Comment by nicoburns
2 days ago
> But it’s still too many dependencies and too slow.
I definitely agree that it's too slow. I just don't think the cause is "too many dependencies" because I've compiled Rust codebases with twice as many dependencies in half the time!
It seems to produce a 94MB binary. So it may be partly that there are some very big dependencies. But the amount of compilation time that ends up in the top-level crate (even with LTO disabled) also makes me feel like this must be triggering a compiler bug. Either that or using far too many generics.
I agree it's probably monomorphization (speculation without looking at it). Generic function parameters might be the root cause, but number of dependencies is a combinatorial multiplier.
I've hit compiler bugs that behave this way. Here's one from an LLVM upgrade [1]. The test case I discovered apparently took over 20 minutes to compile, up from 26 seconds on stable! Their value tracking algorithm was accidentally quadratic.
[1]: https://github.com/rust-lang/rust/issues/137909