Paul Berry
eec56c088e
When an `is` test is trivially satisfied (i.e. `expr is T`, when the static type of `expr` is a subtype of `T`), the `is` test is guaranteed by soundness to evaluate to `true`, so any code path that follows from the `is` test evaluating to `false` is unreachable. This reasoning wasn't valid prior to sound null safety, because in mixed mode programs, it was possible for an expression to evaluate to `null` even if its static type wasn't nullable, and hence `expr is T` might evaluate to `false` even if the static type of `expr` was a subtype of `T`. So this change is gated on the `sound-flow-analysis` language flag (which is enabled in Dart 3.9). Fixes https://github.com/dart-lang/sdk/issues/60718. Change-Id: I66a65580b738162f23b6fb468b71fcac66bfbb95 Bug: https://github.com/dart-lang/sdk/issues/60718 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/431740 Commit-Queue: Paul Berry <paulberry@google.com> Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
FE/analyzer shared code
This package contains logic that is shared between the front_end and analyzer packages. It is intended solely to facilitate development of the Dart SDK, and is not intended for use by end users. In particular, this package has no public API, so no guarantee is made of compatibility between one version of the package and the next.
End users should consider using the analyzer package to analyze Dart source code.