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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: 0.213s | source
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AndyKelley ◴[26 Jun 25 20:16 UTC] No.44390865[source]▶
My homepage takes 73ms to rebuild: 17ms to recompile the static site generator, then 56ms to run it.

    andy@bark ~/d/andrewkelley.me (master)> zig build --watch -fincremental
    Build Summary: 3/3 steps succeeded
    install success
    └─ run exe compile success 57ms MaxRSS:3M
       └─ compile exe compile Debug native success 331ms
    Build Summary: 3/3 steps succeeded
    install success
    └─ run exe compile success 56ms MaxRSS:3M
       └─ compile exe compile Debug native success 17ms
    watching 75 directories, 1 processes
replies(8): >>44390894 #>>44390942 #>>44390948 #>>44391020 #>>44391060 #>>44391265 #>>44391881 #>>44393741 #
taylorallred ◴[26 Jun 25 20:25 UTC] No.44390942[source]▶
@AndyKelley I'm super curious what you think the main factors are that make languages like Zig super fast at compiling where languages like Rust and Swift are quite slow. What's the key difference?
replies(4): >>44390972 #>>44391002 #>>44391022 #>>44396531 #
1. AlienRobot ◴[27 Jun 25 13:08 UTC] No.44396531[source]▶
One difference that Zig has is that it doesn't have multiline comments or multiline strings, meaning that the parser can parse any line correctly without context. I assume this makes parallelization trivial.

There is ino operator overloading like C, so A + B can only mean one thing.

You can't redeclare a variable, so foo can only map to one thing.

The list goes on.

Basically it was designed to compile faster, and that means many issues on Github have been getting rejected in order to keep it that way. It's full of compromises.