Avoid duplicated character classes in rx

For example, (any digit digit) should produce "[[:digit:]]",
not "[[:digit:][:digit:]]".

* lisp/emacs-lisp/rx.el (rx--translate-any): Deduplicate character classes.
* test/lisp/emacs-lisp/rx-tests.el (rx-any): Add test case.

1 files changed, 3 insertions, 1 deletions

diff --git a/test/lisp/emacs-lisp/rx-tests.el b/test/lisp/emacs-lisp/rx-tests.el
index 4ecc805aead..26e39f8c8ed 100644
--- a/test/lisp/emacs-lisp/rx-tests.el
+++ b/test/lisp/emacs-lisp/rx-tests.el
@@ -128,7 +128,9 @@
   (should (equal (rx (any) (not (any)))
                  "\\`a\\`[^z-a]"))
   (should (equal (rx (any "") (not (any "")))
-                 "\\`a\\`[^z-a]")))
+                 "\\`a\\`[^z-a]"))
+  (should (equal (rx (any space ?a digit space))
+                 "[a[:space:][:digit:]]")))
 
 (ert-deftest rx-pcase ()
   (should (equal (pcase "a 1 2 3 1 1 b"