rustc is using three versions of rand

[scottmcm]

I noticed this scrolling by while "Building stage0 compiler artifacts" today:

   Compiling rand_pcg v0.1.1
   Compiling rand v0.6.1
   Compiling flate2 v1.0.6
   Compiling rand v0.4.3
   Compiling rand v0.5.5
   Compiling winapi-util v0.1.1

Optimistically flagging E-easy

[JohnTitor]

@scottmcm I'd like to work on this, how can I fix? make rustc use one version(maybe v0.6.1)?

[ishitatsuyuki]

@JohnTitor You will need to look into each dependency that depends on rand (by searching through Cargo.lock), check if they have a newer version that depends on new rand, and finally use cargo update -p <crate> to upgrade those crates.

[JohnTitor]

@ishitatsuyuki Thanks! When I checked, it seems each rand version is used.

[ishitatsuyuki]

Yeah, it's natural that they are all used, and you could try to eliminate those crates using old rand by upgrading or refactoring. That said, there isn't much drawback with an older rand, so in that case this issue can be just closed.

[JohnTitor]

Oh, I'm sorry, I misunderstood. Hmmm, I think we don't have to fix this quickly and this may be a catalyst for a newbie like me to contribute, so I leave this, okay?

[hellow554]

@ishitatsuyuki but one could argue that it will lower the time to compile so it's worth to fix IMHO ;)

[JohnTitor]

Uh, would it be better to fix?

[hellow554]

Disclaimer: I'm not a core member, but IMHO this is worth fixing. Also scottmcm who is a core member opened this issue, so I guess you're good to go and fix that issue @JohnTitor :)

[JohnTitor]

Okay, I want to try to fix. For instance, crossbeam-channel depends on rand v0.5.5, how can I update or refactor this?

[hellow554]

That's one thing you can't edit, because rand is a dependency of crossbeam-channel here, so the crate crossbeam-channel needs to update its dependecy (maybe it already did and you just need to update crossbeam-channel itself)?

[Aaron1011]

For future reference, running cargo tree -d from src/rustc is an easy way to identify the source of all duplicates.

[JohnTitor]

Thanks @Aaron1011 ! I got this tree(gist).
I updated parking_lot, but rustc-rayon v0.1.1 is latest and depends on rand v0.4.3(https://crates.io/crates/rustc-rayon).
What should I do?

[scottmcm]

@hellow554 I'm not on compiler (or core), so don't take my word on this one :slightly_smiling_face:

@JohnTitor It looks like upstream rayon needs 0.5, so you could consider making a PR to upgrade it to 0.6. (Maybe ask someone on rayon first.) Also, it seems that rustc-rayon hasn't been updated in 6+ months, so they'd probably appreciate a PR to upgrade it to newer upstream.

[cuviper]

Current rayon only uses rand as a dev-dependency, since rayon-rs/rayon#571. That wouldn't show up in Cargo.lock here at all, if rustc-rayon follows suit.

[lnicola]

So the latest versions are rustc-rayon 1.0.3 and rustc-rayon-core 1.4.1, but 0.1.1 is used in this repository. They come from librustc_data_structures. Maybe those dependencies should be updated or made optional?

[polybuildr]

It looks like this was fixed in PR #58908 and merged by bors. Should this issue be closed now?

[sfackler]

There are still 3 versions of rand in use: https://github.com/rust-lang/rust/blob/master/Cargo.lock#L4173-L4175

[mati865]

https://github.com/rust-lang/rust/pull/58805 will remove rand 0.5, I can get rid of 0.4 anytime but there are many PRs modifying Cargo.lock right now.

[lnicola]

Update: rand 0.4.3 is used by phf_generator, rayon_core and redox_users (via dirs).

[cuviper]

That's with rayon-core 1.4.0 -- 1.4.1 only uses rand 0.5 as a dev-dependency.

[lnicola]

I didn't check now, but at some point rustc was using an old version of a custom fork of rayon.

[cuviper]

rustc-rayon has rebased since then, so it already reflects that dependency change.

[lnicola]

I tried to fix a part of this in https://github.com/rust-lang/rust/pull/61597, but it didn't come out as planned. There is dependency and license whitelist that needs to be updated.

I think just running cargo update leaves only one usage of rand 0.4 via ammonia and mdbook 1 (which can be updated). But then there is the licensing story, and it's not very clear to me which dependencies are used by the tools, and which by the compiler.

[mati865]

Last time I checked mdbook and rustc-rayon were the only thing preventing of rand 0.4, otherwise I'd fix it already.
We are working on removing it but it's blocked on releasing new version of mdbook.

[lnicola]

I think rustc-rayon goes away after a cargo update, so that one might be easy to fix.

I don't know how dependencies are updated across the rust repository. Is it just that most of them are for the tools, not for std and rustc? Does somebody run cargo update from time to time? And why does the tidy license check fail on bors on my PR, but not on Travis or on my computer?

[mati865]

So rustc-rayon released new version since.

Is it just that most of them are for the tools, not for std and rustc?

Correct, dependencies of everything that is created by dist are tracked by single Cargo.lock.

Does somebody run cargo update from time to time?

Dependencies are often updated separately as needed because upgrading everything at once is likely to break something and it's easier to find what is wrong when you change like 5 dependencies instead of 50.

And why does the tidy license check fail on bors on my PR, but not on Travis or on my computer?

I think it should error when you run ./x.py build.

[mati865]

Also you can run the same image that found the error (x86_64-gnu-llvm-6.0 in this case) by using these steps https://github.com/rust-lang/rust/blob/master/src/ci/docker/README.md