TypeScript React HOC using `forwardRef`

foo.tsx

import * as React from 'react';
import { Component, ComponentClass, createRef, forwardRef, Ref } from 'react';

const myHoc = <ComposedComponentProps extends {}>(
    ComposedComponent: ComponentClass<ComposedComponentProps>,
) => {
    type ComposedComponentInstance = InstanceType<typeof ComposedComponent>;

    type WrapperComponentProps = ComposedComponentProps & {
        wrapperComponentProp: number;
    };
    type WrapperComponentPropsWithForwardedRef = WrapperComponentProps & {
        forwardedRef: Ref<ComposedComponentInstance>;
    };

    class WrapperComponent extends Component<
        WrapperComponentPropsWithForwardedRef,
        {}
    > {
        render() {
            const {
                forwardedRef,
                wrapperComponentProp,
                ...composedComponentProps
            } = this.props;

            return (
                <ComposedComponent
                    ref={forwardedRef}
                    // We need a cast because:
                    // https://github.com/DefinitelyTyped/DefinitelyTyped/issues/32355
                    // https://github.com/Microsoft/TypeScript/issues/28938#issuecomment-450636046
                    {...composedComponentProps as ComposedComponentProps}
                />
            );
        }
    }

    return forwardRef<ComposedComponentInstance, WrapperComponentProps>(
        (props, ref) => <WrapperComponent forwardedRef={ref} {...props} />,
    );
};

type MyComponentProps = { composedComponentProp: number };
class MyComponent extends Component<MyComponentProps> {}

const ref = createRef<MyComponent>();
const badRef = createRef<ComponentClass<{}>>();

const MyComponentAfterHoc = myHoc(MyComponent);

//
// Tests
//

// should succeed:
<MyComponentAfterHoc composedComponentProp={1} wrapperComponentProp={1} />;
<MyComponentAfterHoc
    composedComponentProp={1}
    wrapperComponentProp={1}
    ref={e => {}}
/>;
<MyComponentAfterHoc
    composedComponentProp={1}
    wrapperComponentProp={1}
    ref={ref}
/>;

// should error:
<MyComponentAfterHoc
    composedComponentProp={1}
    wrapperComponentProp={1}
    ref={badRef}
/>;
<MyComponentAfterHoc composedComponentProp={'1'} wrapperComponentProp={1} />;
<MyComponentAfterHoc composedComponentProp={'1'} wrapperComponentProp={'1'} />;
<MyComponentAfterHoc />;

Actually, this doesn't quite cut it: if you try to pass the result of one HOC into another HOC, you'll get an error:

const MyComponentAfterHoc2 = myHoc(MyComponentAfterHoc);

See DefinitelyTyped/DefinitelyTyped#35834 (comment). The answer isn't pretty…

I'm also curious how you can pass defaultProps from component to the ComponentAfterHoc

I ended up using decomposing the ref and prop types from ForwardRefExoticComponent, see my gist.

It let me wrap the HOC multiple times and errored on badRefs, although not the most extensively tested.