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Why is the Rust compiler so slow?

(sharnoff.io)
302 points Bogdanp | 1 comments | 26 Jun 25 19:29 UTC | HN request time: 0.001s | source
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taylorallred ◴[26 Jun 25 20:29 UTC] No.44390996[source]▶
So there's this guy you may have heard of called Ryan Fleury who makes the RAD debugger for Epic. The whole thing is made with 278k lines of C and is built as a unity build (all the code is included into one file that is compiled as a single translation unit). On a decent windows machine it takes 1.5 seconds to do a clean compile. This seems like a clear case-study that compilation can be incredibly fast and makes me wonder why other languages like Rust and Swift can't just do something similar to achieve similar speeds.
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1. Aurornis ◴[26 Jun 25 20:50 UTC] No.44391214[source]▶
> makes me wonder why other languages like Rust and Swift can't just do something similar to achieve similar speeds.

One of the primary features of Rust is the extensive compile-time checking. Monomorphization is also a complex operation, which is not exclusive to Rust.

C compile times should be very fast because it's a relatively low-level language.

On the grand scale of programming languages and their compile-time complexity, C code is closer to assembly language than modern languages like Rust or Swift.