I think it's pretty nice just referring to a C module from a Rust project and calling functions from it with it built and linked together for you without dealing with the details since it generates the bindings for you as part of cross-compilation to the appropriate target.
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Yes that sounds great except I want it as part of a cargo workflow with no external dependencies besides cargo and rustc
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I don't think rustc and cargo intend to provide that though. I'm not familiar with bazelbuild.github.io/rules_rust/ but it's basically the same thing outside AOSP. cargo-raze converts Cargo to Bazel and then it fits into the overall Bazel system with other languages like C.
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I want this
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Replying to @bascule @rikarends and 2 others
D recently added an "ImportC" feature like this.
The implementation was only 4klocs, which is pretty cool:
github.com/dlang/dmd/pull
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It feels like you have this when using Rust in AOSP because you never need to use bindgen. You depend on the library, call the C code and when you modify the C code, the ABI has changed for the Rust code built with it too. So rustc doesn't do it, but it feels like it's doing it.
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Cargo could provide comparable UX but I think it just doesn't have the ambition / goal to provide this. You would get better error messages from rustc being aware of it, but I don't think it's essential. I can't really see it either happening though.
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Per the D patch, it seems like it could be a 4 kloc-ish change to rustc.
It would require an expert on the C standard. Maybe could do it.
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Rust has a strong culture of wanting to delegate solving problem to standalone projects maintained by other people and I think it makes it a lot harder to successfully land something like this.
Before Rust cared about wanting independence from LLVM, it could have used libclang.
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I say it can be done and it’s not that hard and it’s a small and self-contained patch
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The hardest part is actually understanding/language lawyering the C standard
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Agree that it's not a large project or something that would be hard to maintain since C is largely static and it can skip nonsense like _Generic. I just think you'd struggle to convince them to include this instead of it being a separate project with a compiler extension, etc.