Add anychar' as alias to anything' in rx (bug#37659)

* lisp/emacs-lisp/rx.el (rx--translate-symbol, rx--builtin-symbols, rx):
* test/lisp/emacs-lisp/rx-tests.el (rx-atoms):
* doc/lispref/searching.texi (Rx Constructs):
* etc/NEWS:
Add `anychar', an alias for `anything'.  Since `anychar' is more
descriptive (and slightly shorter), treat it as the preferred name.

doc/lispref/searching.texi

@@ -1220,7 +1220,8 @@ Corresponding string regexp: @samp{[^@dots{}]}, @samp{\S@var{code}},
 Match any character except a newline.@*
 Corresponding string regexp: @samp{.} (dot)
 
-@item @code{anything}
+@item @code{anychar}, @code{anything}
+@cindex @code{anychar} in rx
 @cindex @code{anything} in rx
 Match any character.@*
 Corresponding string regexp: @samp{.\|\n} (for example)

etc/NEWS

@@ -1854,6 +1854,10 @@ at run time, instead of a constant string.
 *** New rx extension mechanism: 'rx-define', 'rx-let', 'rx-let-eval'.
 These macros add new forms to the rx notation.
 
++++
+*** 'anychar' is now an alias for 'anything'
+Both match any single character; 'anychar' is more descriptive.
+
 ** Frames
 
 +++

lisp/emacs-lisp/rx.el

@@ -126,7 +126,6 @@ Each entry is:
       (get name 'rx-definition)))
 
 ;; TODO: Additions to consider:
-;; - A better name for `anything', like `any-char' or `anychar'.
 ;; - A name for (or), maybe `unmatchable'.
 ;; - A construct like `or' but without the match order guarantee,
 ;;   maybe `unordered-or'.  Useful for composition or generation of
@@ -138,7 +137,7 @@ Each entry is:
     ;; Use `list' instead of a quoted list to wrap the strings here,
     ;; since the return value may be mutated.
     ((or 'nonl 'not-newline 'any) (cons (list ".") t))
-    ('anything                    (rx--translate-form '(or nonl "\n")))
+    ((or 'anychar 'anything)      (rx--translate-form '(or nonl "\n")))
     ((or 'bol 'line-start)        (cons (list "^") 'lseq))
     ((or 'eol 'line-end)          (cons (list "$") 'rseq))
     ((or 'bos 'string-start 'bot 'buffer-start) (cons (list "\\`") t))
@@ -913,7 +912,7 @@ can expand to any number of values."
   "List of built-in rx function-like symbols.")
 
 (defconst rx--builtin-symbols
-  (append '(nonl not-newline any anything
+  (append '(nonl not-newline any anychar anything
             bol eol line-start line-end
             bos eos string-start string-end
             bow eow word-start word-end
@@ -1016,7 +1015,7 @@ CHAR           Match a literal character.
                 can be (any ...), (syntax ...), (category ...),
                 or a character class.
 not-newline     Match any character except a newline.  Alias: nonl.
-anything        Match any character.
+anychar         Match any character.  Alias: anything.
 
 CHARCLASS       Match a character from a character class.  One of:
  alpha, alphabetic, letter   Alphabetic characters (defined by Unicode).

test/lisp/emacs-lisp/rx-tests.el

@@ -184,8 +184,8 @@
                  "ab")))
 
 (ert-deftest rx-atoms ()
-  (should (equal (rx anything)
-                 ".\\|\n"))
+  (should (equal (rx anychar anything)
+                 "\\(?:.\\|\n\\)\\(?:.\\|\n\\)"))
   (should (equal (rx line-start not-newline nonl any line-end)
                  "^...$"))
   (should (equal (rx bol string-start string-end buffer-start buffer-end