Example Travis config in README does not work

[davidalber]

#2683 changed the README Travis config example to use --write-mode=check instead of --write-mode=diff. That's not currently working in Travis. See this build, for example.

$ cargo fmt --all -- --write-mode=check
Invalid write-mode: check

The command "cargo fmt --all -- --write-mode=check" exited with 1.

Is this a matter of waiting for a new version to be stamped or is there something more fundamental wrong?

[nrc]

I think it might just need a more up to date rustfmt in the Rust repo, which should happen with today's nightly.

[volzkzg]

I use a nightly version rustfmt, but it says
root@d115673865b5:~/cita# cargo fmt -- --write-mode=check Unrecognized option: 'write-mode'

[davidalber]

The Travis config snippet in the README still fails. I added a line (in a different repository) to print version information. Here's the relevant output for the current snippet:

$ rustup component add rustfmt-preview
$ cargo fmt -- --version
rustfmt 0.4.1-stable (7a80726 2018-04-20)

The command "cargo fmt -- --version" exited with 0.
$ cargo fmt --all -- --check
Unrecognized option: 'check'

The command "cargo fmt --all -- --check" exited with 1.

Thus, the change that added --check is not yet available in stable.

It works in nightly, though:

$ rustup component add rustfmt-preview
$ cargo fmt -- --version
rustfmt 0.7.0-nightly (db8cb0b 2018-05-16)

The command "cargo fmt -- --version" exited with 0.
$ cargo fmt --all -- --check

The command "cargo fmt --all -- --check" exited with 0.

When will the stable version change? Should we switch the config snippet to use nightly?

[nrc]

Yeah, we should use nightly. Stable should switch at the next release, i.e., 5-ish weeks time