[analyzer] rewrite mostSpecificTypeArgument to use asInstanceOf
Change-Id: If7c9e9e9cdc1999c6f7d3c74d081a457f9fc229e
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/97278
Auto-Submit: Mike Fairhurst <mfairhurst@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Commit-Queue: Mike Fairhurst <mfairhurst@google.com>
diff --git a/pkg/analyzer/lib/src/generated/type_system.dart b/pkg/analyzer/lib/src/generated/type_system.dart
index 6e978a6..969cac5 100644
--- a/pkg/analyzer/lib/src/generated/type_system.dart
+++ b/pkg/analyzer/lib/src/generated/type_system.dart
@@ -1918,41 +1918,25 @@
* Searches the superinterfaces of [type] for implementations of [genericType]
* and returns the most specific type argument used for that generic type.
*
+ * For a more general/robust solution, use [InterfaceTypeImpl.asInstanceOf].
+ *
* For example, given [type] `List<int>` and [genericType] `Iterable<T>`,
* returns [int].
*
* Returns `null` if [type] does not implement [genericType].
*/
- // TODO(jmesserly): this is very similar to code used for flattening futures.
- // The only difference is, because of a lack of TypeProvider, the other method
- // has to match the Future type by its name and library. Here was are passed
- // in the correct type.
DartType mostSpecificTypeArgument(DartType type, DartType genericType) {
if (type is! InterfaceType) return null;
+ if (genericType is! InterfaceType) return null;
- // Walk the superinterface hierarchy looking for [genericType].
- List<DartType> candidates = <DartType>[];
- HashSet<ClassElement> visitedClasses = new HashSet<ClassElement>();
- void recurse(InterfaceType interface) {
- if (interface.element == genericType.element &&
- interface.typeArguments.isNotEmpty) {
- candidates.add(interface.typeArguments[0]);
- }
- if (visitedClasses.add(interface.element)) {
- if (interface.superclass != null) {
- recurse(interface.superclass);
- }
- interface.mixins.forEach(recurse);
- interface.interfaces.forEach(recurse);
- visitedClasses.remove(interface.element);
- }
+ var asInstanceOf = (type as InterfaceTypeImpl)
+ .asInstanceOf((genericType as InterfaceType).element);
+
+ if (asInstanceOf != null) {
+ return asInstanceOf.typeArguments[0];
}
- recurse(type);
-
- // Since the interface may be implemented multiple times with different
- // type arguments, choose the best one.
- return InterfaceTypeImpl.findMostSpecificType(candidates, this);
+ return null;
}
/**
