Extract getFreeParameters method from `TypeSystemImpl.instantiateTypeFormalsToBounds`.
I'm going to need to use this logic for
https://github.com/dart-lang/language/issues/731 (improved inference
for fold etc.)
Change-Id: I9232e42ccfd29b028fb393af06541a9a51f57579
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/239161
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Reviewed-by: Samuel Rawlins <srawlins@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>
diff --git a/pkg/analyzer/lib/src/dart/element/type_system.dart b/pkg/analyzer/lib/src/dart/element/type_system.dart
index e782c15..d420c963 100644
--- a/pkg/analyzer/lib/src/dart/element/type_system.dart
+++ b/pkg/analyzer/lib/src/dart/element/type_system.dart
@@ -347,6 +347,52 @@
return null;
}
+ /// Computes the set of free type parameters appearing in [rootType].
+ ///
+ /// If a non-null [candidates] set is given, then only type parameters
+ /// appearing in it are considered; otherwise all type parameters are
+ /// considered.
+ List<TypeParameterElement>? getFreeParameters(DartType rootType,
+ {Set<TypeParameterElement>? candidates}) {
+ List<TypeParameterElement>? parameters;
+ Set<DartType> visitedTypes = HashSet<DartType>();
+ Set<TypeParameterElement> boundTypeParameters =
+ HashSet<TypeParameterElement>();
+
+ void appendParameters(DartType? type) {
+ if (type == null) {
+ return;
+ }
+ if (visitedTypes.contains(type)) {
+ return;
+ }
+ visitedTypes.add(type);
+ if (type is TypeParameterType) {
+ var element = type.element;
+ if ((candidates == null || candidates.contains(element)) &&
+ !boundTypeParameters.contains(element)) {
+ parameters ??= <TypeParameterElement>[];
+ parameters!.add(element);
+ }
+ } else {
+ if (type is FunctionType) {
+ assert(!type.typeFormals.any((t) => boundTypeParameters.contains(t)));
+ boundTypeParameters.addAll(type.typeFormals);
+ appendParameters(type.returnType);
+ type.parameters.map((p) => p.type).forEach(appendParameters);
+ // TODO(scheglov) https://github.com/dart-lang/sdk/issues/44218
+ type.alias?.typeArguments.forEach(appendParameters);
+ boundTypeParameters.removeAll(type.typeFormals);
+ } else if (type is InterfaceType) {
+ type.typeArguments.forEach(appendParameters);
+ }
+ }
+ }
+
+ appendParameters(rootType);
+ return parameters;
+ }
+
/// Computes the greatest lower bound of [T1] and [T2].
DartType getGreatestLowerBound(DartType T1, DartType T2) {
return _greatestLowerBoundHelper.getGreatestLowerBound(T1, T2);
@@ -541,46 +587,12 @@
}
}
- List<TypeParameterElement>? getFreeParameters(DartType rootType) {
- List<TypeParameterElement>? parameters;
- Set<DartType> visitedTypes = HashSet<DartType>();
-
- void appendParameters(DartType? type) {
- if (type == null) {
- return;
- }
- if (visitedTypes.contains(type)) {
- return;
- }
- visitedTypes.add(type);
- if (type is TypeParameterType) {
- var element = type.element;
- if (all.contains(element)) {
- parameters ??= <TypeParameterElement>[];
- parameters!.add(element);
- }
- } else {
- if (type is FunctionType) {
- appendParameters(type.returnType);
- type.parameters.map((p) => p.type).forEach(appendParameters);
- // TODO(scheglov) https://github.com/dart-lang/sdk/issues/44218
- type.alias?.typeArguments.forEach(appendParameters);
- } else if (type is InterfaceType) {
- type.typeArguments.forEach(appendParameters);
- }
- }
- }
-
- appendParameters(rootType);
- return parameters;
- }
-
bool hasProgress = true;
while (hasProgress) {
hasProgress = false;
for (TypeParameterElement parameter in partials.keys) {
DartType value = partials[parameter]!;
- var freeParameters = getFreeParameters(value);
+ var freeParameters = getFreeParameters(value, candidates: all);
if (freeParameters == null) {
defaults[parameter] = value;
partials.remove(parameter);
