How to determine when being packaged under Debian?

[Jeffrey Walton <noloader@gmail.com>]

Hi Everyone,

I work with the Crypto++ project. Debian carries the project and makes
it available through the package
https://packages.debian.org/source/libcrypto++.

We have specific recommendations for packaging Crypto++ for
distribution (cf., http://cryptopp.com/wiki/Config.h#Recommendations).
Soon to be released Crypto 5.6.3 introduces two new defines, and we
feel distros should enable them by default. The defines are
CRYPTOPP_NO_UNALIGNED_DATA_ACCESS and CRYPTOPP_INIT_PRIORITY.

When being packaged for distribution, we want to fail the compile
unless the defines are in effect. However, we only want it to apply to
distros at this point (and not the general user community). We are not
trying to be rude; rather we are trying to ensure the library is in
the best state it can be to avoid problems on a mass scale.

(In Crypto++ 6.0, they will be in effect, and this wrinkle will go
away. But we can't make the breaking change on a patch-level revision
bump).

Is there a way I can detect when Debian is building the library for
packaging and distribution? Crypto++ does not use Autotools, so we
need to detect it in the Makefile or preprocessor.

Or, are there any other thoughts on strategy that we should consider?

Jeff