Fix #3561: Correctly handle switches followed by other tests in matches

Author: odersky

compiler/src/dotty/tools/dotc/transform/PatternMatcher.scala

@@ -845,10 +845,10 @@ object PatternMatcher {
 
     /** Emit cases of a switch */
     private def emitSwitchCases(cases: List[Plan]): List[CaseDef] = (cases: @unchecked) match {
-      case TestPlan(EqualTest(tree), _, _, ons, _) :: cases1 =>
-        CaseDef(tree, EmptyTree, emit(ons)) :: emitSwitchCases(cases1)
       case (default: Plan) :: Nil =>
         CaseDef(Underscore(defn.IntType), EmptyTree, emit(default)) :: Nil
+      case TestPlan(EqualTest(tree), _, _, ons, _) :: cases1 =>
+        CaseDef(tree, EmptyTree, emit(ons)) :: emitSwitchCases(cases1)
     }
 
     /** If selfCheck is `true`, used to check whether a tree gets generated twice */

tests/pos/i3561.scala

@@ -0,0 +1,15 @@
+class Test {
+  val Constant = 'Q' // OK if final
+  def tokenMe(ch: Char) = (ch: @annotation.switch) match {
+    case ' ' => 1
+    case 'A' => 2
+    case '5' | Constant => 3
+  }
+
+  def test2(x: Any) = x match {
+    case 1 => 1
+    case 2 => 2
+    case 3 => 3
+    case x: String => 4
+  }
+}