Update MD052/reference-links-images to add a shortcut_syntax parameter for opting into shortcut scanning (fixes #915).

test/reference-links-and-images-shortcuts.md

@@ -0,0 +1,112 @@
+# Reference Links and Images (Shortcuts)
+
+## Shortcut Handling
+
+Validates the shortcut: [shortcut]
+
+[shortcut]: https://example.com/shortcut
+
+Missing reference: [missing] {MD052}
+
+## Valid Links
+
+Full reference link: [text][label]
+
+Collapsed reference link: [label][]
+
+Shortcut reference link: [label]
+
+Same line: [text][label] [label][] [label]
+
+Mixed case: [TEXT][LABEL] [LABEL][] [LABEL]
+
+With nested brackets: [t\[ex\]t][label]
+
+Shortcut inline code span: [`code`]
+
+Shortcut ending in colon: [colon]:
+
+## Invalid Links
+
+Missing: [missing] {MD052}
+
+> Missing in blockquote: [missing] {MD052}
+
+## Non-Links
+
+Code span: `[code]`
+
+Escaped left: \[escaped]
+
+Escaped right: [escaped\]
+
+Escaped both: \[escaped\]
+
+Unmatched [ in text
+
+Unmatched ] in text
+
+## Valid Images
+
+Full style: ![text][image0]
+
+Collapsed style: ![image1][]
+
+Shortcut style: ![image2]
+
+Image in link: [![text][image3]](link) [![image4][]](link) [![image5]](link)
+
+Image in shortcut link: [![text][image6]][unique6] [![image7][]][unique7] [![image8]][unique8]
+
+Wrapped in brackets: \[![text][unique9]\]
+
+Embedded \[in ![text][unique10] brackets\]
+
+## Invalid Images
+
+Missing: ![missing] {MD052}
+
+> Missing in blockquote: ![missing] {MD052}
+
+## Non-Images
+
+Escaped left: !\[escaped]
+
+Escaped right: ![escaped\]
+
+Escaped both: !\[escaped\]
+
+## Valid Footnotes
+
+Footnote[^1]
+
+## Invalid Footnotes
+
+Missing[^2] {MD052}
+
+## Valid Labels
+
+[label]: https://example.com/label
+[image0]: https://example.com/image0
+[image1]: https://example.com/image1
+[image2]: https://example.com/image2
+[image3]: https://example.com/image3
+[image4]: https://example.com/image4
+[image5]: https://example.com/image5
+[image6]: https://example.com/image6
+[image7]: https://example.com/image7
+[image8]: https://example.com/image8
+[`code`]: https://example.com/code
+[colon]: https://example.com/colon
+[unique6]: https://example.com/unique6
+[unique7]: https://example.com/unique7
+[unique8]: https://example.com/unique8
+[unique9]: https://example.com/unique9
+[unique10]: https://example.com/unique10
+[^1]: https://example.com/footnote {MD034}
+
+<!-- markdownlint-configure-file {
+  "reference-links-images": {
+    "shortcut_syntax": true
+  }
+} -->