Merge from origin/emacs-28

ae1ace1cf4 Adjust help-fns.el tests for recent change
04bdcf4aaa * src/terminal.c (Fframe_terminal): Use active voice
7fa491a9e9 Improve 'terminal-live-p' docstring some more
b9ac8c29ae Improve terminal-live-p docstring
0b4c81a152 * lisp/net/tramp-gvfs.el (tramp-gvfs-dbus-event-vector): F...
8f8373170f * lisp/progmodes/cperl-mode.el: Don't mention obsolete arc...
25bc330a6d Make 'describe-function' say "byte-compiled" when appropriate
2b31e667be ;Improve documentation of locale-specific string comparison

1 files changed, 15 insertions, 6 deletions

diff --git a/doc/lispref/strings.texi b/doc/lispref/strings.texi
index addf195fad2..cb9019daa9b 100644
--- a/doc/lispref/strings.texi
+++ b/doc/lispref/strings.texi
@@ -567,11 +567,19 @@ equal with respect to collation rules.  A collation rule is not only
 determined by the lexicographic order of the characters contained in
 @var{string1} and @var{string2}, but also further rules about
 relations between these characters.  Usually, it is defined by the
-@var{locale} environment Emacs is running with.
-
-For example, characters with different coding points but
-the same meaning might be considered as equal, like different grave
-accent Unicode characters:
+@var{locale} environment Emacs is running with and by the Standard C
+library against which Emacs was linked@footnote{
+For more information about collation rules and their locale
+dependencies, see @uref{https://unicode.org/reports/tr10/, The Unicode
+Collation Algorithm}.  Some Standard C libraries, such as the
+@acronym{GNU} C Library (a.k.a.@: @dfn{glibc}) implement large
+portions of the Unicode Collation Algorithm and use the associated
+locale data, Common Locale Data Repository, or @acronym{CLDR}.
+}.
+
+For example, characters with different code points but the same
+meaning, like different grave accent Unicode characters, might, in
+some locales, be considered as equal:
 
 @example
 @group
@@ -759,7 +767,8 @@ The strings are compared by the numeric values of their characters.
 For instance, @var{str1} is considered less than @var{str2} if
 its first differing character has a smaller numeric value.  If
 @var{ignore-case} is non-@code{nil}, characters are converted to
-upper-case before comparing them.  Unibyte strings are converted to
+upper-case, using the current buffer's case-table (@pxref{Case
+Tables}), before comparing them.  Unibyte strings are converted to
 multibyte for comparison (@pxref{Text Representations}), so that a
 unibyte string and its conversion to multibyte are always regarded as
 equal.