building 3.7.1 from source, _ctypes and libffi troubles

[Anssi Saari]

"Fetchinson . via Python-list" <python-list at python.org> writes:

> And as far as I know pkg-config is used by python's configure script
> so everything should be fine. I also set
> LD_LIBRARY_PATH=/home/fetch/opt/lib:/home/fetch/opt/lib64 and also
> C_INCLUDE_PATH=/home/fetch/opt/include

I looked into this a little. I found that setting C_INCLUDE_PATH as you
did disables finding libffi headers since pkg-config prints nothing with
pkg-config --cflags libffi then and it seems the headers are found with
pkg-config.

As for the libraries, detect_modules() in setup.py wants to find extra
library directories from the generated makefile so you need to make sure
they actually go in there, like this for example:

LDFLAGS=`pkg-config --libs-only-L libffi` ./configure

Then you'll have CONFIGURE_LDFLAGS and PY_LDFLAGS set in the generated
makefile and setup.py will pick up the directory from there.

Anyways, hope it helps. This worked for me on Ubuntu 16.04.5 LTS.