Apparently this was done intentionally. The rationale given is that we don't want to allow non-safe C to be used in fil-C programs. Fair enough.
But why should we prevent fil-C programs to be used from Rust (or C, for that matter)?
I don't understand much about compilers, but I guess allowing one would also allow the other? i.e. it's not possible to make fil-C ABI compatible with C (so that it can be more easily called), while also not letting you use call C from it?
It's not a replacement for Fil-C's role as a precise ASAN/Valgrind, but it works great if you want to call a C library without letting it freely spray caller's memory.
Any reason why you don't use clang's `-fbounds-safety`? It offers ABI compatibility and incremental adoption. The author of Fil-C worked on it also :-)
This would also mean that you wouldn't need unsafe{} to call into the Fil-C ffi. The majority of unsafe{} in (non pure-rust) cargo dependencies is calling C ffi. Rust + Fil-C is a great match that fills a particular niche, I'd love to see it happen.
> [...] instead of accidentally linking ordinary C into it
Out of curiosity. If you really needed to, could a language speak both the C ABI and the Fil-C ABI? As I understand Fil-C itself can't do this without having Python-like FFI overhead, but maybe a different compiler implementation could?
Hm on first reading I was confused by the extern "fil-c" framing -- that seems to imply a bridge between C and Fil-C, which introduces some nasty language/runtime inter-op issues.
But I like this part
I want a Rust FFI that speaks the Fil-C ABI. ... We could use Rust for compile-time safety and then pay a performance penalty for using C.
Extern "fil-C" can't be compatible with Rust code or something similar. It requires a metadata block attached to each allocation. So, if a memory block has been allocated in Rust and a pointer to it is passed to a fil-C function, it can't access it correctly. The only way to allow such cross-langauge-and-abi calls is to compile Rust code itself like fil-C, which requires doubled memory consumption, expensive runtime checks and GC overhead.
LLM-written post, but I think the core idea is okay. I would advocate for more opportunities for safety, even if some of the safety is runtime safety rather than "only" Rust's borrow checker.
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[ 0.25 ms ] story [ 19.6 ms ] threadhttps://fil-c.org/runtime
Apparently this was done intentionally. The rationale given is that we don't want to allow non-safe C to be used in fil-C programs. Fair enough.
But why should we prevent fil-C programs to be used from Rust (or C, for that matter)?
I don't understand much about compilers, but I guess allowing one would also allow the other? i.e. it's not possible to make fil-C ABI compatible with C (so that it can be more easily called), while also not letting you use call C from it?
https://rlbox.dev/
It's not a replacement for Fil-C's role as a precise ASAN/Valgrind, but it works great if you want to call a C library without letting it freely spray caller's memory.
https://clang.llvm.org/docs/BoundsSafety.html#overview
Out of curiosity. If you really needed to, could a language speak both the C ABI and the Fil-C ABI? As I understand Fil-C itself can't do this without having Python-like FFI overhead, but maybe a different compiler implementation could?
Hm on first reading I was confused by the extern "fil-c" framing -- that seems to imply a bridge between C and Fil-C, which introduces some nasty language/runtime inter-op issues.
But I like this part
I want a Rust FFI that speaks the Fil-C ABI. ... We could use Rust for compile-time safety and then pay a performance penalty for using C.
Solvable by turning the usual C library allocation pattern inside-out:
Only the C side allocates, Rust gets views of that memory.
Also well established - calling WebAssembly components requires exactly the same pattern, as the only way to malloc is to call into the WASM side.
While this cannot compile C/C++, it can serve as a fil-C alternative for unsafe pure rust code.
https://news.ycombinator.com/item?id=49284966