gh-99284: [ctypes] remove _use_broken_old_ctypes_structure_semantics_

[sobolevn]

• Issue: [ctypes] Do we still need _use_broken_old_ctypes_structure_semantics_? #99284

[sobolevn]

I've messed up the issue number, sorry!

[gpshead]

Looks like this hack was added in ~2006. Some research of existing code to see if anything still relies on it is warranted before merging, it seems very unlikely. if so we'd want a deprecation period.

[sobolevn]

Quoting the original issue:

I've never seen this before, so I went and searched for this on the internet: https://cs.github.com/?scopeName=All+repos&scope=&q=_use_broken_old_ctypes_structure_semantics_

I've done a minimal research. I was not able to find any references to it.
Even Google does not have any significant references: https://www.google.com/search?newwindow=1&q=_use_broken_old_ctypes_structure_semantics_&nfpr=1&sa=X&ved=2ahUKEwiXxoHT_av7AhUQuIsKHcpYAfAQvgUoAXoECAUQAg&biw=1280&bih=726&dpr=2

I don't feel qualified in this specific module and its history to make an educated decision here. However, deprecation period is always a good idea 👍

[vstinner]

LGTM, but please complete the doc.

This attribute was untested and undocumented. I never heard about it.

Looks like not a single GitHub project uses it.

I ran a code search in PyPI top 5000 projects: no projects use it.

$ ./search_pypi_top.py PYPI-2020-09-01/ '_use_broken_old_ctypes_structure_semantics_' -q

Found 0 matching lines in 0 projects

[gpshead]

Thanks! FWIW I also searched our huge internal codebase at Google, nothing found that uses this odd thing.