Implicit Argument / vararg with Dynamic Trait fails

[max-leuthaeuser]

Consider the following simple example:

class ImplicitExample() extends Dynamic {
  def someMethod()(implicit s: String = "World"): String = s
  def applyDynamic(name: String)(args: Any*)(implicit s: String = "World"): String = name + s
}

And its test:

class ImplicitTest {
  @Test def t1(): Unit = {
    assertEquals("World", new ImplicitExample().someMethod())
  }

  @Test def t2(): Unit = {
    implicit val s: String = "Hello"
    assertEquals("Hello", new ImplicitExample().someMethod())
  }

  @Test def t3(): Unit = {
    assertEquals("runWorld", new ImplicitExample().run())
  }

  @Test def t4(): Unit = {
    implicit val s: String = "Hello"
    assertEquals("runHello", new ImplicitExample().run())
  }
}

Test t1 and t2 always work, while t3 fails with the latest Nightly build (0.9.0-bin-20180529-be6ae0e-NIGHTLY):

[error] -- Error: ... ImplicitTest.scala: ...
[error] 15 |    assertEquals("runWorld", new ImplicitExample().run())
[error]    |                                                      ^
[error]    |no implicit argument of type String was found for parameter s of method applyDynamic in class ImplicitExample
[error] one error found
[error] (Test / compileIncremental) Compilation failed

If you remove the vararg args, it compiles but the implicit parameter is not considered anymore and t4 fails with:

[error] Test ImplicitTest.t4 failed: expected:<run[Hello]> but was:<run[World]>

Everything is fine with 0.8.0-RC1.

[allanrenucci]

Regression from #4428

[liufengyun]

I'm pushing a fix soon, found a bug both in Dotty & Scalac:

class Foo(config: String) {
  case class Bar(val x: Int) {
    def doThings: String = config //Do whatever here
  }
}


object Test {
  def test(foo: Foo)(bar: foo.Bar = foo.Bar(5))(implicit s: String = "ok") = ???

  test(new Foo("port"))()              // failed, should succeed!
}