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

[Max Nikulin <manikulin@gmail.com>]

On 20/11/2022 11:18, Ihor Radchenko wrote:
>> Max Nikulin writes:
>>>   From my point of view it is a reason to file an Emacs bug because I get
>>>
>>>       (string-collate-lessp "a" "B" "C" t) ; => t
>>
>> See https://debbugs.gnu.org/cgi/bugreport.cgi?bug=59275
> 
> According to the discussion on debbugs, it looks like we can use
> `compare-strings' instead. It will be independent of the system locale
> and always follow Unicode rules.
> 
> 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.

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.

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.)