Combine call-by-name colon operator and space incoherency [duplicate]

Question

Here is the following problem. When I run the following:

object  Test {
  def /:(s: => Unit) = {
    println("/:")
    s
  }
}

println("A") /: Test

It prints:

A
/:

However, I was expecting it to print:

/:
A

since the last expression was supposedly rewritten Test./:(println("A")) - which by the way, gives the second value.

Does anybody know a way to make the first syntax work, e.g. println("A") /: Test but with call-by-name ?

Edit

Using the desugar method, I found out that the calls are desugared differently.

> desugar { println("A") /: Test}
 val x$1: Unit = println("A");
 Test./:(x$1)

Hence I am still wondering why this choice.

Answer 1

It is a known issue. If you compile with -Xlint option you should see a warning.

$ scalac -Xlint temp.scala
temp.scala:2: warning: by-name parameters will be evaluated eagerly when called 
              as a right-associative infix operator. For more details, see SI-1980.
    def /:(s: => Unit) = {
        ^
one warning found