[New-bugs-announce] [issue39399] Cross compilation using different libc is broken

[Andrew Aladjev]

New submission from Andrew Aladjev <aladjev.andrew at gmail.com>:

Hello. I am implementing python cross compilation using "x86_64-pc-linux-musl" toolchain: "x86_64-pc-linux-musl-emerge -v1 python:3.6". Please see the following build log https://gist.github.com/andrew-aladev/e10fa5a8151ffb3c5782edd64ae08b28.

We can see the following part:

Traceback (most recent call last):
  File "/usr/x86_64-pc-linux-musl/tmp/portage/dev-lang/python-3.6.9/image//usr/lib/python3.6/compileall.py", line 17, in <module>
    import struct
  File "/usr/x86_64-pc-linux-musl/tmp/portage/dev-lang/python-3.6.9/image/usr/lib/python3.6/struct.py", line 13, in <module>
    from _struct import *
ImportError: libc.so: cannot open shared object file: No such file or directory

It means that cross compilation of python is not reliable today by design. Python is trying to use PYTHON_FOR_BUILD for loading cross compiled modules. It is not possible in general case. PYTHON_FOR_BUILD should not try to load cross compiled modules.

Please see the following gentoo issue https://bugs.gentoo.org/705970. I've attached a gentoo specific workaround there.

----------
components: Build
messages: 360330
nosy: puchenyaka
priority: normal
severity: normal
status: open
title: Cross compilation using different libc is broken
type: behavior
versions: Python 2.7, Python 3.5, Python 3.6, Python 3.7, Python 3.8, Python 3.9

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<https://bugs.python.org/issue39399>
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