Bug Report

• I would like to work on a fix!

Current behavior

No syntax error is thrown.

REPL

Input Code

class C {
  declare [key: string]: string;
}

Expected behavior

The parser should throw a syntax error 'declare' modifier cannot appear on an index signature.. Like TypeScript.

Babel Configuration (babel.config.js, .babelrc, package.json#babel, cli command, .eslintrc)

parse(code, { plugins: ["typescript"] });

Environment

Possible Solution

Additional context