[boost] Boost.Test, cygwin, and ISO/POSIX

Subject: [boost] Boost.Test, cygwin, and ISO/POSIX
From: James E. King, III (jking_at_[hidden])
Date: 2018-05-19 23:12:53

Hello,

I have been adding some CI infrastructure to the CMT repositories and found
I am able to reproduce a failure building boost libraries that use
Boost.Test for their unit tests.  If you build with "cxxstd=03" you can get
to some undefined functions. See:

https://github.com/boostorg/test/issues/144

It looks like one needs to define _POSIX_C_SOURCE=200112L or
cxxstd-dialect=gnu in order for these functions to become visible.  I was
thinking of addressing this two ways:

1. I want to change boost build (bjam) to define _POSIX_C_SOURCE when
building on cygwin to this value if it is not otherwise defined.  I can't
find the right place to add this.

2. I don't think it's reasonable for Boost.Test to modify _POSIX_C_SOURCE
since it could be included after sys/functional header, so I would like to
either change Boost.Test so it does not depend on these three functions, or
check to see if the right preprocessor definitions are set on cygwin and
put up a better error message, or simply change the documentation and
update all the CI build scripts in all the affected repositories to set
_POSIX_C_SOURCE as part of the CI build.

Any thoughts or other ideas on this?

Thanks,

Jim