c2nim VS CompCert

Also on the game development front, I maintain a raylib wrapper https://github.com/planetis-m/naylib As long utilities like c2nim https://github.com/nim-lang/c2nim exist, it's trivial to create bindings of C/C++ libraries. One thing I want to experiment more is making it more automatic by writing a callback exposed by c2nim that transform the generated code using Nim's AST. But regardless in that project I was able to write safe language abstractions on top of the bindings that provide a more native experience. It has scope-based memory management, generics and ... function overloading.

Rust also has a library called safer_ffi that makes FFI easier, and I tried to use that, but the library seems to be immature, and I could not get arguments in Rust functions. If this library can be used properly, it will be possible to output C header files from Rust functions and automatically generate Nim interface functions from C header files using c2nim. We look forward to further development of this feature.

Well I'm 99.5% certain at least. Even now I'm uncertain of the C syntax. And I've not been bold enough to test 3rd order C function pointers. I figure that's probably C code you don't wanna touch if possible.

https://github.com/nim-lang/c2nim/blob/11f2c5363dfe7e8c7c8ce...

The other annoying one is that "signed" and "unsigned" are basically adjectives, but "long" can be both a type and a modifier. So it's difficult to parse unless you're the target C compiler. Technically you can, but you have to use backtracking.

c2nim is a tool to translate ANSI C code to Nim. The output is human-readable Nim code that is meant to be tweaked by hand after the translation process. If you are tired of wrapping C library, you can try futhark which supports "simply import C header files directly into Nim". Similar to futhark, cinterop allows one to interop with C/C++ code without having to create wrappers. nimLUA is a glue code generator to bind Nim and Lua together using Nim's powerful macro. nimpy and nimporter is a bridge between Nim and Python. rnim is a bridge between R and Nim. nimjl is a bridge between Nim and Julia! Last but not least, genny generates a shared library and bindings for many languages such as Python, Node.js, C.

Now if only a full binding generator for C and C++ headers to Nim was done, the language would really be cooking!

"What do you mean, Nim has two of these already?"

Yeah, I know, and -- not to hurt anyone's feelings -- but: they kind of suck. And there's no way I see them able to be extended to do the job fully, based on the way they're currently built.

Those are some bold claims to make!

So before I get stoned to death (no offense to the authors, I am grateful that they exist and have used them both) let me attempt an explanation and back up these statements.

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To start off, the two tools available are "c2nim" and "nimterop". c2nim is a Nim official library, while nimterop is a community library.

  https://github.com/nim-lang/c2nim

Yes. Nim compiles to C and has a lot of features for interacting with C code. You can easily call C routines from Nim and Nim functions from C. There's a bit of a ceremony you need to go through, but most of it can be automated with c2nim tool: https://github.com/nim-lang/c2nim

A big problem is that proving that transformations preserve semantics is very hard. Formal methods has huge potential and I believe it will be a big part of the future, but it hasn't become mainstream yet. Probably a big reason why is that right now it's simply not practical: the things you can prove are much more limited than the things you can do, and it's a lot less work to just create a large testsuite.

Example: CompCert (https://compcert.org/), a formally-verified compiler AKA formally-verified sequence of semantics-preserving transformations from C code to Assembly. It's a great accomplishment, but few people are actually compiling their code with CompCert. Because GCC and LLVM are much faster[1], and have been used so widely that >99.9% of code is going to be compiled correctly, especially code which isn't doing anything extremely weird.

But as articles like this show, no matter how large a testsuite there may always be bugs, tests will never provide the kind of guarantees formal verification does.

[1] From CompCert, "Performance of the generated code is decent but not outstanding: on PowerPC, about 90% of the performance of GCC version 4 at optimization level 1"

Also a C compiler (https://compcert.org/). I did exaggerate bit in saying that anything non-trivial is "nearly impossible".

However, both CompCert and sel4 took a few years to develop, whereas it would only take months if not weeks to make versions of both which aren't formally verified but heavily tested.

From my experience, while many MCUs have settled for the big compilers (GCC and Clang), DSPs and some FPGAs (not Intel and Xilinx, those have lately settled for Clang and a combination of Clang and GCC respectively) use some pretty bespoke compilers (just running ./ --version is enough to verify this, if the compiler even offers that option). That's not necessarily bad, since many of them offer some really useful features, but error messages can be really cryptic in some cases. Also some industries require use of verified compilers, like CompCert[1], and in such cases GCC and Clang just don't cut it.

[1]: https://compcert.org/

CompCert sends its regards

But that's fine, because we can do even better with things like the CompCert C compiler, which is formally proven to produce correct asm output for ISO C 2011 source. It's designed for high-reliability, safety-critical applications; it's used for things like Airbus A380 avionics software, or control software for emergency generators at nuclear power plants. Software that's probably not overly sophisticated and doesn't need to be highly optimized, but does need to work ~100% correctly, ~100% of the time.

For context, CompCert is a formally verified compiler. My former advisor helped with a fuzzer called CSmith which found plenty of bugs in GCC and LLVM but not in CompCert.

Does anybody know how does this compare to https://compcert.org/ ?

This is a common property for proof-oriented languages. Coq shares this property for instance, and you can write an optimizing C compiler in Coq: https://github.com/AbsInt/CompCert .