Fix #6060: Don't insert apply or implicits on constructor calls

This mirrors scalac's behavior.

Author: odersky

compiler/src/dotty/tools/dotc/ast/TreeInfo.scala

@@ -106,6 +106,12 @@ trait TreeInfo[T >: Untyped <: Type] { self: Trees.Instance[T] =>
     case _ => Nil
   }
 
+  /** Is tree a constructor call this(...) or new C(...)? */
+  def isConstrCall(tree: Tree): Boolean = methPart(tree) match {
+    case Select(_, nme.CONSTRUCTOR) => true
+    case _ => false
+  }
+
   /** Is tree a self constructor call this(...)? I.e. a call to a constructor of the
    *  same object?
    */

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

@@ -2282,7 +2282,10 @@ class Typer extends Namer
         pt.markAsDropped()
         tree
       case _ =>
-        if (isApplyProto(pt) || isMethod(tree) || isSyntheticApply(tree)) tryImplicit(fallBack)
+        if (isConstrCall(tree))
+          fallBack
+        if (isApplyProto(pt) || isMethod(tree) || isSyntheticApply(tree))
+          tryImplicit(fallBack)
         else tryEither(tryApply(_)) { (app, appState) =>
           tryImplicit {
             if (tree.tpe.member(nme.apply).exists) {

tests/neg/i6060.scala

@@ -0,0 +1,11 @@
+class I1(i2: Int) {
+  def apply(i3: Int) = 1  // error: constructor I1 in class I1 does not take more parameters
+  new I1(1)(2) {}
+}
+
+class I0(i1: Int) {
+  class I0[I2] {
+    def apply(i3: Int) = 1
+    new I0[Int]()(2) {} // error: constructor I0 in class I0 does not take more parameters
+  }
+}