Treat #[Pure(true)] in PhpStorm stubs as hasSideEffects => true

[zonuexe]

PhpStorm marks functions that have side effects but whose return value is important as #[Pure(true)], which in current PHPStan functionality means [hasSideEffects => true].

refs #3867 (comment)
refs phpstan/phpstan#12738

[phpstan-bot]

This pull request has been marked as ready for review.

[staabm]

before this PR phpstan errored
https://phpstan.org/r/57c356b1-b4f6-4a36-94f8-01a21b8996d4

Call to function checkdate() on a separate line has no effect.

after this change it no longer does

➜  phpstan-src git:(pr/3880) ✗ cat test.php
<?php declare(strict_types = 1);

class HelloWorld
{
        public function sayHello($m): void
        {
                checkdate($m, $m, $m);
        }
}                                                                           
                                                                                                                        

➜  phpstan-src git:(pr/3880) ✗ php bin/phpstan analyze test.php --debug
Note: Using configuration file /Users/staabm/workspace/phpstan-src/phpstan.neon.dist.
/Users/staabm/workspace/phpstan-src/test.php
 ------ --------------------------------------------- 
  Line   test.php                                     
 ------ --------------------------------------------- 
  3      Class HelloWorld must be abstract or final.  
         🪪  phpstan.finalClass                       
 ------ --------------------------------------------- 


                                                                                                                        
 [ERROR] Found 1 error                                                                                                  
                                                                                                                        

➜  phpstan-src git:(2.1.x) ✗ php bin/phpstan analyze test.php --debug
Note: Using configuration file /Users/staabm/workspace/phpstan-src/phpstan.neon.dist.
/Users/staabm/workspace/phpstan-src/test.php
 ------ ---------------------------------------------------------------- 
  Line   test.php                                                        
 ------ ---------------------------------------------------------------- 
  3      Class HelloWorld must be abstract or final.                     
         🪪  phpstan.finalClass                                          
  7      Call to function checkdate() on a separate line has no effect.  
         🪪  function.resultUnused                                       
 ------ ---------------------------------------------------------------- 


                                                                                                                        
 [ERROR] Found 2 errors                                                                                                 
                                                                                                                        

➜  phpstan-src git:(2.1.x) ✗ 

[zonuexe]

@staabm Thanks, I've sent a PR upstream since the checkdate() function is clearly a pure function.
https://github.com/JetBrains/phpstorm-stubs/pull/1726/files#r1997508160

[staabm]

This also looks wrong. I guess you should review all lines which changed from false to true

[zonuexe]

Although they appear to be pure, they actually rely on some external state associated with the resource, so it makes sense that PhpStorm marks them as #[Pure(true)].

While it may be convenient to make curl_errno() pure for convenience in common use cases, it is inconsistent with impure functions like ob_get_level()(#12577).

To solve this problem, must_use/#[NoDiscard] needs to be supported separately from @pure/@impure.

[claudepache]

As I understand, both #[Pure(false)] and #[Pure(true)] mean that the function has no side-effect, the difference between the two is that a function marked with #[Pure(true)] may depend on global state (and therefore is not pure).

In case "hasSideEffects" => (bool) doesn’t mean more than what it says (which I have not checked), those functions should be marked with "hasSideEffects" => false.

[ondrejmirtes]

Thank you!

[staabm]

nice, this fixed a few more bugs, see https://github.com/phpstan/phpstan-src/actions/runs/13851103733

regression tests would be awesome

[ondrejmirtes]

I don't think we need them, they'd just verify "yeah, this function is in this array", not any real logic 😊

[ondrejmirtes]

But yeah, three issues can be closed thanks to this :)

[mvorisek]

https://3v4l.org/O43Rb

what side effects does it have?

[ondrejmirtes]

Thanks to this line we solved this issue phpstan/phpstan#10342

[mvorisek]

Sure, I mean we should differentiate between pure and side effects. In my understanding "pure" is about return value, "side effects" are about effects on other functions. So I would expect this function to have no side effects, but be pure instead.

related with #118