Hidden file scanning support with an option

[soullivaneuh]

Summary

Currently, phpcs is completely ignoring hidden file from its scanning process:

# Files have the same content.
❯ ls -la .test
-rw-rw-r-- 1 sullivan sullivan   75 nov.  24 12:17 .test.php
-rw-rw-r-- 1 sullivan sullivan   75 nov.  24 12:17 test.php
# Only test.php is scanned
❯ php phpcs.phar .test

FILE: /home/sullivan/p/gitlab.com/ss-open/ci/recipes/.test/test.php
----------------------------------------------------------------------
FOUND 1 ERROR AFFECTING 1 LINE
----------------------------------------------------------------------
 2 | ERROR | Missing file doc comment
----------------------------------------------------------------------

Time: 65ms; Memory: 6MB
# The hidden file is ignored even when it is directly specified
❯ php phpcs.phar .test/.test.php 

By digging on the code, I figured out it looks to be intended:

PHP_CodeSniffer/src/Ruleset.php

Lines 634 to 637 in 7763e2e

	// Skip hidden files.
	if (substr($filename, 0, 1) === '.') {
	continue;
	}

Also, this problematic was already reported in #1928 but closed without solution because it will introduce a breaking change that not worth it regarding the interest of the feature.

Concern and interest

In my opinion, considering the scan of hidden files "because it is worthless" is a matter of opinion and we should let the user decide about that.

For my case, I have some special hidden files that are written in PHP and I would like them to be scanned by the linter as well.
This is, for example, the case of the php-cs-fixer's configuration file, named .php-cs-fixer.dist.php.

@gsherwood On #1928, you said this kind of feature addition will introduce a breaking change. May you please elaborate about which kind of breaking change would be introduced here? I am assuming the breaking change would be the tool being scanning additional files "by itself" once updated. Am I right?

Feature proposal

The proposal is simple: Let the tool being able to scan hidden files. According to what I found above, the implementation would be quite simple, meaning adapting the skip condition.

However, we still have the breaking change concern. For that, I propose to add CLI options named --include-hidden-files and --skip-hidden-files (or similar).

For the current major version (v3), the --skip-hidden-files would be the default option, which will produce the same behavior as before.

On the next major version (v4), I suggest to make --include-hidden-files the default which make more sense to me, regarding my statement about the "matter of opinion" fact.

What do you think about that?

Thanks for the reading!

[jrfnl]

Loosely related to #2916.

I can imagine a change that if - and only if - a dot-prefixed file is explicitly passed using the <file> syntax, the file would be scanned as of v4. Adding the CLI options is IMO not the way to go.