On Tue, 18 Apr 2023 13:43:17 GMT, Maurizio Cimadamore <mcimadam...@openjdk.org>
wrote:
>> Jan Lahoda has updated the pull request incrementally with six additional
>> commits since the last revision:
>>
>> - Fixing infinite loop where a binding pattern is replaced with a binding
>> pattern for the same type.
>> - Reflecting review comments.
>> - Fixing exhaustiveness for unsealed supertype pattern.
>> - No need to enable features after error reported.
>> - SwitchBootstraps.typeSwitch should not initialize enum classes.
>> - A prototype of avoiding enum initialization.
>
> src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Flow.java line 812:
>
>> 810: if (l instanceof JCPatternCaseLabel patternLabel) {
>> 811: for (Type component :
>> components(selector.type)) {
>> 812: patterns =
>> patterns.prepend(PatternDescription.from(types, component,
>> patternLabel.pat));
>
> I noted that this code ends up adding redundant pattern descriptions to the
> list - for instance:
>
>
> class Test {
> sealed interface I1 permits B, C { }
> sealed interface I2 permits B, C { }
>
> static final class B implements I1, I2 { }
> static final class C implements I1, I2 { }
>
> <Z extends I1 & I2> int test(Z z) {
> return switch (z) {
> case B c -> 2;
> case C d -> 3;
> };
> }
> }
>
>
> In this case the list ends up with 6 elements, [ B, B, B, C, C, C ]. Given
> that the complexity of the algorithm depends on the number of patterns in the
> list, it would probably be better to use a set here and try to make the list
> as small as possible from early on.
I've also found an infinite loop with this:
class Test {
sealed interface I0 permits I1, I2 { }
sealed interface I00 permits I1, I2 { }
sealed interface I1 extends I0, I00 permits B, C { }
sealed interface I2 extends I0, I00 permits B, C { }
static final class B implements I1, I2 { }
static final class C implements I1, I2 { }
int test(Object o) {
return switch (o) {
case B c -> 2;
case C d -> 3;
};
}
}
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/13074#discussion_r1170079092
