Breaking change interpreting jquery promise types

TypeScript Version: 2.8.0-dev.20180302

Code

/// <reference types="jquery" /> // version 3.3.0
const t: JQuery.Promise2<string, Error, number, boolean, any, any> = {} as any;
$.when(t).then((a, b) => {
    const s: string = b; //should fail!
});

Expected behavior:

Error: b is boolean.

Actual behavior:

No error: b is any.

Has expected behavior in 2.8.0-dev.20180301, but behavior changed in 2.8.0-dev.20180302.
There are some additional error locations on DefinitelyTyped -- just run dtslint --installAll (to ensure you're using typescript@next), then dtslint types jquery. (The errors don't reproduce with just tsc because they come from // $ExpectType assertions.)

Andy (Andrewkraft) (@Andy-MS)

Andy (Andrewkraft) (@Andy-MS) can you get to the root of this and see if it's something we need to fix on our side before 2.8 goes out?

Confirmed regression 2.7 -> 2.8. Worked in all prior releases

Specifically, here is the breaking change, added at the very top of inferFromTypes.

if (source.flags & TypeFlags.Any) {
    // We are inferring from an 'any' type. We want to infer this type for every type parameter
    // referenced in the target type, so we record it as the propagation type and infer from the
    // target to itself. Then, as we find candidates we substitute the propagation type.
    const savePropagationType = propagationType;
    propagationType = source;
    inferFromTypes(target, target);
    propagationType = savePropagationType;
    return;
}

This propagationType is then used in place of the current source when it is available. This adds 'any' for all type parameter found in the structure of the target type.

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Breaking change interpreting jquery promise types #22362

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Breaking change interpreting jquery promise types #22362

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RyanCavanaugh commented on Mar 20, 2018

RyanCavanaugh commented on Mar 20, 2018

sandersn commented on Mar 20, 2018

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