Clippy doesn't compile

[realcr]

Might be related to:
rust-lang/rust-clippy#2718

[realcr]

@kamyuentse : I checked the output from the Travis continuous integration, and I noticed that it runs the command:
cargo check --features=dev
How can Travis know to run this command? I couldn't find it anywhere inside the files of the cswitch repository. In addition, I noticed that we don't have any travis.yml file. How does it work? Looks like a miracle to me!

[kamyuentse]

A hidden file: .travis.yml, I think this is a upstream issue, the clippy race with rustc-nightly, so we just need to wait?

[realcr]

@kamyuentse : I have seen the idea by CAD97 here:
rust-lang/rust-clippy#2704
He suggests to pin rust version and clippy version, like this:

env:
matrix:
  include:
  # Clippy/Format
  - rust: nightly-2018-04-28
    env: CLIPPY_VERSION="1742229ebb7843a65c05ee495d8de5366fcc5567"
    install:
    - rustup component add rustfmt-preview || true
    - cargo install clippy --git https://github.com/rust-lang-nursery/rust-clippy.git --rev $CLIPPY_VERSION || true
    script:
    - cargo clippy --all-targets --tests -- -D clippy
    - cargo fmt -- --write-mode=diff

Maybe we should do something like this? Then we can update it from time to time.
I love to be on the edge with Rust, but it seems like Rust nightly and Clippy have compilation errors together very often.

I even thought about going back to Rust beta, but I am pretty sure some things that we use will not work there. We might be able to do this in the future, but not today (: