\JanGregor\Prophecy\Reflection\ObjectProphecyMethodReflection::hasSideEffects() should be 'yes' for PHP >7.0

[func0der]

\JanGregor\Prophecy\Reflection\ObjectProphecyMethodReflection::hasSideEffects() returns no. As I found not documentation as for what \PHPStan\Reflection\MethodReflection::hasSideEffects() should really mark, I can only guess, that this marks methods that simply return stuff or work on copies of internal values.

As for \Prophecy\Prophecy\ObjectProphecy::__call() has side effects. I returns a new \Prophecy\Prophecy\MethodProphecy, which's __constructor() method changes the ObjectProphecy it was was called on as of PHP >7.0.
I tries to guess the return type of the method that is prophecied registers itself on the ObjectProphepcy in the \Prophecy\Prophecy\MethodProphecy::will() call.

I might be wrong here, because I really can not find ANY definition of sideEffect regarding a method, but as this not only creates a new object, but also changes the object it was created AND also changes the outcome of the test it is constructed in (changes return type to X instead of null for unregistered calls), it should not considered to be side effect free.

[localheinz]

@func0der

To be honest, I have no idea!

Perhaps @ondrejmirtes can help us out here?

[ondrejmirtes]

Some internal methods from PHP are marked as having/not having side effects (https://github.com/phpstan/phpstan-src/blob/master/src/Reflection/SignatureMap/functionMetadata.php), so you can draw some inspiration from that.

How it currently manifests:

1. All methods returning void always have side effects.
2. Calling a method on a separate line with no side effects is marked as dead code (https://phpstan.org/r/c0f21464-a900-4c51-866e-fc0184fea782).
3. Calling a method with side effects resets memorized state of other methods and properties (https://phpstan.org/r/5ee512dd-ecff-4d88-b0d2-1be03fb49dce vs. https://phpstan.org/r/80bbafed-e5f1-4bc8-a329-5a38a3975cfd).

If you don't want either of these things, return TrinaryLogic::maybe().

[localheinz]

Thank you for the explanation, @ondrejmirtes!

[func0der]

@ondrejmirtes
Thank you for your clarification.
I am not sure that I am on board with 2.
I do not see how methods like this (https://phpstan.org/r/fca1b63c-5056-4bee-8317-51f357c2dee0) may be a problem.
Can you elaborate or point me to a place where I can read up on that?

[ondrejmirtes]

@func0der What do you mean by "a problem"? When you're calling something that's not supposed to have a side effect (like a getter or a method on an immutable object), so the user is supposed to read the return value of the method, but they don't do it, then you get the error "on a separate line has no effect." because you cen simply remove the line.

[func0der]

Ah, sorry. I overlooked the immutable object part. My bad. :)

@localheinz Pretty sure it should be yes in this case, at least for PHP >7.0 :)
But maybe is good for now.

Thanks for the work.

[localheinz]

@func0der

No problem!

Let me know if you run into any issues - I will be here to quickly turn things around when necessary!