Re: test-org-table/sort-lines: Failing test on macOS

[Ihor Radchenko <yantar92@posteo.net>]

Max Nikulin <manikulin@gmail.com> writes:

>> However, I am not sure if ignoring locale is something we really want.
>> WDYT?
>
> I think we should keep `string-collate-lessp' in the 
> `org-table-sort-lines' implementation. Users expect sorting accordingly 
> to their locales. However it is better to add a warning to 
> `org-table-sort-lines' docstring and to the manual that caseless sort 
> depends on its implementation in libc, so currently it does not work in 
> clang/llvm and so e.g. on MacOS.

Sounds reasonable.

Note that not only `org-table-sort-lines' is using
`string-collate-lessp'. The full list of functions potentially affected
by libc sorting is:

1. Bibliography order in `org-cite-basic-export-bibliography'
   (via org-cite-basic--sort-keys -> org-cite-basic--field-less-p)
2. `org-sort-list'
3. `org-table-sort-lines'
4. `org-set-tags' (tag order), when `org-tags-sort-function' is set to
   "Alphabetical" or "Reverse alphabetical".
5. `org-sort-entries'
6. Agenda sorting, when alphabetical sorting is involved
7. `org-map-entries'

I am not 100% sure where we should add the information to
docstring/manual and where we should not.

> Concerning the test, I would split the current testcase into 2 parts 
> depending on WITH-CASE argument, check if caseless collation is 
> available and skip the related test otherwise.

How can we check the availability?

> As to the thread linked to the bug report 
> https://lists.gnu.org/archive/html/emacs-devel/2022-07/msg00940.html 
> "case-insensitive string comparison." Tue, 19 Jul 2022 13:27:50 -0400, 
> there is a link
> https://stackoverflow.com/questions/319426/how-do-i-do-a-case-insensitive-string-comparison
> unrelated to the issue, but comments and answers there describe a lot of 
> pitfalls and explain why string comparison ignoring case is not trivial. 
> (It is a Sisyphean task in some sense, I like the comment on 3 sigmas.)

Indeed. Also, see https://nullprogram.com/blog/2014/06/13/. However,
what we are concerned about here is consistency. Not the pitfalls per
se.

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
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