Symbols with colon in the middle get wrong syntax highlighting

[daveliepmann]

Symbols with colons in the middle (like a:b) get separate font faces before and after the colon.

Expected behavior

Symbols or bindings with a single colon : not at beginning or end should be recognized as a single symbol unit for the purpose of syntax highlighting. Specifically, it seems they should get font-lock-variable-name-face.

Per the Clojure reader reference docs for symbols:

Symbols beginning or ending with ':' are reserved by Clojure. A symbol can contain one or more non-repeating ':'s.

Actual behavior

A symbol with a colon (not at beginning or end) in the name-defining position gets the correct font-face (apparently font-lock-variable-name-face), but other instances get default for the pre-colon portion and clojure-keyword-face thereafter.

This makes every usage of the symbol or binding to get styled like a half-keyword, half-symbol.

Steps to reproduce the problem

(ns repl.clojure-mode-font-bug-colon)

(let [foo:bar 1]
  foo:bar)

(def baz:qux 2)

baz:qux

(defn qqq:zzz [] 5)

qqq:zzz

Environment & Version information

clojure-mode version

clojure-mode (version nil)

However, jumping to a clojure font-face definition gives me clojure-mode-20230626.715. (The clojure-mode invocation was broken in my previous spring 2022 version, too. I installed with package-list-packages from melpa.)

Emacs version

GNU Emacs 28.2 (build 1, aarch64-apple-darwin22.1.0, Carbon Version 169 AppKit 2299) of 2022-12-10

Operating system

macOS Ventura 13.4

[daveliepmann]

the issue seems to be this snippet in clojure-font-lock-keywords:

(,(concat "\\(:\\{1,2\\}\\)\\(" clojure--keyword-sym-regexp "\\)")
       (1 'clojure-keyword-face)
       (2 'clojure-keyword-face))

https://github.com/clojure-emacs/clojure-mode/blob/master/clojure-mode.el#L1065