updating_binary_builds_2024.txt

Notes on how to update our binary builds for PyPI uploads.


* BACKGROUND: THE PROBLEM:

Since we use delocate to copy shared libs (fftw, gsl, etc.) into our wheel, so the user
doesn't need to worry about installing them, the wheels need to be single-binary.

Currently, python setup.py bdist_wheel automatically generates a "universal2" wheel,
e.g., pyimfit-0.12.2-cp312-cp312-macosx_10_9_universal2.whl
which does indeed have a universal2 version of the main .so library file.
BUT if we're using delocate on our Intel MBPro, it will copy the x86-64 shared libs
(the only ones that exist!) into the .dylibs/ subdirectory inside the wheel.

This is fine for running x86-64 versions of Python, since they'll load the x86-64 part
of the .so file and link to the x86-64 shared libs. But this *won't* work under arm64
Python, which will load the arm64 version of the .so file, but then try to link against
the x86-64 shared libs.

(Presumably the complementary problem will obtain if we build the wheel on an arm64 machine
like my M1 MBPro.)


HOW TO INSPECT A WHEEL

$ wheel unpack pyimfit-0.12.2-cp312-cp312-macosx_10_9_universal2.whl

This creates a directory pyimfit-0.12.2/
	pyimfit/ -- has module files, including the binary library file, as well as the
		.dylibs subdirectory with shared libs copied in by delocate
	pyimfit-0.12.2.dist-info/ -- assorted metadata
		NOTE that the WHEEL file in this subdirectory has a "Tag:" entry with the
		python, macos, and binary info, e.g.
		Tag: cp312-cp312-macosx_10_9_universal2


* IDEAL FINAL APPROACH:

Generage single-binary wheels (e.g., separate x86-64 and arm64 wheels, *not* universal2 wheels)

Then upload all of these to PyPI (along with the source-only Linux wheel).



* ONE APPROACH

Generate the universal2 wheels as we currently do, then edit them to remove the non-native
code (e.g. arm64 if building on x86-64) and rename the wheel

We should probably also rename the "Tag:"" entry in pyimfit-<version>.dist-info/WHEEL,
which currently is
Tag: cp312-cp312-macosx_10_9_universal2



* POSSIBLE WAYS TO GENERATE SINGLE-BINARY OUTPUT WHEELS PROPERLY:

https://github.com/pypa/wheel/issues/573
https://github.com/pypa/cibuildwheel/blob/93542c397cfe940bcbb8f1eff5c37d345ea16653/cibuildwheel/macos.py#L247-L260