catacomb_ii-64k VS openjpeg

Conditional to your definition of "serious", I did: https://github.com/64kramsystem/catacomb_ii-64k. I essentially don't do technical writing anymore (and I had the impression that this topic isn't generally considered interesting), however, my considerations are:

1. there are three levels of refactoring: removing the extensive (unbearable, to be honest) boilerplate that C2Rust introduces; converting the design from C to safe Rust; convert the design from unidiomatic Rust to idiomatic

2. as another poster pointed out, for non-trivial projects, writing refactoring tooling is a must (to remove the C2Rust boilerplate), in order to perform step 1

3. design refactoring (step 3) difficulty depends on the source code design; the code I worked with was hard to refactor, as it was old (school), in particular, lots of globals; the difficulty was not caused by the conversion C<>Rust, rather, the typical freedoms that C gives and Rust doesn't (in other words, the very obvious design differences between C and Rust)

4. regarding the code understanding, if one performs the translation in the three-steps mentioned in point 1, at the end of step 2, one has effectively a safe Rust codebase, "just" unidiomatic

5. beside a few steps, I was able to perform a conversion in self-contained steps, which is very good news for this type of work. Even better, it's possible (but that's a niche case) to port an SDL project by using at the same time the C library and the Rust one!

6. however, I can imagine projects like Wolfenstein 3d to be very hard, since it's hard to port memory allocators and similar

99. most important of all: just converting to Rust will quickly (even immediately) find bugs in the source; I've found approximately four bugs in the source code, including one by Carmack!

All in all, I find this tool great, but somebody needs to work on refactoring tools, and C2Rust's output must be improved in order to be found usable by the public.

5. c2rust expands macros and constants from `#define`. Being able to do side-by-side comparison of the C code will help with adding constants back in and removing expanded code with Rust macros or just normal Rust functions.

[0] https://github.com/Neopallium/openjpeg/tree/master/openjp2-r...

I just started using c2rust on openjpeg [0] (jpeg 2000 encoder/decoder) today and already have it working as a drop in replacement for the C libopenjp2.so on Linux. Still has a lot of unsafe code, but it does work. Which will be a big help with testing during refactoring to idiomatic safe Rust.

c2rust also has a refactor command that helps with refactoring the generated Rust code.

[0] https://github.com/Neopallium/openjpeg/tree/c2rust