Restore Sequence conformance to FlattenSequence.Iterator (#18027)

airspeedswift · web-flow · commit 5fdf1074546c · 2018-07-18T08:31:04.000-07:00
diff --git a/stdlib/public/core/Flatten.swift b/stdlib/public/core/Flatten.swift
@@ -85,6 +85,8 @@ extension FlattenSequence.Iterator: IteratorProtocol {
   }
 }
 
+extension FlattenSequence.Iterator: Sequence { }
+
 extension FlattenSequence: Sequence {
   /// Returns an iterator over the elements of this sequence.
   ///
diff --git a/validation-test/stdlib/Collection/FlattenCollection.swift.gyb b/validation-test/stdlib/Collection/FlattenCollection.swift.gyb
@@ -66,10 +66,15 @@ tests.test("FlattenCollection instances (${traversal}${kind})") {
   do {
     let expected = ["apple", "orange", "banana", "grapefruit", "lychee"]
     let base = [["apple", "orange"], ["banana", "grapefruit"], ["lychee"]]
+    let flattened = Minimal${traversal}${kind}(elements: base).joined()
     check${traversal}${kind}(
       expected,
       Minimal${traversal}${kind}(elements: base).joined(),
       sameValue: { $0 == $1 })
+    checkSequence(
+      expected,
+      flattened.makeIterator(),
+      sameValue: { $0 == $1 })
   }
 }
 % end

Original file line number	Diff line number	Diff line change
`@@ -85,6 +85,8 @@ extension FlattenSequence.Iterator: IteratorProtocol {`
`85`	`85`	`}`
`86`	`86`	`}`
`87`	`87`
	`88`	`+extension FlattenSequence.Iterator: Sequence { }`
	`89`	`+`
`88`	`90`	`extension FlattenSequence: Sequence {`
`89`	`91`	`/// Returns an iterator over the elements of this sequence.`
`90`	`92`	`///`