Fix #3467: Don't pre-check kinds in TypeAssigner

In the existing tests we only need to pre-check kinds in Typer in order
to avoid self-applications that can lead to crashes. By avoiding them in
TypeAssigner we also avoid the error exhibited by i3467 in the strawman
collections.

This change required some changes in the tests because errors now get reported
at different times.

Author: odersky

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

@@ -13,7 +13,7 @@ import NameOps._
 import collection.mutable
 import reporting.diagnostic.Message
 import reporting.diagnostic.messages._
-import Checking.{preCheckKind, preCheckKinds, checkNoPrivateLeaks}
+import Checking.checkNoPrivateLeaks
 
 trait TypeAssigner {
   import tpd._
@@ -375,7 +375,7 @@ trait TypeAssigner {
             else if (!paramNames.contains(name))
               ctx.error(UndefinedNamedTypeParameter(name, paramNames), arg.pos)
             else
-              namedArgMap(name) = preCheckKind(arg, paramBoundsByName(name.asTypeName)).tpe
+              namedArgMap(name) = arg.tpe
 
           // Holds indexes of non-named typed arguments in paramNames
           val gapBuf = new mutable.ListBuffer[Int]
@@ -408,7 +408,7 @@ trait TypeAssigner {
           }
         }
         else {
-          val argTypes = preCheckKinds(args, pt.paramInfos).tpes
+          val argTypes = args.tpes
           if (sameLength(argTypes, paramNames)) pt.instantiate(argTypes)
           else wrongNumberOfTypeArgs(fn.tpe, pt.typeParams, args, tree.pos)
         }

tests/neg/i2771.scala

@@ -4,21 +4,16 @@ trait C { type M <: A }
 trait D { type M >: B }
 
 object Test {
-  def test(x: C with D): Unit = {
-    def f(y: x.M)(z: y.L[y.L]) = z      // error: y.L has wrong kind
-    f(new B { type L[F[_]] = F[F] })(1) // error: F has wrong kind
-  }
-
   type LB[F[_]]
 
   type LL[F[_]] <: LB[F] // ok
 
   def foo[X[_] <: Any]() = ()
-  foo[Int]()  // error: Int has wrong kind
+  foo[Int]()  // error: Type argument Int does not conform to upper bound
 
   def bar[X, Y]() = ()
-  bar[List, Int]()   // error: List has wrong kind
+  bar[List, Int]()   // error: missing type parameter(s) for List
 
-  bar[Y = List, X = Int]()  // error: List has wrong kind
+  bar[Y = List, X = Int]()  // error: missing type parameter(s) for List
 
 }

tests/neg/i2771a.scala

@@ -0,0 +1,11 @@
+trait A { type L[X] }
+trait B { type L }
+trait C { type M <: A }
+trait D { type M >: B }
+
+object Test {
+  def test(x: C with D): Unit = {
+    def f(y: x.M)(z: y.L[y.L]) = z      // error: y.L has wrong kind
+    f(new B { type L[F[_]] = F[F] })(1) // error: F has wrong kind
+  }
+}

tests/neg/kinds1.scala

@@ -0,0 +1,16 @@
+object Test {
+
+  class C[T]
+  class C2[T[X]]
+
+  class B
+
+  val x: C[C] = ??? // error: Type argument has not the same kind as its bound
+  val y: C2[C] = ???
+
+  def f[T] = ???
+
+  def f2[T[X]] = ???
+
+  f2[C]
+}

tests/neg/kinds.scala renamed to tests/neg/kinds2.scala

@@ -5,7 +5,6 @@ object Test {
 
   class B
 
-  val x: C[C] = ??? // error: missing type parameter(s)
   val y: C2[C] = ???
 
   def f[T] = ???

tests/neg/tcpoly_overloaded.scala

@@ -21,5 +21,5 @@ trait Test {
     def flatMap[S]
             (f: T => List[S], foo: Int): List[S]  = sys.error("foo")
   }
-  val l: MList[String] = moo.flatMap[String, List, Any, MList]((x: Int) => new MList("String")) // error: wrong kind
+  val l: MList[String] = moo.flatMap[String, List, Any, MList]((x: Int) => new MList("String"))
 }

tests/pos/i3467/Test_2.scala

@@ -0,0 +1,7 @@
+package collection
+
+class Test {
+  def test(xs: Array[Int]): Unit = {
+    new ArrayOps(xs)
+  }
+}

tests/pos/i3467/collection_1.scala

@@ -0,0 +1,21 @@
+package collection
+
+abstract class WithFilter[+A, +CC[_]]
+
+trait IndexedSeq[+A] extends Any with IndexedSeqOps[A, IndexedSeq, IndexedSeq[A]]
+
+trait IndexedSeqOps[+A, +CC[X] <: IndexedSeq[X], +C] extends Any {
+  def withFilter(p: A => Boolean): WithFilter[A, CC] = ???
+}
+
+package immutable {
+  trait IndexedSeq[+A] extends collection.IndexedSeq[A] with collection.IndexedSeqOps[A, IndexedSeq, IndexedSeq[A]]
+}
+
+object ArrayOps {
+  abstract class WithFilter[A] extends collection.WithFilter[A, immutable.IndexedSeq]
+}
+
+class ArrayOps[A](val xs: Array[A]) extends AnyVal with IndexedSeqOps[A, immutable.IndexedSeq, Array[A]] {
+  override def withFilter(p: A => Boolean): ArrayOps.WithFilter[A] = ???
+}