tree 3e8e16f2b37d0af7fdea2966844d7b5970f4ded4
parent 5152269d2891785f7c8d4f0c760dc945de466de8
author Paul Berry <paulberry@google.com> 1556644880 +0000
committer commit-bot@chromium.org <commit-bot@chromium.org> 1556644880 +0000

Change representation of ExpressionChecks.

Previously, this class held on to a ConstraintVariable indicating
whether a null check should be inserted.  Now it holds on to
NullabilityNodes indicating whether the source and destination of an
assignment are nullable, and it can infer from this whether a null
check needs to be inserted.

This paves the way for removing the old constraint solving logic in
favor of a more direct nullability propagation approach using
nullability nodes.

Change-Id: I96b95c400ed40bd12f9c9dcbb4c09a69849e51c5
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/100885
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>