Fix corner case w types ALL passed by name & out of order

This commit removes a problematic duplicated `checkBounds` call on `TypeApply`.
To verify correctness of this change on has to check that `normalizeTree` used only once [1],
and the function using `normalizeTree` already takes care of calling `checkBounds`.

[1]: https://github.com/lampepfl/dotty/blob/0e8f05d88bfef95fac59f522fd9d06792126bd11/src/dotty/tools/dotc/transform/PostTyper.scala#L205

Author: OlivierBlanvillain

src/dotty/tools/dotc/transform/PostTyper.scala

@@ -93,7 +93,7 @@ class PostTyper extends MacroTransform with IdentityDenotTransformer  { thisTran
    *
    *  should behave differently.
    *
-   *     O1.x  should have the same effect as   { println("43"; 42 }
+   *     O1.x  should have the same effect as   { println("43"); 42 }
    *
    *  whereas
    *
@@ -103,10 +103,7 @@ class PostTyper extends MacroTransform with IdentityDenotTransformer  { thisTran
    *  purity of the prefix unless the selection goes to an inline val.
    */
   private def normalizeTree(tree: Tree)(implicit ctx: Context): Tree = tree match {
-    case tree: TypeTree => tree
-    case TypeApply(fn, args) =>
-      Checking.checkBounds(args, fn.tpe.widen.asInstanceOf[PolyType])
-      tree
+    case _: TypeTree | _: TypeApply => tree
     case _ =>
       if (tree.isType) {
         Checking.typeChecker.traverse(tree)

src/dotty/tools/dotc/typer/Checking.scala

@@ -37,7 +37,7 @@ object Checking {
    *  well as for AppliedTypeTree nodes. Also checks that type arguments to
    *  *-type parameters are fully applied.
    */
-  def checkBounds(args: List[tpd.Tree], boundss: List[TypeBounds], instantiate: (Type, List[Type]) => Type)(implicit ctx: Context) = {
+  def checkBounds(args: List[tpd.Tree], boundss: List[TypeBounds], instantiate: (Type, List[Type]) => Type)(implicit ctx: Context): Unit = {
     (args, boundss).zipped.foreach { (arg, bound) =>
       if (!bound.isHK && arg.tpe.isHK)
         ctx.error(ex"missing type parameter(s) for $arg", arg.pos)

tests/pos/t1513b.scala

@@ -1,5 +1,9 @@
 object Test {
-  def f[T1 <: String, T2 <: Int, T3 <: Boolean](a1: T1, a2: T2, a3: T3) = ()
+  def f[
+    T1 <: String,
+    T2 <: Int,
+    T3 <: Boolean
+  ](a1: T1, a2: T2, a3: T3) = ()
 
   f                                          ("", 1, true)
   f[T1 = String]                             ("", 1, true)
@@ -12,5 +16,10 @@ object Test {
   f[T3 = Boolean, T2 = Int]                  ("", 1, true)
   f[T3 = Boolean, T1 = String]               ("", 1, true)
   f[T1 = String,  T2 = Int,     T3 = Boolean]("", 1, true)
+  f[T1 = String,  T3 = Boolean, T2 = Int]    ("", 1, true)
+  f[T2 = Int,     T1 = String,  T3 = Boolean]("", 1, true)
+  f[T2 = Int,     T3 = Boolean, T1 = String] ("", 1, true)
+  f[T3 = Boolean, T1 = String,  T2 = Int]    ("", 1, true)
+  f[T3 = Boolean, T2 = Int,     T1 = String] ("", 1, true)
   f[String,       Int,          Boolean]     ("", 1, true)
 }