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Merge pull request #18042 from Microsoft/fixMappedTypeIndexedAccess

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Defer mapped type indexed access transformations
This commit is contained in:
Anders Hejlsberg 2017-08-25 20:59:16 +01:00 committed by GitHub
parent fe1242c8a9 e79d75a383
commit 555a742d16
10 changed files with 300 additions and 126 deletions
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57
src/compiler/checker.ts
View file

@ -7612,22 +7612,6 @@ namespace ts {
return anyType;
}
function getIndexedAccessForMappedType(type: MappedType, indexType: Type, accessNode?: ElementAccessExpression | IndexedAccessTypeNode) {
if (accessNode) {
// Check if the index type is assignable to 'keyof T' for the object type.
if (!isTypeAssignableTo(indexType, getIndexType(type))) {
error(accessNode, Diagnostics.Type_0_cannot_be_used_to_index_type_1, typeToString(indexType), typeToString(type));
return unknownType;
}
if (accessNode.kind === SyntaxKind.ElementAccessExpression && isAssignmentTarget(accessNode) && type.declaration.readonlyToken) {
error(accessNode, Diagnostics.Index_signature_in_type_0_only_permits_reading, typeToString(type));
}
}
const mapper = createTypeMapper([getTypeParameterFromMappedType(type)], [indexType]);
const templateMapper = type.mapper ? combineTypeMappers(type.mapper, mapper) : mapper;
return instantiateType(getTemplateTypeFromMappedType(type), templateMapper);
}
function isGenericObjectType(type: Type): boolean {
return type.flags & TypeFlags.TypeVariable ? true :
getObjectFlags(type) & ObjectFlags.Mapped ? isGenericIndexType(getConstraintTypeFromMappedType(<MappedType>type)) :
@ -7653,12 +7637,14 @@ namespace ts {
return false;
}
// Given an indexed access type T[K], if T is an intersection containing one or more generic types and one or
// more object types with only a string index signature, e.g. '(U & V & { [x: string]: D })[K]', return a
// transformed type of the form '(U & V)[K] | D'. This allows us to properly reason about higher order indexed
// access types with default property values as expressed by D.
// Transform an indexed access to a simpler form, if possible. Return the simpler form, or return
// undefined if no transformation is possible.
function getTransformedIndexedAccessType(type: IndexedAccessType): Type {
const objectType = type.objectType;
// Given an indexed access type T[K], if T is an intersection containing one or more generic types and one or
// more object types with only a string index signature, e.g. '(U & V & { [x: string]: D })[K]', return a
// transformed type of the form '(U & V)[K] | D'. This allows us to properly reason about higher order indexed
// access types with default property values as expressed by D.
if (objectType.flags & TypeFlags.Intersection && isGenericObjectType(objectType) && some((<IntersectionType>objectType).types, isStringIndexOnlyType)) {
const regularTypes: Type[] = [];
const stringIndexTypes: Type[] = [];
@ -7675,20 +7661,23 @@ namespace ts {
getIntersectionType(stringIndexTypes)
]);
}
// If the object type is a mapped type { [P in K]: E }, where K is generic, 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)) {
const mapper = createTypeMapper([getTypeParameterFromMappedType(<MappedType>objectType)], [type.indexType]);
const objectTypeMapper = (<MappedType>objectType).mapper;
const templateMapper = objectTypeMapper ? combineTypeMappers(objectTypeMapper, mapper) : mapper;
return instantiateType(getTemplateTypeFromMappedType(<MappedType>objectType), templateMapper);
}
return undefined;
}
function getIndexedAccessType(objectType: Type, indexType: Type, accessNode?: ElementAccessExpression | IndexedAccessTypeNode): Type {
// If the object type is a mapped type { [P in K]: E }, where K is generic, we 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)) {
return getIndexedAccessForMappedType(<MappedType>objectType, indexType, accessNode);
}
// Otherwise, if the index type is generic, or if the object type is generic and doesn't originate in an
// expression, we are performing a higher-order index access where we cannot meaningfully access the properties
// of the object type. Note that for a generic T and a non-generic K, we eagerly resolve T[K] if it originates
// in an expression. This is to preserve backwards compatibility. For example, an element access 'this["foo"]'
// If the index type is generic, or if the object type is generic and doesn't originate in an expression,
// we are performing a higher-order index access where we cannot meaningfully access the properties of the
// object type. Note that for a generic T and a non-generic K, we eagerly resolve T[K] if it originates in
// an expression. This is to 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.ElementAccessExpression) && isGenericObjectType(objectType)) {
if (objectType.flags & TypeFlags.Any) {
@ -9310,7 +9299,7 @@ namespace ts {
else if (target.flags & TypeFlags.IndexedAccess) {
// A type S is related to a type T[K] if S is related to A[K], where K is string-like and
// A is the apparent type of S.
const constraint = getConstraintOfType(<IndexedAccessType>target);
const constraint = getConstraintOfIndexedAccess(<IndexedAccessType>target);
if (constraint) {
if (result = isRelatedTo(source, constraint, reportErrors)) {
errorInfo = saveErrorInfo;
@ -9350,7 +9339,7 @@ namespace ts {
else if (source.flags & TypeFlags.IndexedAccess) {
// A type S[K] is related to a type T if A[K] is related to T, where K is string-like and
// A is the apparent type of S.
const constraint = getConstraintOfType(<IndexedAccessType>source);
const constraint = getConstraintOfIndexedAccess(<IndexedAccessType>source);
if (constraint) {
if (result = isRelatedTo(constraint, target, reportErrors)) {
errorInfo = saveErrorInfo;
@ -18839,6 +18828,10 @@ namespace ts {
const objectType = (<IndexedAccessType>type).objectType;
const indexType = (<IndexedAccessType>type).indexType;
if (isTypeAssignableTo(indexType, getIndexType(objectType))) {
if (accessNode.kind === SyntaxKind.ElementAccessExpression && isAssignmentTarget(accessNode) &&
getObjectFlags(objectType) & ObjectFlags.Mapped && (<MappedType>objectType).declaration.readonlyToken) {
error(accessNode, Diagnostics.Index_signature_in_type_0_only_permits_reading, typeToString(objectType));
}
return type;
}
// Check if we're indexing with a numeric type and if either object or index types

6
tests/baselines/reference/isomorphicMappedTypeInference.types
View file

@ -69,7 +69,7 @@ function boxify<T>(obj: T): Boxified<T> {
result[k] = box(obj[k]);
>result[k] = box(obj[k]) : Box<T[keyof T]>
>result[k] : Box<T[keyof T]>
>result[k] : Boxified<T>[keyof T]
>result : Boxified<T>
>k : keyof T
>box(obj[k]) : Box<T[keyof T]>
@ -107,7 +107,7 @@ function unboxify<T>(obj: Boxified<T>): T {
>k : keyof T
>unbox(obj[k]) : T[keyof T]
>unbox : <T>(x: Box<T>) => T
>obj[k] : Box<T[keyof T]>
>obj[k] : Boxified<T>[keyof T]
>obj : Boxified<T>
>k : keyof T
}
@ -131,7 +131,7 @@ function assignBoxified<T>(obj: Boxified<T>, values: T) {
obj[k].value = values[k];
>obj[k].value = values[k] : T[keyof T]
>obj[k].value : T[keyof T]
>obj[k] : Box<T[keyof T]>
>obj[k] : Boxified<T>[keyof T]
>obj : Boxified<T>
>k : keyof T
>value : T[keyof T]

24
tests/baselines/reference/keyofAndForIn.types
View file

@ -27,8 +27,8 @@ function f1<K extends string, T>(obj: { [P in K]: T }, k: K) {
>obj : { [P in K]: T; }
let x1 = obj[k1];
>x1 : T
>obj[k1] : T
>x1 : { [P in K]: T; }[K]
>obj[k1] : { [P in K]: T; }[K]
>obj : { [P in K]: T; }
>k1 : K
}
@ -37,8 +37,8 @@ function f1<K extends string, T>(obj: { [P in K]: T }, k: K) {
>obj : { [P in K]: T; }
let x2 = obj[k2];
>x2 : T
>obj[k2] : T
>x2 : { [P in K]: T; }[K]
>obj[k2] : { [P in K]: T; }[K]
>obj : { [P in K]: T; }
>k2 : K
}
@ -70,8 +70,8 @@ function f2<T>(obj: { [P in keyof T]: T[P] }, k: keyof T) {
>obj : { [P in keyof T]: T[P]; }
let x1 = obj[k1];
>x1 : T[keyof T]
>obj[k1] : T[keyof T]
>x1 : { [P in keyof T]: T[P]; }[keyof T]
>obj[k1] : { [P in keyof T]: T[P]; }[keyof T]
>obj : { [P in keyof T]: T[P]; }
>k1 : keyof T
}
@ -80,8 +80,8 @@ function f2<T>(obj: { [P in keyof T]: T[P] }, k: keyof T) {
>obj : { [P in keyof T]: T[P]; }
let x2 = obj[k2];
>x2 : T[keyof T]
>obj[k2] : T[keyof T]
>x2 : { [P in keyof T]: T[P]; }[keyof T]
>obj[k2] : { [P in keyof T]: T[P]; }[keyof T]
>obj : { [P in keyof T]: T[P]; }
>k2 : keyof T
}
@ -115,8 +115,8 @@ function f3<T, K extends keyof T>(obj: { [P in K]: T[P] }, k: K) {
>obj : { [P in K]: T[P]; }
let x1 = obj[k1];
>x1 : T[K]
>obj[k1] : T[K]
>x1 : { [P in K]: T[P]; }[K]
>obj[k1] : { [P in K]: T[P]; }[K]
>obj : { [P in K]: T[P]; }
>k1 : K
}
@ -125,8 +125,8 @@ function f3<T, K extends keyof T>(obj: { [P in K]: T[P] }, k: K) {
>obj : { [P in K]: T[P]; }
let x2 = obj[k2];
>x2 : T[K]
>obj[k2] : T[K]
>x2 : { [P in K]: T[P]; }[K]
>obj[k2] : { [P in K]: T[P]; }[K]
>obj : { [P in K]: T[P]; }
>k2 : K
}

2
tests/baselines/reference/keyofAndIndexedAccess.types
View file

@ -2194,7 +2194,7 @@ class Form<T> {
this.childFormFactories[prop](value)
>this.childFormFactories[prop](value) : Form<T[K]>
>this.childFormFactories[prop] : (v: T[K]) => Form<T[K]>
>this.childFormFactories[prop] : { [K in keyof T]: (v: T[K]) => Form<T[K]>; }[K]
>this.childFormFactories : { [K in keyof T]: (v: T[K]) => Form<T[K]>; }
>this : this
>childFormFactories : { [K in keyof T]: (v: T[K]) => Form<T[K]>; }

49
tests/baselines/reference/mappedTypeIndexedAccess.errors.txt Normal file
View file

@ -0,0 +1,49 @@
tests/cases/compiler/mappedTypeIndexedAccess.ts(18,5): error TS2322: Type '{ key: "foo"; value: number; }' is not assignable to type '{ key: "foo"; value: string; } | { key: "bar"; value: number; }'.
Type '{ key: "foo"; value: number; }' is not assignable to type '{ key: "foo"; value: string; }'.
Types of property 'value' are incompatible.
Type 'number' is not assignable to type 'string'.
tests/cases/compiler/mappedTypeIndexedAccess.ts(24,5): error TS2322: Type '{ key: "foo"; value: number; }' is not assignable to type '{ key: "foo"; value: string; } | { key: "bar"; value: number; }'.
Type '{ key: "foo"; value: number; }' is not assignable to type '{ key: "foo"; value: string; }'.
Types of property 'value' are incompatible.
Type 'number' is not assignable to type 'string'.
==== tests/cases/compiler/mappedTypeIndexedAccess.ts (2 errors) ====
// Repro from #15756
type Pairs<T> = {
[TKey in keyof T]: {
key: TKey;
value: T[TKey];
};
};
type Pair<T> = Pairs<T>[keyof T];
type FooBar = {
foo: string;
bar: number;
};
// Error expected here
let pair1: Pair<FooBar> = {
~~~~~
!!! error TS2322: Type '{ key: "foo"; value: number; }' is not assignable to type '{ key: "foo"; value: string; } | { key: "bar"; value: number; }'.
!!! error TS2322: Type '{ key: "foo"; value: number; }' is not assignable to type '{ key: "foo"; value: string; }'.
!!! error TS2322: Types of property 'value' are incompatible.
!!! error TS2322: Type 'number' is not assignable to type 'string'.
key: "foo",
value: 3
};
// Error expected here
let pair2: Pairs<FooBar>[keyof FooBar] = {
~~~~~
!!! error TS2322: Type '{ key: "foo"; value: number; }' is not assignable to type '{ key: "foo"; value: string; } | { key: "bar"; value: number; }'.
!!! error TS2322: Type '{ key: "foo"; value: number; }' is not assignable to type '{ key: "foo"; value: string; }'.
!!! error TS2322: Types of property 'value' are incompatible.
!!! error TS2322: Type 'number' is not assignable to type 'string'.
key: "foo",
value: 3
};

43
tests/baselines/reference/mappedTypeIndexedAccess.js Normal file
View file

@ -0,0 +1,43 @@
//// [mappedTypeIndexedAccess.ts]
// Repro from #15756
type Pairs<T> = {
[TKey in keyof T]: {
key: TKey;
value: T[TKey];
};
};
type Pair<T> = Pairs<T>[keyof T];
type FooBar = {
foo: string;
bar: number;
};
// Error expected here
let pair1: Pair<FooBar> = {
key: "foo",
value: 3
};
// Error expected here
let pair2: Pairs<FooBar>[keyof FooBar] = {
key: "foo",
value: 3
};
//// [mappedTypeIndexedAccess.js]
"use strict";
// Repro from #15756
// Error expected here
var pair1 = {
key: "foo",
value: 3
};
// Error expected here
var pair2 = {
key: "foo",
value: 3
};

206
tests/baselines/reference/mappedTypeRelationships.errors.txt
View file

@ -26,17 +26,64 @@ tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(26,5): error TS2
Type 'T[string]' is not assignable to type 'U[string]'.
Type 'T' is not assignable to type 'U'.
tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(26,12): error TS2536: Type 'K' cannot be used to index type 'T'.
tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(30,5): error TS2322: Type 'T[keyof T] | undefined' is not assignable to type 'T[keyof T]'.
Type 'undefined' is not assignable to type 'T[keyof T]'.
Type 'undefined' is not assignable to type 'T[string]'.
tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(35,5): error TS2322: Type 'T[K] | undefined' is not assignable to type 'T[K]'.
Type 'undefined' is not assignable to type 'T[K]'.
Type 'undefined' is not assignable to type 'T[string]'.
tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(40,5): error TS2322: Type 'U[keyof T] | undefined' is not assignable to type 'T[keyof T]'.
Type 'undefined' is not assignable to type 'T[keyof T]'.
Type 'undefined' is not assignable to type 'T[string]'.
tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(41,5): error TS2322: Type 'T[keyof T]' is not assignable to type 'U[keyof T] | undefined'.
Type 'T[string]' is not assignable to type 'U[keyof T] | undefined'.
tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(30,5): error TS2322: Type 'Partial<T>[keyof T]' is not assignable to type 'T[keyof T]'.
Type 'T[keyof T] | undefined' is not assignable to type 'T[keyof T]'.
Type 'undefined' is not assignable to type 'T[keyof T]'.
Type 'undefined' is not assignable to type 'T[string]'.
Type 'Partial<T>[keyof T]' is not assignable to type 'T[string]'.
Type 'T[keyof T] | undefined' is not assignable to type 'T[string]'.
Type 'undefined' is not assignable to type 'T[string]'.
tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(35,5): error TS2322: Type 'Partial<T>[K]' is not assignable to type 'T[K]'.
Type 'T[K] | undefined' is not assignable to type 'T[K]'.
Type 'undefined' is not assignable to type 'T[K]'.
Type 'undefined' is not assignable to type 'T[string]'.
Type 'Partial<T>[K]' is not assignable to type 'T[string]'.
Type 'T[K] | undefined' is not assignable to type 'T[string]'.
Type 'undefined' is not assignable to type 'T[string]'.
tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(40,5): error TS2322: Type 'Partial<U>[keyof T]' is not assignable to type 'T[keyof T]'.
Type 'U[keyof T] | undefined' is not assignable to type 'T[keyof T]'.
Type 'undefined' is not assignable to type 'T[keyof T]'.
Type 'undefined' is not assignable to type 'T[string]'.
Type 'Partial<U>[keyof T]' is not assignable to type 'T[string]'.
Type 'U[keyof T] | undefined' is not assignable to type 'T[string]'.
Type 'undefined' is not assignable to type 'T[string]'.
tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(41,5): error TS2322: Type 'T[keyof T]' is not assignable to type 'Partial<U>[keyof T]'.
Type 'T[string]' is not assignable to type 'Partial<U>[keyof T]'.
Type 'T[string]' is not assignable to type 'U[keyof T] | undefined'.
Type 'T[string]' is not assignable to type 'U[keyof T]'.
Type 'T[keyof T]' is not assignable to type 'U[keyof T] | undefined'.
Type 'T[string]' is not assignable to type 'U[keyof T] | undefined'.
Type 'T[string]' is not assignable to type 'U[keyof T]'.
Type 'T[keyof T]' is not assignable to type 'U[keyof T]'.
Type 'T[string]' is not assignable to type 'U[keyof T]'.
Type 'T[string]' is not assignable to type 'U[string]'.
Type 'T[keyof T]' is not assignable to type 'U[string]'.
Type 'T[string]' is not assignable to type 'U[string]'.
Type 'T' is not assignable to type 'U'.
tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(45,5): error TS2322: Type 'Partial<U>[K]' is not assignable to type 'T[K]'.
Type 'U[K] | undefined' is not assignable to type 'T[K]'.
Type 'undefined' is not assignable to type 'T[K]'.
Type 'undefined' is not assignable to type 'T[string]'.
Type 'Partial<U>[K]' is not assignable to type 'T[string]'.
Type 'U[K] | undefined' is not assignable to type 'T[string]'.
Type 'undefined' is not assignable to type 'T[string]'.
tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(46,5): error TS2322: Type 'T[K]' is not assignable to type 'Partial<U>[K]'.
Type 'T[string]' is not assignable to type 'Partial<U>[K]'.
Type 'T[string]' is not assignable to type 'U[K] | undefined'.
Type 'T[string]' is not assignable to type 'U[K]'.
Type 'T[K]' is not assignable to type 'U[K] | undefined'.
Type 'T[string]' is not assignable to type 'U[K] | undefined'.
Type 'T[string]' is not assignable to type 'U[K]'.
Type 'T[K]' is not assignable to type 'U[K]'.
Type 'T[string]' is not assignable to type 'U[K]'.
Type 'T[string]' is not assignable to type 'U[string]'.
Type 'T[K]' is not assignable to type 'U[string]'.
Type 'T[string]' is not assignable to type 'U[string]'.
Type 'T' is not assignable to type 'U'.
tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(51,5): error TS2542: Index signature in type 'Readonly<T>' only permits reading.
tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(56,5): error TS2542: Index signature in type 'Readonly<T>' only permits reading.
tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(61,5): error TS2322: Type 'T[keyof T]' is not assignable to type 'Readonly<U>[keyof T]'.
Type 'T[string]' is not assignable to type 'Readonly<U>[keyof T]'.
Type 'T[string]' is not assignable to type 'U[keyof T]'.
Type 'T[keyof T]' is not assignable to type 'U[keyof T]'.
Type 'T[string]' is not assignable to type 'U[keyof T]'.
@ -44,11 +91,9 @@ tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(41,5): error TS2
Type 'T[keyof T]' is not assignable to type 'U[string]'.
Type 'T[string]' is not assignable to type 'U[string]'.
Type 'T' is not assignable to type 'U'.
tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(45,5): error TS2322: Type 'U[K] | undefined' is not assignable to type 'T[K]'.
Type 'undefined' is not assignable to type 'T[K]'.
Type 'undefined' is not assignable to type 'T[string]'.
tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(46,5): error TS2322: Type 'T[K]' is not assignable to type 'U[K] | undefined'.
Type 'T[string]' is not assignable to type 'U[K] | undefined'.
tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(61,5): error TS2542: Index signature in type 'Readonly<U>' only permits reading.
tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(66,5): error TS2322: Type 'T[K]' is not assignable to type 'Readonly<U>[K]'.
Type 'T[string]' is not assignable to type 'Readonly<U>[K]'.
Type 'T[string]' is not assignable to type 'U[K]'.
Type 'T[K]' is not assignable to type 'U[K]'.
Type 'T[string]' is not assignable to type 'U[K]'.
@ -56,21 +101,6 @@ tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(46,5): error TS2
Type 'T[K]' is not assignable to type 'U[string]'.
Type 'T[string]' is not assignable to type 'U[string]'.
Type 'T' is not assignable to type 'U'.
tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(51,5): error TS2542: Index signature in type 'Readonly<T>' only permits reading.
tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(56,5): error TS2542: Index signature in type 'Readonly<T>' only permits reading.
tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(61,5): error TS2322: Type 'T[keyof T]' is not assignable to type 'U[keyof T]'.
Type 'T[string]' is not assignable to type 'U[keyof T]'.
Type 'T[string]' is not assignable to type 'U[string]'.
Type 'T[keyof T]' is not assignable to type 'U[string]'.
Type 'T[string]' is not assignable to type 'U[string]'.
Type 'T' is not assignable to type 'U'.
tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(61,5): error TS2542: Index signature in type 'Readonly<U>' only permits reading.
tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(66,5): error TS2322: Type 'T[K]' is not assignable to type 'U[K]'.
Type 'T[string]' is not assignable to type 'U[K]'.
Type 'T[string]' is not assignable to type 'U[string]'.
Type 'T[K]' is not assignable to type 'U[string]'.
Type 'T[string]' is not assignable to type 'U[string]'.
Type 'T' is not assignable to type 'U'.
tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(66,5): error TS2542: Index signature in type 'Readonly<U>' only permits reading.
tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(72,5): error TS2322: Type 'Partial<T>' is not assignable to type 'T'.
tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(78,5): error TS2322: Type 'Partial<Thing>' is not assignable to type 'Partial<T>'.
@ -168,57 +198,81 @@ tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(168,5): error TS
function f10<T>(x: T, y: Partial<T>, k: keyof T) {
x[k] = y[k]; // Error
~~~~
!!! error TS2322: Type 'T[keyof T] | undefined' is not assignable to type 'T[keyof T]'.
!!! error TS2322: Type 'undefined' is not assignable to type 'T[keyof T]'.
!!! error TS2322: Type 'undefined' is not assignable to type 'T[string]'.
!!! error TS2322: Type 'Partial<T>[keyof T]' is not assignable to type 'T[keyof T]'.
!!! error TS2322: Type 'T[keyof T] | undefined' is not assignable to type 'T[keyof T]'.
!!! error TS2322: Type 'undefined' is not assignable to type 'T[keyof T]'.
!!! error TS2322: Type 'undefined' is not assignable to type 'T[string]'.
!!! error TS2322: Type 'Partial<T>[keyof T]' is not assignable to type 'T[string]'.
!!! error TS2322: Type 'T[keyof T] | undefined' is not assignable to type 'T[string]'.
!!! error TS2322: Type 'undefined' is not assignable to type 'T[string]'.
y[k] = x[k];
}
function f11<T, K extends keyof T>(x: T, y: Partial<T>, k: K) {
x[k] = y[k]; // Error
~~~~
!!! error TS2322: Type 'T[K] | undefined' is not assignable to type 'T[K]'.
!!! error TS2322: Type 'undefined' is not assignable to type 'T[K]'.
!!! error TS2322: Type 'undefined' is not assignable to type 'T[string]'.
!!! error TS2322: Type 'Partial<T>[K]' is not assignable to type 'T[K]'.
!!! error TS2322: Type 'T[K] | undefined' is not assignable to type 'T[K]'.
!!! error TS2322: Type 'undefined' is not assignable to type 'T[K]'.
!!! error TS2322: Type 'undefined' is not assignable to type 'T[string]'.
!!! error TS2322: Type 'Partial<T>[K]' is not assignable to type 'T[string]'.
!!! error TS2322: Type 'T[K] | undefined' is not assignable to type 'T[string]'.
!!! error TS2322: Type 'undefined' is not assignable to type 'T[string]'.
y[k] = x[k];
}
function f12<T, U extends T>(x: T, y: Partial<U>, k: keyof T) {
x[k] = y[k]; // Error
~~~~
!!! error TS2322: Type 'U[keyof T] | undefined' is not assignable to type 'T[keyof T]'.
!!! error TS2322: Type 'undefined' is not assignable to type 'T[keyof T]'.
!!! error TS2322: Type 'undefined' is not assignable to type 'T[string]'.
!!! error TS2322: Type 'Partial<U>[keyof T]' is not assignable to type 'T[keyof T]'.
!!! error TS2322: Type 'U[keyof T] | undefined' is not assignable to type 'T[keyof T]'.
!!! error TS2322: Type 'undefined' is not assignable to type 'T[keyof T]'.
!!! error TS2322: Type 'undefined' is not assignable to type 'T[string]'.
!!! error TS2322: Type 'Partial<U>[keyof T]' is not assignable to type 'T[string]'.
!!! error TS2322: Type 'U[keyof T] | undefined' is not assignable to type 'T[string]'.
!!! error TS2322: Type 'undefined' is not assignable to type 'T[string]'.
y[k] = x[k]; // Error
~~~~
!!! error TS2322: Type 'T[keyof T]' is not assignable to type 'U[keyof T] | undefined'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[keyof T] | undefined'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[keyof T]'.
!!! error TS2322: Type 'T[keyof T]' is not assignable to type 'U[keyof T]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[keyof T]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[string]'.
!!! error TS2322: Type 'T[keyof T]' is not assignable to type 'U[string]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[string]'.
!!! error TS2322: Type 'T' is not assignable to type 'U'.
!!! error TS2322: Type 'T[keyof T]' is not assignable to type 'Partial<U>[keyof T]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'Partial<U>[keyof T]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[keyof T] | undefined'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[keyof T]'.
!!! error TS2322: Type 'T[keyof T]' is not assignable to type 'U[keyof T] | undefined'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[keyof T] | undefined'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[keyof T]'.
!!! error TS2322: Type 'T[keyof T]' is not assignable to type 'U[keyof T]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[keyof T]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[string]'.
!!! error TS2322: Type 'T[keyof T]' is not assignable to type 'U[string]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[string]'.
!!! error TS2322: Type 'T' is not assignable to type 'U'.
}
function f13<T, U extends T, K extends keyof T>(x: T, y: Partial<U>, k: K) {
x[k] = y[k]; // Error
~~~~
!!! error TS2322: Type 'U[K] | undefined' is not assignable to type 'T[K]'.
!!! error TS2322: Type 'undefined' is not assignable to type 'T[K]'.
!!! error TS2322: Type 'undefined' is not assignable to type 'T[string]'.
!!! error TS2322: Type 'Partial<U>[K]' is not assignable to type 'T[K]'.
!!! error TS2322: Type 'U[K] | undefined' is not assignable to type 'T[K]'.
!!! error TS2322: Type 'undefined' is not assignable to type 'T[K]'.
!!! error TS2322: Type 'undefined' is not assignable to type 'T[string]'.
!!! error TS2322: Type 'Partial<U>[K]' is not assignable to type 'T[string]'.
!!! error TS2322: Type 'U[K] | undefined' is not assignable to type 'T[string]'.
!!! error TS2322: Type 'undefined' is not assignable to type 'T[string]'.
y[k] = x[k]; // Error
~~~~
!!! error TS2322: Type 'T[K]' is not assignable to type 'U[K] | undefined'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[K] | undefined'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[K]'.
!!! error TS2322: Type 'T[K]' is not assignable to type 'U[K]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[K]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[string]'.
!!! error TS2322: Type 'T[K]' is not assignable to type 'U[string]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[string]'.
!!! error TS2322: Type 'T' is not assignable to type 'U'.
!!! error TS2322: Type 'T[K]' is not assignable to type 'Partial<U>[K]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'Partial<U>[K]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[K] | undefined'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[K]'.
!!! error TS2322: Type 'T[K]' is not assignable to type 'U[K] | undefined'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[K] | undefined'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[K]'.
!!! error TS2322: Type 'T[K]' is not assignable to type 'U[K]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[K]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[string]'.
!!! error TS2322: Type 'T[K]' is not assignable to type 'U[string]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[string]'.
!!! error TS2322: Type 'T' is not assignable to type 'U'.
}
function f20<T>(x: T, y: Readonly<T>, k: keyof T) {
@ -239,12 +293,15 @@ tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(168,5): error TS
x[k] = y[k];
y[k] = x[k]; // Error
~~~~
!!! error TS2322: Type 'T[keyof T]' is not assignable to type 'U[keyof T]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[keyof T]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[string]'.
!!! error TS2322: Type 'T[keyof T]' is not assignable to type 'U[string]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[string]'.
!!! error TS2322: Type 'T' is not assignable to type 'U'.
!!! error TS2322: Type 'T[keyof T]' is not assignable to type 'Readonly<U>[keyof T]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'Readonly<U>[keyof T]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[keyof T]'.
!!! error TS2322: Type 'T[keyof T]' is not assignable to type 'U[keyof T]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[keyof T]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[string]'.
!!! error TS2322: Type 'T[keyof T]' is not assignable to type 'U[string]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[string]'.
!!! error TS2322: Type 'T' is not assignable to type 'U'.
~~~~
!!! error TS2542: Index signature in type 'Readonly<U>' only permits reading.
}
@ -253,12 +310,15 @@ tests/cases/conformance/types/mapped/mappedTypeRelationships.ts(168,5): error TS
x[k] = y[k];
y[k] = x[k]; // Error
~~~~
!!! error TS2322: Type 'T[K]' is not assignable to type 'U[K]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[K]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[string]'.
!!! error TS2322: Type 'T[K]' is not assignable to type 'U[string]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[string]'.
!!! error TS2322: Type 'T' is not assignable to type 'U'.
!!! error TS2322: Type 'T[K]' is not assignable to type 'Readonly<U>[K]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'Readonly<U>[K]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[K]'.
!!! error TS2322: Type 'T[K]' is not assignable to type 'U[K]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[K]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[string]'.
!!! error TS2322: Type 'T[K]' is not assignable to type 'U[string]'.
!!! error TS2322: Type 'T[string]' is not assignable to type 'U[string]'.
!!! error TS2322: Type 'T' is not assignable to type 'U'.
~~~~
!!! error TS2542: Index signature in type 'Readonly<U>' only permits reading.
}

2
tests/baselines/reference/mappedTypes4.types
View file

@ -45,7 +45,7 @@ function boxify<T>(obj: T): Boxified<T> {
result[k] = { value: obj[k] };
>result[k] = { value: obj[k] } : { value: T[keyof T]; }
>result[k] : Box<T[keyof T]>
>result[k] : Boxified<T>[keyof T]
>result : Boxified<T>
>k : keyof T
>{ value: obj[k] } : { value: T[keyof T]; }

8
tests/baselines/reference/typeGuardsTypeParameters.types
View file

@ -84,15 +84,15 @@ function fun<T>(item: { [P in keyof T]: T[P] }) {
>item : { [P in keyof T]: T[P]; }
const value = item[key];
>value : T[keyof T]
>item[key] : T[keyof T]
>value : { [P in keyof T]: T[P]; }[keyof T]
>item[key] : { [P in keyof T]: T[P]; }[keyof T]
>item : { [P in keyof T]: T[P]; }
>key : keyof T
if (typeof value === "string") {
>typeof value === "string" : boolean
>typeof value : "string" | "number" | "boolean" | "symbol" | "undefined" | "object" | "function"
>value : T[keyof T]
>value : { [P in keyof T]: T[P]; }[keyof T]
>"string" : "string"
strings.push(value);
@ -100,7 +100,7 @@ function fun<T>(item: { [P in keyof T]: T[P] }) {
>strings.push : (...items: string[]) => number
>strings : string[]
>push : (...items: string[]) => number
>value : T[keyof T] & string
>value : { [P in keyof T]: T[P]; }[keyof T] & string
}
}
}

29
tests/cases/compiler/mappedTypeIndexedAccess.ts Normal file
View file

@ -0,0 +1,29 @@
// @strict: true
// Repro from #15756
type Pairs<T> = {
[TKey in keyof T]: {
key: TKey;
value: T[TKey];
};
};
type Pair<T> = Pairs<T>[keyof T];
type FooBar = {
foo: string;
bar: number;
};
// Error expected here
let pair1: Pair<FooBar> = {
key: "foo",
value: 3
};
// Error expected here
let pair2: Pairs<FooBar>[keyof FooBar] = {
key: "foo",
value: 3
};