Handle styled-jsx in newLinkBehavior codemod (#36628)

Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>

Author: timneutkens

packages/next-codemod/transforms/__testfixtures__/new-link/styled-jsx.input.js

@@ -0,0 +1,26 @@
+import Link from 'next/link';
+
+const CustomLink = ({
+  href,
+  title,
+  children,
+}) => {
+  return (
+    <span className="link-container">
+      <Link href={href}>
+        <a className="link" title={title}>
+          {children}
+        </a>
+      </Link>
+      <style jsx>{`
+        .link {
+          text-decoration: none;
+          color: var(--geist-foreground);
+          font-weight: 500;
+        }
+      `}</style>
+    </span>
+  );
+};
+
+export default CustomLink;

packages/next-codemod/transforms/__testfixtures__/new-link/styled-jsx.output.js

@@ -0,0 +1,26 @@
+import Link from 'next/link';
+
+const CustomLink = ({
+  href,
+  title,
+  children,
+}) => {
+  return (
+    <span className="link-container">
+      <Link href={href} legacyBehavior>
+        <a className="link" title={title}>
+          {children}
+        </a>
+      </Link>
+      <style jsx>{`
+        .link {
+          text-decoration: none;
+          color: var(--geist-foreground);
+          font-weight: 500;
+        }
+      `}</style>
+    </span>
+  );
+};
+
+export default CustomLink;

packages/next-codemod/transforms/__tests__/new-link.test.js

@@ -9,7 +9,8 @@ const fixtures = [
   'excludes-links-with-legacybehavior-prop',
   'children-interpolation',
   'spread-props',
-  'link-string'
+  'link-string',
+  'styled-jsx',
 ]
 
 for (const fixture of fixtures) {

packages/next-codemod/transforms/new-link.ts

@@ -22,6 +22,13 @@ export default function transformer(file: FileInfo, api: API) {
       }
 
       const linkElements = $j.findJSXElements(variableName)
+      const hasStylesJSX = $j.findJSXElements('style').some((stylePath) => {
+        const $style = j(stylePath)
+        const hasJSXProp =
+          $style.find(j.JSXAttribute, { name: { name: 'jsx' } }).size() !== 0
+
+        return hasJSXProp
+      })
 
       linkElements.forEach((linkPath) => {
         const $link = j(linkPath).filter((childPath) => {
@@ -37,6 +44,15 @@ export default function transformer(file: FileInfo, api: API) {
           return
         }
 
+        // If file has <style jsx> enable legacyBehavior
+        // and keep <a> to  stay on the safe side
+        if (hasStylesJSX) {
+          $link
+            .get('attributes')
+            .push(j.jsxAttribute(j.jsxIdentifier('legacyBehavior')))
+          return
+        }
+
         const linkChildrenNodes = $link.get('children')
 
         // Text-only link children are already correct with the new behavior