New submission from Michael Stapelberg <michael+pyt...@stapelberg.ch>:
(Tested with Python 3.7, but AFAICT, the situation hasn’t changed in Python
3.8.)
Python’s configure tries to fill the LIBFFI_INCLUDEDIR system variable with the
value of -I as returned by pkg-config libffi --cflags-only-I.
Python’s setup.py tries to determine whether libffi is present by searching a
couple of well-known library directories.
Both of these checks fail in my environment (think Linux From Scratch). I’m
setting the following environment variables:
CPATH=/home/michael/libffi-3.2.1/include
LIBRARY_PATH=/home/michael/libffi-3.2.1/lib64
gcc can build against libffi just fine:
% echo echo '#include <ffi.h>
> int main() {}' > foo.c
% gcc -o foo foo.c -lffi
% ldd foo
linux-vdso.so.1 (0x00007ffe4450a000)
libffi.so.6 => /home/michael/libffi-3.2.1/lib64/libffi.so.6
(0x00007f3935aba000)
libc.so.6 => /home/michael/glibc-2.27/lib/libc.so.6 (0x00007f3935902000)
/lib64/ld-linux-x86-64.so.2 =>
/home/michael/glibc-2.27/lib/ld-linux-x86-64.so.2 (0x00007f3935aca000)
However, when compiling Python, I’m getting the following error message,
resulting in the _ctypes module not being built:
INFO: Could not locate ffi libs and/or headers
Now, one issue is that pkg-config understands CPATH, so calling pkg-config
--cflags-only-I is not sufficient to obtain the include directory, one also
needs to clear CPATH:
% pkg-config libffi --cflags-only-I
% CPATH= pkg-config libffi --cflags-only-I
-I/home/michael/libffi-3.2.1/include
After patching this in configure, LIBFFI_INCLUDEDIR is set correctly, but the
build still fails, as the libffi shared object is located in my non-standard
path, which setup.py doesn’t check.
Without knowing much about the Python internals, it seems to me that both of
these issues would be fixed if Python stopped trying to find the libffi
include/lib locations and just used pkg-config to detect the required CFLAGS
and LDFLAGS, just like Python currently does with openssl.
Is there any reason we can’t use pkg-config for libffi like that?
Thanks!
----------
components: Installation
messages: 326572
nosy: stapelberg
priority: normal
severity: normal
status: open
title: libffi detection doesn’t work in my setup
type: compile error
versions: Python 3.7
_______________________________________
Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue34823>
_______________________________________
_______________________________________________
Python-bugs-list mailing list
Unsubscribe:
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
