address review feedback

Author: liufengyun

compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala

@@ -791,9 +791,9 @@ object messages {
 
     val explanation =
       hl"""|There are several ways to make the match exhaustive:
-           | - add missing cases as shown in the warning
-           | - change the return type of irrefutable extractors as `Some[T]` if exist
-           | - add a wildcard `_` case at the end
+           | - Add missing cases as shown in the warning
+           | - If an extractor always return Some(...), write Some[X] for its return type
+           | - Add a case _ => ... at the end to match all remaining cases
            |"""
   }
 

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

@@ -654,11 +654,6 @@ class SpaceEngine(implicit ctx: Context) extends SpaceLogic {
           if (mergeList) "_*" else "_: List"
         else if (scalaConsType.isRef(sym))
           if (mergeList) "_" else "List(_)"
-        else if (tp.classSymbol.is(CaseClass))
-        // use constructor syntax for case class
-          showType(tp) + signature(tp).map(_ => "_").mkString("(", ", ", ")")
-        else if (sym.is(Flags.Case) && signature(tp).nonEmpty)
-          tp.classSymbol.name + signature(tp).map(_ => "_").mkString("(", ", ", ")")
         else if (decomposed) "_: " + showType(tp)
         else "_"
       case Kon(tp, params) =>

tests/patmat/gadt.check

@@ -1,4 +1,4 @@
-13: Pattern Match Exhaustivity: IntLit(_)
-22: Pattern Match Exhaustivity: Or(_, _)
-45: Pattern Match Exhaustivity: BooleanLit(_), IntLit(_)
-55: Pattern Match Exhaustivity: Sum(_, _)
+13: Pattern Match Exhaustivity: _: IntLit
+22: Pattern Match Exhaustivity: _: Or
+45: Pattern Match Exhaustivity: _: BooleanLit, _: IntLit
+55: Pattern Match Exhaustivity: _: Sum

tests/patmat/i2502b.check

@@ -0,0 +1 @@
+5: Pattern Match Exhaustivity: _: BTypes.ClassBType

tests/patmat/i2502b.scala

@@ -0,0 +1,17 @@
+abstract class BTypes {
+  trait BType
+
+  sealed trait RefBType extends BType {
+    def classOrArrayType: String = this match {
+      case ClassBType(internalName) => internalName
+      case a: ArrayBType            => ""
+    }
+  }
+
+  final case class ClassBType(val internalName: String) extends RefBType
+  class ArrayBType extends RefBType
+
+  object ClassBType {
+    def unapply(x: RefBType): Option[String] = None
+  }
+}

tests/patmat/nontrivial-andtype.check

@@ -1 +1 @@
-16: Pattern Match Exhaustivity: D, _: C, B(), _: A
+16: Pattern Match Exhaustivity: D, _: C, _: B, _: A

tests/patmat/patmat-adt.check

@@ -1,5 +1,5 @@
-7: Pattern Match Exhaustivity: Bad(Good(_)), Good(Bad(_))
+7: Pattern Match Exhaustivity: Bad(_: Good), Good(_: Bad)
 19: Pattern Match Exhaustivity: Some(_)
-24: Pattern Match Exhaustivity: (_, Some(_))
-29: Pattern Match Exhaustivity: (None, None), (Some(_), Some(_))
+24: Pattern Match Exhaustivity: (_, _: Some)
+29: Pattern Match Exhaustivity: (None, None), (_: Some, _: Some)
 50: Pattern Match Exhaustivity: LetL(BooleanLit), LetL(IntLit)

tests/patmat/patmatexhaust.check

@@ -1,9 +1,9 @@
 7: Pattern Match Exhaustivity: Baz
-11: Pattern Match Exhaustivity: Bar(_)
-23: Pattern Match Exhaustivity: (Qult(), Qult()), (Kult(_), Kult(_))
+11: Pattern Match Exhaustivity: _: Bar
+23: Pattern Match Exhaustivity: (_: Qult, _: Qult), (_: Kult, _: Kult)
 49: Pattern Match Exhaustivity: _: Gp
 59: Pattern Match Exhaustivity: Nil
 75: Pattern Match Exhaustivity: _: B
 100: Pattern Match Exhaustivity: _: C1
-114: Pattern Match Exhaustivity: D2(), D1
+114: Pattern Match Exhaustivity: _: D2, D1
 126: Pattern Match Exhaustivity: _: C1

tests/patmat/t3683a.check

@@ -1 +1 @@
-14: Pattern Match Exhaustivity: XX()
+14: Pattern Match Exhaustivity: _: XX

tests/patmat/t6582_exhaust_big.check

@@ -1 +1 @@
-27: Pattern Match Exhaustivity: Z.Z11()
+27: Pattern Match Exhaustivity: _: Z.Z11

tests/patmat/t7631.check

@@ -1 +1 @@
-8: Pattern Match Exhaustivity: TestB()
+8: Pattern Match Exhaustivity: _: TestB

tests/patmat/t7669.check

@@ -1 +1 @@
-10: Pattern Match Exhaustivity: NotHandled(_)
+10: Pattern Match Exhaustivity: _: NotHandled

tests/patmat/t8178.check

@@ -1,3 +1,3 @@
-6: Pattern Match Exhaustivity: FailsChild2(_)
-14: Pattern Match Exhaustivity: VarArgs1(_)
-27: Pattern Match Exhaustivity: SeqArgs2(_)
+6: Pattern Match Exhaustivity: _: FailsChild2
+14: Pattern Match Exhaustivity: _: VarArgs1
+27: Pattern Match Exhaustivity: _: SeqArgs2

tests/patmat/t8412.check

@@ -1 +1 @@
-7: Pattern Match Exhaustivity: Lit(_)
+7: Pattern Match Exhaustivity: _: Lit

tests/patmat/t8511.check

@@ -1 +1 @@
-18: Pattern Match Exhaustivity: Baz(), Bar(_)
+18: Pattern Match Exhaustivity: _: Baz, _: Bar

tests/patmat/t9232.check

@@ -1 +1 @@
-13: Pattern Match Exhaustivity: Node2(), Node1(Foo(_))
+13: Pattern Match Exhaustivity: _: Node2, Node1(Foo(_))

tests/patmat/t9289.check

@@ -1,2 +1,2 @@
-9: Pattern Match Exhaustivity: module.LetR()
-20: Pattern Match Exhaustivity: module.LetR()
+9: Pattern Match Exhaustivity: _: module.LetR
+20: Pattern Match Exhaustivity: _: module.LetR

tests/patmat/t9351.check

@@ -1,3 +1,3 @@
 8: Pattern Match Exhaustivity: _: A
-17: Pattern Match Exhaustivity: (_, None), (_, Some(_))
+17: Pattern Match Exhaustivity: (_, None), (_, _: Some)
 28: Pattern Match Exhaustivity: (_, _)

tests/patmat/t9573.check

@@ -1 +1 @@
-9: Pattern Match Exhaustivity: Horse(_)
+9: Pattern Match Exhaustivity: _: Horse

tests/patmat/t9657.check

@@ -1,4 +1,4 @@
-29: Pattern Match Exhaustivity: Bus(_)
-38: Pattern Match Exhaustivity: Bus(_)
-49: Pattern Match Exhaustivity: Bus(_)
-58: Pattern Match Exhaustivity: Bus(_)
+29: Pattern Match Exhaustivity: _: Bus
+38: Pattern Match Exhaustivity: _: Bus
+49: Pattern Match Exhaustivity: _: Bus
+58: Pattern Match Exhaustivity: _: Bus

tests/patmat/t9672.check

@@ -1 +1 @@
-22: Pattern Match Exhaustivity: SimpleExpr.IntExpr(_)
+22: Pattern Match Exhaustivity: _: SimpleExpr.IntExpr