[issue36721] Add pkg-config python-3.8-embed

[STINNER Victor]

STINNER Victor <vstinner at redhat.com> added the comment:

I mark this issue as a release blocker: bpo-21536 basically broke the compilation of all applications which embed Python. IMHO this issue is the best solution to fix it.


> I don't understand the need for this.

Oh. Let me explain this issue differently. There are two use cases for libpython:

* Build a C extension and load it in Python: use case called "pyext" by waf
* Embed Python into an application: use case called "pyembed" by waf

My bpo-21536 broke waf "pyembed" which fails to detect Python. waf "pyembed" creates a C program which calls Py_Initialize(), but the linker fails to locate Py_Initialize() symbol. To embed Python into an application, we really need to link the application to libpython: we need -lpython3.8.

In Python 3.7, "pyext" and "pyembed" use cases were covered both by default "python3.7-config --libs" and "pkg-config python3.7 --libs" configuration.

In Python 3.8, we now have to distinguish both use cases and provide *different* configuration depending if binary must be linked to libpython or not.

More info about waf breakage in my waf bug report:
https://gitlab.com/ita1024/waf/issues/2239

FYI the waf breakage was discovered by trying to build libtdb on Fedora Rawhide with Python 3.8a4, it's a dependency of Samba which embeds Python:
https://bugzilla.redhat.com/show_bug.cgi?id=1711638

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nosy: +lukasz.langa
priority: normal -> release blocker

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