Keil, of course.

Nope. Never heard of it.

I’m from Europe i literal don’t know anyone who uses WhatsApp.

How would they add runtime checking without breaking all existing code?

But I think warning people is a good start, because those checks can be added to your CI pipeline and reject any incoming code that contains warnings. That way you can enforce type checking for a subset of modules and keep backwards compatibility.

First semester of my cs degree, it was around 50/50. After 3 semesters very few women were left. Spoiler: it was not because they could not handle the courses.