Skip to content

Type inference fails for generic React props with JSX syntax, works with regular syntax #16499

Closed
@alshain

Description

@alshain

TypeScript Version: 2.3.4

Code

With the react TS starter pack: create-react-app.cmd generics-fail --scripts-version=react-scripts-ts, modify index.tsx as follows:

import * as React from 'react';
import * as ReactDOM from 'react-dom';
import registerServiceWorker from './registerServiceWorker';
import './index.css';

interface Problematic<T> {
    key: T;
}

interface Props<T, R> {
    data: T;
    renderer: (props: Problematic<T>) => React.ReactElement<R>;
}

class InferenceFail<T, R> extends React.Component<Props<T, R>, {}> {

}

class Data {
  key: string;
}

let works = new InferenceFail({data: new Data(), renderer: ({key}) => <div>{key.key}</div>});

let fails = <InferenceFail data={new Data()} renderer={({key}) => <div>{key.key}</div>} />;
//                                                                          ^^^

ReactDOM.render(
  (
    <div>
    {works}
    {fails}
  </div>),
  document.getElementById('root') as HTMLElement
);
registerServiceWorker();

Expected behavior:

No compiler error. The InferenceFail instance should be correctly inferred to have actual type parameter Data for T.

Actual behavior:

Compiler error:

(25,77): error TS2339: Property 'key' does not exist on type '{}'.

T is inferred to be {}.

Metadata

Metadata

Assignees

No one assigned

    Labels

    DuplicateAn existing issue was already created

    Type

    No type

    Projects

    No projects

    Milestone

    No milestone

    Relationships

    None yet

    Development

    No branches or pull requests

    Issue actions