Type inference destructure object

Bug Report

Typescript seems to not be able to infer correctly a rest object type.

I’ve found a workaround for it by nesting the value (in playground)

🔎 Search Terms

Destructuring

🕗 Version & Regression Information

Tested in 4.5.5, 4.8.2 and next (time of writing = v4.9.0-dev.20220908)

⏯ Playground Link

Playground

💻 Code

type Value = { // This properties should be always inside the dataset, to be able to render the graph
  key: string;
  color: string;
  value: number;
};

export type GraphDataSetType<
  T extends Record<string, unknown> = Record<string, never> // This represents extra data that can be used when rendering the legend for a value
> = (
(Value & T) & {
  legend: JSXElementConstructor<Value & T>
})[];

type Props<T extends Record<string, unknown> = Record<string, never>> = {
  values: GraphDataSetType<T>;
};

/* This doesn't work */
const Component = <T extends Record<string, unknown>>({values}: Props<T>) => values.map(({ legend: CustomLegend, ...props }) => <CustomLegend {...props} />)
                                                                                                                              // ^ Error

🙁 Actual behavior

Throws an error

Type 'Omit<Value & T & { legend: JSXElementConstructor<Value & T>; }, "legend">' is not assignable to type 'IntrinsicAttributes & Value & T'.
  Type 'Omit<Value & T & { legend: JSXElementConstructor<Value & T>; }, "legend">' is missing the following properties from type 'Value': key, color, value

🙂 Expected behavior

Expect to not throw an error as Omit<Value & T & { legend: ... }, "legend" }> === Value & T

[andrewbranch]

@herrlegno that’s a duplicate of #241 (congrats, you found a three-digit one!)

[andrewbranch]

#50604 is definitely working as intended. If T is instantiated with an object that also has a property x, the result of Omit<T & { x: X }, "x"> will not be assignable to T.

Likewise, the pattern in the OP here (and my reduced case) should be an error, since T can be instantiated with an object including the legend property (or foo in my reduced case), but the elaboration in the error message is nonsensical:

Type 'Omit<Value & T & { foo: unknown; }, "foo">' is missing the following properties from type 'Value': key, color, value(2322)

This makes me think that it’s an error for a completely incorrect reason.