Partial type passes for values that are strings and incorrect objects

[luke-john]

TypeScript Version: 2.3.4

Code

interface Foo {
    key: string
    value: string
}

const shouldFail0: Partial<Foo> = '' // does not fail
const shouldPass0: Partial<Foo> = {} // does not fail
const shouldFail1: Partial<Foo> = {
    ker: ''
} // fails

interface Bar {
    (): Partial<Foo>
}

const shouldFail2: Bar = () => ({
    car: ''
}) // does not fails
const shouldFail3: Bar = () => ('') // does not fails
const shouldFail4: Bar = () => {
    return undefined
} // fails

I've setup a typescript playground example.

Expected behavior:

Partial type should not pass for values that are strings or incorrect objects.

Actual behavior:

Partial type passes for values that are strings and incorrect objects.

[ikatyang]

Duplicate of #16333, fixed by #16343 (v2.4.1 milestone).

For now, you can try typescript@next to get the following result:

[luke-john]

Just updated to 2.4.1 and it's all working now.

Cheers.