eta-expansion for method on target that needs implicit conversion

[scabug]

object Test extends App {
  class C

  implicit class CompatibleC(c: C) {
    def foo(x: Int) = ???
  }

  val c: C = ???
  println(c.foo _)
}

15:44 ~/Projects/Master/sandbox (master)$ s
Test.scala:9: error: missing arguments for method foo in class CompatibleC;
follow this method with `_' if you want to treat it as a partially applied function
  println(c.foo _)
            ^
one error found

The error is the same if I manually create an implicit def.

[scabug]

Imported From: https://issues.scala-lang.org/browse/SI-8299?orig=1
Reporter: @xeno-by
Affected Versions: 2.11.0-M8, 2.12.1

[scabug]

@adriaanm said:
Looks like an interaction with implicit conversion. Either convert the target first or annotate the argument type, you can't have both. Most likely a won't fix.

scala> lazy  val c: CompatibleC = ???
c: CompatibleC = <lazy>

scala>  println(c.foo _ )
<function1>

[scabug]

@som-snytt said:
The clever error message looks less clever:

scala> c.f _
<console>:14: error: missing argument list for method f in class CC
Unapplied methods are only converted to functions when a function type is expected.
You can make this conversion explicit by writing `f _` or `f(_)` instead of `f`.
       c.f _
         ^

scala> c.f(_)
res3: Int => Int = $$Lambda$1088/149526537@e62319f

[scabug]

@som-snytt said:
Can anyone recommend a good beginner book for learning Scala?

Welcome to Scala 2.12.1 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_111).
Type in expressions for evaluation. Or try :help.

scala> List(1,3,5).map("abc".isDefinedAt)
res0: List[Boolean] = List(true, false, false)

scala> List(1,3,5).map("abc".isDefinedAt _)
<console>:12: error: _ must follow method; cannot follow Int => Boolean
       List(1,3,5).map("abc".isDefinedAt _)
                             ^

scala> List(1,3,5).map("abc".isDefinedAt(_))
res2: List[Boolean] = List(true, false, false)