swc/crates/swc_ecma_parser/tests/tsc/subtypingWithNumericIndexer5.ts

// Derived type indexer must be subtype of base type indexer

interface Base { foo: string; }
interface Derived extends Base { bar: string; }
interface Derived2 extends Derived { baz: string; }

interface A {
    [x: number]: Derived;
}

class B implements A {
    [x: string]: Base; // error
}

class B2 implements A {
    [x: string]: Derived2; // ok
}

module Generics {
    interface A<T extends Base> {
        [x: number]: T;
    }

    class B implements A<Base> {
        [x: string]: Derived; // ok
    }

    class B2 implements A<Derived> {
        [x: string]: Derived2; // ok
    }

    class B3<T extends Derived> implements A<T> {
        [x: string]: Base; // error
    }

    class B4<T extends Derived> implements A<T> {
        [x: string]: Derived; // error
    }

    class B5<T extends Derived2> implements A<T> {
        [x: string]: Derived2; // error
    }
}