Not all characters literals are font locked properly

[yuhan0]

Expected behavior

Character literals such as \A should be highlighted with clojure-character-face.

The official guide does not explicitly state what is allowed, but current Clojure readers accept practically any Unicode character such \λ, \字, even \ (space)

Actual behavior

Only punctuation, numbers and lowercase characters are correctly highlighted according to the current rules.

clojure-mode/clojure-mode.el

Line 865 in 147bf84

("\\\\\\([[:punct:]]\\|[a-z0-9]+\\>\\)" 0 'clojure-character-face)

Steps to reproduce the problem

Insert \A in a clojure-mode buffer

Environment & Version information

clojure-mode version information

clojure-mode (version 5.11.0)

Emacs version

26.3

Operating system

macOS 10.14

[yuhan0]

The actual rules could perhaps be expressed in a regexp like

(rx "\\" (or "newline" "space" "tab" "formfeed" "backspace" "return"
             (: "u" (= 4 (char "0-9A-Fa-f")))
             (: "o" (repeat 1 3 (char "0-7")))
             any)
    (or symbol-end space))
;; =>
"\\\\\\(?:newline\\|space\\|tab\\|formfeed\\|backspace\\|return\\|u[0-9A-Fa-f]\\{4\\}\\|o[0-7]\\{1,3\\}\\|.\\)\\(?:\\_>\\|[[:space:]]\\)"

or the more lenient (rx "\\" (+ any) (or symbol-end space))

[bbatsov]

Agreed. Seems I messed up that regex.