Run using: tsc --module commonjs --jsx preserve app.tsx

This is intended to show that without isolating referenced globals even for proper external modules you will run into issues. This project has the following structure:

• app
  • react
  • someComponent
    • react

Note that react and someComponent are proper external modules. react introduces a global in the JSX namespace which is required for proper JSX integration. someComponent also references a react definition so that it can access React.Component. In this case, the JSX namespace results in a "Duplicate identifier" error.