Paul Berry
7436b97ba4
The way this is accomplished is that in `_FlowAnalysisImpl.nullAwareAccess_rightBegin`, any expression reference associated with the target of the null-aware access is restored, and the corresponding SSA node is associated with the guard variable (if any). These changes ensure that if the null-aware access is a property get, the subsequent call to `propertyGet` will pick up the appropriate SSA node, so it will be able to locate the promotion key for the property. This functionality is only enabled when the language feature `sound-flow-analysis` is enabled. To prevent test regressions, a few related changes need to be made at the same time: - `_FlowAnalysisImpl.nullAwareAccess_end` is changed so that it clears any expression info or expression reference that was associated with the null-aware access expression. This prevents flow analysis information from being erroneously propagated out of a null-aware expression, which would have led to assertion failures when analyzing null-aware expressions inside of conditional expressions. This wasn't previously a problem because the expression reference used to be consumed by `_FlowAnalysisImpl.nullAwareAccess_rightBegin`, preventing further expression references and expression infos from being recorded further along in the null-aware access. - The test framework in `mini_ast.dart` is fixed so that `!` is considered to participate in null shorting. This was a bug in the test framework that wasn't previously caught because it happened not to produce any test failures. - The analyzer's method `PostfixExpressionResolver._resolveNullCheck` is changed so that it calls `nonNullAssert_end` before terminating null-aware access. Previously, the order was swapped, causing `nullAwareAccess_end` to be called before `nonNullAssert_end` when analyzing expressions like `a?.b!`. This used to be benign, but now that non-cascaded field accesses participate in field promotion, flow analysis needs the methods to be called in the correct order. Fixes https://github.com/dart-lang/language/issues/4344. Bug: https://github.com/dart-lang/language/issues/4344 Change-Id: I523be1b4be1af3f68654a745187a546728c878fe Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/427820 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.