Add new ArrayUnpackingRule

[canvural]

Before PHP 8.1, unpacking an array that contains string keys results in fatal error: https://3v4l.org/A4gqa

This PR adds a rule that can check this.

Not sure if this rule would be too annoying or not. All the mixed or array-key keyed arrays that being unpacked would error now. Which sounds in line with the runtime though.

[ondrejmirtes]

Hi, I think we have to acknowledge multiple things here:

1. Unpacking syntax can be used in literal arrays and also in call arguments.
2. We should also check for other invalid unpacks like this: https://3v4l.org/0OJA5
3. New rules can only be added for bleeding edge: https://phpstan.org/user-guide/backward-compatibility-promise

So I suggest this:

1. Add some logic to https://github.com/phpstan/phpstan-src/blob/master/src/Rules/FunctionCallParametersCheck.php that checks this for all the rules that call this class - it covers new, function calls, instance method calls, static method calls, callables calls...
2. Add a new rule called UnpackingRule that checks all possible invalid unpacks.

If you're unsure about bleeding edge, you can code the rule as normal and I'll configure it in a later commit :)

Thank you!

[ondrejmirtes]

@canvural If you ever feel like finishing this, I'm looking forward to it! :)

[canvural]

@canvural If you ever feel like finishing this, I'm looking forward to it! :)

Yes, in my to-do list. I'll definitely do something about this when I have the time. Hope it's ok if this stays in draft.

[canvural]

@ondrejmirtes It looks like there is already an error reported for all the things FunctionCallParametersCheck does: https://phpstan.org/r/1d920739-b94e-421d-8afe-9e86e509f196 (Named arguments are supported only on PHP 8.0 and later.) I think that's enough.

Also the invalid usage (strpos(...1)) is reported correctly.

So the current rule in this PR seems sufficient?

[ondrejmirtes]

Named arguments are supported only on PHP 8.0 and later.

Yeah, but on PHP 8.0 PHPStan should complain about array with string keys being unpacked. Am I right?

[ondrejmirtes]

Can you please adapt this similarly to this commit? 7627b52

[canvural]

Updated.

[ondrejmirtes]

 PHPStan should complain about array with string keys being unpacked. Am I right?

Oh right, that's what this PR does. I need coffee.

[canvural]

Hmm. Looks like no: https://3v4l.org/7lTWP Only for PHP < 8

[ondrejmirtes]

Did a couple more adjustments: https://github.com/phpstan/phpstan-src/pull/856/commits

[ondrejmirtes]

Thank you!

[staabm]

not sure why yet, but the test from this PR errors on macOS with php 8.1.2

There was 1 error:

1) PHPStan\Rules\Arrays\ArrayUnpackingRuleTest::testRuleOnPHP81
Error: Typed property PHPStan\Rules\Arrays\ArrayUnpackingRuleTest::$checkUnions must not be accessed before initialization

/Users/staabm/workspace/phpstan-src/tests/PHPStan/Rules/Arrays/ArrayUnpackingRuleTest.php:23
/Users/staabm/workspace/phpstan-src/src/Testing/RuleTestCase.php:47
/Users/staabm/workspace/phpstan-src/src/Testing/RuleTestCase.php:95
/Users/staabm/workspace/phpstan-src/tests/PHPStan/Rules/Arrays/ArrayUnpackingRuleTest.php:91

FAILURES!                                                
Tests: 12850, Assertions: 83007, Errors: 1, Skipped: 142.
make: *** [tests] Error 2

php -v
PHP 8.1.2 (cli) (built: Jan 21 2022 04:34:05) (NTS)
Copyright (c) The PHP Group
Zend Engine v4.1.2, Copyright (c) Zend Technologies
    with Zend OPcache v8.1.2, Copyright (c), by Zend Technologies

[ondrejmirtes]

Fixed: e131e35

[ondrejmirtes]

Turns out there was a feature request for this :) phpstan/phpstan#5764