(expression)::class cannot be used in constant expressions

Description

This error appears when the value of a constant is not entirely static, but may depend on context. In this case, the self::A will only be known when the trait t is used in a class.

Example

<?php

trait T {
    const A = parent::class;
    const B = self::A::class;
}

?>

Solutions

• Keep values of constants simple.

Changed Behavior

This error may appear following an evolution in behavior, in previous versions. See ` <https://php-changed-behaviors.readthedocs.io/en/latest/behavior/.html>`_.