emacs-30 856a58e2827: Update documentation of 'etags' regexps some more

[Paul Eggert]

branch: emacs-30
commit 856a58e28279139cfd6503917954fd75fcdd7e78
Author: Paul Eggert <eggert@cs.ucla.edu>
Commit: Paul Eggert <eggert@cs.ucla.edu>

    Update documentation of 'etags' regexps some more
    
    * doc/emacs/maintaining.texi (Etags Regexps):
    * doc/man/etags.1: Give more details about what's not supported.
---
 doc/emacs/maintaining.texi | 8 ++++++--
 doc/man/etags.1            | 5 ++++-
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/doc/emacs/maintaining.texi b/doc/emacs/maintaining.texi
index adda923af7c..bc7a47482a8 100644
--- a/doc/emacs/maintaining.texi
+++ b/doc/emacs/maintaining.texi
@@ -3094,8 +3094,12 @@ and all the C character escape sequences are supported: 
@samp{\a} for
 bell, @samp{\b} for back space, @samp{\e} for escape, @samp{\f} for
 formfeed, @samp{\n} for newline, @samp{\r} for carriage return,
 @samp{\t} for tab, and @samp{\v} for vertical tab.  In addition,
-@samp{\d} stands for the @code{DEL} character.  Shy groups are not
-supported by @command{etags}.
+@samp{\d} stands for the @code{DEL} character.  Otherwise,
+the regular expression syntax is the same as Emacs
+except that backslash escapes are the same
+as GNU grep (which means, for example, that shy groups are not supported),
+and @samp{[:ascii:]}, @samp{[:multibyte:]}, @samp{[:nonascii:]},
+@samp{[:word:]}, and @samp{[:unibyte:]} are not supported.
 
   Ideally, @var{tagregexp} should not match more characters than are
 needed to recognize what you want to tag.  If the syntax requires you
diff --git a/doc/man/etags.1 b/doc/man/etags.1
index 12c2afc88b2..d26e2445e44 100644
--- a/doc/man/etags.1
+++ b/doc/man/etags.1
@@ -185,7 +185,10 @@ useless characters.  If the match is such that more 
characters than
 needed are unavoidably matched by \fItagregexp\fP, it may be useful to
 add a \fInameregexp\fP, to narrow down the tag scope.  \fBctags\fP
 ignores regexps without a \fInameregexp\fP.  The syntax of regexps is
-the same as in emacs, except that shy groups are not supported.
+the same as in Emacs, except that backslash escapes are the same
+as GNU grep (which means, for example, that shy groups are not supported),
+and \fB[:ascii:]\fP, \fB[:multibyte:]\fP, \fB[:nonascii:]\fP,
+\fB[:word:]\fP, and \fB[:unibyte:]\fP are not supported.
 The following character escape sequences are supported:
 \\a, \\b, \\d, \\e, \\f, \\n, \\r, \\t, \\v, which respectively
 stand for the ASCII characters BEL, BS, DEL, ESC, FF, NL, CR, TAB, VT.