Fix check not to run after typer

After typer we can get two consecutive type argument sections. If the first
section consists of named parameters that leave out some parameter bindings they
are supplied in the second section. I considered merging the two type parameter
sections, but that would complicate too many other things.

The current scheme is still unambiguous if we consider types. I.e. two consecutive
argument sections match a single formal parameter section if the first section
is named and the length of both argument sections together matches the number
of formal parameters.

Also, fix tests.

Author: odersky

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

@@ -881,7 +881,7 @@ trait Applications extends Compatibility { self: Typer with Dynamic =>
     typedExpr(tree.fun, PolyProto(typedArgs, pt)) match {
       case ExtMethodApply(app) =>
         app
-      case _: TypeApply =>
+      case _: TypeApply if !ctx.isAfterTyper =>
         errorTree(tree, "illegal repeated type application")
       case typedFn =>
         typedFn.tpe.widen match {

tests/neg/namedTypeParams.scala

@@ -12,5 +12,11 @@ object Test {
   def f[X, Y](x: X, y: Y): Int = ???
 
   f[X = Int, String](1, "") // error // error
-  f[X = Int][X = Int][Y = String](1, "") // error
+  f[X = Int][X = Int][Y = String](1, "") // error: illegal repeated type application
+
+  f[X = Int][Y = String](1, "") // error: illegal repeated type application
+  f[X = Int][String](1, "") // error: illegal repeated type application
+
+  f[Y = String][X = Int](1, "") // error: illegal repeated type application
+  f[Y = String][Int](1, "") // error: illegal repeated type application
 }

tests/pos/i5328.scala

@@ -0,0 +1,8 @@
+class C[X, Y] { def apply[Z](x: X, y: Y, z: Z) = (x, y, z) }
+
+object Test {
+  def f[X, Y, Z]: C[X, Y] = new C[X, Y]
+  f[Int, Boolean, Any][String](1, true, "") // OK
+  f[X = Int](1, true, "") // OK, Y and Z are inferred
+  f[Z = Any, X = Int](1, true, "") // OK
+}

tests/pos/namedTypeParams.scala

@@ -7,9 +7,5 @@ object Test {
   f[X = Int](1, "")
   f[Y = String](1, "")
 
-  f[X = Int][Y = String](1, "")
-  f[X = Int][String](1, "")
 
-  f[Y = String][X = Int](1, "")
-  f[Y = String][Int](1, "")
 }