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gh-99942: correct the pkg-config/python-config flags for cygwin/android by eli-schwartz · Pull Request #100967 · python/cpython

…/android

On shared build configurations, Cygwin and Android need to link to
libpython. See bpo-21536.

This was corrected in distutils with an explicit check to only link when
libpython is built shared, but implemented in configure.ac
unconditionally. The correct approach is to follow distutils, which
includes a comment regarding why:

- on Android, a shared libpython is RTLD_LOCAL, and thus available only
  to the main executable, not exported to loaded modules, but a static
  libpython *is* the main executable and thus exported

- on Cygwin, symbols in shared libraries must be resolved at link time

It's actually not clear to me what to do for Cygwin. Cygwin doesn't
actually build static libpython successfully. If it did, then extensions
probably need to be linked to the import library for the executable,
rather than the full static library. So omitting this here is probably
correct, but incomplete. Either way, it won't matter until other fixes
are made.

dnicolodi pushed a commit to dnicolodi/meson that referenced this pull request

Sep 8, 2023

dnicolodi pushed a commit to dnicolodi/meson that referenced this pull request

Sep 8, 2023

dnicolodi pushed a commit to dnicolodi/meson that referenced this pull request

Sep 8, 2023

dnicolodi pushed a commit to dnicolodi/meson that referenced this pull request

Sep 9, 2023

eli-schwartz added a commit to eli-schwartz/meson that referenced this pull request

Sep 22, 2023
…nt python

On python >=3.8, this information is expected to be encoded in the
sysconfig vars.

In distutils, it is always necessary to link to libpython on Windows;
for posix platforms, it depends on the value of LIBPYTHON (which is the
library to link to, possibly the empty string) as generated by
configure.ac and embedded into python.pc and python-config.sh, and then
coded a second time in the distutils python sources.

There are a couple of caveats which have ramifications for Cygwin and
Android:

- python.pc and python-config.sh disagree with distutils when python is
  not built shared. In that case, the former act the same as a shared
  build, while the latter *never* links to libpython

- python.pc disagrees with python-config.sh and distutils when python is
  built shared. The former never links to libpython, while the latter do

The disagreement is resolved in favor of distutils' behavior in all
cases, and python.pc is correct for our purposes on python 3.12; see:
python/cpython#100356
python/cpython#100967

Although it was not backported to older releases, Cygwin at least has
always patched in a fix for python.pc, which behavior is now declared
canonical. We can reliably assume it is always correct.

This is the other half of the fix for mesonbuild#7702

eli-schwartz added a commit to eli-schwartz/meson that referenced this pull request

Oct 2, 2023
…nt python

On python >=3.8, this information is expected to be encoded in the
sysconfig vars.

In distutils, it is always necessary to link to libpython on Windows;
for posix platforms, it depends on the value of LIBPYTHON (which is the
library to link to, possibly the empty string) as generated by
configure.ac and embedded into python.pc and python-config.sh, and then
coded a second time in the distutils python sources.

There are a couple of caveats which have ramifications for Cygwin and
Android:

- python.pc and python-config.sh disagree with distutils when python is
  not built shared. In that case, the former act the same as a shared
  build, while the latter *never* links to libpython

- python.pc disagrees with python-config.sh and distutils when python is
  built shared. The former never links to libpython, while the latter do

The disagreement is resolved in favor of distutils' behavior in all
cases, and python.pc is correct for our purposes on python 3.12; see:
python/cpython#100356
python/cpython#100967

Although it was not backported to older releases, Cygwin at least has
always patched in a fix for python.pc, which behavior is now declared
canonical. We can reliably assume it is always correct.

This is the other half of the fix for mesonbuild#7702

eli-schwartz added a commit to eli-schwartz/meson that referenced this pull request

Oct 3, 2023
…nt python

On python >=3.8, this information is expected to be encoded in the
sysconfig vars.

In distutils, it is always necessary to link to libpython on Windows;
for posix platforms, it depends on the value of LIBPYTHON (which is the
library to link to, possibly the empty string) as generated by
configure.ac and embedded into python.pc and python-config.sh, and then
coded a second time in the distutils python sources.

There are a couple of caveats which have ramifications for Cygwin and
Android:

- python.pc and python-config.sh disagree with distutils when python is
  not built shared. In that case, the former act the same as a shared
  build, while the latter *never* links to libpython

- python.pc disagrees with python-config.sh and distutils when python is
  built shared. The former never links to libpython, while the latter do

The disagreement is resolved in favor of distutils' behavior in all
cases, and python.pc is correct for our purposes on python 3.12; see:
python/cpython#100356
python/cpython#100967

Although it was not backported to older releases, Cygwin at least has
always patched in a fix for python.pc, which behavior is now declared
canonical. We can reliably assume it is always correct.

This is the other half of the fix for mesonbuild#7702

(cherry picked from commit 2d6c109)

robtaylor pushed a commit to robtaylor/meson that referenced this pull request

Oct 14, 2023
…nt python

On python >=3.8, this information is expected to be encoded in the
sysconfig vars.

In distutils, it is always necessary to link to libpython on Windows;
for posix platforms, it depends on the value of LIBPYTHON (which is the
library to link to, possibly the empty string) as generated by
configure.ac and embedded into python.pc and python-config.sh, and then
coded a second time in the distutils python sources.

There are a couple of caveats which have ramifications for Cygwin and
Android:

- python.pc and python-config.sh disagree with distutils when python is
  not built shared. In that case, the former act the same as a shared
  build, while the latter *never* links to libpython

- python.pc disagrees with python-config.sh and distutils when python is
  built shared. The former never links to libpython, while the latter do

The disagreement is resolved in favor of distutils' behavior in all
cases, and python.pc is correct for our purposes on python 3.12; see:
python/cpython#100356
python/cpython#100967

Although it was not backported to older releases, Cygwin at least has
always patched in a fix for python.pc, which behavior is now declared
canonical. We can reliably assume it is always correct.

This is the other half of the fix for mesonbuild#7702

nirbheek pushed a commit to mesonbuild/meson that referenced this pull request

Oct 17, 2023
…nt python

On python >=3.8, this information is expected to be encoded in the
sysconfig vars.

In distutils, it is always necessary to link to libpython on Windows;
for posix platforms, it depends on the value of LIBPYTHON (which is the
library to link to, possibly the empty string) as generated by
configure.ac and embedded into python.pc and python-config.sh, and then
coded a second time in the distutils python sources.

There are a couple of caveats which have ramifications for Cygwin and
Android:

- python.pc and python-config.sh disagree with distutils when python is
  not built shared. In that case, the former act the same as a shared
  build, while the latter *never* links to libpython

- python.pc disagrees with python-config.sh and distutils when python is
  built shared. The former never links to libpython, while the latter do

The disagreement is resolved in favor of distutils' behavior in all
cases, and python.pc is correct for our purposes on python 3.12; see:
python/cpython#100356
python/cpython#100967

Although it was not backported to older releases, Cygwin at least has
always patched in a fix for python.pc, which behavior is now declared
canonical. We can reliably assume it is always correct.

This is the other half of the fix for #7702

Volker-Weissmann pushed a commit to Volker-Weissmann/meson that referenced this pull request

May 1, 2025
…nt python

On python >=3.8, this information is expected to be encoded in the
sysconfig vars.

In distutils, it is always necessary to link to libpython on Windows;
for posix platforms, it depends on the value of LIBPYTHON (which is the
library to link to, possibly the empty string) as generated by
configure.ac and embedded into python.pc and python-config.sh, and then
coded a second time in the distutils python sources.

There are a couple of caveats which have ramifications for Cygwin and
Android:

- python.pc and python-config.sh disagree with distutils when python is
  not built shared. In that case, the former act the same as a shared
  build, while the latter *never* links to libpython

- python.pc disagrees with python-config.sh and distutils when python is
  built shared. The former never links to libpython, while the latter do

The disagreement is resolved in favor of distutils' behavior in all
cases, and python.pc is correct for our purposes on python 3.12; see:
python/cpython#100356
python/cpython#100967

Although it was not backported to older releases, Cygwin at least has
always patched in a fix for python.pc, which behavior is now declared
canonical. We can reliably assume it is always correct.

This is the other half of the fix for mesonbuild#7702