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Constrained nullable generics are not control flow checked #14415

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tinganho opened this issue Mar 2, 2017 · 1 comment
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Constrained nullable generics are not control flow checked #14415

tinganho opened this issue Mar 2, 2017 · 1 comment
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@tinganho
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tinganho commented Mar 2, 2017

interface Banana {
    color: 'yellow';
}

class Monkey<T extends Banana | undefined> {
    a: T;

    render() {
        if (this.a) {
            this.a.color; // error Property 'color' does not exists on type 'T'
        }
    }
}

interface BigBanana extends Banana {
}

class BigMonkey extends Monkey<BigBanana> {
    render() {
        if (this.a) {
            this.a.color;
        }
    }
}
@ahejlsberg
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Looks like the same issue as #12636.

@mhegazy mhegazy added the Duplicate An existing issue was already created label Mar 3, 2017
@tinganho tinganho closed this as completed Mar 4, 2017
@microsoft microsoft locked and limited conversation to collaborators Jun 19, 2018
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