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Cache getConstraintOfDistributiveConditionalType (#53358)

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Jake Bailey 2023-03-27 14:12:06 -07:00 committed by GitHub
parent b34371a444
commit 3efcfcb70c
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2 changed files with 8 additions and 0 deletions
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6
src/compiler/checker.ts
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@ -13605,6 +13605,10 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
}
function getConstraintOfDistributiveConditionalType(type: ConditionalType): Type | undefined {
if (type.resolvedConstraintOfDistributive !== undefined) {
return type.resolvedConstraintOfDistributive || undefined;
}
// Check if we have a conditional type of the form 'T extends U ? X : Y', where T is a constrained
// type parameter. If so, create an instantiation of the conditional type where T is replaced
// with its constraint. We do this because if the constraint is a union type it will be distributed
@ -13622,10 +13626,12 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
if (constraint && constraint !== type.checkType) {
const instantiated = getConditionalTypeInstantiation(type, prependTypeMapping(type.root.checkType, constraint, type.mapper));
if (!(instantiated.flags & TypeFlags.Never)) {
type.resolvedConstraintOfDistributive = instantiated;
return instantiated;
}
}
}
type.resolvedConstraintOfDistributive = false;
return undefined;
}

2
src/compiler/types.ts
View File

@ -6645,6 +6645,8 @@ export interface ConditionalType extends InstantiableType {
/** @internal */
resolvedDefaultConstraint?: Type;
/** @internal */
resolvedConstraintOfDistributive?: Type | false;
/** @internal */
mapper?: TypeMapper;
/** @internal */
combinedMapper?: TypeMapper;