Fix dictionary merge bug under optimization

natecook1000 · DougGregor · commit 579f944f3a59 · 2017-05-03T14:55:31.000-07:00
(cherry picked from commit 3f68f28)
diff --git a/stdlib/public/core/HashedCollections.swift.gyb b/stdlib/public/core/HashedCollections.swift.gyb
@@ -4923,6 +4923,7 @@ internal enum _Variant${Self}Buffer<${TypeParametersDecl}> : _HashBuffer {
   ) rethrows where S.Iterator.Element == (Key, Value) {
     if _fastPath(guaranteedNative) {
       try nativeMerge(keysAndValues, uniquingKeysWith: combine)
+      return
     }
 
     switch self {

Original file line number	Diff line number	Diff line change
`@@ -4923,6 +4923,7 @@ internal enum _Variant${Self}Buffer<${TypeParametersDecl}> : _HashBuffer {`
`4923`	`4923`	`) rethrows where S.Iterator.Element == (Key, Value) {`
`4924`	`4924`	`if _fastPath(guaranteedNative) {`
`4925`	`4925`	`try nativeMerge(keysAndValues, uniquingKeysWith: combine)`
	`4926`	`+ return`
`4926`	`4927`	`}`
`4927`	`4928`
`4928`	`4929`	`switch self {`