support option-less patmat as complete match

Author: liufengyun

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

@@ -323,7 +323,7 @@ class SpaceEngine(implicit ctx: Context) extends SpaceLogic {
   import SpaceEngine._
   import tpd._
 
-  private val scalaSomeClass       = ctx.requiredClassRef("scala.Some".toTermName).symbol.asClass
+  private val scalaOptionClass     = ctx.requiredClassRef("scala.Option".toTypeName).symbol.asClass
   private val scalaSeqFactoryClass = ctx.requiredClass("scala.collection.generic.SeqFactory".toTypeName)
   private val scalaListType        = ctx.requiredClassRef("scala.collection.immutable.List".toTypeName)
   private val scalaNilType         = ctx.requiredModuleRef("scala.collection.immutable.Nil".toTermName)
@@ -420,7 +420,7 @@ class SpaceEngine(implicit ctx: Context) extends SpaceLogic {
         Kon(pat.tpe.stripAnnots, pats.map(pat => project(pat)))
       else if (fun.symbol.owner == scalaSeqFactoryClass && fun.symbol.name == nme.unapplySeq)
         projectList(pats)
-      else if (fun.symbol.info.resultType.isRef(scalaSomeClass))
+      else if (!fun.symbol.info.finalResultType.isRef(scalaOptionClass))
         Kon(pat.tpe.stripAnnots, pats.map(pat => project(pat)))
       else
         Fun(pat.tpe.stripAnnots, fun.tpe, pats.map(pat => project(pat)))

tests/patmat/optionless.check

@@ -0,0 +1 @@
+28: Pattern Match Exhaustivity: _: Tree

tests/patmat/optionless.scala

@@ -0,0 +1,32 @@
+sealed trait Tree
+case class Ident(name: String) extends Tree
+
+object Ident1 {
+  def unapply(tree: Tree): Ident = ???
+}
+
+trait Cap
+object Ident2 {
+  def unapply(tree: Tree)(implicit cap: Cap): Ident = ???
+}
+
+object Ident3 {
+  def unapply(tree: Tree)(implicit cap: Cap): Option[Ident] = ???
+}
+
+
+
+class Test {
+  def foo(t: Tree): Unit = t match {
+    case Ident1(t) =>
+  }
+
+  def bar(t: Tree)(implicit c: Cap): Unit = t match {
+    case Ident2(t) =>
+  }
+
+  def qux(t: Tree)(implicit c: Cap): Unit = t match {
+    case Ident3(t) =>
+  }
+
+}