The `-n` flag will ignore warnings completely, while often it is useful to see them and to fix them.
Using `--runtime-set ignore_warnings_on_exit 1` in the Travis script instead, warnings will be shown, both when a developer runs PHPCS on their own machine, as well as in Travis, but warnings will not cause a failed Travis build.
The `-v` flag will list each file being scanned. This is intended for debugging purposes and not needed for normal use.
As WPCS and PHPCompatibility were for a little while (May - July 2017) not compatible with PHPCS 3.x, the library tags cloned were previously fixed to prevent issues with that.
As both WPCS as well as the PHPCompatibility standard are now compatible with PHPCS 3.x, the changes made in PR 1110 and PR 1183 can be reverted.
Notes:
* PHPCS - use `master`.
WPCS uses a limited set of sniffs from PHPCS itself.
Most of these sniffs are long established, stable and rarely get updated, so using PHPCS `master` should be safe.
* WPCS - use the latest release `0.14.0`.
WPCS is the main source of CS violations and is under active development. This means that new versions of WPCS will easily break the build, so should be managed.
* PHPCompatibility - use `master`.
PHPCompatibility checks PHP cross-version compatibility.
It is actively developed and heavily unit tested, so any new violations found in `_s` because of changes in that library, should actually be addressed in `_s` ASAP.
The PHPCompatibility library became compatible with PHPCS 3.x and improved compatibility with Composer installs in version `8.0.0` which was a breaking change.
To account for that, the location where the library is cloned to and the `phpcs --installed_paths` command have been updated.
Ref: https://github.com/wimg/PHPCompatibility/pull/446
The new Trusty images as per Sept 7 include an image for PHP 7.2 (even though it hasn't been released yet).
The `_s` build tests are run against the lowest/highest supported PHP version for 5 and 7.
As `7.2` is now available, it should replace the `7.1` build.