Merge pull request #3003 from AleksanderBG/consistent-list-printing

Print Lists consistently in exhaustivity warnings

Author: liufengyun

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

@@ -661,7 +661,7 @@ class SpaceEngine(implicit ctx: Context) extends SpaceLogic {
         else if (scalaListType.isRef(sym))
           if (mergeList) "_*" else "_: List"
         else if (scalaConsType.isRef(sym))
-          if (mergeList) "_" else "List(_)"
+          if (mergeList) "_, _*"  else "List(_, _*)"
         else if (tp.classSymbol.is(CaseClass) && !hasCustomUnapply(tp.classSymbol))
         // use constructor syntax for case class
           showType(tp) + signature(tp).map(_ => "_").mkString("(", ", ", ")")

tests/patmat/exhausting.check

@@ -1,4 +1,4 @@
-21: Pattern Match Exhaustivity: List(_), List(_, _, _)
+21: Pattern Match Exhaustivity: List(_), List(_, _, _, _*)
 27: Pattern Match Exhaustivity: Nil
 32: Pattern Match Exhaustivity: List(_, _*)
 39: Pattern Match Exhaustivity: Bar3

tests/patmat/t4408.check

@@ -1 +1 @@
-2: Pattern Match Exhaustivity: List(_, _, _)
+2: Pattern Match Exhaustivity: List(_, _, _, _*)

tests/patmat/t5440.check

@@ -1 +1 @@
-2: Pattern Match Exhaustivity: (Nil, List(_)), (List(_), Nil)
+2: Pattern Match Exhaustivity: (Nil, List(_, _*)), (List(_, _*), Nil)