On Fri, 21 Apr 2023 16:25:04 GMT, Jan Lahoda <jlah...@openjdk.org> wrote:
>> This is the first draft of a patch for JEP 440 and JEP 441. Changes included:
>>
>> - the pattern matching for switch and record patterns features are made
>> final, together with updates to tests.
>> - parenthesized patterns are removed.
>> - qualified enum constants are supported for case labels.
>>
>> This change herein also includes removal record patterns in for each loop,
>> which may be split into a separate PR in the future.
>
> Jan Lahoda has updated the pull request incrementally with two additional
> commits since the last revision:
>
> - Adding test.
> - Removing redundant continue, as noted on the review.
I believe the exhaustiveness algorithm needs rules for union types, both in
javac and in the JLS:
class Foo extends Exception { }
class Bar extends Exception { }
void m() {
try {
g();
} catch (Foo | Bar ex) {
String s = switch (ex) {
case Foo f -> "Foo";
case Bar f -> "Bar";
};
}
}
void g() throws Foo, Bar { }
I would expect the above switch to be exhaustive, since it covers all possible
components of the union type. In other words, the union type should act as a
sealed hierarchy which permits Foo and Bar - and the two cases should be merged
together (e.g. `case Foo` + `case Bar` should cover `Foo | Bar`). For the
records, I get same error on JDK 20.
-------------
PR Comment: https://git.openjdk.org/jdk/pull/13074#issuecomment-1519655297
