If one was to do this as something other than a "fun project", wouldn't it make more sense to do a CIL backend for LLVM? That way any language utilizing LLVM would get be able to target .NET, or am I completely misunderstanding how rustc and LLVM works?
I -think- that CIL being a bytecode-y language runtime that actually has things like an object model, going straight from MIR to CIL offers a ... higher fidelity translation, or so.
(I apologise for this being vague, but this isn't really my area so if I tried to get more detailed I'd rapidly go from "quite possibly wrong" to "definitely wrong")
From my understanding LLVM's intermediate language is at a "lower level" (which is the LL after all) than the .NET CLR (or the Java JVM), losing some higher level parts of type understanding and looking a lot closer to machine language. You'd have to reconstruct or synthesize a new understanding of the "lost" high level information to target them as an LLVM backend.
It sounds like Rust's internal MIR intermediate language is a somewhat closer level match to CIL.
Adding a .NET backend to Rust could give you high-level two way interop.
Adding a similar backend to LLVM would let you use .NET target similarly to WASM in that you could compile pretty much any software (C/C++, Go, Rust, etc) and run it on any supported platform without recompiling (well, it would JIT). But you'd have to stick to C-level APIs.
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If one was to do this as something other than a "fun project", wouldn't it make more sense to do a CIL backend for LLVM? That way any language utilizing LLVM would get be able to target .NET, or am I completely misunderstanding how rustc and LLVM works?
I -think- that CIL being a bytecode-y language runtime that actually has things like an object model, going straight from MIR to CIL offers a ... higher fidelity translation, or so.
(I apologise for this being vague, but this isn't really my area so if I tried to get more detailed I'd rapidly go from "quite possibly wrong" to "definitely wrong")
From my understanding LLVM's intermediate language is at a "lower level" (which is the LL after all) than the .NET CLR (or the Java JVM), losing some higher level parts of type understanding and looking a lot closer to machine language. You'd have to reconstruct or synthesize a new understanding of the "lost" high level information to target them as an LLVM backend.
It sounds like Rust's internal MIR intermediate language is a somewhat closer level match to CIL.
I think these two have different use cases.
Adding a .NET backend to Rust could give you high-level two way interop.
Adding a similar backend to LLVM would let you use .NET target similarly to WASM in that you could compile pretty much any software (C/C++, Go, Rust, etc) and run it on any supported platform without recompiling (well, it would JIT). But you'd have to stick to C-level APIs.