Description

Adds TS support to docgen. This does not require adding any new parsers, the currently used parsers are sufficient (🎉).

All of the new logic exists inside of get-type-annotation. This basically consists of a huge switch function over all of the possible types of type annotation nodes. The module then opinionatedly formats the type annotation based on the AST and returns the new type annotation. If a type annotation already exists (for example, in the case of JSDoc) it just uses that instead.

This does require explicit typing of all exported function returns, however, which is why I added the return type annotation to react-i18n. docgen isn't running any actual TypeScript engine so there's no way to infer the return type like TS normally would be able to do. However, I don't see this as a shortcoming but as a feature: it forces us to explicitly document the inputs and outputs of our exported functions (ESLint should enforce this anyway, once #27143 is merged.

Most of this code is currently unused. Testing it is going to be a chore, so if someone wants to jump in and help me with that, I'd love the assistance (but of course is not necessary). I'll slowly add some unit tests over the next week or so. If anyone has suggestions for how/what exactly is worth testing in this new area, please let me know.

Note: I did remove a nonsense param annotation in the first commit. Like I said, it was a nonsense annotation so I think it's safe to remove it.

How has this been tested?

Run npm run docs:build. Ensure that there are no changes except to react-i18n.

Types of changes

Adds support for TypeScript type annotations without affecting existing JSDoc support.

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• [N/A] My code follows the accessibility standards.
• [N/A] I've tested my changes with keyboard and screen readers.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.
• [N/A] I've updated all React Native files affected by any refactorings/renamings in this PR.