TypeScript/tests/cases/compiler/inferenceShouldFailOnEvolvingArrays.ts
Wesley Wigham 6e5e09cef8
Reject return type inferences to the autoType or autoArrayType (#27169)
* Reject return type inferences to the autoType or autoArrayType

* Accept new error positions
2018-10-22 16:44:32 -07:00

19 lines
695 B
TypeScript

// @strict: true
// repro from https://github.com/Microsoft/TypeScript/issues/25675
// The type of `arg` blocks inference but simplifies to T.
function logLength<T extends string, U extends string>(arg: { [K in U]: T }[U]): T {
console.log(arg.length);
return arg;
}
logLength(42); // error
let z;
z = logLength(42); // no error; T is inferred as `any`
function logFirstLength<T extends string[], U extends string>(arg: { [K in U]: T }[U]): T {
console.log(arg[0].length);
return arg;
}
logFirstLength([42]); // error
let zz = [];
zz.push(logLength(42)); // no error; T is inferred as `any`
zz = logFirstLength([42]); // no error; T is inferred as `any[]`