NeverType: accept nothing

[jiripudil]

I was surprised to find out that NeverType accepts everything. Shouldn't it be the opposite? It's the bottom type, it's empty. No value can be of this type. Why accept every value then?

Consider this PR me poking around and waiting to see what builds break.

[ondrejmirtes]

An idea - only explicit never should have this behaviour. If you have implicit never, it means that the function signature is wrong, and you already have an error at the declaration - no need for a new error when calling it :)

[staabm]

interessting :)

you should have a look at the impact this change has on open issues: https://github.com/phpstan/phpstan-src/actions/runs/3693563281#summary-10085912763 (Issue-Bot summary)

[jiripudil]

An idea - only explicit never should have this behaviour. If you have implicit never, it means that the function signature is wrong, and you already have an error at the declaration - no need for a new error when calling it :)

Oh, thanks a lot for this comment! This probably explains why it has been implemented to accept everything. I'll update this so that only the behaviour of explicit never is changed 👍

[ondrejmirtes]

Thank you, it makes total sense and issue bot agrees :)

Please:

1. Add a regression test for the one implemented feature request that asks for this :)
2. Please add a test that shows that explicit never can be passed into explicit never :)

[ondrejmirtes]

Thank you!

[ondrejmirtes]

I'm really gonna go crazy here :D Because of this change, this now reports problem like this:

 ------ ----------------------------------------------------------------------- 
  Line   test.php                                                
 ------ ----------------------------------------------------------------------- 
  73     Parameter #1 $element of method                                        
         Doctrine\Common\Collections\ArrayCollection<*NEVER*,*NEVER*>::add()    
         expects *NEVER*,                                                       
         object given.                                                    
 ------ ----------------------------------------------------------------------- 

So if you create a new ArrayCollection and immediately try to add something to it, it's gonna report an error.

Maybe we'll have to postpone this until generics are smarter 🤔

[herndlm]

That's phpstan/phpstan#8511 / phpstan/phpstan#6731 again, right? Did you not see the failing test Ondřej? :P