Improve enum fromOrdinal and valueOf error messages

[Lasering]

Compiler version

3.3.1

Minimized example

enum Foo:
  case A

Foo.fromOrdinal(3)
Foo.valueOf("Bar")

Output Error/Warning message

fromOrdinal

java.util.NoSuchElementException: 3

valueOf

java.lang.IllegalArgumentException: enum case not found: Bar

Why this Error/Warning was not helpful

It does not state from which enum the error has originated, making it harder to track it down.

Suggested improvement

fromOrdinal:

java.util.NoSuchElementException: enum `Foo` has no case with ordinal: 3

valueOf

java.lang.IllegalArgumentException: enum `Foo` has no case with value: Bar

[bishabosha]

sure we can change the message but is looking at the stack trace no good?

[Lasering]

Sure the stack trace helps, but why make it harder, specially for newbies? This way you just look at the error message and you get all the information you need.

The message could be even more helpful stating the possible expected values.

[som-snytt]

You could "split the difference" and throw IndexOutOfBoundsException for both methods. (joke)

Enumeration threw NoSuchElement for lookup by name, like Map#apply but once omitted even the name scala/scala#4229

java.lang.IllegalArgumentException: No enum constant java.lang.Thread.State.foo

I guess the full name is usefuller.

Listing elements could be very verbose.

[Lasering]

Pretty sure this does not make sense since these are runtime errors, but is it possible to show the elements based on some compiler verbose flag?

[som-snytt]

In the discussion over whether case class toString can be made verbose, I proposed a compiler flag to enable it, with the idea that during development you want more verbose output always.

That is an easier sell if the compiler had a native notion of dev vs prod target. Flag fiddling at the build tool level is more fraught.