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Do not include undefined in indexed access on tuple types within range of total fixed elements (#54558)

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This commit is contained in:
Mateusz Burzyński
2023-07-29 00:59:31 +02:00
committed by GitHub
parent 21bb2160c8
commit 4320104404
11 changed files with 156 additions and 34 deletions
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40
src/compiler/checker.ts
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@@ -16277,6 +16277,10 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
return type.elementFlags.length - findLastIndex(type.elementFlags, f => !(f & flags)) - 1;
}
function getTotalFixedElementCount(type: TupleType) {
return type.fixedLength + getEndElementCount(type, ElementFlags.Fixed);
}
function getElementTypes(type: TupleTypeReference): readonly Type[] {
const typeArguments = getTypeArguments(type);
const arity = getTypeReferenceArity(type);
@@ -17402,10 +17406,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
}
if (index >= 0) {
errorIfWritingToReadonlyIndex(getIndexInfoOfType(objectType, numberType));
return mapType(objectType, t => {
const restType = getRestTypeOfTupleType(t as TupleTypeReference) || undefinedType;
return accessFlags & AccessFlags.IncludeUndefined ? getUnionType([restType, missingType]) : restType;
});
return getTupleElementTypeOutOfStartCount(objectType, index, accessFlags & AccessFlags.IncludeUndefined ? missingType : undefined);
}
}
}
@@ -17745,8 +17746,8 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
// preserve backwards compatibility. For example, an element access 'this["foo"]' has always been resolved
// eagerly using the constraint type of 'this' at the given location.
if (isGenericIndexType(indexType) || (accessNode && accessNode.kind !== SyntaxKind.IndexedAccessType ?
isGenericTupleType(objectType) && !indexTypeLessThan(indexType, objectType.target.fixedLength) :
isGenericObjectType(objectType) && !(isTupleType(objectType) && indexTypeLessThan(indexType, objectType.target.fixedLength)) || isGenericReducibleType(objectType))) {
isGenericTupleType(objectType) && !indexTypeLessThan(indexType, getTotalFixedElementCount(objectType.target)) :
isGenericObjectType(objectType) && !(isTupleType(objectType) && indexTypeLessThan(indexType, getTotalFixedElementCount(objectType.target))) || isGenericReducibleType(objectType))) {
if (objectType.flags & TypeFlags.AnyOrUnknown) {
return objectType;
}
@@ -23325,18 +23326,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
return propType;
}
if (everyType(type, isTupleType)) {
return mapType(type, t => {
const tupleType = t as TupleTypeReference;
const restType = getRestTypeOfTupleType(tupleType);
if (!restType) {
return undefinedType;
}
if (compilerOptions.noUncheckedIndexedAccess &&
index >= tupleType.target.fixedLength + getEndElementCount(tupleType.target, ElementFlags.Fixed)) {
return getUnionType([restType, undefinedType]);
}
return restType;
});
return getTupleElementTypeOutOfStartCount(type, index, compilerOptions.noUncheckedIndexedAccess ? undefinedType : undefined);
}
return undefined;
}
@@ -23454,6 +23444,20 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
return getElementTypeOfSliceOfTupleType(type, type.target.fixedLength);
}
function getTupleElementTypeOutOfStartCount(type: Type, index: number, undefinedOrMissingType: Type | undefined) {
return mapType(type, t => {
const tupleType = t as TupleTypeReference;
const restType = getRestTypeOfTupleType(tupleType);
if (!restType) {
return undefinedType;
}
if (undefinedOrMissingType && index >= getTotalFixedElementCount(tupleType.target)) {
return getUnionType([restType, undefinedOrMissingType]);
}
return restType;
});
}
function getRestArrayTypeOfTupleType(type: TupleTypeReference) {
const restType = getRestTypeOfTupleType(type);
return restType && createArrayType(restType);