Collation tests in fns-tests.el

[Ken Brown]

Hi Michael,

I'm curious why you put the following test in fns-tests.el:

;; Punctuation and whitespace characters are not taken into account
  ;; for collation in other locales.
  (should
   (equal
    (sort '("11" "12" "1 1" "1 2" "1.1" "1.2")
          (lambda (a b)
            (let ((w32-collate-ignore-punctuation t))
              (string-collate-lessp
               a b (if (eq system-type 'windows-nt) "enu_USA" "en_US.UTF-8")))))
    '("11" "1 1" "1.1" "12" "1 2" "1.2")))

This suggests that punctuation and whitespace should definitely not be 
taken into account in non-POSIX locales.  But the docstring of 'sort' is 
much less definitive:

"This function obeys the conventions for collation order in your locale 
settings.  For example, punctuation and whitespace characters *might* be 
considered less significant for sorting."  [My emphasis.]

Is there some place where emacs relies on punctuation and whitespace 
being ignored?  That certainly isn't the case on all supported systems, 
nor is it mandated by POSIX.

Ken

P.S. My question is motivated by the fact that punctuation and 
whitespace are not ignored on Cygwin in non-POSIX locales, and it does 
not seem to be easy to make this happen.  If you're interested in the 
gory details, start here:

  https://www.cygwin.com/ml/cygwin/2015-10/msg00516.html