New submission from STINNER Victor <vstin...@redhat.com>:
The bpo-21536 modified how C extensions are built: they are no longer linked to
libpython. The problem is that when an application embeds Python: the
application wants to be linked to libpython.
commit 8c3ecc6bacc8d0cd534f2b5b53ed962dd1368c7b (HEAD -> master,
upstream/master)
Author: Victor Stinner <vstin...@redhat.com>
Date: Thu Apr 25 20:13:10 2019 +0200
bpo-21536: C extensions are no longer linked to libpython (GH-12946)
On Unix, C extensions are no longer linked to libpython.
It is now possible to load a C extension built using a shared library
Python with a statically linked Python.
When Python is embedded, libpython must not be loaded with
RTLD_LOCAL, but RTLD_GLOBAL instead. Previously, using RTLD_LOCAL, it
was already not possible to load C extensions which were not linked
to libpython, like C extensions of the standard library built by the
"*shared*" section of Modules/Setup.
distutils, python-config and python-config.py have been modified.
I chose to modify distutils, python-config (shell) and python-config.py
(Python), but *not* Misc/python.pc (pkg-config).
Previously, we had:
$ pkg-config python-3.7 --libs
-lpython3.7m
$ python3.7-config --libs
-lpython3.7m -lcrypt -lpthread -ldl -lutil -lm
$ python3.7-config.py --libs
-lpython3.7m -lcrypt -lpthread -ldl -lutil -lm
Now, we get:
$ pkg-config python-3.8 --libs
-lpython3.8
$ python3.8-config --libs
-lcrypt -lpthread -ldl -lutil -lm -lm
$ python-config.py --libs
-lcrypt -lpthread -ldl -lutil -lm -lm
python-config and python-config.py can now be used to build C extensions, but
not to build an application embedding Python.
pkg-config should not be used to build a C extenstion since it links to
libpython, but we don't want to do that (see bpo-21536).
I'm not sure that different tools should return different results.
I propose:
* Add a new command "pkg-config python-3.8-embed"
* Add a new "--embed" option to python3.8-config and python3.8-config.py
commands
* Remove "-lpython@VERSION@@ABIFLAGS@" from "Libs: -L${libdir}
-lpython@VERSION@@ABIFLAGS@" of Misc/python.pc.in
On Windows, we already provide different binaries for embedded Python with
"-embed" suffix:
* Download Windows x86-64 embeddable zip file: python-3.7.3-embed-amd64.zip
* Download Windows x86-64 executable installer: python-3.7.3-amd64.exe
https://www.python.org/downloads/windows/
----------
components: Build
messages: 340853
nosy: doko, vstinner
priority: normal
severity: normal
status: open
title: Add pkg-config python-3.8-embed
versions: Python 3.8
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<https://bugs.python.org/issue36721>
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