Make [:print:] support non-ASCII characters correctly

* src/regex.c (ISPRINT): Call 'printablep' for multibyte characters.
(BIT_PRINT): New bit mask.
(re_wctype_to_bit): Return BIT_PRINT for RECC_PRINT.
* src/character.c (printablep): New function.
* src/character.h (printablep): Add prototype.

* lisp/emacs-lisp/rx.el (rx): Doc fix: document the new behavior
of 'print', 'alnum', and 'alphabetic'.

* doc/lispref/searching.texi (Char Classes): Document the new
behavior of [:print:].

* etc/NEWS: Mention the new behavior of [:print:].

1 files changed, 6 insertions, 6 deletions

diff --git a/lisp/emacs-lisp/rx.el b/lisp/emacs-lisp/rx.el
index 20af59f2abf..a5a228e5876 100644
--- a/lisp/emacs-lisp/rx.el
+++ b/lisp/emacs-lisp/rx.el
@@ -969,16 +969,16 @@ CHAR
      space, and DEL.
 
 `printing', `print'
-     matches printing characters--everything except ASCII control chars
-     and DEL.
+     matches printing characters--everything except ASCII and non-ASCII
+     control characters, surrogates, and codepoints unassigned by Unicode.
 
 `alphanumeric', `alnum'
-     matches letters and digits.  (But at present, for multibyte characters,
-     it matches anything that has word syntax.)
+     matches alphabetic characters and digits.  (For multibyte characters,
+     it matches according to Unicode character properties.)
 
 `letter', `alphabetic', `alpha'
-     matches letters.  (But at present, for multibyte characters,
-     it matches anything that has word syntax.)
+     matches alphabetic characters.  (For multibyte characters,
+     it matches according to Unicode character properties.)
 
 `ascii'
      matches ASCII (unibyte) characters.