Composition of properities in trait and class might be incompatible in PHP < 7

[dnaber-de]

I discoverd a weird bug on a PHP 5.6 system, when I ran Wonolog within a complete site stack using wp cli:

$ wp site list
PHP Fatal error:  Cannot instantiate abstract class Inpsyde\Wonolog\Data\Log in /.../vendor/inpsyde/wonolog/src/PhpErrorController.php on line 73

It turned out that the error that is actually triggering Wonolog's error handler has the following message:

Inpsyde\Wonolog\Data\Log and Inpsyde\Wonolog\Data\LogDataTrait define the same property ($message) in the composition of Inpsyde\Wonolog\Data\Log. This might be incompatible, to improve maintainability consider using accessor methods in traits instead. Class was composed

This E_STRICT error causes that PHP handles the Log class as abstract one, obviously.

However, here's how you can reproduce it (in PHP 5.6):

<?php # -*- coding: utf-8 -*-

namespace Inpsyde\Wonolog;

use Inpsyde\Wonolog\Data\Log;

set_error_handler( function( ...$args ) {
	//echo $args[1];
	var_dump( ( new \ReflectionClass( \Inpsyde\Wonolog\Data\Log::class ) )->isAbstract() );

	new Log();
	return FALSE;
}, E_ALL );

error_reporting( E_ALL );

$require = function() {
	require_once __DIR__ . '/vendor/psr/log/Psr/Log/LoggerInterface.php';
	require_once __DIR__ . '/vendor/monolog/monolog/src/Monolog/Logger.php';
	require_once __DIR__ . '/vendor/inpsyde/wonolog/src/Data/LogDataInterface.php';
	require_once __DIR__ . '/vendor/inpsyde/wonolog/src/Data/LogDataTrait.php';
	require_once __DIR__ . '/vendor/inpsyde/wonolog/src/Data/Log.php';
	require_once __DIR__ . '/vendor/inpsyde/wonolog/src/Channels.php';
};
$require();

Running this script via CLI will give you this error:

$ php testfile.php
bool(true)
PHP Fatal error:  Cannot instantiate abstract class Inpsyde\Wonolog\Data\Log in /.../testfile.php on line 11

The solution is to remove any duplicate declaration of properties in classes, that was declared by any used trait.

[dnaber-de]

I think that can be closed now.