Only variable references should be yielded by reference

Description

With the & option in the signature, a generator is yielding values by reference, and not by value. This way, literal values cannot be yielded: they must be stored in a variable or property first.

Example

<?php

function &gen() {
    yield foo;
}

$gen = gen();
var_dump($gen->current());

?>

Solutions

• Store the literal in a variable and yield the variable.

• Remove the & in the method signature.