[Boost-build] Creating a configuration rule?

Subject: [Boost-build] Creating a configuration rule?
From: John Maddock (john_at_[hidden])
Date: 2008-11-01 14:15:45

OK here's the issue:

In Boost.Math I have some library binaries, and some tests that should only 
be built if some feature X is present (say long double support for example).

So... I can make those targets depend upon an "obj" rule that builds the 
feature-test program.  Now those targets only get built if the feature is 
supported, which is a lot better than 1000's of meaningless error 
messages... but,

What I would really prefer is for the tests and libraries to get a <build>no 
property if the feature test fails to compile, that way I won't see all 
those "skipping target X for lack of Y" messages.  I'd also like the feature 
test failure to be quiet, so it doesn't get reported as an error at the end.

Is any of this possible?

Many thanks, John.