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!

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

@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.

@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?

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?

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

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

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

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

Thank you!

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

Fixed: e131e35

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