Strict comparison using !== between xxx|void and null will always evaluate to true.

[mvorisek]

Bug report

Code snippet that reproduces the problem

https://phpstan.org/r/e8b73d6d-a543-48d1-a67c-dd6a4b6036d1

Expected output

no phpstan error, the condition is clearly not always true, as void returns natively/implicitly null

when Closure result is assigned, check for void - https://phpstan.org/r/bc2bb528-17b2-4976-81f2-6187b60e3e14 - is correct, but if void is part of an union, void should be converted to null internally probably

[ondrejmirtes]

void makes sense only as a standalone type, not in a union. Your example is even a compile-time error in PHP: https://3v4l.org/LCRng

This is the correct code: https://phpstan.org/r/891c379d-38f9-4493-ab0a-f22783aec94a

[mvorisek]

Thank you, you are right with the native type, but how to allow passing Closure that can return nothing - https://phpstan.org/r/c67377cf-3b08-4f29-88de-5fdae8a1c157?

[ondrejmirtes]

The easiest way to pass your code: https://phpstan.org/r/0899c462-60f4-400e-bc7d-ea30298182ef

[mvorisek]

Please see https://phpstan.org/r/560235d6-759e-45e7-a432-0baf3f09d5a2 and https://3v4l.org/TnQTX .

The php code is valid, phpstan is simply wrong here when the type is unioned. See this issue description for possible fix.

[mvorisek]

@ondrejmirtes let say that two types are comming from a local/global aliases - https://phpstan.org/writing-php-code/phpdoc-types#global-type-aliases and unioned.

Then this has to be a bug, when unioned type is assigned and there are 2+ Closures with mixed void/non-void return, the voided one must be casted to null as php does natively.

[mvorisek]

@ondrejmirtes I would be happy if this issue can be reopened as unioning any 2 Closures should be valid.

[github-actions]

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