Until now SWIG quietly ignored such errors unless -Wextra (or -Wall
which implies -Wextra) was passed, but this is unhelpful as it hides
problems. To illustrate this point, enabling this warning by
default revealled a typo in the preproc_defined.i testcase in
SWIG's own testsuite.
If you really don't want to see this warning, you can suppress it
with command line option -w202 or by using this in your interface
file:
%warnfilter(SWIGWARN_PP_EVALUATION);
Both will work with older versions of SWIG too.
Fixes#1465Fixes#2389
