[Bug]: @babel/plugin-transform-typescript outputs warnings on export of global-scope identifiers

[marcusdarmstrong]

💻

• Would you like to work on a fix?

How are you using Babel?

@babel/cli

Input code

export default undefined;

Configuration file name

babel.config.json

Configuration

{
  "presets": ["@babel/preset-typescript"]
}

Current and expected behavior

Upon running babel with this input and configuration, a warning is emitted:

% ./node_modules/@babel/cli/bin/babel.js ./test.ts
The exported identifier "undefined" is not declared in Babel's scope tracker
as a JavaScript value binding, and "@babel/plugin-transform-typescript"
never encountered it as a TypeScript type declaration.
It will be treated as a JavaScript value.

This problem is likely caused by another plugin injecting
"undefined" without registering it in the scope tracker. If you are the author
 of that plugin, please use "scope.registerDeclaration(declarationPath)".

Given that this is a perfectly valid snippet and not due to a misconfigured upstream plugin, this warning seems inappropriate and no output should be produced.

Environment

System:
OS: macOS 11.6
Binaries:
Node: 16.10.0 - ~/.nvm/versions/node/v16.10.0/bin/node
npm: 7.24.0 - ~/.nvm/versions/node/v16.10.0/bin/npm
npmPackages:
@babel/cli: 7.18.10 => 7.18.10
@babel/preset-typescript: 7.18.6 => 7.18.6

Possible solution

I suspect the issue is that the Typescript transform only checks the scope for it's own bindings, rather than hasBinding, but obviously I'm not particularly familiar with this code.

Additional context

No response

[babel-bot]

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