Partials with extends works incorrectly with object literals

[cevek]

TypeScript Version: 2.5.0 nightly

Code

type X = {a: number};
const y:X = {a: 1, b: 2}; // it's ok - errored

function foo<Super, Part extends Super>(superObj: Partial<Super>, partObj: Partial<Part>) {}
foo({foo: 1, bar: '2'}, {foo: 1,bar: ''}); // it's ok
foo({foo: 1, bar: '2'}, {foo: 1}); // it's ok
foo({foo: 1, bar: '2'}, {foo: 1, Bar: ''}); // it's ok - errored Bar unknown prop
foo({foo: 1, bar: '2'}, {foo: 1, bar: '', baz: ''}); // bad - no error

[RyanCavanaugh]

This does what you want

function foo<Super>(superObj: Partial<Super>, partObj: Partial<Super & {}>) { }
foo({ foo: 1, bar: '2' }, { foo: 1, bar: '' }); // it's ok
foo({ foo: 1, bar: '2' }, { foo: 1 }); // it's ok
foo({ foo: 1, bar: '2' }, { foo: 1, Bar: '' }); // errors
foo({ foo: 1, bar: '2' }, { foo: 1, bar: '', baz: '' }); // errors

See also #14829

[cevek]

Also doesn't work for Records

function foo<Super, Part extends Partial<Record<keyof Super, any>>>(superObj: Super, partObj: Part) {}

foo({foo: 'foo', bar: 'bar'}, {foo: 1, bar: 1, sdf: 1}); // no error but should be

[cevek]

@RyanCavanaugh How can I return partObj type from function?

function foo<Super>(superObj: Partial<Super>, partObj: Partial<Super & {}>) { return partObj }
foo({ foo: 1, bar: '2' }, { foo: 1 }).bar // no errored

[RyanCavanaugh]

It would be helpful to understand what you want the semantics of the function to be.

[cevek]

@RyanCavanaugh
I need some validator for my graphql functions which can validate right object fields to contain only Class interface fields

interface Class<T> {
    new (): T;
}
class Foo {
    foo: number;
    bar: string;
}
function validate<Super, Args>(Cls: Partial<Class<Super>>, partObj: Partial<Super & {}>, args: Args) { 
    return {...partObj, __class: Cls, __args: args} 
}

function fetchGraphQL<T>(scheme: T): Promise<T> {}
fetchGraphQL(validate(Foo, { foo: 1 }, {arg: 1})).then(obj => obj.foo);

[cevek]

This case works, but without fields autocomplete

function validate<Super extends Part, Part, Args>(Cls: Class<Super>, partObj: Part, args: Args): Part {}

[mhegazy]

Automatically closing this issue for housekeeping purposes. The issue labels indicate that it is unactionable at the moment or has already been addressed.