Describe the bug

Array destructuring is a syntax in PHP where items of an array are assigned to single variables, using an array construct on the left of the assignment, e.g.

[$foo, $bar, $baz] = $source_array;

It's a common pattern to include a terminal comma to indicate that we know not all of the array's elements are being assigned.

E.g. in Composer:

                    [$defaultUsername, ] = explode(':', $authParts, 2);

However, this fails the Squiz.Arrays.ArrayDeclaration.CommaAfterLast sniff:

124 | ERROR | [x] Comma not allowed after last value in single-line array
     |       |     declaration (Squiz.Arrays.ArrayDeclaration.CommaAfterLast)

Code sample

<?php

[$alpha, ] = explode('/', 'alpha/beta');

To reproduce

Steps to reproduce the behavior:

1. Create a file called test.php with the code sample above...
2. Run phpcs --standard=Squiz --sniffs=Squiz.Arrays.ArrayDeclaration test.php
3. See error message displayed

 3 | ERROR | [x] Comma not allowed after last value in single-line array declaration

Expected behavior

A clear and concise description of what you expected to happen.

Versions (please complete the following information)

Additional context

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Please confirm

• I have searched the issue list and am not opening a duplicate issue.
• I have read the Contribution Guidelines and this is not a support question.
• I confirm that this bug is a bug in PHP_CodeSniffer and not in one of the external standards.
• I have verified the issue still exists in the master branch of PHP_CodeSniffer.