More applied constructor types fixes

- only type applied constructor types in Typer
- handle multiple parameter lists
- add tests for mixed tracked and not tracked parameters

Author: KacperFKorban

compiler/src/dotty/tools/dotc/typer/Applications.scala

@@ -1715,18 +1715,18 @@ trait Applications extends Compatibility {
   def typedUnApply(tree: untpd.UnApply, selType: Type)(using Context): UnApply =
     throw new UnsupportedOperationException("cannot type check an UnApply node")
 
-  def typedAppliedConstructorType(tree: untpd.Apply)(using Context) = tree.fun match
-    case Select(New(tpt), _) =>
-      val tree1 = typedExpr(tree)
-      val widenSkolemsMap = new TypeMap:
-        def apply(tp: Type) = mapOver(tp.widenSkolem)
-      val preciseTp = widenSkolemsMap(tree1.tpe)
-      val classTp = typedType(tpt).tpe
-      if !preciseTp.isError && (preciseTp frozen_=:= classTp) then
-        report.warning(PointlessAppliedConstructorType(tpt, tree.args, classTp), tree.srcPos)
-      TypeTree(preciseTp)
-    case _ =>
-      throw TypeError(em"Unexpected applied constructor type: $tree")
+  def typedAppliedConstructorType(tree: untpd.Apply)(using Context) = untpd.methPart(tree) match
+      case Select(New(tpt), _) =>
+        val tree1 = typedExpr(tree)
+        val widenSkolemsMap = new TypeMap:
+          def apply(tp: Type) = mapOver(tp.widenSkolem)
+        val preciseTp = widenSkolemsMap(tree1.tpe)
+        val classTp = typedType(tpt).tpe
+        if !preciseTp.isError && (preciseTp frozen_=:= classTp) then
+          report.warning(PointlessAppliedConstructorType(tpt, tree.args, classTp), tree.srcPos)
+        TypeTree(preciseTp)
+      case _ =>
+        throw TypeError(em"Unexpected applied constructor type: $tree")
 
   /** Is given method reference applicable to argument trees `args`?
    *  @param  resultType   The expected result type of the application

compiler/src/dotty/tools/dotc/typer/Typer.scala

@@ -3552,7 +3552,7 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
         def typedUnnamed(tree: untpd.Tree): Tree = tree match {
           case tree: untpd.Apply =>
             if (ctx.mode is Mode.Pattern) typedUnApply(tree, pt)
-            else if (ctx.mode is Mode.Type) typedAppliedConstructorType(tree)
+            else if (ctx.mode.is(Mode.Type) && !ctx.isAfterTyper) typedAppliedConstructorType(tree)
             else typedApply(tree, pt)
           case tree: untpd.This => typedThis(tree)
           case tree: untpd.Number => typedNumber(tree, pt)

docs/_docs/reference/experimental/modularity.md

@@ -208,7 +208,7 @@ the comment is the resulting type of the applied constructor types.
 ```scala
 import scala.language.experimental.modularity
 
-class Box(tracked val v: Any)
+class C(tracked val v: Any)
 
 val c: C(42) /* C { val v: 42 } */ = C(42)
 ```

tests/pos/applied_constructor_types.scala

@@ -8,8 +8,12 @@ class F[A](tracked val a: Int)
 class G[A](tracked val a: A)
 class NF[A](tracked val f: F[A])
 
+class Person(val name: String, tracked val age: Int)
+class PersonPrime(val name: String)(tracked val age: Int)
+class PersonBis(tracked val name: String)(val age: Int)
+
 object O:
-  val m: Int = 42
+  val m: Int = 27
 
   class InnerClass(tracked val x: Int)
 
@@ -23,11 +27,23 @@ object Test extends App {
   val f3: F(42) = F(42)
   val g: G(42) = G(42)
 
-  val n: Int = 42
+  val n: Int = 27
   val c2: C(n) = C(n)
   val c3: C(O.m) = C(O.m)
 
   val box: Box(O.InnerClass(42)) = Box(O.InnerClass(42))
   val box2: Box(O.InnerClass(n)) = Box(O.InnerClass(n))
   val box3: Box(O.InnerClass(O.m)) = Box(O.InnerClass(O.m))
+
+  val person: Person("Kasia", 27) = Person("Kasia", 27)
+  val person1: Person("Kasia", n) = Person("Kasia", n)
+  val person2: Person("Kasia", O.m) = Person("Kasia", O.m)
+
+  val personPrime: PersonPrime("Kasia")(27) = PersonPrime("Kasia")(27)
+  val personPrime1: PersonPrime("Kasia")(n) = PersonPrime("Kasia")(n)
+  val personPrime2: PersonPrime("Kasia")(O.m) = PersonPrime("Kasia")(O.m)
+
+  val personBis: PersonBis("Kasia")(27) = PersonBis("Kasia")(27)
+  val personBis1: PersonBis("Kasia")(n) = PersonBis("Kasia")(n)
+  val personBis2: PersonBis("Kasia")(O.m) = PersonBis("Kasia")(O.m)
 }