type T22_8 = { [k: string|symbol|number]: string | number; a: string; b: number; c: 1; } type Signs<T> = Exclude<keyof { [k in keyof T as ( true extends IsIndexSignaturePrimitiveType<k> ? k : never )]: T[k]; }, never>; type Keys<T> = keyof { [k in keyof T as ( true extends IsIndexSignaturePrimitiveType<k> ? never : k )]: T[k]; } type signs = Signs<T22_8>; type keys = Keys<T22_8>;