Complete the support for unapply

Author: liufengyun

compiler/src/dotty/tools/dotc/transform/init/Objects.scala

@@ -1203,16 +1203,16 @@ object Objects:
         // TODO: handle unapplySeq
         Bottom
 
-      case UnApply(fun, _, pats) =>
+      case UnApply(fun, implicits, pats) =>
         val fun1 = funPart(fun)
         val funRef = fun1.tpe.asInstanceOf[TermRef]
         if fun.symbol.name == nme.unapplySeq then
           // TODO: handle unapplySeq
           ()
         else
           val receiver = evalType(funRef.prefix, thisV, klass)
-          // TODO: apply implicits
-          val unapplyRes = call(receiver, funRef.symbol, TraceValue(scrutinee, summon[Trace]) :: Nil, funRef.prefix, superType = NoType, needResolve = true)
+          val implicitValues = evalArgs(implicits.map(Arg.apply), thisV, klass)
+          val unapplyRes = call(receiver, funRef.symbol, TraceValue(scrutinee, summon[Trace]) :: implicitValues, funRef.prefix, superType = NoType, needResolve = true)
           // distribute unapply to patterns
           val unapplyResTp = funRef.widen.finalResultType
           if isProductMatch(unapplyResTp, pats.length) then
@@ -1227,14 +1227,16 @@ object Objects:
             ()
           else
             // Get match
-            val getMember = unapplyResTp.member(nme.get).suchThat(_.info.isParameterless)
-            // TODO: call isEmpty as well
-            val getRes = call(unapplyRes, getMember.symbol, Nil, unapplyResTp, superType = NoType, needResolve = true)
+            val isEmptyDenot = unapplyResTp.member(nme.isEmpty).suchThat(_.info.isParameterless)
+            call(unapplyRes, isEmptyDenot.symbol, Nil, unapplyResTp, superType = NoType, needResolve = true)
+
+            val getDenot = unapplyResTp.member(nme.get).suchThat(_.info.isParameterless)
+            val getRes = call(unapplyRes, getDenot.symbol, Nil, unapplyResTp, superType = NoType, needResolve = true)
             if pats.length == 1 then
               // single match
               evalPattern(getRes, pats.head)
             else
-              val getResTp = getMember.info.widen.finalResultType
+              val getResTp = getDenot.info.finalResultType
               val selectors = productSelectors(getResTp).take(pats.length)
               selectors.zip(pats).map { (sel, pat) =>
                 val selectRes = call(unapplyRes, sel, Nil, unapplyResTp, superType = NoType, needResolve = true)
@@ -1245,6 +1247,9 @@ object Objects:
         end if
         scrutinee
 
+      case Ident(nme.WILDCARD) =>
+        scrutinee
+
       case Typed(pat, _) =>
         evalPattern(scrutinee, pat)
 

compiler/src/dotty/tools/dotc/transform/init/Util.scala

@@ -26,6 +26,9 @@ object Util:
   opaque type Arg  = Tree | ByNameArg
   case class ByNameArg(tree: Tree)
 
+  object Arg:
+    def apply(tree: Tree): Arg = tree
+
   extension (arg: Arg)
     def isByName = arg.isInstanceOf[ByNameArg]
     def tree: Tree = arg match

tests/init/neg/patmat.scala

@@ -12,3 +12,25 @@ object B:
     if A.a.isEmpty then println(xs.size)
   case Nil =>
     println(0)
+
+case class Box[T](value: T)
+case class Holder[T](value: T)
+object C:
+  (Box(5): Box[Int] | Holder[Int])  match
+  case Box(x) => x
+  case Holder(x) => x
+
+  (Box(5): Box[Int] | Holder[Int])  match
+  case box: Box[Int] => box.value
+  case holder: Holder[Int] => holder.value
+
+  val a: Int = Inner.b
+
+  object Inner:                // error
+    val b: Int = 10
+
+    val foo: () => Int = () => C.a
+
+    (Box(foo): Box[() => Int] | Holder[Int]) match
+    case Box(f) => f()
+    case Holder(x) => x