Allow tail calls after return statements

[mbovel]

Minimal example

  @annotation.tailrec
  def sum(n: Int, acc: Int): Int =
    if n != 0 then return sum(n - 1, n + acc)
    acc

fails:

3 |    if n != 0 then return sum(n - 1, n + acc)
  |                          ^^^^^^^^^^^^^^^^^^^
  |                 Cannot rewrite recursive call: it is not in tail position

Rational

Early-returns are useful to avoid nesting conditions. For example, this would be better written with early returns.

Note: this might be a nice issue for a spree.

[som-snytt]

Related ticket under the rubric "muck with return make return useful again" #256

[DavidGregory084]

Looks like this was merged in scala/scala3#14067 so perhaps this can be closed?