Build checks failing on macOS in `xrefdelta.tex`

[AlisdairM]

The macOS validation checks are consistently failing, complaining about missing entries immediately followed by a spurious entry for the same stable label:

Run ../tools/check-output.sh
incorrect entries in xrefdelta.tex:
missing ios::Init
spurious ios::Init
spurious move.iter.op.-
spurious move.iter.op.-=
missing move.iter.op.-
missing move.iter.op.-=
spurious reverse.iter.op-
spurious reverse.iter.op--
spurious reverse.iter.op-=
spurious reverse.iter.op.star
missing reverse.iter.op-
missing reverse.iter.op--
missing reverse.iter.op-=
missing reverse.iter.op.star
Error: Process completed with exit code 1.

[frederick-vs-ja]

The failure started to occur around 2025-04-10, but nothing in xrefprev or xrefdelta.tex was changed at that time.

[tkoeppe]

I think the issue is that the list is getting sorted differently on MacOS than on Linux, but I'm not sure why that's the case -- maybe something to do with locales? I don't have a Mac to test.

[AlisdairM]

Should we disable the Mac runner until this issue is tracked and fixed? It causes the Linux build to stop early too.

[tkoeppe]

Does anyone know anyone who has a Mac and could try this out? Maybe there's an easy fix. Check also whether it's about BSD tools vs GNU tools (my expectation is that we use GNU tools everywhere), and also whether it has to do with locales.

[AlisdairM]

I have a Mac :)
I do not know our tooling though. I can test patches with direction, but not good to diagnose and solve the problem.