Various literals allowed in postfix position on expr

[bishabosha]

tested in Dotty REPL 0.12-RC1, I believe only these cases are an issue:

val foo = <expr> <booleanLiteral
                  | characterLiteral
                  | stringLiteral
                  | symbolLiteral
                  | "null">

e.g.

val foo = 123 'bar;

in Dotty REPL results in val foo: Int = 123, this is particularly bad as the Symbol literal is ignored, where otherwise an error is generated for their presence.

However, in Scala REPL 2.12.8 results in:

<console>:1: error: ';' expected but symbol literal found.
       val foo = 123 'bar;
                     ^

[odersky]

Seems to be REPL only. I could not reproduce standalone.

[bishabosha]

This compiles with dotc.

object Main {
  def main(args: Array[String]): Unit = {
    val foo = 123 "";
    println(foo)
  }
}

Although I'm not really sure if this is an issue or just semicolon inference behaving differently when a non-identifier is used in postfix.

[Blaisorblade]

Tokens are being swallowed and ignored — seems a dup of #4934.

[odersky]

Fixed by #6209