one null warning

Author: liufengyun

compiler/src/dotty/tools/dotc/ast/Desugar.scala

@@ -429,7 +429,6 @@ object desugar {
         }
         val hasRepeatedParam = constrVparamss.exists(_.exists {
           case ValDef(_, tpt, _) => isRepeated(tpt)
-          case _ => false
         })
         if (mods.is(Abstract) || hasRepeatedParam) Nil  // cannot have default arguments for repeated parameters, hence copy method is not issued
         else {

compiler/src/dotty/tools/dotc/printing/PlainPrinter.scala

@@ -490,8 +490,6 @@ class PlainPrinter(_ctx: Context) extends Printer {
             Text()
 
         nodeName ~ "(" ~ elems ~ tpSuffix ~ ")" ~ (Str(node.pos.toString) provided ctx.settings.YprintPos.value)
-      case _ =>
-        tree.fallbackToText(this)
     }
   }.close // todo: override in refined printer
 

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

@@ -86,7 +86,6 @@ object Splicer {
          """.stripMargin
         ctx.error(msg, pos)
         None
-      case ex: Throwable => throw ex
     }
   }
 

compiler/src/dotty/tools/dotc/transform/patmat/Space.scala

@@ -331,6 +331,10 @@ class SpaceEngine(implicit ctx: Context) extends SpaceLogic {
     case Typed(pat @ UnApply(_, _, _), _) => project(pat)
     case Typed(expr, tpt) =>
       Typ(erase(expr.tpe.stripAnnots), true)
+    case This(_) =>
+      Typ(pat.tpe.stripAnnots, false)
+    case EmptyTree =>         // default rethrow clause of try/catch, check tests/patmat/try2.scala
+      Typ(WildcardType, false)
     case _ =>
       debug.println(s"unknown pattern: $pat")
       Empty
@@ -917,13 +921,15 @@ class SpaceEngine(implicit ctx: Context) extends SpaceLogic {
             else Empty
           }.reduce((a, b) => Or(List(a, b)))
 
-      val curr = project(cases(i).pat)
+      if (cases(i).pat != EmptyTree) { // rethrow case of catch
+        val curr = project(cases(i).pat)
 
-      debug.println(s"---------------reachable? ${show(curr)}")
-      debug.println(s"prev: ${show(prevs)}")
+        debug.println(s"---------------reachable? ${show(curr)}")
+        debug.println(s"prev: ${show(prevs)}")
 
-      if (isSubspace(intersect(curr, Typ(selTyp, false)), prevs)) {
-        ctx.warning(MatchCaseUnreachable(), cases(i).body.pos)
+        if (isSubspace(intersect(curr, Typ(selTyp, false)), prevs)) {
+          ctx.warning(MatchCaseUnreachable(), cases(i).body.pos)
+        }
       }
     }
   }

tests/patmat/byte.scala

@@ -0,0 +1,7 @@
+class Test {
+  def foo(x: Byte) = x match {
+    case 23 =>
+    case 33 =>
+    case _  =>
+  }
+}

tests/patmat/identifier.scala

@@ -0,0 +1,11 @@
+trait Type
+case class TermParamRef(binder: Type, index: Int) extends Type
+case class TypeRef(prefix: Type, name: String) extends Type
+
+class LambdaType extends Type { thisLambdaType =>
+  def foo(tp: Type): Unit = tp match {
+    case TermParamRef(`thisLambdaType`, _) =>
+    case tp: TypeRef =>
+    case _ =>
+  }
+}

tests/patmat/reader.scala

@@ -0,0 +1,10 @@
+import java.io.BufferedReader
+
+class Test {
+  def loop(reader: BufferedReader): Unit = reader.read match {
+    case 'a' | 'A' =>
+    case 's' | 'S' =>
+    case 'r' | 'R' =>
+    case _ =>
+  }
+}

tests/patmat/try2.scala

@@ -0,0 +1,7 @@
+import scala.util.control.NonFatal
+
+object Test {
+  try 2/0 catch {
+    case NonFatal(ex) =>
+  }
+}