commit 709c0e4ccd3731ba4f68fbb628786b595dd1c33a
author Paul Berry <paulberry@google.com> Thu Jun 01 15:53:18 2023 +0000
committer Commit Queue <dart-scoped@luci-project-accounts.iam.gserviceaccount.com> Thu Jun 01 15:53:18 2023 +0000
tree 70fccfe2ba68bb54faa816719b3362d073ee0164
parent 990fdea1d503edff95a9662a9d16439bb3641c6a

Flow analysis: combine ExpressionInfo, ReferenceWithType, and EqualityInfo.

Previously, flow analysis used three classes to keep track of
information about expressions that have been visited:

- ExpressionInfo, to keep track of information about expressions whose
  truth or falsity has an effect on flow analysis (such as `== null`
  checks, `is` checks, and combinations thereof those using `&&` and
  `||`), as well as identifying the literal expression `Null`.

- ReferenceWithType, to keep track of information about expressions
  that represent something that can be promoted (references to
  variables and fields), as well as the static type of the expression.

- EqualityInfo, which wrapped ExpressionInfo and ReferenceWithType,
  and also redundantly stored the static type of the expression.

These have now been combined into a single class hierarchy with a base
class called `ExpressionInfo`. This makes the code easier to reason
about, because it is no longer necessary to think about which of the
three above classes is needed in a given situation. Also, it helps
prepare for a follow-up CL in which I plan to refactor how flow
analysis gathers this information; the refactor will be easier with
just a single class hierarchy of information to be gathered.

This required a modest expansion of the API to flow analysis to
include more static types, since previously, static types weren't
needed by the ExpressionInfo class.

Change-Id: Id3de8b19049f8d920ebe85ab58c624ae3e55f226
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/304211
Reviewed-by: Johnni Winther <johnniwinther@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>