| commit | c4677b9d545af5c51eaacbd47baea35b7775a050 | [log] [tgz] |
|---|---|---|
| author | Johnni Winther <johnniwinther@google.com> | Thu Mar 30 11:24:13 2023 +0000 |
| committer | Commit Queue <dart-scoped@luci-project-accounts.iam.gserviceaccount.com> | Thu Mar 30 11:24:13 2023 +0000 |
| tree | 795ce75f3b2ca16b9550606ee0226c8156a518eb | |
| parent | a7f2562b389d0939865fdbb4854b927861b88356 [diff] |
[_fe_shared_analyzer] Check supertype before subtypes in exhaustiveness checking This updates the checking order of the exhaustiveness algorithm to process the sealed type on its own before checking the subtypes. This has the benefit that for fields that fully covered by (a supertype of) the sealed type itself, like a wildcard pattern, we avoid checking each individual subtype. For the exponential cases added in https://dart-review.googlesource.com/c/sdk/+/291800 this avoids the exponential growth, bringing the number of checked witness candidates from 837932 to 6 for the "subtype" test with n = 30 and from 12207032 to 12 for the "fields" test with n = 10. The change also fixes a problem in the 'future_or_members.dart' caused by the non-null version of 'FutureOr<dynamic>' still being nullable. The old algorithm tried to use 'Object' as a witness canditate but filtered out 'FutureOr<dynamic>' because 'Object' wasn't a subtype if it. The new algorithm starts by using 'Object?' and therefore sees that 'FutureOr<dynamic>' exhausts it. This is an inherent problem in the modelling of StaticType and it should still be addressed. Change-Id: Iaa5d5604afc4662fe1983d670638223eae5dbf6b Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/291822 Reviewed-by: Paul Berry <paulberry@google.com> Commit-Queue: Johnni Winther <johnniwinther@google.com>
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