// RUN: %target-swift-frontend -parse -primary-file %S/../Inputs/empty.swift %s -verify

struct A: Collection {
  struct Index: Comparable {}
}

extension A.Index {
  // Force validate "A".
}

// RUN: %target-swift-frontend -parse -primary-file %S/../Inputs/empty.swift %s -verify

struct A: Collection {
  struct Index: BidirectionalIndex {}
}

extension A.Index {
  // Force validate "A".
}

--- 
+++ 
@@ -1,7 +1,7 @@
 // RUN: %target-swift-frontend -parse -primary-file %S/../Inputs/empty.swift %s -verify
 
 struct A: Collection {
-  struct Index: BidirectionalIndex {}
+  struct Index: Comparable {}
 }
 
 extension A.Index {
Update test to refer to Comparable rather than BidirectionalIndex.
