Incorrect behavior of MixedTypeRector

[maks-rafalko]

Bug Report

Subject	Details
Rector version	last dev-main
Installed as	composer dependency

Minimal PHP Code Causing Issue

See https://getrector.com/demo/393aa099-ae74-4edc-a562-f65d5d2f1491

<?php

interface FileFilter {}

class ConcreteFileFilter implements FileFilter {}

/**
 * @param ConcreteFileFilter|FileFilter $fileFilter
 */
function usesFileFilter(FileFilter $fileFilter) {}

Change

@@ -4,7 +4,4 @@
 
 class ConcreteFileFilter implements FileFilter {}
 
-/**
- * @param ConcreteFileFilter|FileFilter $fileFilter
- */
 function usesFileFilter(FileFilter $fileFilter) {}

Responsible rules

• MixedTypeRector

Expected Behavior

No change is expected (Rector didn't remove phpdoc on 1.0.3, started removing on 1.0.4 and later)

[samsonasik]

The @param usage is invalid, as it use child and parent in union, which one invalidate another, choose one instead if you one to keep the doc, eg:

@param ConcreteFileFilter $fileFilter

https://getrector.com/demo/019ddfd5-98e9-455a-80e6-044a4fa686a9

[maks-rafalko]

Let me ask a couple of questions:

1. why it's invalid? what rule this union type breaks? From static analysis point of view, everything is good: https://phpstan.org/r/09f93713-b38e-4255-90f3-cdb825f45307
2. is it MixedTypeRector's job to decide to remove or not remove this param? It's a bit confusing cause this rule's description says "Change mixed docs type to mixed typed"

[samsonasik]

1. The @param is still invalid, even phpstan decide it is fine, that dead code, that will still be removed if you enable deadCode set list.
2. the MixedTypeRector indeed should not remove the doc if it not change the mixed type, I will add check for that.

[staabm]

fyi, phpstan normalized the phpdoc away:
https://phpstan.org/r/177beddc-6dd6-47e8-afe2-0f852e05661d

so we could argue that the phpdoc is misleading and leads to wrong assumptions by the dev.
(still you are right its not the MixedTypeRector rules job, to delete it)
see also PHPStan type normalization docs