Type combination of SubtractableType instances

[herndlm]

Assuming I have 2 types, both are MixedType, but only one has subtractedType configured. Is it expected that both intersect and union combinations of those 2 always result in a MixedType without the substractedType?

I'm not entirely sure if there is a bug somewhere or not. I'm having a scenario where I start with a plain mixed, some expressions add information via subtractable mixed (e.g. is mixed but not String) and then I want to intersect those 2. I would expect to get the mixed with more information instead of the plain one.

Thought I ask before I loose myself in some rabbit hole :)

[herndlm]

Aha, apparently it is dependent on the order currently. TypeCombinator::intersect($mixedWithSubtractedType, $plainMixed) works as I expect it, while the other way around it doesn't :)

[herndlm]

Fyi this was fixed/improved in phpstan/phpstan-src@68e6443