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Type for-in initializer as string #54856

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7 changes: 1 addition & 6 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -17115,11 +17115,6 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
return extractTypeAlias ? getTypeAliasInstantiation(extractTypeAlias, [type, stringType]) : stringType;
}

function getIndexTypeOrString(type: Type): Type {
const indexType = getExtractStringType(getIndexType(type));
return indexType.flags & TypeFlags.Never ? stringType : indexType;
}

function getTypeFromTypeOperatorNode(node: TypeOperatorNode): Type {
const links = getNodeLinks(node);
if (!links.resolvedType) {
Expand Down Expand Up @@ -41554,7 +41549,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
if (varExpr.kind === SyntaxKind.ArrayLiteralExpression || varExpr.kind === SyntaxKind.ObjectLiteralExpression) {
error(varExpr, Diagnostics.The_left_hand_side_of_a_for_in_statement_cannot_be_a_destructuring_pattern);
}
else if (!isTypeAssignableTo(getIndexTypeOrString(rightType), leftType)) {
else if (!isTypeAssignableTo(stringType, leftType)) {
error(varExpr, Diagnostics.The_left_hand_side_of_a_for_in_statement_must_be_of_type_string_or_any);
}
else {
Expand Down
11 changes: 11 additions & 0 deletions tests/baselines/reference/forIn3.errors.txt
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@@ -0,0 +1,11 @@
forIn3.ts(3,8): error TS2405: The left-hand side of a 'for...in' statement must be of type 'string' or 'any'.


==== forIn3.ts (1 errors) ====
function test(obj: { a: 1; b: 2 }) {
let key: "a" | "b";
for (key in obj) {} // error
~~~
!!! error TS2405: The left-hand side of a 'for...in' statement must be of type 'string' or 'any'.
}

17 changes: 17 additions & 0 deletions tests/baselines/reference/forIn3.symbols
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@@ -0,0 +1,17 @@
//// [tests/cases/compiler/forIn3.ts] ////

=== forIn3.ts ===
function test(obj: { a: 1; b: 2 }) {
>test : Symbol(test, Decl(forIn3.ts, 0, 0))
>obj : Symbol(obj, Decl(forIn3.ts, 0, 14))
>a : Symbol(a, Decl(forIn3.ts, 0, 20))
>b : Symbol(b, Decl(forIn3.ts, 0, 26))

let key: "a" | "b";
>key : Symbol(key, Decl(forIn3.ts, 1, 5))

for (key in obj) {} // error
>key : Symbol(key, Decl(forIn3.ts, 1, 5))
>obj : Symbol(obj, Decl(forIn3.ts, 0, 14))
}

17 changes: 17 additions & 0 deletions tests/baselines/reference/forIn3.types
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@@ -0,0 +1,17 @@
//// [tests/cases/compiler/forIn3.ts] ////

=== forIn3.ts ===
function test(obj: { a: 1; b: 2 }) {
>test : (obj: { a: 1; b: 2;}) => void
>obj : { a: 1; b: 2; }
>a : 1
>b : 2

let key: "a" | "b";
>key : "a" | "b"

for (key in obj) {} // error
>key : "a" | "b"
>obj : { a: 1; b: 2; }
}

44 changes: 44 additions & 0 deletions tests/baselines/reference/keyofAndForIn.errors.txt
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@@ -0,0 +1,44 @@
keyofAndForIn.ts(4,10): error TS2405: The left-hand side of a 'for...in' statement must be of type 'string' or 'any'.
keyofAndForIn.ts(15,10): error TS2405: The left-hand side of a 'for...in' statement must be of type 'string' or 'any'.
keyofAndForIn.ts(26,10): error TS2405: The left-hand side of a 'for...in' statement must be of type 'string' or 'any'.


==== keyofAndForIn.ts (3 errors) ====
function f1<K extends string, T>(obj: { [P in K]: T }, k: K) {
const b = k in obj;
let k1: K;
for (k1 in obj) {
~~
!!! error TS2405: The left-hand side of a 'for...in' statement must be of type 'string' or 'any'.
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This should be an error because this is a valid call:

declare const obj: { a: 1, b: 2, c: 3 }
declare const key: 'a' | 'b'
f1(obj, key)

'c' is not assignable to K

let x1 = obj[k1];
}
for (let k2 in obj) {
let x2 = obj[k2];
}
}

function f2<T>(obj: { [P in keyof T]: T[P] }, k: keyof T) {
const b = k in obj;
let k1: keyof T;
for (k1 in obj) {
~~
!!! error TS2405: The left-hand side of a 'for...in' statement must be of type 'string' or 'any'.
let x1 = obj[k1];
}
for (let k2 in obj) {
let x2 = obj[k2];
}
}

function f3<T, K extends keyof T>(obj: { [P in K]: T[P] }, k: K) {
const b = k in obj;
let k1: K;
for (k1 in obj) {
~~
!!! error TS2405: The left-hand side of a 'for...in' statement must be of type 'string' or 'any'.
let x1 = obj[k1];
}
for (let k2 in obj) {
let x2 = obj[k2];
}
}
3 changes: 0 additions & 3 deletions tests/baselines/reference/keyofAndForIn.js
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@@ -1,8 +1,6 @@
//// [tests/cases/conformance/types/keyof/keyofAndForIn.ts] ////

//// [keyofAndForIn.ts]
// Repro from #12513

function f1<K extends string, T>(obj: { [P in K]: T }, k: K) {
const b = k in obj;
let k1: K;
Expand Down Expand Up @@ -37,7 +35,6 @@ function f3<T, K extends keyof T>(obj: { [P in K]: T[P] }, k: K) {
}

//// [keyofAndForIn.js]
// Repro from #12513
function f1(obj, k) {
var b = k in obj;
var k1;
Expand Down
148 changes: 73 additions & 75 deletions tests/baselines/reference/keyofAndForIn.symbols
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@@ -1,126 +1,124 @@
//// [tests/cases/conformance/types/keyof/keyofAndForIn.ts] ////

=== keyofAndForIn.ts ===
// Repro from #12513

function f1<K extends string, T>(obj: { [P in K]: T }, k: K) {
>f1 : Symbol(f1, Decl(keyofAndForIn.ts, 0, 0))
>K : Symbol(K, Decl(keyofAndForIn.ts, 2, 12))
>T : Symbol(T, Decl(keyofAndForIn.ts, 2, 29))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 2, 33))
>P : Symbol(P, Decl(keyofAndForIn.ts, 2, 41))
>K : Symbol(K, Decl(keyofAndForIn.ts, 2, 12))
>T : Symbol(T, Decl(keyofAndForIn.ts, 2, 29))
>k : Symbol(k, Decl(keyofAndForIn.ts, 2, 54))
>K : Symbol(K, Decl(keyofAndForIn.ts, 2, 12))
>K : Symbol(K, Decl(keyofAndForIn.ts, 0, 12))
>T : Symbol(T, Decl(keyofAndForIn.ts, 0, 29))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 0, 33))
>P : Symbol(P, Decl(keyofAndForIn.ts, 0, 41))
>K : Symbol(K, Decl(keyofAndForIn.ts, 0, 12))
>T : Symbol(T, Decl(keyofAndForIn.ts, 0, 29))
>k : Symbol(k, Decl(keyofAndForIn.ts, 0, 54))
>K : Symbol(K, Decl(keyofAndForIn.ts, 0, 12))

const b = k in obj;
>b : Symbol(b, Decl(keyofAndForIn.ts, 3, 9))
>k : Symbol(k, Decl(keyofAndForIn.ts, 2, 54))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 2, 33))
>b : Symbol(b, Decl(keyofAndForIn.ts, 1, 9))
>k : Symbol(k, Decl(keyofAndForIn.ts, 0, 54))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 0, 33))

let k1: K;
>k1 : Symbol(k1, Decl(keyofAndForIn.ts, 4, 7))
>K : Symbol(K, Decl(keyofAndForIn.ts, 2, 12))
>k1 : Symbol(k1, Decl(keyofAndForIn.ts, 2, 7))
>K : Symbol(K, Decl(keyofAndForIn.ts, 0, 12))

for (k1 in obj) {
>k1 : Symbol(k1, Decl(keyofAndForIn.ts, 4, 7))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 2, 33))
>k1 : Symbol(k1, Decl(keyofAndForIn.ts, 2, 7))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 0, 33))

let x1 = obj[k1];
>x1 : Symbol(x1, Decl(keyofAndForIn.ts, 6, 11))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 2, 33))
>k1 : Symbol(k1, Decl(keyofAndForIn.ts, 4, 7))
>x1 : Symbol(x1, Decl(keyofAndForIn.ts, 4, 11))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 0, 33))
>k1 : Symbol(k1, Decl(keyofAndForIn.ts, 2, 7))
}
for (let k2 in obj) {
>k2 : Symbol(k2, Decl(keyofAndForIn.ts, 8, 12))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 2, 33))
>k2 : Symbol(k2, Decl(keyofAndForIn.ts, 6, 12))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 0, 33))

let x2 = obj[k2];
>x2 : Symbol(x2, Decl(keyofAndForIn.ts, 9, 11))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 2, 33))
>k2 : Symbol(k2, Decl(keyofAndForIn.ts, 8, 12))
>x2 : Symbol(x2, Decl(keyofAndForIn.ts, 7, 11))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 0, 33))
>k2 : Symbol(k2, Decl(keyofAndForIn.ts, 6, 12))
}
}

function f2<T>(obj: { [P in keyof T]: T[P] }, k: keyof T) {
>f2 : Symbol(f2, Decl(keyofAndForIn.ts, 11, 1))
>T : Symbol(T, Decl(keyofAndForIn.ts, 13, 12))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 13, 15))
>P : Symbol(P, Decl(keyofAndForIn.ts, 13, 23))
>T : Symbol(T, Decl(keyofAndForIn.ts, 13, 12))
>T : Symbol(T, Decl(keyofAndForIn.ts, 13, 12))
>P : Symbol(P, Decl(keyofAndForIn.ts, 13, 23))
>k : Symbol(k, Decl(keyofAndForIn.ts, 13, 45))
>T : Symbol(T, Decl(keyofAndForIn.ts, 13, 12))
>f2 : Symbol(f2, Decl(keyofAndForIn.ts, 9, 1))
>T : Symbol(T, Decl(keyofAndForIn.ts, 11, 12))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 11, 15))
>P : Symbol(P, Decl(keyofAndForIn.ts, 11, 23))
>T : Symbol(T, Decl(keyofAndForIn.ts, 11, 12))
>T : Symbol(T, Decl(keyofAndForIn.ts, 11, 12))
>P : Symbol(P, Decl(keyofAndForIn.ts, 11, 23))
>k : Symbol(k, Decl(keyofAndForIn.ts, 11, 45))
>T : Symbol(T, Decl(keyofAndForIn.ts, 11, 12))

const b = k in obj;
>b : Symbol(b, Decl(keyofAndForIn.ts, 14, 9))
>k : Symbol(k, Decl(keyofAndForIn.ts, 13, 45))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 13, 15))
>b : Symbol(b, Decl(keyofAndForIn.ts, 12, 9))
>k : Symbol(k, Decl(keyofAndForIn.ts, 11, 45))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 11, 15))

let k1: keyof T;
>k1 : Symbol(k1, Decl(keyofAndForIn.ts, 15, 7))
>T : Symbol(T, Decl(keyofAndForIn.ts, 13, 12))
>k1 : Symbol(k1, Decl(keyofAndForIn.ts, 13, 7))
>T : Symbol(T, Decl(keyofAndForIn.ts, 11, 12))

for (k1 in obj) {
>k1 : Symbol(k1, Decl(keyofAndForIn.ts, 15, 7))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 13, 15))
>k1 : Symbol(k1, Decl(keyofAndForIn.ts, 13, 7))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 11, 15))

let x1 = obj[k1];
>x1 : Symbol(x1, Decl(keyofAndForIn.ts, 17, 11))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 13, 15))
>k1 : Symbol(k1, Decl(keyofAndForIn.ts, 15, 7))
>x1 : Symbol(x1, Decl(keyofAndForIn.ts, 15, 11))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 11, 15))
>k1 : Symbol(k1, Decl(keyofAndForIn.ts, 13, 7))
}
for (let k2 in obj) {
>k2 : Symbol(k2, Decl(keyofAndForIn.ts, 19, 12))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 13, 15))
>k2 : Symbol(k2, Decl(keyofAndForIn.ts, 17, 12))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 11, 15))

let x2 = obj[k2];
>x2 : Symbol(x2, Decl(keyofAndForIn.ts, 20, 11))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 13, 15))
>k2 : Symbol(k2, Decl(keyofAndForIn.ts, 19, 12))
>x2 : Symbol(x2, Decl(keyofAndForIn.ts, 18, 11))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 11, 15))
>k2 : Symbol(k2, Decl(keyofAndForIn.ts, 17, 12))
}
}

function f3<T, K extends keyof T>(obj: { [P in K]: T[P] }, k: K) {
>f3 : Symbol(f3, Decl(keyofAndForIn.ts, 22, 1))
>T : Symbol(T, Decl(keyofAndForIn.ts, 24, 12))
>K : Symbol(K, Decl(keyofAndForIn.ts, 24, 14))
>T : Symbol(T, Decl(keyofAndForIn.ts, 24, 12))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 24, 34))
>P : Symbol(P, Decl(keyofAndForIn.ts, 24, 42))
>K : Symbol(K, Decl(keyofAndForIn.ts, 24, 14))
>T : Symbol(T, Decl(keyofAndForIn.ts, 24, 12))
>P : Symbol(P, Decl(keyofAndForIn.ts, 24, 42))
>k : Symbol(k, Decl(keyofAndForIn.ts, 24, 58))
>K : Symbol(K, Decl(keyofAndForIn.ts, 24, 14))
>f3 : Symbol(f3, Decl(keyofAndForIn.ts, 20, 1))
>T : Symbol(T, Decl(keyofAndForIn.ts, 22, 12))
>K : Symbol(K, Decl(keyofAndForIn.ts, 22, 14))
>T : Symbol(T, Decl(keyofAndForIn.ts, 22, 12))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 22, 34))
>P : Symbol(P, Decl(keyofAndForIn.ts, 22, 42))
>K : Symbol(K, Decl(keyofAndForIn.ts, 22, 14))
>T : Symbol(T, Decl(keyofAndForIn.ts, 22, 12))
>P : Symbol(P, Decl(keyofAndForIn.ts, 22, 42))
>k : Symbol(k, Decl(keyofAndForIn.ts, 22, 58))
>K : Symbol(K, Decl(keyofAndForIn.ts, 22, 14))

const b = k in obj;
>b : Symbol(b, Decl(keyofAndForIn.ts, 25, 9))
>k : Symbol(k, Decl(keyofAndForIn.ts, 24, 58))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 24, 34))
>b : Symbol(b, Decl(keyofAndForIn.ts, 23, 9))
>k : Symbol(k, Decl(keyofAndForIn.ts, 22, 58))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 22, 34))

let k1: K;
>k1 : Symbol(k1, Decl(keyofAndForIn.ts, 26, 7))
>K : Symbol(K, Decl(keyofAndForIn.ts, 24, 14))
>k1 : Symbol(k1, Decl(keyofAndForIn.ts, 24, 7))
>K : Symbol(K, Decl(keyofAndForIn.ts, 22, 14))

for (k1 in obj) {
>k1 : Symbol(k1, Decl(keyofAndForIn.ts, 26, 7))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 24, 34))
>k1 : Symbol(k1, Decl(keyofAndForIn.ts, 24, 7))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 22, 34))

let x1 = obj[k1];
>x1 : Symbol(x1, Decl(keyofAndForIn.ts, 28, 11))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 24, 34))
>k1 : Symbol(k1, Decl(keyofAndForIn.ts, 26, 7))
>x1 : Symbol(x1, Decl(keyofAndForIn.ts, 26, 11))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 22, 34))
>k1 : Symbol(k1, Decl(keyofAndForIn.ts, 24, 7))
}
for (let k2 in obj) {
>k2 : Symbol(k2, Decl(keyofAndForIn.ts, 30, 12))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 24, 34))
>k2 : Symbol(k2, Decl(keyofAndForIn.ts, 28, 12))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 22, 34))

let x2 = obj[k2];
>x2 : Symbol(x2, Decl(keyofAndForIn.ts, 31, 11))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 24, 34))
>k2 : Symbol(k2, Decl(keyofAndForIn.ts, 30, 12))
>x2 : Symbol(x2, Decl(keyofAndForIn.ts, 29, 11))
>obj : Symbol(obj, Decl(keyofAndForIn.ts, 22, 34))
>k2 : Symbol(k2, Decl(keyofAndForIn.ts, 28, 12))
}
}
2 changes: 0 additions & 2 deletions tests/baselines/reference/keyofAndForIn.types
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@@ -1,8 +1,6 @@
//// [tests/cases/conformance/types/keyof/keyofAndForIn.ts] ////

=== keyofAndForIn.ts ===
// Repro from #12513

function f1<K extends string, T>(obj: { [P in K]: T }, k: K) {
>f1 : <K extends string, T>(obj: { [P in K]: T; }, k: K) => void
>obj : { [P in K]: T; }
Expand Down
7 changes: 7 additions & 0 deletions tests/cases/compiler/forIn3.ts
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@@ -0,0 +1,7 @@
// @strict: true
// @noEmit: true

function test(obj: { a: 1; b: 2 }) {
let key: "a" | "b";
for (key in obj) {} // error
}
2 changes: 0 additions & 2 deletions tests/cases/conformance/types/keyof/keyofAndForIn.ts
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@@ -1,7 +1,5 @@
// @declaration: true

// Repro from #12513

function f1<K extends string, T>(obj: { [P in K]: T }, k: K) {
const b = k in obj;
let k1: K;
Expand Down