Fixed specialized pattern matches.

specialized implementations.

1 files changed, 20 insertions, 1 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/Duplicators.scala b/src/compiler/scala/tools/nsc/typechecker/Duplicators.scala
index 40cf9e82c0..7ca2ff81bb 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Duplicators.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Duplicators.scala
@@ -240,9 +240,28 @@ abstract class Duplicators extends Analyzer {
           log("changed " + tree + " to " + tree1)
           super.typed(atPos(tree.pos)(tree1))
 
+        case Match(scrut, cases) =>
+          val scrut1 = typed(scrut, EXPRmode | BYVALmode, WildcardType)
+          val scrutTpe = scrut1.tpe.widen
+          val cases1 = if (scrutTpe.isFinalType) cases filter {
+            case CaseDef(Bind(_, pat @ Typed(_, tpt)), EmptyTree, body) =>
+              // the typed pattern is not incompatible with the scrutinee type
+              scrutTpe.matchesPattern(fixType(tpt.tpe))
+            case CaseDef(Typed(_, tpt), EmptyTree, body) =>
+              // the typed pattern is not incompatible with the scrutinee type
+              scrutTpe.matchesPattern(fixType(tpt.tpe))
+            case _ => true
+          } else cases
+
+          super.typed(atPos(tree.pos)(Match(scrut, cases1)), mode, pt)
+
+        case EmptyTree =>
+          // no need to do anything, in particular, don't set the type to null, EmptyTree.tpe_= asserts
+          tree
+
         case _ =>
           if (tree.hasSymbol && tree.symbol != NoSymbol && (tree.symbol.owner == definitions.AnyClass)) {
-            tree.symbol = NoSymbol // maybe we can find a more specific member in a subclass of Any
+            tree.symbol = NoSymbol // maybe we can find a more specific member in a subclass of Any (see AnyVal members, like ==)
           }
           tree.tpe = null
           super.typed(tree, mode, pt)