[New-bugs-announce] [issue34212] Cygwin link failure with builtin modules since issue30860

[Erik Bray]

New submission from Erik Bray <erik.m.bray at gmail.com>:

Since issue30860, libpython is no longer able to be linked as a shared library, because built-in modules are not compiled with the correct external linkage flags.

This is due to the removal of -DPy_BUILD_CORE, which in pyport.h is used to control wither __declspec(dllexport) is used as opposed to __declspec(dllimport).

Fortunately Eric Snow already added in https://github.com/python/cpython/pull/3458 a new flag Py_BUILD_CORE_BUILTIN which is used sparingly on Windows, and which should also be used, e.g. on Cygwin or MinGW, when compiling modules that are linked into libpython as built-ins.  It sets the right external linkage flags without carrying the additional weight of Py_BUILD_CORE.

This along with issue34211 need to be fixed in order to get Python 3.7+ building on Cygwin again.

----------
components: Build
keywords: 3.7regression
messages: 322316
nosy: erik.bray
priority: normal
severity: normal
status: open
title: Cygwin link failure with builtin modules since issue30860
versions: Python 3.7, Python 3.8

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue34212>
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