Thread

Emitting metadata early makes building/checking Rust up to twice as fast

136 points · 32 comments · knuckleheads

IshKebab · 1791122109 · focus · HN ↗
Seems like an easy win! I'm kind of surprised nobody did this already. I guess someone will need to reimplement this by hand given Rust's AI policy, but this is still great because it demonstrates that it's a really good idea.
1. kibwen · 1791123446 · focus · HN ↗
  Rust has been taking steps in this direction for several years now, having first added pipelining via eager metadata emission in 2019: <a href="https://internals.rust-lang.org/t/evaluating-pipelined-rustc-compilation/10199" rel="nofollow">https://internals.rust-lang.org/t/evaluating-pipelined-rustc... . There have been several other steps in this process since then, e.g. working to make metadata less verbose, experimenting with different approaches to compression, etc. People have been eyeing making pipelining even more eager for a while now, as the submitter here noted a few days ago: <a href="https://news.ycombinator.com/item?id=49924257">https://news.ycombinator.com/item?id=49924257 , but there remain some decisions to be made regarding what to do when encountering errors in crates that were speculatively approved.
  1. IshKebab · 1791132649 · focus · HN ↗
    Uhm... emit the errors and fail the compilation? What else would you do?
    Maybe there's some work to do to make that happen cleanly but the desired behaviour seems pretty obvious.

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