DisallowMultipleAssignments false positive when assigning to variable property of an object in an array

[GaryJones]

Describe the bug

False positive on a complex statement that suggests the assignment is not the first block of code.

Try assigning a value to a property of an object contained in an (indexed) array.

Code sample

<?php

$filtered_results[ $i ]->$field = $result;

Custom ruleset

Can be reproduced with the WordPress-Extra or Squiz rulesets, or any combination using the Squiz.PHP.DisallowMultipleAssignments rule.

To reproduce

Steps to reproduce the behavior:

1. Create a file called test.php with the code sample above...
2. Run phpcs test.php --standard=Squiz --sniffs=Squiz.PHP.DisallowMultipleAssignments -s or similar
3. See error message displayed

3 | ERROR | Assignments must be the first block of code on a line (Squiz.PHP.DisallowMultipleAssignments.Found)

Expected behavior

No violation reported.

Versions (please complete the following information)

Operating System	MacOS 14.6.1
PHP version	7.4
PHP_CodeSniffer version	3.9.2
Standard	Squiz
Install type	Composer

Additional context

None of the tests seem to have an assignment to a property of an object in an array.

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.

[jrfnl]

@GaryJones Thanks for reporting this. I can confirm the issue, which appears to be caused by the variable variable, i.e. the variable for the property name:

$filtered_results[] = $result;
$filtered_results[ $i ] = $result;

$filtered_results->field = $result;
$filtered_results->$field = $result;

$filtered_results[ $i ]->field = $result;
$filtered_results[ $i ]->$field = $result; // <- This is the bug, all other test cases in this code sample are handled correctly.

[jrfnl]

@GaryJones PR #610 should fix this. Testing appreciated.