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+#### Fix leading comments in mapped types with `readonly` (#13427 by @thorn0, @sosukesuzuki)
+
+<!-- prettier-ignore -->
+```tsx
+// Input
+type Type = {
+  // comment
+  readonly [key in Foo];
+};
+
+// Prettier stable
+type Type = {
+  readonly // comment
+  [key in Foo];
+};
+
+// Prettier main
+type Type = {
+  // comment
+  readonly [key in Foo];
+};
+```