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Improve detection of type variables in instantiated object types #53246

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ahejlsberg merged 1 commit into from
Mar 19, 2023
Merged

Improve detection of type variables in instantiated object types #53246

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10 changes: 8 additions & 2 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -18686,6 +18686,12 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
result = target.objectFlags & ObjectFlags.Reference ? createDeferredTypeReference((type as DeferredTypeReference).target, (type as DeferredTypeReference).node, newMapper, newAliasSymbol, newAliasTypeArguments) :
target.objectFlags & ObjectFlags.Mapped ? instantiateMappedType(target as MappedType, newMapper, newAliasSymbol, newAliasTypeArguments) :
instantiateAnonymousType(target, newMapper, newAliasSymbol, newAliasTypeArguments);
// If none of the type arguments for the outer type parameters contain type variables, it follows
// that the instantiated type doesn't reference type variables.
if (result.flags & TypeFlags.ObjectFlagsType && !((result as ObjectFlagsType).objectFlags & ObjectFlags.CouldContainTypeVariablesComputed)) {
(result as ObjectFlagsType).objectFlags |= ObjectFlags.CouldContainTypeVariablesComputed |
(some(typeArguments, couldContainTypeVariables) ? ObjectFlags.CouldContainTypeVariables : 0);
}
target.instantiations.set(id, result);
}
return result;
Expand Down Expand Up @@ -18856,7 +18862,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
}

function instantiateAnonymousType(type: AnonymousType, mapper: TypeMapper, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): AnonymousType {
const result = createObjectType(type.objectFlags | ObjectFlags.Instantiated, type.symbol) as AnonymousType;
const result = createObjectType(type.objectFlags & ~(ObjectFlags.CouldContainTypeVariablesComputed | ObjectFlags.CouldContainTypeVariables) | ObjectFlags.Instantiated, type.symbol) as AnonymousType;
if (type.objectFlags & ObjectFlags.Mapped) {
(result as MappedType).declaration = (type as MappedType).declaration;
// C.f. instantiateSignature
Expand Down Expand Up @@ -23858,7 +23864,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
}
const result = !!(type.flags & TypeFlags.Instantiable ||
type.flags & TypeFlags.Object && !isNonGenericTopLevelType(type) && (
objectFlags & ObjectFlags.Reference && ((type as TypeReference).node || forEach(getTypeArguments(type as TypeReference), couldContainTypeVariables)) ||
objectFlags & ObjectFlags.Reference && ((type as TypeReference).node || some(getTypeArguments(type as TypeReference), couldContainTypeVariables)) ||
objectFlags & ObjectFlags.Anonymous && type.symbol && type.symbol.flags & (SymbolFlags.Function | SymbolFlags.Method | SymbolFlags.Class | SymbolFlags.TypeLiteral | SymbolFlags.ObjectLiteral) && type.symbol.declarations ||
objectFlags & (ObjectFlags.Mapped | ObjectFlags.ReverseMapped | ObjectFlags.ObjectRestType | ObjectFlags.InstantiationExpressionType)) ||
type.flags & TypeFlags.UnionOrIntersection && !(type.flags & TypeFlags.EnumLiteral) && !isNonGenericTopLevelType(type) && some((type as UnionOrIntersectionType).types, couldContainTypeVariables));
Expand Down