Generating code coverage report in Clover XML format ... Fatal error: Cannot redeclare preprocessGrammar()

My mistake was here:

<include>
    <directory suffix=".php">.</directory>
</include>

I wanted to cover all the files, they were in src and in the root directory of the project.

In the root directory were tests and they were included for the test coverage. It made a recursive call.

For solving this problem I set concrete directory (src) and files (.php-cs-fixer.). I have used this directives:

<include>
    <directory suffix=".php">src</directory>
    <directory prefix=".php-cs-fixer.">.</directory>
</include>

I also could use <file>, but I had several files and using directory for me more useful. https://phpunit.readthedocs.io/en/9.5/configuration.html#the-file-element

The <exclude> directive didn't for me.

My finally configuration.

<?xml version="1.0" encoding="UTF-8"?>
<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.5/phpunit.xsd"
         bootstrap="vendor/autoload.php"
         cacheResultFile=".phpunit.cache/test-results">
    <testsuites>
        <testsuite name="default">
            <directory>tests</directory>
        </testsuite>
    </testsuites>

    <coverage processUncoveredFiles="true">
        <include>
            <directory suffix=".php">src</directory>
            <directory prefix=".php-cs-fixer.">.</directory>
        </include>
        <report>
            <clover outputFile="phpunit.coverage.xml"/>
        </report>
    </coverage>

    <logging>
        <junit outputFile="phpunit.report.xml"/>
    </logging>
</phpunit>