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Defer index types on remapping mapped types (#55140)

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Co-authored-by: Nathan Shively-Sanders <293473+sandersn@users.noreply.github.com>
This commit is contained in:
Mateusz Burzyński
2023-11-30 17:21:05 +01:00
committed by GitHub
parent 3258d75169
commit 2c4cbd98fa
6 changed files with 504 additions and 273 deletions
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25
src/compiler/checker.ts
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@@ -1304,6 +1304,12 @@ const enum MappedTypeModifiers {
ExcludeOptional = 1 << 3,
}
const enum MappedTypeNameTypeKind {
None,
Filtering,
Remapping,
}
const enum ExpandingFlags {
None = 0,
Source = 1,
@@ -13741,7 +13747,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
const constraintType = getConstraintTypeFromMappedType(type);
const mappedType = (type.target as MappedType) || type;
const nameType = getNameTypeFromMappedType(mappedType);
const shouldLinkPropDeclarations = !nameType || isFilteringMappedType(mappedType);
const shouldLinkPropDeclarations = getMappedTypeNameTypeKind(mappedType) !== MappedTypeNameTypeKind.Remapping;
const templateType = getTemplateTypeFromMappedType(mappedType);
const modifiersType = getApparentType(getModifiersTypeFromMappedType(type)); // The 'T' in 'keyof T'
const templateModifiers = getMappedTypeModifiers(type);
@@ -13923,9 +13929,12 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
return false;
}
function isFilteringMappedType(type: MappedType): boolean {
function getMappedTypeNameTypeKind(type: MappedType): MappedTypeNameTypeKind {
const nameType = getNameTypeFromMappedType(type);
return !!nameType && isTypeAssignableTo(nameType, getTypeParameterFromMappedType(type));
if (!nameType) {
return MappedTypeNameTypeKind.None;
}
return isTypeAssignableTo(nameType, getTypeParameterFromMappedType(type)) ? MappedTypeNameTypeKind.Filtering : MappedTypeNameTypeKind.Remapping;
}
function resolveStructuredTypeMembers(type: StructuredType): ResolvedType {
@@ -17700,7 +17709,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
function shouldDeferIndexType(type: Type, indexFlags = IndexFlags.None) {
return !!(type.flags & TypeFlags.InstantiableNonPrimitive ||
isGenericTupleType(type) ||
isGenericMappedType(type) && !hasDistributiveNameType(type) ||
isGenericMappedType(type) && (!hasDistributiveNameType(type) || getMappedTypeNameTypeKind(type) === MappedTypeNameTypeKind.Remapping) ||
type.flags & TypeFlags.Union && !(indexFlags & IndexFlags.NoReducibleCheck) && isGenericReducibleType(type) ||
type.flags & TypeFlags.Intersection && maybeTypeOfKind(type, TypeFlags.Instantiable) && some((type as IntersectionType).types, isEmptyAnonymousObjectType));
}
@@ -18282,7 +18291,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
// K is generic and N is assignable to P, instantiate E using a mapper that substitutes the index type for P.
// For example, for an index access { [P in K]: Box<T[P]> }[X], we construct the type Box<T[X]>.
if (isGenericMappedType(objectType)) {
if (!getNameTypeFromMappedType(objectType) || isFilteringMappedType(objectType)) {
if (getMappedTypeNameTypeKind(objectType) !== MappedTypeNameTypeKind.Remapping) {
return type[cache] = mapType(substituteIndexedMappedType(objectType, type.indexType), t => getSimplifiedType(t, writing));
}
}
@@ -40108,7 +40117,11 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
// Check if the index type is assignable to 'keyof T' for the object type.
const objectType = (type as IndexedAccessType).objectType;
const indexType = (type as IndexedAccessType).indexType;
if (isTypeAssignableTo(indexType, getIndexType(objectType, IndexFlags.None))) {
// skip index type deferral on remapping mapped types
const objectIndexType = isGenericMappedType(objectType) && getMappedTypeNameTypeKind(objectType) === MappedTypeNameTypeKind.Remapping
? getIndexTypeForMappedType(objectType, IndexFlags.None)
: getIndexType(objectType, IndexFlags.None);
if (isTypeAssignableTo(indexType, objectIndexType)) {
if (
accessNode.kind === SyntaxKind.ElementAccessExpression && isAssignmentTarget(accessNode) &&
getObjectFlags(objectType) & ObjectFlags.Mapped && getMappedTypeModifiers(objectType as MappedType) & MappedTypeModifiers.IncludeReadonly