Update MD053/link-image-reference-definitions to handle references within references (i.e., Pandoc-style footnotes), verify Pandoc footnote indent is not treated as comment when markdown-it-footnote plugin is used (fixes #599).

test/snapshots/markdownlint-test-scenarios.js.md

@@ -32084,6 +32084,80 @@ Generated by [AVA](https://avajs.dev).
       `,
     }
 
+## pandoc-footnotes.md
+
+> Snapshot 1
+
+    {
+      errors: [
+        {
+          errorContext: '[Another2]: https://www.exampl...',
+          errorDetail: 'Unused link or image reference definition: "another2"',
+          errorRange: [
+            1,
+            56,
+          ],
+          fixInfo: {
+            deleteCount: -1,
+          },
+          lineNumber: 36,
+          ruleDescription: 'Link and image reference definitions should be needed',
+          ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/Rules.md#md053',
+          ruleNames: [
+            'MD053',
+            'link-image-reference-definitions',
+          ],
+        },
+      ],
+      fixed: `# Pandoc Footnotes␊
+      ␊
+      > Examples taken from [GitHub issue 599](https://github.com/DavidAnson/markdownlint/issues/599)␊
+      ␊
+      ## Example with Pandoc Footnotes␊
+      ␊
+      A sentence with footnotes: [^1] [^2]␊
+      A sentence with named footnotes: [^name] [^name2]␊
+      A sentence with a link reference: [Pandoc's User Guide][Pandoc1]␊
+      ␊
+      [^1]: I am a footnote!␊
+      [^2]: I reference a [PCW][PCW1] article!␊
+      [^name]: I am a footnote with name!␊
+      [^name2]: I am also a named footnote! I also reference the [PCW][PCW1] article!␊
+      ␊
+      [PCW1]: https://www.example.com/article.html␊
+      [Pandoc1]: https://pandoc.org/MANUAL.html#extension-footnotes␊
+      ␊
+      ## Example with Long Pandoc Footnotes␊
+      ␊
+      A sentence with a long footnotes: [^long] [^longer] [^longest]␊
+      ␊
+      [^long]: I am a long footnote!␊
+          I don't do any harm :)␊
+      [^longer]: I am a longer footnote. I do reference the [PCW][PCW2] article.␊
+          I do harm. Though, not here: [Pandoc's User Guide][Pandoc2]␊
+      [^longest]: I am the longest footnote. I also reference the [PCW][PCW2] article.␊
+      ␊
+          I am a harmful new block of text: [Another][Another2]␊
+      ␊
+      > The previous line of text is treated by CommonMark as an indented code block.␊
+      > To handle it as a Pandoc footnote, consider the \`markdown-it-footnote\` plugin.␊
+      ␊
+      [PCW2]: https://www.example.com/article.html␊
+      [Pandoc2]: https://pandoc.org/MANUAL.html#extension-footnotes␊
+      ␊
+      ## GitHub Footnotes␊
+      ␊
+      Sample footnotes [^3] [^note3]␊
+      ␊
+      [^3]: A line␊
+        A new line␊
+      ␊
+      [^note3]:␊
+          I am a new block of text␊
+          With a new line as well␊
+      `,
+    }
+
 ## proper-names-alternate.md
 
 > Snapshot 1
@@ -34592,6 +34666,14 @@ Generated by [AVA](https://avajs.dev).
       Unmatched [ in text␊
       ␊
       Hidden reference: [hidden][] {MD052}␊
+      ␊
+      ## Link references inside reference definitions␊
+      ␊
+      Text with a [^footnote] in it␊
+      ␊
+      [^footnote]: Footnote with an [embedded-reference][] in it␊
+      ␊
+      [embedded-reference]: https://example.com/embedded-reference␊
       `,
     }