Hardly anything is. Literally none of the programs on my machine are coded in Rust. (Firefox is reputed to have a bit in it.)

About FF and Rust:

https://news.ycombinator.com/item?id=30743577

If you're running Windows 11, you have Rust running in your kernel. Look it up.

Someone else posted statistics that show Firefox being 10% Rust, but I'm not sure it makes sense to include HTML and Python and JavaScript in the comparison. If you compare Rust against C/C++, it's 20%

Who runs Windows?

There is no such language as C/C++. I presume you mean the sum of C and C++, and that you omit external libraries from the tally.

> I presume you mean the sum of C and C++

"I'd just like to interject for a moment. What you're refering to as Linux, is in fact, GNU/Linux, or as I've recently taken to calling it, GNU plus Linux. Linux is not an operating system unto itself, but rather another free component of a fully functioning GNU system made useful by the GNU corelibs, shell utilities and vital system components comprising a full OS as defined by POSIX."

Pedant

>and that you omit external libraries from the tally.

Mozilla vendors their dependencies. They're counted.

Lots of things 'aren't Rust'. In fact almost everything isn't Rust. For now. That may change in due course but right now I would guestimate the amount of Rust code running on my daily drivers to pretty close to zero%. The bulk is C or C++.