Merge pull request #10094 from dotty-staging/fix-10085

Fix #10085: check if enum case confirms to scrutinee type

Author: liufengyun

compiler/src/dotty/tools/dotc/core/TypeOps.scala

@@ -633,8 +633,6 @@ object TypeOps:
    *  returned. Otherwise, `NoType` is returned.
    */
   def refineUsingParent(parent: Type, child: Symbol)(using Context): Type = {
-    if (child.isTerm && child.is(Case, butNot = Module)) return child.termRef // enum vals always match
-
     // <local child> is a place holder from Scalac, it is hopeless to instantiate it.
     //
     // Quote from scalac (from nsc/symtab/classfile/Pickler.scala):

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

@@ -527,15 +527,9 @@ class SpaceEngine(using Context) extends SpaceLogic {
   /** Parameter types of the case class type `tp`. Adapted from `unapplyPlan` in patternMatcher  */
   def signature(unapp: TermRef, scrutineeTp: Type, argLen: Int): List[Type] = {
     val unappSym = unapp.symbol
-    def caseClass = unappSym.owner.linkedClass
 
     // println("scrutineeTp = " + scrutineeTp.show)
 
-    lazy val caseAccessors = caseClass.caseAccessors.filter(_.is(Method))
-
-    def isSyntheticScala2Unapply(sym: Symbol) =
-      sym.isAllOf(SyntheticCase) && sym.owner.is(Scala2x)
-
     val mt: MethodType = unapp.widen match {
       case mt: MethodType => mt
       case pt: PolyType   =>
@@ -564,9 +558,7 @@ class SpaceEngine(using Context) extends SpaceLogic {
     val resTp = mt.finalResultType
 
     val sig =
-      if (isSyntheticScala2Unapply(unappSym) && caseAccessors.length == argLen)
-        caseAccessors.map(_.info.asSeenFrom(mt.paramInfos.head, caseClass).widenExpr)
-      else if (resTp.isRef(defn.BooleanClass))
+      if (resTp.isRef(defn.BooleanClass))
         List()
       else {
         val isUnapplySeq = unappSym.name == nme.unapplySeq
@@ -584,7 +576,7 @@ class SpaceEngine(using Context) extends SpaceLogic {
           if (arity > 0)
             productSelectorTypes(resTp, unappSym.srcPos)
           else {
-            val getTp = resTp.select(nme.get).finalResultType.widen
+            val getTp = resTp.select(nme.get).finalResultType.widenTermRefExpr
             if (argLen == 1) getTp :: Nil
             else productSelectorTypes(getTp, unappSym.srcPos)
           }

tests/patmat/i10085.scala

@@ -0,0 +1,14 @@
+enum Bool:
+  case True
+  case False
+
+import Bool._
+
+enum SBool[B <: Bool]:
+  case STrue extends SBool[True.type]
+  case SFalse extends SBool[False.type]
+
+import SBool._
+
+def f(b: SBool[True.type]): Unit = b match
+  case STrue => ()

tests/patmat/i9190.scala

@@ -0,0 +1,23 @@
+class Test {
+  case object X; type X = X.type
+  case object Y; type Y = Y.type
+
+  type XorY = X | Y
+
+  val testee1: XorY = X
+  testee1 match {
+    case value: XorY => println(value)
+  }
+
+  val testee2: Tuple1[XorY] = Tuple1(X)
+  testee2 match {
+    case Tuple1(value: XorY) => println(value)
+  }
+
+  type IntOrString = Int | String
+
+  val testee3: Tuple1[IntOrString] = Tuple1(42)
+  testee3 match {
+    case Tuple1(value: IntOrString) => println(value)
+  }
+}