Merge pull request scala#6150 from milessabin/topic/singleton-type-patterns

When checking for a non-empty type intersection don't treat Singleton as final

Author: lrytz

src/reflect/scala/reflect/internal/Symbols.scala

@@ -1017,7 +1017,7 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
 
     /** Is this symbol effectively final? I.e, it cannot be overridden */
     final def isEffectivelyFinal: Boolean = (
-         (this hasFlag FINAL | PACKAGE)
+         ((this hasFlag FINAL | PACKAGE) && this != SingletonClass)
       || isModuleOrModuleClass && (isTopLevel || !settings.overrideObjects)
       || isTerm && (isPrivate || isLocalToBlock || (hasAllFlags(notPRIVATE | METHOD) && !hasFlag(DEFERRED)))
       || isClass && originalOwner.isTerm && children.isEmpty // we track known subclasses of term-owned classes, use that infer finality

src/reflect/scala/reflect/internal/Types.scala

@@ -4133,12 +4133,13 @@ trait Types
         throw new MatchError((tp1, tp2))
     }
 
-    def check(tp1: Type, tp2: Type) = (
-      if (tp1.typeSymbol.isClass && tp1.typeSymbol.hasFlag(FINAL))
-        tp1 <:< tp2 || isNumericValueClass(tp1.typeSymbol) && isNumericValueClass(tp2.typeSymbol)
+    def check(tp1: Type, tp2: Type) = {
+      val sym1 = tp1.typeSymbol
+      if (sym1.isClass && sym1.hasFlag(FINAL) && sym1 != SingletonClass)
+        tp1 <:< tp2 || isNumericValueClass(sym1) && isNumericValueClass(tp2.typeSymbol)
       else tp1.baseClasses forall (bc =>
         tp2.baseTypeIndex(bc) < 0 || isConsistent(tp1.baseType(bc), tp2.baseType(bc)))
-    )
+    }
 
     check(tp1, tp2) && check(tp2, tp1)
   }

test/files/pos/t10569.scala

@@ -0,0 +1,6 @@
+object Test {
+  object Foo
+  Tuple1[Foo.type](Foo) match {
+    case Tuple1(foo: Singleton) => foo
+  }
+}