What does incremental compilation have to do with writing your own compiler from scratch? Isn't Rust supports incremental compilation as does every language out there?
- 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]*
Also if they value compilation speed that much, maybe they shouldn't be that pushy into compiling always from source, without any support for Zig binary libraries.
Nope. Different languages have different priorities and different USPs. For Zig sub-second compilation / incremental compilation, cross compiling toolchain are flagship features. Without those there is no point in releasing 1.0.