Document behavior of collation on Cygwin

* test/automated/fns-tests.el (fns-tests-collate-sort): Mark as
expected failure on Cygwin.
* doc/lispref/strings.texi (Text Comparison): Document that
punctuation and whitespace are not ignored for sorting on Cygwin.

1 files changed, 5 insertions, 2 deletions

diff --git a/doc/lispref/strings.texi b/doc/lispref/strings.texi
index 143de82d9ad..f8685d9312c 100644
--- a/doc/lispref/strings.texi
+++ b/doc/lispref/strings.texi
@@ -584,8 +584,8 @@ determined by the lexicographic order of the characters contained in
 relations between these characters.  Usually, it is defined by the
 @var{locale} environment Emacs is running with.
 
-For example, punctuation and whitespace characters might be considered
-less significant for @ref{Sorting,,sorting}.
+For example, punctuation and whitespace characters might be ignored
+for sorting (@pxref{Sequence Functions}):
 
 @example
 @group
@@ -594,6 +594,9 @@ less significant for @ref{Sorting,,sorting}.
 @end group
 @end example
 
+This behavior is system-dependent; punctuation and whitespace are
+never ignored on Cygwin, regardless of locale.
+
 The optional argument @var{locale}, a string, overrides the setting of
 your current locale identifier for collation.  The value is system
 dependent; a @var{locale} @code{"en_US.UTF-8"} is applicable on POSIX