Scala string interpolation empty string compile error

Question

Why does an empty string with the string interpolation prefix fail to compile when followed by a statement?

For example

val test = s""
println("hello")

Fails to compile with error

error: value println is not a member of String
possible cause: maybe a semicolon is missing before `value println'?
       println("hello")

But the following all compile fine:

---

val test = s""

---

val test = ""
println("hello")

---

def test() { s"" }
println("hello")

---

val test = s" "
println("hello")

---

Answer 1

It's a parser bug, fixed last January, so this should be ok in the latest 2.11.x releases.

Here's the bug report: https://issues.scala-lang.org/browse/SI-7919. The relevant comment (by Paul Phillips) is:

It's losing the newline token after a completely empty interpolated string. If it's s"1", or a semicolon instead of a newline, or two newlines, or a comment after the empty string, it compiles.

class A {
  s""
  5
}

Here's the PR that fixed it: https://github.com/scala/scala/pull/3411