And for all this complex analysis we get... some different exception types?
Doesn't seem like a worthwhile trade.
As I've mentioned already, I think the exception-type thing is mostly a
red herring. We have some existing precendent, which is pretty hard to
extrapolate from:
- Existing switches on enum/string/boxes throw NPE on a null target;
- (As of 12) enum expression switches throw ICCE when confronted with
a novel value.
All the discussion about exception types are trying to extrapolate from
these, but it's pretty hard to actually do so. I would be happy to just
have some sort of SwitchRemainderException.
What I'd like to do instead: switch expressions that are optimistically/weakly
total get an implicit 'default' case that throws 'UnmatchedSwitchException' or
something like that for *everything* that goes unhandled. Exactly what
diagnostic information we choose to put in the exception is a quality of
implementation issue. As a special case, if the unmatched value is 'null' (not
'Box(null)'), we *might* decide to throw an NPE instead (depending on how your
ideas about null hostility in switches pan out)
That is, essentially, what I have proposed in my "Totality" thread (I
suspect you're still catching up, as it took us a long time to get there.)
This is a behavioral change for enum switch expressions in Java 14+ code, which
makes me feel a bit sheepish, but I don't think anybody will mind a change now
that the design has evolved enough to recognize the need for a specific
exception class.
I don't think we need an incompatible change; we're already sealing off
some legacy behavior with enum/string/box switches, we can seal this one
off there too.
