Optional array key is not recognized with !empty

[mrpavlikov]

Bug report

Optional array key is not recongized when using !empty, only works with isset.

Code snippet that reproduces the problem

https://phpstan.org/r/896f13be-9ac0-43bd-9940-d53fbdb6e4be

Expected output

Expected no error.

[ArtemGoutsoul]

Sems like a very common use case - checking if a value exists and then using it.

isset is handling this correctly, but changing !empty usages to isset would require also checking that the value is not falsy... E.g.:

if (isset($param['opt']) && $param['opt']) {

Works!: https://phpstan.org/r/2ae43dc1-4ec4-419f-8f43-7f4345b9e328

This would feel a bit wrong since empty has exactly this functionality...

[ArtemGoutsoul]

Could this be handled exactly the same way as isset at least? isset check causes phpstan to consider that the key exists, !empty could do the same thing. If someone could point to where is this implemented for isset, I could probably try to implement it for !empty?

[ondrejmirtes]

It definitely can. Look for Isset_ handling in TypeSpecifier.

[ArtemGoutsoul]

Thanks for the pointer!

I don't really understand the code yet, since I've never worked with code analyzers / parsers. But could the issue be here?

For Expr\Isset it adds new HasOffsetType($scope->getType($var->dim)), on line https://github.com/phpstan/phpstan-src/blob/3cebee92aaea0271f5f4eef269d6142ea2c00eef/src/Analyser/TypeSpecifier.php#L692, but in the else block (https://github.com/phpstan/phpstan-src/blob/3cebee92aaea0271f5f4eef269d6142ea2c00eef/src/Analyser/TypeSpecifier.php#L702) which seems to be for !empty ( $expr instanceof Expr\Empty_ && $context->false() ? ), this same logic is missing.

[ondrejmirtes]

First try to write a failing test, probably in https://github.com/phpstan/phpstan-src/blob/master/tests/PHPStan/Rules/Arrays/NonexistentOffsetInArrayDimFetchRuleTest.php. And then try to do whatever you think should work :)

[ArtemGoutsoul]

Thanks for your pointers @ondrejmirtes! Even though I still don't understand the code well, I created a failing test and fixed it. Hopefully the PR is ok (and lets see if the whole CI pipeline passes :) ).

[ondrejmirtes]

Fixed by: phpstan/phpstan-src#569

[github-actions]

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