Paul Berry
5d78579842
A null-aware access can result in dead code if the target has static
type `Null`. The analyzer wasn't properly accounting for this,
resulting in some confusing ranges reported for the DEAD_CODE warning.
This change causes the following expressions to report dead code for
the code ranges indiced by `^`:
Null myNullVar = null;
myNullVar?[index];
// ^^^^^^ DEAD_CODE
myNullVar?[index] = value;
// ^^^^^^^^^^^^^^ DEAD_CODE
myNullVar?.method();
// ^^^^^^^^ DEAD_CODE
myNullVar?.property;
// ^^^^^^^^ DEAD_CODE
myNullVar?.property = value;
// ^^^^^^^^^^^^^^^^ DEAD_CODE
Note that the bug was confined solely to the logic that reports the
DEAD_CODE warning; there is no change to the reachability inferred by
flow analysis (and hence, this is a non-breaking change).
Fixes https://github.com/dart-lang/sdk/issues/60364.
Bug: https://github.com/dart-lang/sdk/issues/60364
Change-Id: I068826282fba6b9057e9c27d1d9310c65714e203
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/416723
Auto-Submit: Paul Berry <paulberry@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Commit-Queue: 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.