I think it is a bit evil to have NDEBUG defined when building the swig
library but not any other time. Any function declared in a header can
then asserts turned off.
Even worse, various things can change memory layout when NDEBUG is
defined, resulting in random crashes if modules are mixed. We probably
should make sure IMP doesn't have this property, but I have encountered
other libraries which do such things.
I think 'evil' is a strong word for it. ;) But as of r654, there is a
'release' scons option. By default it is False, which will build both
regular libraries and SWIG extensions without -DNDEBUG. If you turn
release on, it'll set NDEBUG for everything. But we definitely shouldn't
have different memory layouts in the two cases - that is a really sloppy
ABI.
On a separate note, since it has been bugging me a bit, you are not
supposed to use identifiers starting with _ or __ as these are reserved
for the compiler. All our header guards start with __. Frankly, I don't
expect this to ever cause problems, but such are the rules.
A huge number of libraries use __ for their header guards, so I'd be
very surprised if this were to ever cause problems. For example,
freetype, gmp, mpfr and glib on my Mac use __. A bunch of others use a
single _, and those with _ or __ are a distinct minority (the situation
is even more pronounced for the stuff in /usr/include). So I think you
can sleep comfortably.