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Regression: Not-null assertion causes implicit any

See original GitHub issue

TypeScript Version: 2.7.0-dev.20171029

Code

function test(numbers: number[]) {
    let last;

    for (const n of numbers) {
        if (n % 2) {
            return n;
        }

        last = n;
    }

    return last!; // without the bang, last is inferred as `number | null`
                  // adding the bang causes implicit any
}

Workaround: Initialise the “tracking” variable with undefined.

function test(numbers: number[]) {
    let last = undefined;

    for (const n of numbers) {
        if (n % 2) {
            return n;
        }

        last = n;
    }

    return last!; // OK
}

Expected behavior: Should compile successfully with and without a bang.

Issue Analytics

State:
Created 6 years ago
Comments:24 (12 by maintainers)

Top GitHub Comments

1reaction

eric-hucommented, Jan 9, 2021

@aminpaks I still see the error in the Typescript playground with the 4.1.3 (current latest version). Your code snippet is missing the non-null assertion (return last; instead of return last!;).

1reaction

Bremyscommented, Apr 8, 2020

Is anyone still on it? Can I give it a shot as a first issue?

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