Hi Internals,
I stumbled upon a difference in behavior between PHP >=7.0 and HHVM when it comes to object-to-string conversion for objects not implementing a __toString which caught me by surprise.
It's probably a pretty common scenario, especially for inexperienced PHP developers, as all it takes is to accidentally name your method _toString() or toString() rather than __toString().
When trying to use an object which does not implement a __toString(), PHP will emit an E_RECOVERABLE_ERROR where HHVM throws an Error.
See https://3v4l.org/WtJff for a minimal example. HHVM's behavior makes more sense to me here.
To me, PHP's behavior is especially unexpected if you consider the behavior in https://3v4l.org/lF7gR where PHP does throw a (Type)Error because of the typehint. Note this example works if you change $a for an instance of something with a proper __toString()-method.
I searched through the discussions on the original 'Exceptions in the engine' RFC and couldn't find any mention of this specific case so I was wondering if anyone remembers if this was deliberately kept this way? I'm not sure if I have the skill to write a patch, I'm willing to try, but it'd be a waste of time if there is some good reason for having kept this an E_RECOVERABLE_ERROR I'm unaware of.
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Marlies Heijkoop
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Hi Internals,
I stumbled upon a difference in behavior between PHP >=7.0 and HHVM when it comes to object-to-string conversion for objects not implementing a
__toStringwhich caught me by surprise.It's probably a pretty common scenario, especially for inexperienced PHP developers, as all it takes is to accidentally name your method
_toString()ortoString()rather than__toString().When trying to use an object which does not implement a __toString(), PHP will emit an
E_RECOVERABLE_ERRORwhere HHVM throws an Error.
See https://3v4l.org/WtJff for a minimal example. HHVM's behavior makes more sense to me here.To me, PHP's behavior is especially unexpected if you consider the behavior in https://3v4l.org/lF7gR where PHP does throw a (Type)Error because of the typehint. Note this example works if you change
$afor an instance of something with a proper__toString()-method.I searched through the discussions on the original 'Exceptions in the engine' RFC and couldn't find any mention of this specific case so I was wondering if anyone remembers if this was deliberately kept this way? I'm not sure if I have the skill to write a patch, I'm willing to try, but it'd be a waste of time if there is some good reason for having kept this an
E_RECOVERABLE_ERRORI'm unaware of.
I assume that this is closely related to the fact that PHP can't throw
from inside of __toString(), see https://3v4l.org/BhPiN and
http://markmail.org/message/lkpmpnhrvcbafhkd.
--
Christoph M. Becker