Dubious parse recovery from for missing do

[som-snytt]

Minimized code

//> using scala 3.6.2

def f(xs: List[Int]) =
  if x.nonEmpty then
    for x <- xs
      println(x)
  end if
end f

Output

-- [E040] Syntax Error: /home/amarki/snips/fordone.scala:7:0 -------------------
7 |  end if
  |^^^
  |'<-' expected, but 'end of statement' found
-- [E006] Not Found Error: /home/amarki/snips/fordone.scala:4:5 ----------------
4 |  if x.nonEmpty then
  |     ^
  |     Not found: x
  |

Expectation

The error on 6 is imprecise. In particular, I'd expect the correctly indented end if to "contain" the parse error.

It's not clear what the three carets correspond to. I have previously seen "encoded" names produce extra carets in messages, especially when synthetic, such as a x$1. This may be an example.

The original problem IRL was a long source file with many cascading errors due to missing definitions and subsequent errors on previous lines; the syntax error seen here was still shown first, as desired.

It looks like the precise error popped out in the middle of the cascade:

[error] 643 |        if unapplied.is(CaseClass) then
[error]     |                                   ^^^^
[error]     |                                   yield or do expected

Before that, it is still really wanting the <-:

[error] 625 |    warnings.result().sorta(_._2.span.point)
[error]     |                     ^
[error]     |                     '<-' expected, but '.' found

and

[error] 638 |        case _ =>
[error]     |               ^^
[error]     |               '<-' expected, but '=>' found

-Vprint:parser is too late to show what the for rewriting was trying to do:

package <empty> {
  def f(xs: List[Int]) =
    if x.nonEmpty then
      for x <- xs; println(x) <- _root_.scala.Predef.???;
        _ <- _root_.scala.Predef.??? do _root_.scala.Predef.???
}

To the untrained eye, it wants an arrow because everything looks like a generator.

The pun is that the past tense of for ... do is fordone.