parser: TypeScript: Parse error on abstract class with abstract method and optional methods in abstract/declare classes.

[armano2]

Bug Report

Current Behavior
Babel expect that abstract methods must have body, this is not a case for typescript.
This is also issue for optional methods in abstract/declare classes.

SyntaxError: Unexpected token, expected "{"

Input Code

abstract class AbstractSocket {
    abstract createSocket(): Promise<string>;
}

abstract class AbstractSocket {
    createSocket?(): Promise<string>;
}

declare class Foo {
    bar?(): any;
}

Expected behavior/code
There should not be any parse errors

Babel Configuration (.babelrc, package.json, cli command)

  const babel = require('@babel/parser');
  const plugins: ParserPlugin[] = [
    'typescript',
    'objectRestSpread',
    'decorators-legacy',
    'classProperties',
    'asyncGenerators',
    'dynamicImport',
    'estree',
    'bigInt',
    'importMeta'
  ];
  if (jsx) {
    plugins.push('jsx');
  }

  return babel.parse(text, {
    sourceType: 'unambiguous',
    allowImportExportEverywhere: true,
    allowReturnOutsideFunction: true,
    ranges: true,
    plugins
  });

Environment

• Babel version(s): 7.2.3
• Node/npm version: 6-11
• OS: ----
• Monorepo: ---
• How you are using Babel: @babel/parser -> parse

[babel-bot]

Hey @armano2! We really appreciate you taking the time to report an issue. The collaborators
on this project attempt to help as many people as possible, but we're a limited number of volunteers,
so it's possible this won't be addressed swiftly.

If you need any help, or just have general Babel or JavaScript questions, we have a vibrant Slack
community that typically always has someone willing to help. You can sign-up here
for an invite.

[armano2]

@existentialism is it something what we want to support?

[RWOverdijk]

Please, yes. If anything, do it for eslint.

[nicolo-ribaudo]

This only happens when the estree plugin is enabled.

[RWOverdijk]

I don't think I'm using that plugin and I'm seeing the same happen. Does that mean eslint adds that?

Update: I'm using a preset, and I can't see it being added there either: https://github.com/facebook/metro/blob/master/packages/metro-react-native-babel-preset/src/configs/main.js

[devongovett]

Should be fixed by #9890

[armano2]

can confirm its fixed