[Downgrade PHP 7.4] Class was not found while trying to analyse it

[leoloso]

Bug Report

Subject	Details
Rector version	v0.9.7
Installed as	composer dependency

Starting from Rector 0.9.7, downgrading Rector to PHP 7.1 fails:

 [ERROR] Could not process "vendor/symfony/cache/CacheItem.php" file, due to:   
         "Analyze error: "Class  was not found while trying to analyse it -     
         discovering symbols is probably not configured properly.". Include your
         files in "$parameters->set(Option::AUTOLOAD_PATHS, [...]);" in         
         "rector.php" config.                                                   
         See https://github.com/rectorphp/rector#configuration".                
                                                                                

                                                                                
 [ERROR] Could not process "vendor/symfony/string/AbstractUnicodeString.php"    
         file, due to:                                                          
         "Analyze error: "Class  was not found while trying to analyse it -     
         discovering symbols is probably not configured properly.". Include your
         files in "$parameters->set(Option::AUTOLOAD_PATHS, [...]);" in         
         "rector.php" config.                                                   
         See https://github.com/rectorphp/rector#configuration".                
                                                                                

                                                                                
 [ERROR] Could not process "vendor/symfony/string/ByteString.php" file, due to: 
         "Analyze error: "Class  was not found while trying to analyse it -     
         discovering symbols is probably not configured properly.". Include your
         files in "$parameters->set(Option::AUTOLOAD_PATHS, [...]);" in         
         "rector.php" config.                                                   
         See https://github.com/rectorphp/rector#configuration".                
                                                                                

                                                                                
 [ERROR] Could not process "vendor/symfony/string/CodePointString.php" file, due
         to:                                                                    
         "Analyze error: "Class  was not found while trying to analyse it -     
         discovering symbols is probably not configured properly.". Include your
         files in "$parameters->set(Option::AUTOLOAD_PATHS, [...]);" in         
         "rector.php" config.                                                   
         See https://github.com/rectorphp/rector#configuration".                
                                                                                

                                                                                
 [ERROR] Could not process "vendor/symfony/string/UnicodeString.php" file, due  
         to:                                                                    
         "Analyze error: "Class  was not found while trying to analyse it -     
         discovering symbols is probably not configured properly.". Include your
         files in "$parameters->set(Option::AUTOLOAD_PATHS, [...]);" in         
         "rector.php" config.                                                   
         See https://github.com/rectorphp/rector#configuration".                

Minimal PHP Code Causing Issue

https://getrector.org/demo/2b94998b-4282-4fdf-88a9-d6b8cfb8d3af

Expected Behaviour

Why is it searching for an empty class? Where is that coming from?

Btw, I did an update for 0.9.7 on class DowngradeContravariantArgumentTypeRector (to avoid applying the rule on __construct), but that's completely unrelated. Undoing this change, the error still happens, so it must be somewhere else.

[leoloso]

I identified the minimal piece of code causing the bug:

https://getrector.org/demo/6ddc6db1-d418-4f63-b123-318adfd4137c

use Symfony\Contracts\Cache\ItemInterface;

abstract class CacheItemTest implements ItemInterface
{
    public function tag($tags): ItemInterface
    {
        return $this;
    }
}

[leoloso]

Here is the minimal Rector config:

https://getrector.org/demo/471e8b57-277e-4f47-b429-8fa621cd73d2

use Rector\DowngradePhp74\Rector\ClassMethod\DowngradeCovariantReturnTypeRector;
use Rector\DowngradePhp74\Rector\ClassMethod\DowngradeReturnSelfTypeDeclarationRector;
use Symfony\Component\DependencyInjection\Loader\Configurator\ContainerConfigurator;

return static function (ContainerConfigurator $containerConfigurator): void {
    $services = $containerConfigurator->services();

    $services->set(DowngradeCovariantReturnTypeRector::class);
    $services->set(DowngradeReturnSelfTypeDeclarationRector::class);
};

The bug happens when both DowngradeCovariantReturnTypeRector and DowngradeReturnSelfTypeDeclarationRector are applied, and in the order above.

Either removing 1 of them, or changing their order, works well!

https://getrector.org/demo/597dacce-4600-4f47-ac0c-66e3b0a9fd1a

Solution?

To fix the issue right now, we can just change the order these 2 rules are executed in downgrade-php74.php

But is that the actual solution? Or is there still some bug, waiting to explode again? To find out, should take the output from executing the first rule, and check why the 2nd rule explodes with that input.

[TomasVotruba]

Is fixed now https://getrector.org/demo/2bf120cc-0d5b-4f49-82ae-3bd547b15a5d

[TomasVotruba]

I got same error reported for a new class const fetch.

This is the fix: #5306

The bug was exactly on this line: https://github.com/rectorphp/rector/pull/5306/files#diff-016ad0c3bfe09fb4b758182a0ea0630b905923756ba947940e82c5364d4c2eabL53
It returned null as a class name without checking it further. Then self created a new class with name '', thus the bug