> and in LibC++’s ‘support/xlocale/__nop_locale_mgmt.h’ as:
>
>
>
> typedef void *locale_t;
>
>
>
> But it is also running into another problem with ‘vasprintf’.  In LibC++
> this is referenced in ‘__bsd_locale_fallbacks.h’, but ‘vasprintf’ is not
> an ISO C function, and the newer version of Newlib has the declaration in ‘
> <stdio.h>’ guarded with ‘__GNU_VISIBLE’ to keep it out of the global
> namespace, thus:
>
>
>
> #if __GNU_VISIBLE
>
> int  _EXFUN(asprintf, (char **__restrict, const char *__restrict, ...)
>
>                _ATTRIBUTE ((__format__ (__printf__, 2, 3))));
>
> int  _EXFUN(vasprintf, (char **, const char *, __VALIST)
>
>                _ATTRIBUTE ((__format__ (__printf__, 2, 0))));
>
> #endif
>
>
>
> I don’t know which version of Newlib changed the declaration of ‘vasprintf’,
> but the current LibC++ does not seem to handle the change.  Should I be
> building LibC++ with ‘__GNU_VISIBLE’ defined?  Any recommendations for
> how I should resolve the multiple definition of ‘locale_t’?
>
>
>
> Thanks,
>
>
>
>             MartinO
>
>
>
> _______________________________________________
> cfe-dev mailing list
> cfe-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-dev/attachments/20170113/136053af/attachment.html>