Well, if your compilations turn to be submilisecond it's not an implementation detail :) *. As of now it is only supported for x86_64 Linux (only ELF format) and it has some bugs; incremental compilation is in its very early stages. Andrew talked about it in the 2024 roadmap video[1] why they are digging so low on the multiplatform toolchain (for besides incremental compilation):- Fast build times (closely related to IC, but LLVM gives very slow development iterations, even for the compiler development)
- Language innovations: besides IC, async/await is a feature Andrew determined to not be feasable to implement with LLVM's coroutines. Async will likely not make it into 1.0, as noted in the 0.13 release notes. It is not discarted yet but neither is it the priority.
- There are architectures that don't work very well on LLVM: SPARC and RISC-V are the ones I remember
My personal point is that a language that is meant to compete with C cannot have a hard dependency on a C++ project. That, and that it's appealing to have an alternative to LLVM whenever you want to do some JIT but don't want to bring a heavy dependency
[1] https://www.youtube.com/watch?v=5eL_LcxwwHg
* There is also the `--watch` flag for `zig build` which re-runs every step (IC helps) everytime a file is saved.
[edit: formatting]*