SafeInt is a C++ header containing the SafeInt class, non-throwing functions to check common operations, and the associated internal mechanisms.
SafeInt is currently used extensively throughout Microsoft, with substantial adoption within Office and Windows.
It can be used with any compiler that has good template support, and is known to work on Visual Studio 7.1 or later.
An update - thanks to Niels Dekker, I'm going to be able to add gcc support.
A release with gcc support is now up as 3.0.12p.