Sorry, we can't use FindPackage(OpenSSL) just yet. There is a problem on Debian jessie, the mismatch of their openssl and their cmake, that makes cmake die in this FindPackage. So we need to keep it until Debian has a proper fix.

This is already fixed in Debian jessie:

see Bug 826656

otto The error was in Jessie 8.5, but no more in Jessie 8.7 . Does this mean we can safely use FIND_PACKAGE(OpenSSL), or still need workaround?

wlad I don't feel confident in giving a blanket answer that it is always safe to use. We could add in the packaging debian/control file that the libssl-dev dependency is versioned to depend on 1.0.1t-1+deb8u6 or newer. I haven't done any testing at all, so this was just some very vague advice..

OpenSSL version status in Debian is visible at https://packages.debian.org/search?keywords=libssl-dev&searchon=names&suite=all&section=all

otto The question is about cmake rather than openssl. 8.5 just packaged an earlier version of cmake that died while parsing a newer openssl.h (extracting version). This is what the bug is about that georg had above : https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=826656 . That "packaging incompatible cmake and openssl " bug seems to be fixed in 8.7 . Thus the question, if we can ignore 8.5 bug that seems to be fixed.

So if your question is, can we assume that people running Debian 8 have all updates installed so they are at the level of 8.7 now and not at the level of 8.5 anymore? Then the answer would be yes, it is safe to assume that people running Debian 8 have all updates installed.

Applied georg's patch.