@babel/parser does not parse non-null members named 'readonly' in TypeScript

[elevatebart]

Bug Report

Current Behavior
When I use @pabel/parser with the following code:

class MyComp {
          readonly!: boolean;
}

I get SyntaxError: Unexpected Token

Expected behavior/code
I expect readonly to be the name of my property

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

import { parse } from '@babel/parser'
const src = 'code above'

parse(src, {
  sourceType: 'module',
  strictMode: false,
  tokens: true,
  plugins:['typescript', 'classProperties']
})

Environment

• Babel version(s): v7.3.3
• Node/npm version: Node 10/npm 6
• OS: OSX 10.13.4
• Monorepo: no
• How you are using Babel: none, I am using only the parser

Additional context/Screenshots
This was found investgating this bug.
vue-styleguidist/vue-styleguidist#281

[babel-bot]

Hey @elevatebart! 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.

[elevatebart]

I forgot to add the call stack

at Object.raise (node_modules/@babel/parser/lib/index.js:3831:17)
      at Object.unexpected (node_modules/@babel/parser/lib/index.js:5143:16)
      at Object.parseIdentifierName (node_modules/@babel/parser/lib/index.js:6970:18)
      at Object.parseIdentifier (node_modules/@babel/parser/lib/index.js:6948:23)
      at Object.parseMaybePrivateName (node_modules/@babel/parser/lib/index.js:6312:19)
      at Object.parsePropertyName (node_modules/@babel/parser/lib/index.js:6768:98)
      at Object.parseClassPropertyName (node_modules/@babel/parser/lib/index.js:8173:22)
      at Object.parseClassMemberWithIsStatic (node_modules/@babel/parser/lib/index.js:10175:12)
      at Object.parseClassMember (node_modules/@babel/parser/lib/index.js:8067:10)
      at Object.parseClassMember (node_modules/@babel/parser/lib/index.js:10138:11)
      at withTopicForbiddingContext (node_modules/@babel/parser/lib/index.js:8022:14)
      at Object.withTopicForbiddingContext (node_modules/@babel/parser/lib/index.js:7150:14)
      at Object.parseClassBody (node_modules/@babel/parser/lib/index.js:7999:10)
      at Object.parseClass (node_modules/@babel/parser/lib/index.js:7973:10)
      at Object.parseExportDefaultExpression (node_modules/@babel/parser/lib/index.js:8394:19)
      at Object.parseExportDefaultExpression (node_modules/@babel/parser/lib/index.js:10113:18)
      at Object.parseExport (node_modules/@babel/parser/lib/index.js:8299:31)
      at Object.parseExport (node_modules/@babel/parser/lib/index.js:10091:20)
      at Object.parseStatementContent (node_modules/@babel/parser/lib/index.js:7347:27)
      at Object.parseStatementContent (node_modules/@babel/parser/lib/index.js:10128:18)
      at Object.parseStatement (node_modules/@babel/parser/lib/index.js:7243:17)
      at Object.parseBlockOrModuleBlockBody (node_modules/@babel/parser/lib/index.js:7810:25)
      at Object.parseBlockBody (node_modules/@babel/parser/lib/index.js:7797:10)
      at Object.parseTopLevel (node_modules/@babel/parser/lib/index.js:7181:10)
      at Object.parse (node_modules/@babel/parser/lib/index.js:8658:17)
      at Object.parse (node_modules/@babel/parser/lib/index.js:10658:38)

I hope it helps

[elevatebart]

I managed to track the bug back to this function parseClassMemberWithIsStatic

babel/packages/babel-parser/src/plugins/typescript.js

Line 1730 in 2817844

parseClassMemberWithIsStatic(

It parses out the modifier before having a token to modify.
Should I try preventing this in a PR ?

[elevatebart]

Actually, I would say that the bang should be added to this list

babel/packages/babel-parser/src/plugins/typescript.js

Lines 77 to 91 in 2817844

	tsNextTokenCanFollowModifier() {
	// Note: TypeScript's implementation is much more complicated because
	// more things are considered modifiers there.
	// This implementation only handles modifiers not handled by @babel/parser itself. And "static".
	// TODO: Would be nice to avoid lookahead. Want a hasLineBreakUpNext() method...
	this.next();
	return (
	!this.hasPrecedingLineBreak() &&
	!this.match(tt.parenL) &&
	!this.match(tt.parenR) &&
	!this.match(tt.colon) &&
	!this.match(tt.eq) &&
	!this.match(tt.question)
	);
	}