No graceful recovery from misplaced `private` modifier in local scope

[som-snytt]

Compiler version

3.6.3

Minimized code

def f: Unit =
  private def cmp ...  // cut/paste error

Output

[error] 274 |    private def cmp(p: Type, q: Type)(using Context): Boolean =
[error]     |    ^^^^^^^
[error]     |    this kind of statement is not allowed here

followed by dozens of diagnostics.

Showing that it blows past the end of the enclosing method at 400, then the next end marker for the class; then errors cascade from outside the local scope.

[error] 274 |    private def cmp(p: Type, q: Type)(using Context): Boolean =
[error]     |    ^^^^^^^
[error]     |    this kind of statement is not allowed here
[error]     |
[error]     | longer explanation available when compiling with `-explain`
[error] -- Error: .../CheckUnused.scala:400:2
[error] 400 |  end resolveUsage
[error]     |  ^^^^^^^^^^^^^^^^
[error]     |  misaligned end marker
[error] -- [E040] Syntax Error: .../CheckUnused.scala:401:0
[error] 401 |end CheckUnused
[error]     |^^^
[error]     |eof expected, but unindent found
[error] -- [E006] Not Found Error: .../CheckUnused.scala:34:38
[error] 34 |class CheckUnused private (phaseMode: PhaseMode, suffix: String) extends MiniPhase:
[error]    |                                      ^^^^^^^^^
[error]    |                                      Not found: type PhaseMode
[error]    |

Expectation

Skipping a misplaced modifier seems like an easy recovery strategy.

Skipping just the (correctly indented) bad local def would help.

Correctly stopping at the (correctly aligned) end marker of the enclosing def would help.

[mbovel]

This issue was picked for the Scala Issue Spree of tomorrow, Monday, February 24th. @hamzaremmal, @ajafri2001 and @Zeleph25 will be working on it. If you have any insight into the issue or guidance on how to fix it, please leave it here.

[dwijnand]

A minimisation that includes the cascade errors (comment in and out the print to see the difference):

import CheckUnused.*

class CheckUnused(phaseMode: PhaseMode):
  def resolveUsage: Unit =
    private def cmp(p: Int, q: Int): Boolean =
      false
    print("")
  end resolveUsage
end CheckUnused

object CheckUnused:
  enum PhaseMode:
    case Aggregate
    case Report
end CheckUnused