Add rule checking arguments to unset (#2605)

[leongersen]

Adds a rule for checking the arguments to unset. Fixes #2605.

[ondrejmirtes]

This is really nice :) Also make sure to run vendor/bin/phing locally before submitting a PR next time, thanks.

I found a few points. Also, I'm not sure if we want to report "possibly undefined variable" - it's perfectly fine to unset something that might (but doesn't have to) exist.

[leongersen]

I've removed the "possibly undefined variable" check and fixed your other remarks, thanks for reviewing.

[ondrejmirtes]

Hi, I spent a little bit more time to bring the rule over the finish line. Here are the changes from your PR to mine: https://gist.github.com/ondrejmirtes/1f8b2512798df18baa579a39453946f9

1. You forgot to add the rule to a level. It wouldn't run at all.
2. Changed namespace.
3. I moved the if about iterable key type to IterableType.
4. I changed the return type of canBeUnset to ?RuleError.
5. I added recursion so that this case is reported too: unset($notSetVariable['a']);

[ondrejmirtes]

Thanks!

[ondrejmirtes]

Please feel free to do a similar thing for ?? operator - PhpParser\Node\Expr\BinaryOp\Coalesce node.

Also, similarly, this isn't detected: https://phpstan.org/r/b56820c1-0e96-45b5-9f98-58dc0fe96d58

We only have VariableCertaintyInIssetRule.

[leongersen]

Thanks for finishing this up! I just realized I kept missing the Travis warnings when running the build locally (on windows), because it stops somewhere along the way. I'll try to figure out why that is.

[ondrejmirtes]

Yeah, Windows build isn’t in a great shape but at least it finishes on Travis.

On Thu, 28 Nov 2019 at 08:27, Leon Gersen ***@***.***> wrote: Thanks for finishing this up! I just realized I kept missing the Travis warnings when running the build locally (on windows), because it stops somewhere along the way. I'll try to figure out why that is. — You are receiving this because you modified the open/close state. Reply to this email directly, view it on GitHub <#25?email_source=notifications&email_token=AAAZTOATKIVNYAJOPJMAJVTQV5XGFA5CNFSM4JRVWDFKYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOEFLWASQ#issuecomment-559374410>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAAZTOAEJ2YAJZHYIALXCELQV5XGFANCNFSM4JRVWDFA> .

-- Ondřej Mirtes