Dealias types before testing for isValueSubType

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

@@ -1038,17 +1038,15 @@ 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)

tasty/test/dotty/tools/tasty/TastyHeaderUnpicklerTest.scala

@@ -57,8 +57,8 @@ object TastyHeaderUnpicklerTest {
     buf.writeNat(exp)
     buf.writeNat(compilerBytes.length)
     buf.writeBytes(compilerBytes, compilerBytes.length)
-    buf.writeUncompressedLong(237478l)
-    buf.writeUncompressedLong(324789l)
+    buf.writeUncompressedLong(237478L)
+    buf.writeUncompressedLong(324789L)
     buf
   }
 

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
+}