[PATCH] Define _C99 in libstdc++ vxworks/os_defines.h

[Olivier Hainque]

Hello,

The attached patch for libstdc++ / VxWorks helps building
the library for old versions of the OS, as witnessed with
VxWorks 6.9 in particular.

It explicitly requests C99 features from old system headers,
on which libstc++ relies since at least c++98. The specific
issue that exposed this was a failure to compile

  libstdc++-v3/src/c++17/floating_to_chars.cc

for VxWorks 6.9 with a batch of errors such as:

  error: 'FP_NAN' was not declared in this scope

The missing definitions are provided by the
system headers with guards on _HAS_C9X, which gets
internally defined when _C99 is.

Ok to commit?

Thanks in advance!

2021-12-07  Olivier Hainque  <hainque@adacore.com>

libstdc++-v3/

	* config/os/vxworks/os_defines.h: #define _C99.

Olivier

-------------- next part --------------
A non-text attachment was scrubbed...
Name: 0001-Define-_C99-in-libstdc-vxworks-os_defines.h.patch
Type: application/octet-stream
Size: 1346 bytes
Desc: not available
URL: <https://gcc.gnu.org/pipermail/libstdc++/attachments/20211210/5f0ef2e7/attachment-0001.obj>