Can't override field with `.keys()`

[d9k]

Getting is not assignable to type 'never' error on overriden field use:

export const CreatureV1Schema = joi.object({
  name: joi.string().required(),

  // accepts textual representation of the size ('big', 'normal', 'small' etc)
  size: joi.string().required(),
});

export const CreatureV2Schema = CreatureV1Schema.keys({
  // accepts size in meters now
  size: joi.number().required(),
});

export type CreatureV2 = joi.extractType<typeof CreatureV2Schema>;

export const creatureV2: CreatureV2 = {
  name: 'ogre',

   // TS2322 error: Type 'number' is not assignable to type 'never'.
  size: 3.5,
};

CreatureV2 renders to

type CreatureV2 = {} & {
    name: string;
    size: string;
} & {} & {
    size: number;
}

[d9k]

Experimenting with field override in TS:

export type A = {
  name: string;
  size: string;
};

export type B = A & {
  size: number;
};

const b: B = {
  name: 'ogre',

  // TS2322 error: Type 'number' is not assignable to type 'never'.
  size: 3.5,
};

export type A2 = {
  name: string;
  size: string;
};

export type B2 = Omit<A2, 'size'> & {
  size: number;
};

const b2: B2 = {
  name: 'ogre',

  // Works
  size: 3.5,
};

Seems type inference from .keys() must be processed with Omit<>

[d9k]

keys<T extends mappedSchemaMap>(
	schema: T
): this extends BoxObjectSchema<infer B>
	? BoxObjectSchema<BoxIntersection<B, extractMap<T>>>
	: never
keys(schema?: Joi.SchemaMap): this

I think

type BoxIntersection<B, nT> = B extends Box<infer oT, infer oR> ? Box<oT & nT, oR> : B

needs to be changed somehow to use Omit<>

but

type BoxIntersection<B, nT> = B extends Box<infer oT, infer oR> ? Box<Omit<oT, keyof nT> & nT, oR> : B;

doesn't work.

[d9k]

@juraj-chripko, @gr-miroslava-filcakova, what are your opinions on this issue?