[explicit-function-return-type] Don't report when using an explicit variable type with an arrow function

[cheezenaan]

Repro

{
  "extends": ["plugin:@typescript-eslint/recommended"],
  "plugins": ["react"]
}

import * as React from 'react';

interface Props {
    message?: string;
}

export const Hello: React.SFC<Props> = ({ message = 'kiniro-mosaic' }) => (
    <div>{`Hello! ${message}`}</div>;
);

Expected Result

Neither errors nor warnings

Actual Result

7:40  warning  Missing return type on function  @typescript-eslint/explicit-function-return-type

Additional Info

Versions

package	version
@typescript-eslint/eslint-plugin	1.1.0
@typescript-eslint/parser	1.1.0
eslint-plugin-react	7.12.4
react	16.7.0
react-dom	16.7.0
TypeScript	3.2.4
ESLint	5.12.1
node	8.11.3
npm	5.6.0

[codepunkt]

Is this the same problem?

type Wat = () => string[]

// Missing return type on function.eslint(@typescript-eslint/explicit-function-return-type)
let fn: Wat = () => {
  return []
}

type Wat = () => string[]

// no errors or warnings
let fn: Wat
fn = () => {
  return []
}

[gilbsgilbs]

@codepunkt Yes.

[codepunkt]

@gilbsgilbs can i help?

[gilbsgilbs]

@codepunkt I don't think so. I already made a PR that adds an option to ignore this rule when the function expression is typed. Just need to wait for merge and release.

[saranshkataria]

I see the latest changes have been published, but I still get an error when writing this:

const App: React.FunctionComponent<{}> = () => <div>Hello World</div>;

[gilbsgilbs]

@saranshkataria thanks. I think it was only released as alpha at the moment. Just to be sure:

• did you install the latest alpha release
• did you enable the allowTypedFunctionExpressions option on the rule? See https://github.com/typescript-eslint/typescript-eslint/blob/master/packages/eslint-plugin/docs/rules/explicit-function-return-type.md#allowtypedfunctionexpressions

[bradzacher]

Yup, as @gilbsgilbs mentioned, this is only on the automatically released canary tag right now.
yarn add @typescript-eslint/eslint-plugin@canary

In future, please keep an eye on the releases section of the repo to see if PRs have released.
https://github.com/typescript-eslint/typescript-eslint/releases

[TidyIQ]

Nevermind, I just saw this issue that explains it. For anyone following along, the rule posted further up in the comments is incorrect. It should be:

  "rules": {
    "@typescript-eslint/explicit-function-return-type": ["error", {
      "allowTypedFunctionExpressions": true
    }],
  }

[ben-xD]

May I ask why we need to set a rule for this? What is the alternative, and why don't we have it ignore missing return types for react components by default?