Description:
------------
When the value of a trait attribute is a concatenation of self::class (or __CLASS__) and another string, the value of the very first instantiation persists.

This problem seems to be introduced at 7.1 and still shows up on 7.2.4.

You may try the example with >=7.0 here: http://sandbox.onlinephpfunctions.com/code/cced66bdfaf2dc5d09a042e4de1947bd8198b95d

Test script:
---------------
trait MyTrait {
	protected $attr = self::class . 'Test';

	public function test() {
		return $this->attr;
	}
}

class A {
	use MyTrait;
}

class B {
	use MyTrait;
}

$a = new A();
$b = new B();

Expected result:
----------------
ATest
BTest

Actual result:
--------------
ATest
ATest