Fix #3683: print x.type for singleton types

[liufengyun]

Fix #3683: print x.type for singleton types

[odersky]

This is clearly the right change.

One follow-on question is whether all print output should use the new behavior except if -Yprint-debug is set.

[liufengyun]

One follow-on question is whether all print output should use the new behavior except if -Yprint-debug is set.

Good question. I think we should reset -Yprint-debug to false in ReplPrinter. WDYT?

// create a new `ctx` with `-Yprint-debug` in `_ctx` reset to `false` 
class ReplPrinter(_ctx: Context) extends DecompilerPrinter( _ctx) { 
}

[odersky]

Good question. I think we should reset -Yprint-debug to false in ReplPrinter. WDYT?

Not sure what you mean? It is off by default. If someone sets it explicitly, we should honor it, I would say.