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Should this 'Parameter of method SubClass::__construct() is not contravariant with parameter of method ParentClass::__construct()' error be unignorable? #12272
Description
Bug report
The code from https://phpstan.org/r/28422159-3b33-499a-9c14-0856c73bf57b generates the following error:
Parameter #2 $code (int) of method SpecificException::__construct() is not contravariant with parameter #2 $previous (Throwable|null) of method BaseException::__construct().
and when I try to add a similar error to the baseline on a project, PHPStan reports that: Unignorable errors could not be added to the baseline.
The code in question could probably have a better structure, but it doesn't generate any PHP warnings or errors: https://3v4l.org/abZFe, so I'm wondering whether that PHPStan error should be marked as unignorable or reported at all. This old issue suggests to me that doing this type of check on the constructor methods may be an accident.
Note that when I remove the ExceptionContract interface from the example, PHPStan no longer detects an error: https://phpstan.org/r/baca06c9-6103-445b-92ec-a0c945ab6d62
Code snippet that reproduces the problem
https://phpstan.org/r/28422159-3b33-499a-9c14-0856c73bf57b
Expected output
I think PHPStan should either allow the error to be ignored or don't report an error.
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Activity
ondrejmirtes commentedon Dec 16, 2024
This is a legit bug which should be fixed.
[-]Should this 'Parameter SubClass::__construct() is not contravariant with parameter ParentClass::__construct()' error be unignorable?[/-][+]Should this 'Parameter of method SubClass::__construct() is not contravariant with parameter of method ParentClass::__construct()' error be unignorable?[/+]stof commentedon Dec 21, 2024
@ondrejmirtes this code is perfectly valid in PHP: https://3v4l.org/LFC0S
A constructor does not need to be contravariant with a parent constructor. Only interfaces enforces some constructor signature for child classes, but
SpecificExceptionis contravariant with the signature of the interface it implements.ondrejmirtes commentedon Dec 21, 2024
Yes, I already stated this is a PHPStan bug that should be fixed. Otherwise I'd close this issue.
phpstan-bot commentedon Feb 26, 2026
Closed via merging phpstan/phpstan-src#4945
github-actions commentedon Mar 30, 2026
This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.