Actually, dead code eliminination should do the trick, if you're compiling a binary at least (same for a library I think, but there could be re-exports there). Did you compile in release mode?
this post was submitted on 23 Jan 2025
6 points (80.0% liked)
Rust
6244 readers
16 users here now
Welcome to the Rust community! This is a place to discuss about the Rust programming language.
Wormhole
Credits
- The icon is a modified version of the official rust logo (changing the colors to a gradient and black background)
founded 2 years ago
MODERATORS
To expand: Just configure whatever profile you're using (dev, release, ...) to have link time optimization (lto) enabled:
[profile.release]
lto = "fat"
This really doesn't seem to do the trick, the binary's still at 63MiB.
Also "fat" and true are identical.
Edit: I'm not sure I replied to the right person, ignore this.
The compiler doesn't consider it to be dead code since it's marked pub.
Sure, but isn't this in a dependency? Can't be reached when only importing your crate anyways? And if you're building a binary, I don't think this could really considered exported, is what I mean :)
Yes that's exactly what I want. The compiler should stop considering it accessible.
I don't recall what the default behavior is with the linker, but it might also benefit from at least thin LTO.
@Doods are you using release ? If you want the best dead-code elimination, you can also enable Link time optimisations (LTO): https://doc.rust-lang.org/cargo/reference/profiles.html#lto
Yes, I am using both LTO and release mode, I can show you:
[profile.release]
opt-level = 3
codegen-units = 1
panic = "abort"
strip = true
lto = true
cargo build --release
@Doods I'm surprised you can gain that much with that already enabled!
Should I bring it up to the 'min-sized-rust' working group or the forums or something?
Yes. This behavior seems strange, so either an explanation or investigation by a compiler dev seems like it would be helpful.
Just so you know I figured it out, re-read the post please.