commit c15f054809ed2dcb1c853895475d24d7a8365d83
author Lasse R.H. Nielsen <lrn@google.com> Tue Sep 12 11:08:42 2023 +0000
committer Commit Queue <dart-scoped@luci-project-accounts.iam.gserviceaccount.com> Tue Sep 12 11:08:42 2023 +0000
tree 99d4e250cb54cfdd4a3bac1ab45b441ba94c9961
parent f7090efca01c130ca419feec269db192a7ad1a68

Hide the existence of `EfficientLengthIterable` better.

The `EfficientLengthIterable` is an internal marker interface
that allows the SDK to more efficiently check, effectively,
`v is List || v is Set || v is Queue`, and some other
known internal types, which allows it to assume that `.length`
is efficient and doesn't iterate the iterable.

It's not intended for external use, but the current design
both has the name mentioned specifically in the declaration
of the public types `List`, `Set` and `Queue`,
and possibly allows the type to leak through the
least-upper-bound algorithm.

This change moves the mention of `EfficientLengthIterable`
from the public types to an anonymously named private type,
and ensures that the private type is never the result of
a least-upper-bound computation, by adding another
interface with the same depth that all the public
types implementing `EfficientLengthIterable` also implement.

(A longer term solution to `EfficientLengthIterable` looking
like it's a public name could be combining the collection-
related code from `dart:collection`, `dart:core` and
`dart:_internal` into a single `dart:_collection_impl`,
and exporting the relevant types from there. Then
we could make the interface be `_EfficientLengthIterable`
again.)

Change-Id: I717743f0ca253782162be0ad9ff05036fdf57159
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/322320
Reviewed-by: Nate Bosch <nbosch@google.com>
Reviewed-by: Slava Egorov <vegorov@google.com>
Reviewed-by: Aske Simon Christensen <askesc@google.com>
Reviewed-by: Stephen Adams <sra@google.com>
Commit-Queue: Lasse Nielsen <lrn@google.com>