Upgrade to crossbeam 0.4

[dwijnand]

Supersedes #5789

[rust-highfive]

r? @matklad

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[matklad]

@bors r+

Thanks!

[bors]

📌 Commit 16681b3 has been approved by matklad

[bors]

⌛ Testing commit 16681b3 with merge 853089a18f4f20f7ea5893ad580df70352f6d71f...

[bors]

💔 Test failed - status-travis

[dwijnand]

This is failing in the Rust 1.27.2 (which is the latest stable) job, with:

error: expected identifier, found `"std"`
  --> /home/travis/.cargo/registry/src/github.com-1ecc6299db9ec823/libc-0.1.1/rust/src/liblibc/lib.rs:79:46
   |
79 | #[cfg(feature = "cargo-build")] extern crate "std" as core;
   |                                              ^^^^^ expected identifier

while the stable job is passing fine, which is confusing.

@matklad can you make sense of it?

[matklad]

This is certainly #5757

r? @Eh2406
:)

[dwijnand]

Thanks @matklad.

lol, from just 2 days ago:

If it turns out that --minimum-versions is a constant painful effort to keep up to date then we could remove it again from CI.

Note: I'm not suggesting it's a constant painful effort or that we should remove it from CI, I just thought it was funny that within less than 24 hours it's affected a PR, albeit one about tweaking dependencies.

[Eh2406]

I was not able to reproduce locally. I do not have libc 0.1.1 in my lock file with minimum-versions. I am updating the latest nightly in the vain hope that that is why.

Can I get an automatic ping on @dependabot PRs?

[dwijnand]

Let's see if it fails after a rerunning (triggered by closing and reopening the PR).

For the record these are the failed CI runs:

• https://ci.appveyor.com/project/rust-lang-libs/cargo/build/1.0.5235
• https://travis-ci.org/rust-lang/cargo/builds/407920096
• https://travis-ci.org/rust-lang/cargo/builds/407923316

[Eh2406]

douw My bad. :-( I did not have the new branch checked out. Sorry.

[Eh2406]

it is a log v0.3.0 problem. From rand v0.3.0 From parking_lot_core v0.2.0

One fix is to add a synthetic dependency on parking_lot_core = "0.2.11".

edit: in #5757 @alexcrichton recommended adding a comment like # required only for minimal-versions. brought in by crossbeam.

[dwijnand]

When you get a chance, if you could document how you figure that out, I think it would be useful.

If you have write permissions to the repo feel free to push to my branch, or continue in your own PR. I was just trying to unblock the original PR 🙂. If not I'll try and apply your comments.

[Eh2406]

I do not have write permissions, It is all yours!

[Eh2406]

https://travis-ci.org/rust-lang/cargo/jobs/408134134 is green! So that is a good sign!

[matklad]

One fix is to add a synthetic dependency on parking_lot_core = "0.2.11".

Adding synthetic deps seems like a wrong solution to the problem... I would expect that the right solution is to bump parking_lot dependency version in crossbeam.

OTOH, I came to really appreciate @Eh2406 idea about non-transitive minimal versions....

[Eh2406]

I like upstreaming the fix, for now this works.

FYI I think it was @joshtriplett idea originally.

[alexcrichton]

Thanks for this! I think that the crossbeam crate has actually been split up a bit, could crossbeam_utils be brought in instead? I think we may just need the scoped thread support there and it should sidestep the minimal versions issue!

[dwijnand]

Oh that sounds plausible. I'll give it a try, Alex.

[alexcrichton]

@bors: r+

[bors]

📌 Commit 8ea90e9 has been approved by alexcrichton

[bors]

⌛ Testing commit 8ea90e9 with merge 80f6922...

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: alexcrichton
Pushing 80f6922 to master...