[nikic]

> LLVM is a trap.

Is it? I think Rust is a great showcase for why it isn't. Of course it depends somewhat on your compiler implementation approach, but actual codegen-to-LLVM tends to only be a tiny part of the compiler, and it is not particularly hard to replace it with codegen-to-something-else if you so desire. Which is why there is now codegen_cranelift, codegen_gcc, etc.

The main "vendor lock-in" LLVM has is if you are exposing the tens of thousands of vendor SIMD intrinsics, but I think that's inherent to the problem space.

Of course, whether you're going to find another codegen backend (or are willing to write one yourself) that provides similar capabilities to LLVM is another question...

> You bootstrap extra fast, you get all sorts of optimization passes and platforms for free, but you lose out on the ability to tune the final optimization passes and performance of the linking stages.

You can tune the pass pipeline when using LLVM. If your language is C/C++ "like", the default pipeline is good enough that many such users of LLVM don't bother, but languages that differ more substantially will usually use fully custom pipelines.

> I think we'll see cranelift take off in Rust quite soon, though I also think it wouldn't be the juggernaut of a language if they hadn't stuck with LLVM those early years.

I'd expect that most (compiled) languages do well to start with an LLVM backend. Having a tightly integrated custom backend can certainly be worthwhile (and Go is a great success story in that space), but it's usually not the defining the feature of the language, and there is a great opportunity cost to implementing one.

[crawshaw]

It is a “trap” in the sense that it limits the design space for your language by forcing some of the choices implicit in C++. Rust went with slow build times like C++ and so was not held back in this dimension by LLVM.

Nothing about LLVM is a trap for C++ as that is what it was designed for.