Incorrect handle of unicode escapes in triple-quoted string

Compiler version

3.0.0-RC1

Minimized code

object Bar{
  def main(args: Array[String]): Unit = {
    println(""""\\\uCAFE"""".getBytes.toList)
  }
}

Output

This is what it prints in 3.0.0-RC1

List(34, 92, 92, 92, 117, 67, 65, 70, 69, 34)

Expectation

This is what it prints in 2.13.4 and 2.12.13

List(34, 92, 92, -20, -85, -66, 34)

[lrytz]

raw""""\\${'\uCAFE'}"""" also works

[martijnhoekstra]

2.13 emits a deprecation warning for the escape in a triple quoted string, scala 3 doesn’t handle the escape anymore. I believe that behaviour follows the principle of least astonishment: Unicode escapes are treated as any other escape, that is to say, they’re escaped in single quoted strings, backquoted identifiers and char literals and by the f and s interpolators.

The three options that will work with any version are

• Use a literal (which is usually the best idea)
• Use a a raw interpolation and interpolate it in, which can be useful for non-printable characters
• Use an interpolation or single-quoted string and escape the other things too, when the unicode escape is the only thing you need to escape (i.e. not here)

For this particular string, those are respectively """"\\쫾"""", raw"$"\\${'\uCAFE'}$"" and "\"\\\\\uCAFE\""

Reference https://github.com/lampepfl/dotty/pull/8480 and https://github.com/scala/scala/pull/8282