No longer warn about #![feature(rust_2018_preview)]

[steveklabnik]

This is no longer needed, and so the warning is outdated.

Fixes #6050

[rust-highfive]

r? @matklad

(rust_highfive has picked a reviewer for you, use r? to override)

[joshtriplett]

@bors r+

[bors]

📌 Commit 7980cc9e14c8e5bd55637a835cb5c8a6e5930f29 has been approved by joshtriplett

[bors]

⌛ Testing commit 7980cc9e14c8e5bd55637a835cb5c8a6e5930f29 with merge a48fa3df9c07994cb9f8516cd49a4ea93cc0c014...

[aturon]

cc @alexcrichton, just to make sure everyone's in the loop.

[bors]

💔 Test failed - status-travis

[steveklabnik]

@bors: r=joshtriplett

Some of the things being tested here are not yet stable, and so do require the edition to fix. As such, they still need the flag in order to pass the tests. I've fixed the tests now; I didn't see that they only run on nightly because they report themselves as passing in other cases.

[bors]

📌 Commit d277c84 has been approved by joshtriplett

[bors]

⌛ Testing commit d277c84 with merge 93e3216...

[ehuss]

I'm still a little confused about this. Does cargo fix --edition do anything without rust_2018_preview? If you don't include that feature, then the new experience will be:

1. Run cargo fix --edition to transition to the new edition.
2. Edit Cargo.toml to add edition="2018"
3. Run cargo build, and it will fail because nothing was fixed.

How is this supposed to work?

[steveklabnik]

Does cargo fix --edition do anything without rust_2018_preview?

Yes.

> cat .\src\lib.rs
trait Foo {
    fn foo(&self, u8);
}
> cargo +nightly fix --edition
    Checking editiontest v0.1.0 (C:\Users\steve\tmp\editiontest)
warning: failed to find `#![feature(rust_2018_preview)]` in `src\lib.rs`
this may cause `cargo fix` to not be able to fix all
issues in preparation for the 2018 edition
      Fixing src\lib.rs (1 fix)
    Finished dev [unoptimized + debuginfo] target(s) in 0.64s
> cat .\src\lib.rs
trait Foo {
    fn foo(&self, _: u8);
}

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: joshtriplett
Pushing 93e3216 to master...