In Python 3.9.0 and 3.9.1rc1 (Packages from Ubuntu Devel Branch or Fedora) the Method
int Py_FrozenMain(int, char**)
is missing in libpython3.9.so

Thus, when trying the provided freeze example via
freeze.py hello.py & make
one gets the linker error
/usr/bin/ld: frozen.o: in function `main': frozen/frozen.c:681: undefined reference to `Py_FrozenMain' .

In previous Python 3.8.x the bug does not show.

Thanks,
Chris

The same under Python 3.9.1 (Package from Debian bullseye/testing). As the method Py_FrozenMain is contained in the source code, maybe ist has something to do with the build process, a change in makefile? As far as I can see, the builder of the distribution packages call the makefile as provided.

Chris

The file containing the source code is Python/frozenmain.c .

I wrote PR 23730 to fix the issue. Would it be possible for you to test it?

Since Python 3.9, symbols which are not explicitly exported are no longer exported. Python now uses -fvisibility=hidden.

Dear Victor,

a simple test with the tools/freeze/hello.py example was successfull with your patch and the newest cpython from github.

1. git clone https://github.com/python/cpython.git
2. Applied a patch of your pull request
3. configure, make, amke install to xxx
4. freeze.py wants wants this for a very long time:
   ln -s /usr/local/lib/python3.10/config-3.10-x86_64-linux-gnu
     /usr/local/lib/python3.10/config-3.10
5. python3 cpython/Tools/freeze.py -o frozen hello.py
6. cd frozen; make; ./hello
   Helo world...

Thanks again,
Chris

New changeset b5c7b38f5ebbc84b5b80192db1743d3e1cdcf4c5 by Victor Stinner in branch 'master':
bpo-42591: Export missing Py_FrozenMain() symbol (GH-23730)
https://github.com/python/cpython/commit/b5c7b38f5ebbc84b5b80192db1743d3e1cdcf4c5

> a simple test with the tools/freeze/hello.py example was successfull with your patch and the newest cpython from github.

Oh great, thanks for your quick feedback! I applied your PR to master and I will backport it to 3.9.

New changeset 6b2ed385094839c1920b934f07d946bf049a3770 by Victor Stinner in branch '3.9':
bpo-42591: Export missing Py_FrozenMain() symbol (GH-23730) (GH-23734)
https://github.com/python/cpython/commit/6b2ed385094839c1920b934f07d946bf049a3770

Thanks Christian Bachmaier for the bug report, it's now fixed.

Christian Bachmaier:
> Thus, when trying the provided freeze example via
> freeze.py hello.py & make

Do you mean freeze.py from Tools/freeze/freeze.py? This tool seems to be broken for 4 years, since Python 3.6: bpo-42613.

> 4. freeze.py wants wants this for a very long time:
>    ln -s /usr/local/lib/python3.10/config-3.10-x86_64-linux-gnu
>      /usr/local/lib/python3.10/config-3.10

Oh, you fixed manually freeze.py?

> Do you mean freeze.py from Tools/freeze/freeze.py?

Yes, unfortunately I have to keep a large old system running and there are only few options left. It is a University learning system, where students upload program code and then a huge amount of automtic quality checks are executed within a sandbox. The grading is done in a half automtic way. A real alternative is not existing, we tried hard to find one...

> This tool seems to 
> be broken for 4 years, since Python 3.6: bpo-42613.
> 4. freeze.py wants wants this for a very long time:
>    ln -s /usr/local/lib/python3.10/config-3.10-x86_64-linux-gnu
>      /usr/local/lib/python3.10/config-3.10

The symlink does the trick. So it may be easy for you to fix that, so it does operate out of the box again.

Christian Bachmaier:
> The symlink does the trick. So it may be easy for you to fix that, so it does operate out of the box again.

I pushed a fix in bpo-42613. It would be great if you could test it.

See my manual test: https://bugs.python.org/issue42613#msg383153

If you can test it, I can backport the fix to stable branches.

Vistor Stinner:
> If you can test it, I can backport the fix to stable branches.

Seems to work like a charm. Basically I used the same testing setup as previously on Dec 10th under Debian testing/bullseye without step 2, as master already contains your fix.

Victor, many thanks again, you are great!