manually test converting a bunch of crates to rust 2018 preview

[nikomatsakis]

What is this?

This is a meta issue for tracking manual testing of "upgrading" crates to Rust 2018 preview. We're hoping to kick the tires for a lot of crates. There's a list below, but feel free to test your own additions and leave comments.

How to test a crate

The steps are described here in the transition guide, but here is a cheat sheet:

• Update nightly:
  • rustup update nightly
• Install rustfix if you haven't already:
  • cargo install cargo-fix --git https://github.com/rust-lang-nursery/rustfix
• Clone the crate in question
• Verify that it builds (if not, that's some other problem we better fix first):
  • cargo +nightly build
• Edit src/lib.rs and add #![feature(rust_2018_preview)]
• Verify that it still builds:
  • cargo +nightly build
• Create a commit, perhaps on a new branch (recommended name: rust-2018-migration):
  • git commit -a -m 'add rust_2018_preview feature'
• Run rustfix:
  • cargo +nightly fix --prepare-for 2018
• Verify that it still builds:
  • cargo +nightly build
• Create another commit on that same branch:
  • git commit -a -m 'run rustfix
• Update to the new edition by adding the following to Cargo.toml:
  • cargo-features = ["edition"]
  • package.edition = "2018"
• Verify that it still builds:
  • cargo +nightly build
• Create another commit on that same branch:
  • git commit -a -m 'upgraded to new edition

If all of this works, great! Leave a comment below, including a link to the commit or branch with the changes.

If you encounter an error due to the migration, leave a comment below with a link to the commit and the error!

Crate listing

• ✅ clap (branch here)
• ✅ futures-core and futures-io 0.2.x (branch here)
• ✅ cargo (branch here)
• ✅ bitflags (comment)
• ✅ serde (comment)
• ❌ libc (comment — libc fails to migrate #51210
• ❌ rand (comment — opened rand fails to migrate #51209
• ❌ rusty-machine (comment) — caveat, build works, #[cfg(test)] code fails, filed some kind of #[cfg] story for rustfix #51208
• ❌ faster (comment) — faster fails to migrate  #51211
• ✅ clippy (comment)
• ✅ ipnetwork (comment)

[teiesti]

crates that work:

• bitflags (branch here)
• serde (branch here)

crates that don't work:

• libc (branch here)

$ cargo +nightly build
   Compiling libc v0.2.41 (file:///home/tobias/dev/libc)
error[E0463]: can't find crate for `dox`
   --> src/macros.rs:44:16
    |
44  |           impl ::dox::Copy for $i {}
    |                  ^^^ can't find crate
    | 
   ::: src/unix/mod.rs:19:1
    |
19  | / s! {
20  | |     pub struct group {
21  | |         pub gr_name: *mut crate::c_char,
22  | |         pub gr_passwd: *mut crate::c_char,
...   |
186 | |     }
187 | | }
    | |_- in this macro invocation

error: aborting due to previous error

• rand (branch here)

$ cargo +nightly build
   Compiling rand v0.5.0 (file:///home/tobias/dev/rand)
error[E0463]: can't find crate for `distributions`
   --> src/distributions/uniform.rs:104:5
    |
104 | use distributions::Distribution;
    |     ^^^^^^^^^^^^^ can't find crate

error: aborting due to previous error

[zackmdavis]

The instructions should include cargo test, which typically runs code that is cfg'd out of a normal cargo build.

---

didn't work:

• rusty-machine (branch tip)

Build works, but tests fail to compile with two errors:

zmd@ReflectiveCoherence:~/Code/rusty-machine$ cargo +nightly test
   Compiling rusty-machine v0.5.4 (file:///home/zmd/Code/rusty-machine)
error[E0463]: can't find crate for `rm`
 --> tests/learning/dbscan.rs:1:5
  |
1 | use rm::linalg::Matrix;
  |     ^^ can't find crate

error: aborting due to previous error

For more information about this error, try `rustc --explain E0463`.
error[E0463]: can't find crate for `linalg`
   --> src/data/transforms/minmax.rs:195:9
    |
195 |     use linalg::Matrix;
    |         ^^^^^^ can't find crate

error: aborting due to previous error

For more information about this error, try `rustc --explain E0463`.
error: Could not compile `rusty-machine`.
warning: build failed, waiting for other jobs to finish...
error: Could not compile `rusty-machine`.

To learn more, run the command again with --verbose.

For the first error, we have a tests/ directory that uses the main crate under the alias rm, and it looks like rustfix/diagnostics doesn't understand that it's an alias rather than a crate literally named rm?

For the second error, we have a use of the crate-local linalg that for whatever reason wasn't rewritten as crate::linalg (even though other uses of linalg were rewritten).

[AdamNiederer]

Failing: https://github.com/AdamNiederer/faster/commits/rust-2018-migration

$ cargo build
   Compiling faster v0.4.3
error[E0463]: can't find crate for `core_or_std`
  --> src/intrin/eq.rs:58:25
   |
58 |                       use core_or_std::mem::transmute;
   |                           ^^^^^^^^^^^ can't find crate
...
79 | / rust_fallback_eq! {
80 | |     impl Eq for u8x16 where "sse2" {
81 | |         eq_mask, eq => u8x16, u8, _mm_cmpeq_epi8(), [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15];
82 | |     }
83 | | }
   | |_- in this macro invocation

error: aborting due to previous error

For more information about this error, try `rustc --explain E0463`.
error: Could not compile `faster`.

To learn more, run the command again with --verbose.

It looks like cargo fix isn't applying a crate:: prefix to my custom core/std module in a few cases. Manually fixing the imports fixes the build. It looks like cargo fix makes no attempt to fix imports in test modules, so the tests are still broken.

[mati865]

Clippy (branch here) builds and passes tests after changing deprecated rustfmt annotation.

[nikomatsakis]

Wow, thanks all =) I updated the issue with notes and filed bugs where appropriate. One point I wanted to make: the transition is not meant to necessarily be perfect, since it is known that there will be edge cases — especially around #[cfg] and macro code — that we cannot handle. That said, we need a better story, particularly around #[cfg(test)] code, which is obviously super common. So I've filed #51208 to discuss that a bit more generally.

[achanda]

ipnetwork works fine!

[mkpankov]

hlua doesn't migrate:

➜  hlua git:(rust-2018-migration) ✗ cargo +nightly build
   Compiling hlua v0.4.1 (file:///home/mkpankov/projects/hlua/hlua)
error[E0463]: can't find crate for `ffi`
 --> hlua/src/any.rs:1:5
  |
1 | use ffi;
  |     ^^^ can't find crate

error: aborting due to previous error

For more information about this error, try `rustc --explain E0463`.
error: Could not compile `hlua`.

To learn more, run the command again with --verbose.

Branch.

[steveklabnik]

I decided "go big or go home", went big, and ... won the game. I dunno where this metaphor is going.

Anyway, Cargo works! I'm going to test some more crates and update this comment as they compile.

• dir-diff works (funny enough, with no changes)
• the intermezzOS kernel works
• semver works
• semver-parser works
• simple-server works

thanks has... problems: https://gist.github.com/steveklabnik/31e1f5b576aa2ed13e5a671c48d03cc0

[Dylan-DPC-zz]

UUID works!

[Mark-Simulacrum]

Thanks everyone for the feedback here; we've filed some issues to track them and will be working to fix the outstanding bugs.