cargo-bloat fails to find std libraries, it expects them to live in /usr/lib/rustlib

[stefson]

how to reproduce, with the example of a fresh git checkout:

cd tmp && git clone https://github.com/eqrion/cbindgen.git
cd cbindgen
cargo bloat 
compiling...
Error: failed to find a dir with std libraries. Expected location: /usr/lib/rustlib/x86_64-unknown-linux-gnu/lib.

this is on a x86_64 machine, hence there's /usr/lib64/${RUSTVERSION}/ where rustlib resides. Not sure wether that is excentric behavior from my distro? :-)

[RazrFalcon]

What rustc --print=sysroot outputs?

[stefson]

here's the output:

rustc --print=sysroot
/usr

[RazrFalcon]

Do you have rustlib at all?

[stefson]

Sure, I've got full rust toolchain available. It's actually the case that cargo build is executed before cargo bloat, and the error only appears when cargo build has finished it's compile. It's most likely a problem that rustlib resides in /usr/lib64, and the folder isn't scanned by cargo-bloat.

[RazrFalcon]

The problem is that I don't know where rustlib is. Currently, cargo-bloat uses the same algorithm as rustc.

Maybe your distro has a patched rust?

[stefson]

here's the file list: rust-files.gz

[RazrFalcon]

Looks like a bug of your distro. Library should be in

/usr/lib64/rustlib/x86_64-unknown-linux-gnu/lib

and not in

/usr/lib64/rust-1.39.0/rustlib/x86_64-unknown-linux-gnu/lib

[stefson]

I initially thought it was the fact that it resides in /usr/lib64, since all debian based distros don't distinguish lib and lib64, but it makes sense to me. Will test now.

[stefson]

this got triggered by a bug in gentoo, as you mentioned. This is now fixed, gentoo bug for reference: https://bugs.gentoo.org/703744

thanks for pointing me towards it! :)

[RazrFalcon]

Glad to hear, since I'm using Gentoo too. =) Only I'm installing Rust via rustup.

[o01eg]

Currently, cargo-bloat uses the same algorithm as rustc.

rustc found out alternative libdir because it compiled with alternative CFG_LIBDIR_RELATIVE environment:

https://github.com/rust-lang/rust/blob/a916ac22b9f7f1f0f7aba0a41a789b3ecd765018/src/librustc_session/filesearch.rs#L159

[RazrFalcon]

Can I access it via CLI?

[o01eg]

No yet, I'm think it better to expose it with --print=libdir or so.

[o01eg]

@RazrFalcon I've opened PR: rust-lang/rust#69608