Porting 1k lines a day, testing and catching and fixing errors to language with incompatible memory model and doing it for a year is insanity. Programmers who propose this kind of productivity most likely have no idea about real world.

I contend that most software engineers (and most engineering houses) don’t spend any time sharpening the axe. Certainly not when it comes to optimizing for development speed. Nobody even talks about deliberate practice in software. Isn’t that weird?

1000 lines of code is way too much code to write from scratch in a day, or code review. I claim it’s not a lot of code to port - especially once you’re familiar with the code base and you’ve built some momentum. The hardest part would be mapping C pointers into rust lifetimes.

> most likely have no idea about real world.

I have no doubt this sort of speed is unheard of in your office, with your processes. That doesn’t tell us anything about the upper bound of porting speed. If you have more real world experience than me, how fast did you port code last time you did it?

Mind you, going hell to leather is probably a terrible idea with something as security sensitive as BoringSSL. It’s not the project to skip code review. And code review would probably take as long again as porting the code itself.

There have been a lot of studies that measure average output of new code at only ~15 or so LOC/day. One can manage more on small projects for a short amount of time.

I could believe porting between two C-like languages is 1 order of magnitude easier, but not 2. Std library differences, porting idioms, it adds up.

Even just reading and really understanding 1K lines/day is a lot.

I agree with that LOC/day output figure for new code. I've been averaging somewhere around that (total) speed for the last few months - once you discard testing code and the code I'll end up deleting. Its slower than I usually code, but I'm writing some very deep, new algorithmic code. So I'm not beating myself up about it.

But porting is very different. You don't need to think about how the code works, or really how to structure the data structures or the program. You don't need much big picture reasoning at all, beyond being aware of how the data structures themselves map to the target language. Most of the work is mechanical. "This array is used as a vec, so it'll become Vec<>. This union maps to an enum. This destructor should actually work like this...". And for something like boringSSL I suspect you could re-expose a rust implementation via a C API and then reuse most of the BoringSSL test suite as-is. Debugging and fuzz testing is also much easier - since you just need to trace along the diff between two implementations until you find a point of divergence. If the library has tests, you can port them across in the same way.

The only data point I have for porting speed is from when I ported chipmunk2d in a month from C to JS. Chipmunk only has a few data structures and it was mostly written by one person. So understanding the code at a high level was reasonably easy. My ported-lines-per-day metric increased dramatically throughout the process as I got used to chipmunk, and as I developed norms around how I wanted to translate different idioms.

I have no idea how that porting speed would translate to a larger project, or with Rust as a target language. As I said, I'd love to hear some stories if people have them. I can't be the only one who's tried this.

IME it doesn't.

I'm not at liberty to discuss all that much detail, but I what I can say is: This was a mixture of C and C++ -> Scala. This was pretty ancient code which used goto fairly liberally, etc. so it would often require quite a lot of control flow rewriting -- that take a looooong time. I'd be lucky to get through a single moderately complex multiply nested loop per day. (Scala may be a bit of an outlier here because it doesn't offer a c-like for loop, nor does it offer a "native" break statement.)

>"I have no doubt this sort of speed is unheard of in your office, with your processes."

I am my own boss for the last 20+ years and I do not have predefined processes. And I am not in a dick size contest.

Static analysis means a wide range of things, and so some do and some don’t work with Rust. I would be very interested to learn about C static analysis that somehow wouldn’t work with Rust at all; it should be easier to do so in rust because there’s generally so much more information available already thanks to the language semantics.