babel: [Bug]: Parser throws when var declaration and function declaration in class static block

💻

• Would you like to work on a fix?

How are you using Babel?

Programmatic API (babel.transform, babel.parse)

Input code

class X {
  static {
    var x;
    function x() {}
  }
}

REPL

Configuration file name

No response

Configuration

n/a

Current and expected behavior

I believe that the above code is legal. It happily runs in NodeJS.

Babel’s parser throws an error Identifier 'x' has already been declared.

This only applies within a class static block. The following parses correctly (when sourceType: 'script'):

var x; function x() {}
class X {
  foo() { var x; function x() {} }
  static foo() { var x; function x() {} }
}
function f() { var x; function x() {} }
() => { var x; function x() {} };
function f2() { 'use strict'; var x; function x() {} }
() => { 'use strict'; var x; function x() {} };

REPL

Environment

System:
  OS: macOS 10.15.7
Binaries:
  Node: 16.14.0 - ~/.nvm/versions/node/v16.14.0/bin/node
  npm: 8.3.1 - ~/.nvm/versions/node/v16.14.0/bin/npm
npmPackages:
  @babel/core: ^7.17.2 => 7.17.2
  @babel/generator: ^7.17.0 => 7.17.0
  @babel/helper-module-transforms: ^7.16.7 => 7.16.7
  @babel/helper-plugin-utils: ^7.16.7 => 7.16.7
  @babel/parser: ^7.17.0 => 7.17.0
  @babel/plugin-transform-arrow-functions: ^7.16.7 => 7.16.7
  @babel/plugin-transform-modules-commonjs: ^7.16.8 => 7.16.8
  @babel/plugin-transform-react-jsx: ^7.16.7 => 7.16.7
  @babel/plugin-transform-strict-mode: ^7.16.7 => 7.16.7
  @babel/traverse: ^7.17.0 => 7.17.0
  @babel/types: ^7.17.0 => 7.17.0
  babel-plugin-dynamic-import-node: ^2.3.3 => 2.3.3
  eslint: ^7.32.0 => 7.32.0
  jest: ^27.5.1 => 27.5.1

Possible solution

No response

Additional context

Happy to work on a PR. But could someone please point in right direction? I’m not at all familiar with the parser.