Actually, there is a very nasty side effect to the "b" prefix: it complicates using the output from token_get_all. You have to be very experienced (i.e. have feel the pain really) to know about this rare edge case - yet it must be dealt with if you want a correct parser in userland. See e.g. https://github.com/symfony/symfony/blob/8f65fc7ec1418593d433e39abb71d3959eb10a0b/src/Symfony/Component/HttpKernel/Kernel.php#L718 in Symfony. It'd have been great if the future would've been freed from this edge case. Too bad it has been rejected.
Regards, Nicolas
