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Deep mocking results in a TypeScript error + extreme compilation slowness

See original GitHub issue

Upgrading to v2.0.7 (see original PR) from v2.0.6 seems to have brought in something fishy when using mockDeep. On a fresh install, TypeScript compilation is now ridiculously slow.

yarn tsc --noEmit

before: 1.5-3.5s
first compilation after upgrading to the new version: 200s (i.e. over 3 minutes)
follow-up compilations on 2.0.7: once again <4s

TypeScript v4.7.4, Node v16.14.2, jest v28.1.3, ts-jest 28.0.7, running on an M1 Pro chip

Reproducible example:

import { DeepMockProxy, mockDeep } from 'jest-mock-extended';

interface Thing {
  foo: {
    bar: () => void;
  };
}

export const mockThing: DeepMockProxy<Thing> = mockDeep<Thing>();

Not only is this excruciatingly slow (but only the first time), it also complains with a type error:

node_modules/jest-mock-extended/lib/Mock.d.ts:27:222 - error TS2536: Type 'K_1' cannot be used to index type 'T[K]'.

27 export declare const mockDeep: <T>(mockImplementation?: DeepPartial<T> | undefined) => { [K in keyof T]: T[K] extends (...args: infer A) => infer B ? CalledWithMock<B, A> & (T[K] extends infer T_1 ? { [K_1 in keyof T_1]: T[K][K_1] extends (...args: infer A) => infer B ? CalledWithMock<B, A> & (T[K][K_1] extends infer T_2 ? { [K_2 in keyof T_2]: T[K][K_1][K_2] extends (...args: infer A) => infer B ? CalledWithMock<B, A> & (T[K][K_1][K_2] extends infer T_3 ? { [K_3 in keyof T_3]: T[K][K_1][K_2][K_3] extends (...args: infer A) => infer B ? CalledWithMock<B, A> & (T[K][K_1][K_2][K_3] extends infer T_4 ? { [K_4 in keyof T_4]: T[K][K_1][K_2][K_3][K_4] extends (...args: infer A) => infer B ? CalledWithMock<B, A> & (T[K][K_1][K_2][K_3][K_4] extends infer T_5 ? { [K_5 in keyof T_5]: T[K][K_1][K_2][K_3][K_4][K_5] extends (...args: infer A) => infer B ? CalledWithMock<B, A> & (T[K][K_1][K_2][K_3][K_4][K_5] extends infer T_6 ? { [K_6 in keyof T_6]: T[K][K_1][K_2][K_3][K_4][K_5][K_6] extends (...args: infer A) => infer B ? CalledWithMock<B, A> & (T[K][K_1][K_2][K_3][K_4][K_5][K_6] extends infer T_7 ? { [K_7 in keyof T_7]: T[K][K_1][K_2][K_3][K_4][K_5][K_6][K_7] extends (...args: infer A) => infer B ? CalledWithMock<B, A> & (T[K][K_1][K_2][K_3][K_4][K_5][K_6][K_7] extends infer T_8 ? { [K_8 in keyof T_8]: T[K][K_1][K_2][K_3][K_4][K_5][K_6][K_7][K_8] extends (...args: infer A) => infer B ? CalledWithMock<B, A> & (T[K][K_1][K_2][K_3][K_4][K_5][K_6][K_7][K_8] extends infer T_9 ? { [K_9 in keyof T_9]: T[K][K_1][K_2][K_3][K_4][K_5][K_6][K_7][K_8][K_9] extends (...args: infer A) => infer B ? CalledWithMock<B, A> & (T[K][K_1][K_2][K_3][K_4][K_5][K_6][K_7][K_8][K_9] extends infer T_10 ? { [K_10 in keyof T_10]: T[K][K_1][K_2][K_3][K_4][K_5][K_6][K_7][K_8][K_9][K_10] extends (...args: infer A) => infer B ? CalledWithMock<B, A> & any & T[K][K_1][K_2][K_3][K_4][K_5][K_6][K_7][K_8][K_9][K_10] : DeepMockProxy<T[K][K_1][K_2][K_3][K_4][K_5][K_6][K_7][K_8][K_9][K_10]>; } : never) & T[K][K_1][K_2][K_3][K_4][K_5][K_6][K_7][K_8][K_9] : DeepMockProxy<T[K][K_1][K_2][K_3][K_4][K_5][K_6][K_7][K_8][K_9]>; } : never) & T[K][K_1][K_2][K_3][K_4][K_5][K_6][K_7][K_8] : DeepMockProxy<T[K][K_1][K_2][K_3][K_4][K_5][K_6][K_7][K_8]>; } : never) & T[K][K_1][K_2][K_3][K_4][K_5][K_6][K_7] : DeepMockProxy<T[K][K_1][K_2][K_3][K_4][K_5][K_6][K_7]>; } : never) & T[K][K_1][K_2][K_3][K_4][K_5][K_6] : DeepMockProxy<T[K][K_1][K_2][K_3][K_4][K_5][K_6]>; } : never) & T[K][K_1][K_2][K_3][K_4][K_5] : DeepMockProxy<T[K][K_1][K_2][K_3][K_4][K_5]>; } : never) & T[K][K_1][K_2][K_3][K_4] : DeepMockProxy<T[K][K_1][K_2][K_3][K_4]>; } : never) & T[K][K_1][K_2][K_3] : DeepMockProxy<T[K][K_1][K_2][K_3]>; } : never) & T[K][K_1][K_2] : DeepMockProxy<T[K][K_1][K_2]>; } : never) & T[K][K_1] : DeepMockProxy<T[K][K_1]>; } : never) & T[K] : DeepMockProxy<T[K]>; } & T;
                                                                                                                                                                                                                                ~~~~~~~~~

node_modules/jest-mock-extended/lib/Mock.d.ts:27:2781 - error TS2536: Type 'K_1' cannot be used to index type 'T[K]'.

27 export declare const mockDeep: <T>(mockImplementation?: DeepPartial<T> | undefined) => { [K in keyof T]: T[K] extends (...args: infer A) => infer B ? CalledWithMock<B, A> & (T[K] extends infer T_1 ? { [K_1 in keyof T_1]: T[K][K_1] extends (...args: infer A) => infer B ? CalledWithMock<B, A> & (T[K][K_1] extends infer T_2 ? { [K_2 in keyof T_2]: T[K][K_1][K_2] extends (...args: infer A) => infer B ? CalledWithMock<B, A> & (T[K][K_1][K_2] extends infer T_3 ? { [K_3 in keyof T_3]: T[K][K_1][K_2][K_3] extends (...args: infer A) => infer B ? CalledWithMock<B, A> & (T[K][K_1][K_2][K_3] extends infer T_4 ? { [K_4 in keyof T_4]: T[K][K_1][K_2][K_3][K_4] extends (...args: infer A) => infer B ? CalledWithMock<B, A> & (T[K][K_1][K_2][K_3][K_4] extends infer T_5 ? { [K_5 in keyof T_5]: T[K][K_1][K_2][K_3][K_4][K_5] extends (...args: infer A) => infer B ? CalledWithMock<B, A> & (T[K][K_1][K_2][K_3][K_4][K_5] extends infer T_6 ? { [K_6 in keyof T_6]: T[K][K_1][K_2][K_3][K_4][K_5][K_6] extends (...args: infer A) => infer B ? CalledWithMock<B, A> & (T[K][K_1][K_2][K_3][K_4][K_5][K_6] extends infer T_7 ? { [K_7 in keyof T_7]: T[K][K_1][K_2][K_3][K_4][K_5][K_6][K_7] extends (...args: infer A) => infer B ? CalledWithMock<B, A> & (T[K][K_1][K_2][K_3][K_4][K_5][K_6][K_7] extends infer T_8 ? { [K_8 in keyof T_8]: T[K][K_1][K_2][K_3][K_4][K_5][K_6][K_7][K_8] extends (...args: infer A) => infer B ? CalledWithMock<B, A> & (T[K][K_1][K_2][K_3][K_4][K_5][K_6][K_7][K_8] extends infer T_9 ? { [K_9 in keyof T_9]: T[K][K_1][K_2][K_3][K_4][K_5][K_6][K_7][K_8][K_9] extends (...args: infer A) => infer B ? CalledWithMock<B, A> & (T[K][K_1][K_2][K_3][K_4][K_5][K_6][K_7][K_8][K_9] extends infer T_10 ? { [K_10 in keyof T_10]: T[K][K_1][K_2][K_3][K_4][K_5][K_6][K_7][K_8][K_9][K_10] extends (...args: infer A) => infer B ? CalledWithMock<B, A> & any & T[K][K_1][K_2][K_3][K_4][K_5][K_6][K_7][K_8][K_9][K_10] : DeepMockProxy<T[K][K_1][K_2][K_3][K_4][K_5][K_6][K_7][K_8][K_9][K_10]>; } : never) & T[K][K_1][K_2][K_3][K_4][K_5][K_6][K_7][K_8][K_9] : DeepMockProxy<T[K][K_1][K_2][K_3][K_4][K_5][K_6][K_7][K_8][K_9]>; } : never) & T[K][K_1][K_2][K_3][K_4][K_5][K_6][K_7][K_8] : DeepMockProxy<T[K][K_1][K_2][K_3][K_4][K_5][K_6][K_7][K_8]>; } : never) & T[K][K_1][K_2][K_3][K_4][K_5][K_6][K_7] : DeepMockProxy<T[K][K_1][K_2][K_3][K_4][K_5][K_6][K_7]>; } : never) & T[K][K_1][K_2][K_3][K_4][K_5][K_6] : DeepMockProxy<T[K][K_1][K_2][K_3][K_4][K_5][K_6]>; } : never) & T[K][K_1][K_2][K_3][K_4][K_5] : DeepMockProxy<T[K][K_1][K_2][K_3][K_4][K_5]>; } : never) & T[K][K_1][K_2][K_3][K_4] : DeepMockProxy<T[K][K_1][K_2][K_3][K_4]>; } : never) & T[K][K_1][K_2][K_3] : DeepMockProxy<T[K][K_1][K_2][K_3]>; } : never) & T[K][K_1][K_2] : DeepMockProxy<T[K][K_1][K_2]>; } : never) & T[K][K_1] : DeepMockProxy<T[K][K_1]>; } : never) & T[K] : DeepMockProxy<T[K]>; } & T;