<aside> 💡 This is pretty outdated, as it applies only to Python 2.6.
It's kept around for posterity.
</aside>
If building from source on macOS, you might encounter this error:
build/temp.macosx-10.11-intel-2.6/_openssl.c:483:10: fatal error: 'openssl/opensslv.h' file not found
#include <openssl/opensslv.h>
^
1 error generated.
error: command 'clang' failed with exit status 1
This is pretty likely if you're having to install on Python 2.6 or earlier (as part of building/testing older releases), since there are no wheels for this version.
To solve this, you'll need homebrew, and will need to install a newer OpenSSL and point pip to it. Run:
$ brew install [email protected]
$ LDFLAGS="-L$(brew --prefix [email protected])/lib" \\
CFLAGS="-I$(brew --prefix [email protected])/include" \\
pip2.6 install cryptography