quickfixes don't include escapes when needed

[coreywoodfield]

Reproduction steps

Scala version: 2.13.12

In Test.scala:

trait Trait {
  def foo: Any
}
class Test extends Trait{
  case object `val`

  override def foo = `val`
}

When you run scalac -quickfix:any -Xsource:3 Test.scala, the file gets updated to

trait Trait {
  def foo: Any
}
class Test extends Trait{
  case object `val`

  override def foo: Test.this.val.type = `val`
}

which does not compile (the val in the type should be surrounded with backticks)

Problem

Quickfixes should escape keywords as needed

[som-snytt]

Printing with backticks would solve related tickets in REPL and autocomplete.

[SethTisue]

attn @lrytz

[lrytz]

We could special case keywords (80 / 20), that idea is in tree printers https://github.com/scala/scala/blob/v2.13.12/src/reflect/scala/reflect/internal/Printers.scala#L34.

Alternatively sprinkle the BackquotedIdentifierAttachment attachement more widely. @som-snytt wdyt?

Either way, I don't see this as a blocker for 2.13.13.

[lrytz]

WIP: https://github.com/scala/scala/compare/2.13.x...lrytz:scala:t12942?expand=1