Don't lowercase Markdown link definition labels

src/language-markdown/clean.js

@@ -43,10 +43,7 @@ function clean(ast, newObj, parent) {
   }
 
   if (ast.type === "definition" || ast.type === "linkReference") {
-    newObj.label = ast.label
-      .trim()
-      .replace(/[\t\n ]+/g, " ")
-      .toLowerCase();
+    newObj.label = ast.label.trim().replace(/[\t\n ]+/g, " ");
   }
 
   if (

src/language-markdown/printer-markdown.js

@@ -352,15 +352,15 @@ function genericPrint(path, options, print) {
         printChildren(path, options, print),
         "]",
         node.referenceType === "full"
-          ? ["[", node.identifier, "]"]
+          ? ["[", node.label, "]"]
           : node.referenceType === "collapsed"
           ? "[]"
           : "",
       ];
     case "imageReference":
       switch (node.referenceType) {
         case "full":
-          return ["![", node.alt || "", "][", node.identifier, "]"];
+          return ["![", node.alt || "", "][", node.label, "]"];
         default:
           return [
             "![",
@@ -373,7 +373,7 @@ function genericPrint(path, options, print) {
       const lineOrSpace = options.proseWrap === "always" ? line : " ";
       return group([
         "[",
-        node.identifier,
+        node.label,
         "]:",
         indent([
           lineOrSpace,
@@ -390,7 +390,7 @@ function genericPrint(path, options, print) {
     case "footnote":
       return ["[^", printChildren(path, options, print), "]"];
     case "footnoteReference":
-      return ["[^", node.identifier, "]"];
+      return ["[^", node.label, "]"];
     case "footnoteDefinition": {
       const nextNode = path.getParentNode().children[path.getName() + 1];
       const shouldInlineFootnote =
@@ -402,7 +402,7 @@ function genericPrint(path, options, print) {
               node.children[0].position.end.line));
       return [
         "[^",
-        node.identifier,
+        node.label,
         "]: ",
         shouldInlineFootnote
           ? printChildren(path, options, print)

tests/format/markdown/linkReference/__snapshots__/jsfmt.spec.js.snap

@@ -182,6 +182,36 @@ proseWrap: "never"
 ================================================================================
 `;
 
+exports[`simple-pascal-case-definition.md - {"proseWrap":"always"} format 1`] = `
+====================================options=====================================
+parsers: ["markdown"]
+printWidth: 80
+proseWrap: "always"
+                                                                                | printWidth
+=====================================input======================================
+[\`AsyncGeneratorFunction\`]: ./index.html
+
+=====================================output=====================================
+[\`AsyncGeneratorFunction\`]: ./index.html
+
+================================================================================
+`;
+
+exports[`simple-pascal-case-definition.md - {"proseWrap":"never"} format 1`] = `
+====================================options=====================================
+parsers: ["markdown"]
+printWidth: 80
+proseWrap: "never"
+                                                                                | printWidth
+=====================================input======================================
+[\`AsyncGeneratorFunction\`]: ./index.html
+
+=====================================output=====================================
+[\`AsyncGeneratorFunction\`]: ./index.html
+
+================================================================================
+`;
+
 exports[`title.md - {"proseWrap":"always"} format 1`] = `
 ====================================options=====================================
 parsers: ["markdown"]

tests/format/markdown/linkReference/simple-pascal-case-definition.md

@@ -0,0 +1 @@
+[`AsyncGeneratorFunction`]: ./index.html