Wmexcep.

1. code for handling the floating point environment based upon the proposed C standard (fenv.h stuff), and
2. code for handling floating point exceptions, allowing you to (for example) count the number of times your program divides by zero.

glibc-2.1 has introduced an implementation of the fenv.h stuff, so if glibc-2.1 is installed in the standard place on your system my package will use that instead of my version.