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tests/cases/compiler/arrayFrom.ts(20,7): error TS2322: Type 'A[]' is not assignable to type 'B[]'.
Property 'b' is missing in type 'A' but required in type 'B'.
tests/cases/compiler/arrayFrom.ts(23,7): error TS2322: Type 'A[]' is not assignable to type 'B[]'.
==== tests/cases/compiler/arrayFrom.ts (2 errors) ====
// Tests fix for #20432, ensures Array.from accepts all valid inputs
// Also tests for #19682
interface A {
a: string;
}
interface B {
b: string;
}
const inputA: A[] = [];
const inputB: B[] = [];
const inputALike: ArrayLike<A> = { length: 0 };
const inputARand = getEither(inputA, inputALike);
const inputASet = new Set<A>();
const result1: A[] = Array.from(inputA);
const result2: A[] = Array.from(inputA.values());
const result3: B[] = Array.from(inputA.values()); // expect error
~~~~~~~
!!! error TS2322: Type 'A[]' is not assignable to type 'B[]'.
!!! error TS2322: Property 'b' is missing in type 'A' but required in type 'B'.
!!! related TS2728 tests/cases/compiler/arrayFrom.ts:9:3: 'b' is declared here.
const result4: A[] = Array.from(inputB, ({ b }): A => ({ a: b }));
const result5: A[] = Array.from(inputALike);
const result6: B[] = Array.from(inputALike); // expect error
~~~~~~~
!!! error TS2322: Type 'A[]' is not assignable to type 'B[]'.
const result7: B[] = Array.from(inputALike, ({ a }): B => ({ b: a }));
const result8: A[] = Array.from(inputARand);
const result9: B[] = Array.from(inputARand, ({ a }): B => ({ b: a }));
const result10: A[] = Array.from(new Set<A>());
const result11: B[] = Array.from(inputASet, ({ a }): B => ({ b: a }));
// if this is written inline, the compiler seems to infer
// the ?: as always taking the false branch, narrowing to ArrayLike<T>,
// even when the type is written as : Iterable<T>|ArrayLike<T>
function getEither<T> (in1: Iterable<T>, in2: ArrayLike<T>) {
return Math.random() > 0.5 ? in1 : in2;
}
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