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>