Readonly class key triggers a warning about declaring new symbols and causing a side effect

[OleksiiBulba]

Describe the bug
I have a readonly class in php 8.2 and PHP_CodeSniffer shows a warning:

FILE: src/AutowireHelper.php
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
FOUND 0 ERRORS AND 1 WARNING AFFECTING 1 LINE
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 1 | WARNING | A file should declare new symbols (classes, functions, constants, etc.) and cause no other side effects, or it should execute logic with side effects, but should not do both. The first symbol is defined on line
   |         | 9 and the first side effect is on line 9.
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Removing readonly keyword helps to fix the issue.

Code sample

readonly class AutowireHelper implements AutowireHelperInterface
{
}

Custom ruleset

<?xml version="1.0" encoding="UTF-8"?>
<ruleset name="pcsg-generated-ruleset">
    <file>src/</file>
    <arg name="basepath" value="."/>
    <arg name="colors"/>
    <description>
        Micro Framework -  сode formatting rules.
    </description>
    <rule ref="Generic.CodeAnalysis.EmptyStatement"/>
    <rule ref="Generic.CodeAnalysis.JumbledIncrementer"/>
    <rule ref="Generic.CodeAnalysis.UnconditionalIfStatement"/>
    <rule ref="Generic.CodeAnalysis.UnnecessaryFinalModifier"/>
    <rule ref="Generic.CodeAnalysis.UselessOverridingMethod"/>
    <rule ref="Generic.ControlStructures.InlineControlStructure"/>
    <rule ref="Generic.Files.ByteOrderMark"/>
    <rule ref="Generic.Files.LineEndings"/>
    <rule ref="Generic.Files.LineLength">
        <properties>
            <property name="lineLimit" value="120"/>
            <property name="absoluteLineLimit" value="120"/>
        </properties>
    </rule>
    <rule ref="Generic.Formatting.DisallowMultipleStatements"/>
    <rule ref="Generic.Formatting.MultipleStatementAlignment"/>
    <rule ref="Generic.Formatting.NoSpaceAfterCast"/>
    <rule ref="Generic.Functions.CallTimePassByReference"/>
    <rule ref="Generic.Functions.OpeningFunctionBraceBsdAllman"/>
    <rule ref="Generic.Metrics.CyclomaticComplexity"/>
    <rule ref="Generic.Metrics.NestingLevel"/>
    <rule ref="Generic.NamingConventions.ConstructorName"/>
    <rule ref="Generic.NamingConventions.UpperCaseConstantName"/>
    <rule ref="Generic.NamingConventions.CamelCapsFunctionName"/>
    <rule ref="Generic.PHP.DeprecatedFunctions"/>
    <rule ref="Generic.PHP.DisallowShortOpenTag"/>
    <rule ref="Generic.PHP.ForbiddenFunctions"/>
    <rule ref="Generic.PHP.LowerCaseConstant"/>
    <rule ref="Generic.PHP.NoSilencedErrors"/>
    <rule ref="Generic.Strings.UnnecessaryStringConcat"/>
    <rule ref="Generic.WhiteSpace.DisallowTabIndent"/>
    <rule ref="MySource.PHP.EvalObjectFactory"/>
    <rule ref="MySource.PHP.GetRequestData"/>
    <rule ref="PEAR.Classes.ClassDeclaration"/>
    <rule ref="PEAR.Commenting.InlineComment"/>
    <rule ref="PEAR.ControlStructures.MultiLineCondition"/>
    <rule ref="PEAR.Files.IncludingFile"/>
    <rule ref="PEAR.Formatting.MultiLineAssignment"/>
    <rule ref="PEAR.Functions.ValidDefaultValue"/>
    <rule ref="PEAR.NamingConventions.ValidClassName"/>
    <rule ref="PEAR.WhiteSpace.ObjectOperatorIndent"/>
    <rule ref="PEAR.WhiteSpace.ScopeClosingBrace"/>
    <rule ref="PEAR.WhiteSpace.ScopeIndent"/>
    <rule ref="PSR1.Classes.ClassDeclaration"/>
    <rule ref="PSR1.Files.SideEffects"/>
    <rule ref="PSR2.Classes.ClassDeclaration"/>
    <rule ref="PSR2.Classes.PropertyDeclaration"/>
    <rule ref="PSR2.ControlStructures.ControlStructureSpacing"/>
    <rule ref="PSR2.ControlStructures.ElseIfDeclaration"/>
    <rule ref="PSR2.ControlStructures.SwitchDeclaration"/>
    <rule ref="PSR2.Files.EndFileNewline"/>
    <rule ref="PSR2.Methods.MethodDeclaration"/>
    <rule ref="PSR2.Namespaces.NamespaceDeclaration"/>
    <rule ref="PSR2.Namespaces.UseDeclaration"/>
</ruleset>

To reproduce
Steps to reproduce the behavior:

1. Create any readonly class A
2. Run phpcs A.php ...
3. See error message displayed

> ./vendor/bin/phpcs --standard=phpcs.xml ./src/

FILE: src/AutowireHelper.php
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
FOUND 0 ERRORS AND 1 WARNING AFFECTING 1 LINE
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 1 | WARNING | A file should declare new symbols (classes, functions, constants, etc.) and cause no other side effects, or it should execute logic with side effects, but should not do both. The first symbol is defined on line
   |         | 9 and the first side effect is on line 9.
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Time: 40ms; Memory: 6MB

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

Versions (please complete the following information):

• OS: Ubuntu 20.04
• PHP: 8.2
• PHPCS: 3.7.1
• Standard: custom, see xml file above

[jrfnl]

Duplicate #3727 for which PR #3728 is already open.

[OleksiiBulba]

@jrfnl, sorry, did not checked it( I will close it as duplicate.