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tests/cases/compiler/indexSignatureAndMappedType.ts(6,5): error TS2322: Type '{ [key: string]: T; }' is not assignable to type 'Record<K, T>'.
tests/cases/compiler/indexSignatureAndMappedType.ts(15,5): error TS2322: Type 'Record<K, U>' is not assignable to type '{ [key: string]: T; }'.
Type 'U' is not assignable to type 'T'.
'T' could be instantiated with an arbitrary type which could be unrelated to 'U'.
tests/cases/compiler/indexSignatureAndMappedType.ts(16,5): error TS2322: Type '{ [key: string]: T; }' is not assignable to type 'Record<K, U>'.
==== tests/cases/compiler/indexSignatureAndMappedType.ts (3 errors) ====
// A mapped type { [P in K]: X }, where K is a generic type, is related to
// { [key: string]: Y } if X is related to Y.
function f1<T, K extends string>(x: { [key: string]: T }, y: Record<K, T>) {
x = y;
y = x; // Error
~
!!! error TS2322: Type '{ [key: string]: T; }' is not assignable to type 'Record<K, T>'.
}
function f2<T>(x: { [key: string]: T }, y: Record<string, T>) {
x = y;
y = x;
}
function f3<T, U, K extends string>(x: { [key: string]: T }, y: Record<K, U>) {
x = y; // Error
~
!!! error TS2322: Type 'Record<K, U>' is not assignable to type '{ [key: string]: T; }'.
!!! error TS2322: Type 'U' is not assignable to type 'T'.
!!! error TS2322: 'T' could be instantiated with an arbitrary type which could be unrelated to 'U'.
!!! related TS2208 tests/cases/compiler/indexSignatureAndMappedType.ts:14:16: This type parameter might need an `extends T` constraint.
y = x; // Error
~
!!! error TS2322: Type '{ [key: string]: T; }' is not assignable to type 'Record<K, U>'.
}
// Repro from #14548
type Dictionary = {
[key: string]: string;
};
interface IBaseEntity {
name: string;
properties: Dictionary;
}
interface IEntity<T extends string> extends IBaseEntity {
properties: Record<T, string>;
}
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