Merge pull request #2035 from dotty-staging/fix-#2033

Fix #2033: Improve handling of unresolved overloaded arguments

Author: smarter

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

@@ -450,7 +450,16 @@ trait Applications extends Compatibility { self: Typer with Dynamic =>
 
     def typedArg(arg: Arg, formal: Type): Arg = arg
     def addArg(arg: TypedArg, formal: Type) =
-      ok = ok & isCompatible(argType(arg, formal), formal)
+      ok = ok & {
+        argType(arg, formal) match {
+          case ref: TermRef if ref.denot.isOverloaded =>
+            // in this case we could not resolve overloading because no alternative
+            // matches expected type
+            false
+          case argtpe =>
+            isCompatible(argtpe, formal)
+        }
+      }
     def makeVarArg(n: Int, elemFormal: Type) = {}
     def fail(msg: => Message, arg: Arg) =
       ok = false

tests/neg/i2033.scala

@@ -0,0 +1,21 @@
+import java.io._
+import collection._
+object Test {
+  def check(obj: AnyRef): Unit = {
+    val bos = new ByteArrayOutputStream()
+    val out = new ObjectOutputStream(println) // error
+    val arr = bos toByteArray ()
+    val in = (())
+    val deser = ()
+    val lhs = mutable LinkedHashSet ()
+    check(lhs)
+  }
+}
+
+// minimization
+object Test2 {
+  class ObjectOutputStream(out: String) {
+    def this() = this("")
+  }
+  val out = new ObjectOutputStream(println) // error
+}