  The C++ Standard Template Library is the flagship example for libraries based
on the generic programming paradigm. The usage of this library is intended to
minimize the number of classical C/C++ errors, but does not warrant bug-free
programs. Furthermore, many new kinds of errors may arise from the inaccurate
use of the generic programming paradigm, like dereferencing invalid iterators
or misunderstanding remove-like algorithms. In this paper we present some
typical scenarios that may cause runtime or portability problems. We emit
warnings and errors while these risky constructs are used. We also present a
general approach to emit "customized" warnings. We support the so-called
"believe-me marks" to disable warnings. We present another typical usage of our
technique, when classes become deprecated during the software lifecycle.
