Unexpected token error when parsing a class with static properties

[philipkaiser]

Description

When parsing an input that defines a class with a static class property an unexpected token error is thrown.

Here is my stack-trace:

SyntaxError: Unexpected token (1:24)
    at pp$4.raise (/.../node_modules/acorn/dist/acorn.js:3560:15)
    at pp$9.unexpected (/.../node_modules/acorn/dist/acorn.js:768:10)
    at pp$9.expect (/.../node_modules/acorn/dist/acorn.js:762:28)
    at pp$5.parseMethod (/.../node_modules/acorn/dist/acorn.js:3315:10)
    at pp$8.parseClassMethod (/.../node_modules/acorn/dist/acorn.js:1529:37)
    at pp$8.parseClassElement (/.../node_modules/acorn/dist/acorn.js:1487:12)
    at pp$8.parseClass (/.../node_modules/acorn/dist/acorn.js:1405:26)
    at pp$8.parseStatement (/.../node_modules/acorn/dist/acorn.js:914:19)
    at pp$8.parseTopLevel (/.../node_modules/acorn/dist/acorn.js:825:23)
    at Parser.parse (/.../node_modules/acorn/dist/acorn.js:597:17) {
  pos: 24,
  loc: Position { line: 1, column: 24 },
  raisedAt: 25
}

Node.js v18.16.0

I assume that the class property is mistakenly identified / parsed as a class method as there is an invocation of parseClassMethod in the middle of the stack-trace. This thought matches with the unexpected token error type as the expected token would be a ( for a class method in this case.

Repro steps

1. run npm init -y
2. run npm i acorn
3. create an index.js file:

const acorn = require("acorn");
acorn.parse("class Example {static x = {};}", { ecmaVersion: 2020 });

4. run the file node index.js

[marijnh]

Which ECMAScript version introduced class properties?

Right, 2022.