[Boost-build] Compile-time probing (Ticket #2597)

Subject: [Boost-build] Compile-time probing (Ticket #2597)
From: Steve M. Robbins (steve_at_[hidden])
Date: 2008-12-18 20:19:02

Hi,

Boost.Math builds a test file to check whether long double math is
supported. If it is not, the build fails with an error which is
misleading because it is not an error but, rather, a successful build
of all parts except the long double version of boost_math_c99 and
boost_math_tr1.

This issue causes the builds to fail for Debian;
c.f. http://tinyurl.com/45feh8

I have opened a Trac ticket about this
(https://svn.boost.org/trac/boost/ticket/2597) and have been told by
John Maddock that this is just the way Boost.Build works.

Maybe the Boost.Build cogniscenti can help out.  How can I
express the following in Boost.Build:

        try to compile foo.cpp
        if successful:
                build library libfoo
        else:
                emit warning

The key point is that the build should *succeed* in both cases;
here, "succeed" means "exit with status 0".

In short, we need a compile-time test similar to what a system like
autotools has.

Thanks,
-Steve