fix(ex) #4238 and add test

CHANGES.md

@@ -10,6 +10,7 @@ Core Grammars:
 - fix(javascript) correctly highlight 'for await' again [wolfgang42][]
 - enh(csp) add missing directives / keywords from MDN (7 more) [Max Liashuk][]
 - enh(ada) add new `parallel` keyword, allow `[]` for Ada 2022 [Max Reznik][]
+- fix(ex) adds support for `?'` char literal and missing `defguardp` keyword [Kevin Bloch][]
 - fix(diff) fix unified diff hunk header regex to allow unpaired numbers [Chris Wilson][]
 - enh(php) support single line and hash comments in attributes, constructor and functions [Antoine Musso][]
 
@@ -18,6 +19,7 @@ CONTRIBUTORS
 [Josh Marchand]: https://github.com/yHSJ
 [Max Liashuk]: https://github.com/probil
 [Max Reznik]: https://github.com/reznikmm
+[Kevin Bloch]: https://github.com/codingthat
 [Chris Wilson]: https://github.com/sushicw
 [Antoine Musso]: https://github.com/hashar
 [Chester Moses]: https://github.com/Chester-Moses-HCL

src/languages/elixir.js

@@ -20,6 +20,7 @@ export default function(hljs) {
     "cond",
     "defstruct",
     "defguard",
+    "defguardp",
     "do",
     "else",
     "end",
@@ -228,7 +229,13 @@ export default function(hljs) {
     beginKeywords: 'defimpl defmodule defprotocol defrecord',
     end: /\bdo\b|$|;/
   });
+  const CHAR_LITERAL = {
+    scope: 'string',
+    match: /\?'/,
+    relevance: 0
+  };
   const ELIXIR_DEFAULT_CONTAINS = [
+    CHAR_LITERAL,
     STRING,
     REGEX_SIGIL,
     UPCASE_SIGIL,

test/detect/elixir/default.txt

@@ -10,6 +10,7 @@ guy = Person.new first_name: "Guy"
 guy.name
 
 defmodule ListServer do
+  defguardp apostrophe?(c) when c == ?'
   @moduledoc """
   This module provides an easy to use ListServer, useful for keeping
   lists of things.

test/markup/elixir/char-literal.expect.txt

@@ -0,0 +1,2 @@
+<span class="hljs-keyword">defguardp</span> apostrophe?(c) <span class="hljs-keyword">when</span> c == <span class="hljs-string">?&#x27;</span>
+<span class="hljs-keyword">defguardp</span> upper?(c) <span class="hljs-keyword">when</span> (c &gt;= ?A <span class="hljs-keyword">and</span> c &lt;= ?Z)

test/markup/elixir/char-literal.txt

@@ -0,0 +1,2 @@
+defguardp apostrophe?(c) when c == ?'
+defguardp upper?(c) when (c >= ?A and c <= ?Z)