On 16-5-2022 17:06, Andreas Leathley wrote:
Hello Internals,
After the first discussion about this topic
(https://externals.io/message/117608) I have created a preliminary
implementation and an RFC for making implicit boolean type coercions
more strict:
https://wiki.php.net/rfc/stricter_implicit_boolean_coercions
With this email I'm starting the two week discussion period. I welcome
any feedback on it and hope to further iron out the implementation if
needed. I mainly chose the route of introducing a deprecation notice
because it is in line with other RFCs that have similar goals (like the
Deprecate implicit non-integer-compatible float to int conversions RFC),
and it is fairly non-intrusive.
This RFC worries me as, in my opinion, it makes PHP's behaviour more
surprising and inconsistent, not less.
It also raises the cognitive complexity for developers by yet another level.
1. It introduces a new interpretation of boolean type coercion, which is
only applied against type declarations.
2. This new interpretation is not consistent with "normal" boolean type
coercion, not consistent with strict types (no coercion) and also not
consistent with what is considered a valid boolean value by the Filter
extension.
While I agree that the current behaviour of PHP can hide bugs, I fear
that even more bugs will be introduced when PHP contains yet a third
form of coercion to boolean and the type coercion used is dependent on
the context.
I see enough bugs on a daily basis which are/were introduced because
people don't know the type coercion rules well enough. Adding yet
another contextual layer to type coercion, makes things MORE complex,
not less.
I fear this will only lead to more bugs, not less (because people new to
PHP will learn the "type declaration" based boolean coercion rules and
assume they apply everywhere).
I also fear that for code bases which do not (yet) use scalar type
declarations, this will be one more argument not to introduce scalar
type declarations (while they should).
I'd say that for this RFC to be acceptable it would need to apply to all
implicit type coercions to boolean. However, the BC-break that would
cause and the fall-out of this for non-greenfields codebases is just too
huge, which, to me, makes this RFC a very strong no-no.
All in all, I largely agree with the flaws in this proposal as
previously pointed out by Christian Schneider in the preliminary
discussion. And I don't see those concerns addressed in the RFC (other
than making it more explicit what the actual intended change is).
Smile,
Juliette
