Merge pull request scala#5357 from SethTisue/topic/sd-206

SAM for subtypes of FunctionN

Author: SethTisue

src/compiler/scala/tools/nsc/typechecker/Typers.scala

@@ -773,7 +773,7 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
         else FunctionClass(numVparams)
       }
 
-      if (samSym.exists && samSym.owner != correspondingFunctionSymbol) // don't treat Functions as SAMs
+      if (samSym.exists && tp.typeSymbol != correspondingFunctionSymbol) // don't treat Functions as SAMs
         wildcardExtrapolation(normalize(tp memberInfo samSym))
       else NoType
     }

test/files/pos/sammy_extends_function.scala

@@ -0,0 +1,4 @@
+// https://github.com/scala/scala-dev/issues/206
+
+trait T extends Function1[String, String]
+object O { (x => x): T }