diff --git a/accepted/future-releases/extension-types/feature-specification.md b/accepted/future-releases/extension-types/feature-specification.md index bd8b689a5..55e4fdfdb 100644 --- a/accepted/future-releases/extension-types/feature-specification.md +++ b/accepted/future-releases/extension-types/feature-specification.md @@ -1298,11 +1298,11 @@ rather than from `Object`)*. *This change is needed because some extension types are subtypes of `Object?` and not subtypes of `Object`, and they need to have a well-defined depth. We could define the depth to be zero for `Object`, for -`Null`, and for every extension type that has no `implements` clause, and -insist that `Object?` isn't an interface type and doesn't have a depth, but +`Null`, and for every extension type that has no `implements` clause, but in that case we no longer have a guarantee that the sets of superinterfaces with the same maximal depth that the Dart 1 least upper bound algorithm -uses will have at least one singleton set.* +uses will have at least one singleton set. All in all it's simpler if we +preserve the property that the superinterface graph has a single root.* ## Dynamic Semantics of Extension Types