fix: Fix backtick and code rendering in links (#3783)

Author: basilaiman

src/rules.ts

@@ -336,7 +336,7 @@ const tag = edit(
   .replace('attribute', /\s+[a-zA-Z:_][\w.:-]*(?:\s*=\s*"[^"]*"|\s*=\s*'[^']*'|\s*=\s*[^\s"'=<>`]+)?/)
   .getRegex();
 
-const _inlineLabel = /(?:\[(?:\\[\s\S]|[^\[\]\\])*\]|\\[\s\S]|`[^`]*`|[^\[\]\\`])*?/;
+const _inlineLabel = /(?:\[(?:\\[\s\S]|[^\[\]\\])*\]|\\[\s\S]|`+[^`]*?`+(?!`)|[^\[\]\\`])*?/;
 
 const link = edit(/^!?\[(label)\]\(\s*(href)(?:(?:[ \t]*(?:\n[ \t]*)?)(title))?\s*\)/)
   .replace('label', _inlineLabel)

test/specs/new/backticks_in_links.html

@@ -0,0 +1 @@
+<p><a href="https://example.com"><code>this is a backtick ` and it breaks stuff</code></a></p>

test/specs/new/backticks_in_links.md

@@ -0,0 +1 @@
+[`` this is a backtick ` and it breaks stuff ``](https://example.com)

test/specs/redos/backticks_alternating_in_link.html

@@ -0,0 +1 @@
+<p><a href="https://example.com"><code>a</code> a <code>a</code> a <code>a</code> a <code>a</code> a <code>a</code> a <code>a</code> a <code>a</code> a <code>a</code> a <code>a</code> a <code>a</code> a <code>a</code> a <code>a</code> a <code>a</code> a <code>a</code> a <code>a</code> a <code>a</code> a <code>a</code> a <code>a</code> a <code>a</code> a <code>a</code> a <code>a</code></a></p>

test/specs/redos/backticks_alternating_in_link.md

@@ -0,0 +1 @@
+[` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a ` a `](https://example.com)

test/specs/redos/backticks_in_link_label.html

@@ -0,0 +1 @@
+<p><a href="https://example.com">``````````````````````````````````````````````````````````````````````````````````````````````````</a></p>

test/specs/redos/backticks_in_link_label.md

@@ -0,0 +1 @@
+[``````````````````````````````````````````````````````````````````````````````````````````````````](https://example.com)