Strange "unconstrained" behavior with React components about flow

[SamChou19815]

This is expected behavior. The difference is caused by whether the generic react component has some typing context coming from the parent. If there is a usable typing context, then even if some type argument cannot be solved from arguments and return hints, we will happily use default of the type parameter or bound (mixed if not specified) of the type parameter as the solution.

[ansonlouis]

So the react element tree changes typing context?

function Component<T: number>(pprops: {a:T}): Node {}

// pass (good)
<Component a={1} />;

// fail (good)
<Component a="str" />;

// pass?
(
    <div>
        <Component a={true} />
    </div>
)

TryFlow

[SamChou19815]

The new example seems like a bug. I will reopen and investigate.

[ansonlouis]

Thanks. Sorry, it took me a second to realize the issue could be boiled down more simply

[ansonlouis]

198.2 seems to fail properly, anyways