Merge pull request #12269 from dotty-staging/fix-12265

Dealias types before testing for isValueSubType

Author: bishabosha

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

@@ -1046,17 +1046,15 @@ object Types {
       TypeComparer.isSameTypeWhenFrozen(this, that)
 
     /** Is this type a primitive value type which can be widened to the primitive value type `that`? */
-    def isValueSubType(that: Type)(using Context): Boolean = widen match {
+    def isValueSubType(that: Type)(using Context): Boolean = widenDealias match
       case self: TypeRef if self.symbol.isPrimitiveValueClass =>
-        that.widenExpr match {
+        that.widenExpr.dealias match
           case that: TypeRef if that.symbol.isPrimitiveValueClass =>
             defn.isValueSubClass(self.symbol, that.symbol)
           case _ =>
             false
-        }
       case _ =>
         false
-    }
 
     def relaxed_<:<(that: Type)(using Context): Boolean =
       (this <:< that) || (this isValueSubType that)

tests/pos/i12265.scala

@@ -0,0 +1,14 @@
+object OK {
+  def apply(n: Int ): Unit = ()
+  def apply(n: Long): Unit = ()
+  apply(3)  // ok
+  apply(3L) // ok
+}
+
+object KO {
+  type Key = Int
+  def apply(n: Key ): Unit = ()
+  def apply(n: Long): Unit = ()
+  apply(3)  // error
+  apply(3L) // ok
+}