Update MD026/no-trailing-punctuation to ignore the trailing semicolon of HTML entity references (fixes #320).

doc/Rules.md

@@ -922,6 +922,10 @@ allowed by default because of how common it is in headings of FAQ-style document
 Setting the `punctuation` parameter to `""` allows all characters - and is
 equivalent to disabling the rule.
 
+Note: The trailing semicolon of
+[HTML entity references](https://en.wikipedia.org/wiki/List_of_XML_and_HTML_character_entity_references)
+like `©`, `©`, and `©` is ignored by this rule.
+
 Rationale: Headings are not meant to be full sentences. More information:
 <https://cirosantilli.com/markdown-style-guide#punctuation-at-the-end-of-headers>
 

lib/md026.js

@@ -5,6 +5,8 @@
 const { addError, allPunctuationNoQuestion, escapeForRegExp, forEachHeading } =
   require("../helpers");
 
+const endOfLineHtmlEntityRe = /&#?[0-9a-zA-Z]+;$/;
+
 module.exports = {
   "names": [ "MD026", "no-trailing-punctuation" ],
   "description": "Trailing punctuation in heading",
@@ -20,7 +22,7 @@ module.exports = {
       const { line, lineNumber } = heading;
       const trimmedLine = line.replace(/[\s#]*$/, "");
       const match = trailingPunctuationRe.exec(trimmedLine);
-      if (match) {
+      if (match && !endOfLineHtmlEntityRe.test(trimmedLine)) {
         const fullMatch = match[0];
         const column = match.index + 1;
         const length = fullMatch.length;

test/headings-with-html-entities.md

@@ -0,0 +1,26 @@
+# headings-with-html-entities
+
+<!-- markdownlint-disable heading-style -->
+
+## Copyright &copy; 2000
+
+## Copyright 2001 &copy;
+
+## Copyright 2002&copy;
+
+## Copyright 2003 &COPY;
+
+## Copyright 2004 &#x000A9;
+
+## Copyright 2005 &#169;
+
+## Copyright 2006 &#169; ##
+
+Copyright 2007 &copy;
+---------------------
+
+## Copyright 2008 {MD026} copy;
+
+## Copyright 2009 {MD026} #x000A9;
+
+## Copyright 2010 {MD026} #169;