[ryium]

Catch deprecated implicit type conversions that occur in PHP 8.1 and later.
The following BinaryOp that may cause deprecation.

This PR is part of phpstan/phpstan#8288 and change regarding the mod operator of #2450

※O = safe, D = deprecated, X = not safe

% Mod

L \ R	int	float	string	numeric-string	Stringable	array
int	O	D	X	D	X	X
float	D	D	X	D	X	X
string	X	X	X	X	X	X
numeric-string	D	D	X	D	X	X
Stringable	X	X	X	X	X	X
array	X	X	X	X	X	X

Closes phpstan/phpstan#11886

[phpstan-bot]

You've opened the pull request against the latest branch 1.11.x. If your code is relevant on 1.10.x and you want it to be released sooner, please rebase your pull request and change its target to 1.10.x.

[ondrejmirtes]

How the type system responds shouldn't change because it's not actually true. The % operator still returns a number but only on some PHP versions it throws a deprecation notice.

[ondrejmirtes]

So just change the rule please. The condition should be written differently.

1. Please verify that all the X from table here Catch implicit conversions in mod operator #2466 are reported with 'Binary operation "%s" between %s and %s results in an error.'.
2. Please write tests that all the D are reported with 'Deprecated in PHP 8.1: Implicit conversion from %s to %s loses precision.'.
3. Please note that types can for example be int|float or mixed. You should be able to take advantage of RuleLevelHelper so that something that's always wrong like int % float is always reported, something that might be wrong like int % float|int is reported on level 7 and int % mixed is reported on level 9.

Please see how RuleLevelHelper::findTypeToCheck is used in many existing rules like InvalidCastRule. Basically there's a callback that checks the type and transforms the type based on the rule level. Then there's $type instanceof ErrorType with early return and then there's the callback called again on the transformed type.

[ondrejmirtes]

I like this much more! 👍

But the rule should report this only on 8.1+. Please add a new method in PhpVersion and ask about it in the rule.

[ondrejmirtes]

Thank you!