Trait in abstract class is only analyzed in context of abstract class, not concrete classes about phpstan HOT 4 CLOSED

The playground doesn't show files, or "in context of class ClassName", which is very confusing in this case. This is what local phpstan shows:

 ------ ---------------------------------------------------------------------------------------------------
  Line   HasCategories.php (in context of class App\Service\Categories\BaseTest)
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  10     Access to an undefined static property static(App\Service\Categories\BaseTest)::$category_prefix.
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with slighty different names.

from phpstan.

In this second case, the concrete class TestTwo really doesn't have the required static property, which would be a real PHP error: https://phpstan.org/r/5567595d-5e09-4111-ad9a-6fd71e162e99 But PHPStan doesn't detect it, because it's not "in context of BaseClass".

from phpstan.

Traits are analysed in context of each class that uses them. And it doesn't matter whether the class is abstract or not. Your code is dangerous. It's not obvious at all that class extending BaseTest should have this property.

You can switch to an abstract method. That's enforceable by the language and by static analysis.

from phpstan.

Why does dangerous matter? That's what stan is supposed to detect, right? But it doesn't detect the actual bug (TestTwo doesn't have the static property), and it does detect the non-bug. Seems like a bug, but okay, maybe it's an edge case of bad programming.

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