Incorrect behavior of NarrowWideUnionReturnTypeRector on assert()

[samsonasik]

Bug Report

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

Minimal PHP Code Causing Issue

See https://getrector.com/demo/8e48a73d-15a7-4c5b-b80d-84e652712f0b

<?php

final class DemoFile
{
    /**
     * @var array{
     *     cache: array{directory: null}
     * }
     */
    protected array $config = [
        'cache' => [
            'directory' => null,
        ],
    ];
    
    public function getCacheDirectory(): ?string
    {
        $dir = $this->config['cache']['directory'] ?? null;
        \assert(\is_string($dir) || $dir === null, 'Invalid cache directory.');

        return $dir;
    }
}

Responsible rules

• NarrowWideUnionReturnTypeRector

Expected Behavior

On assert(), it can still execute, just show warning, so changing return type is invalid here, see https://3v4l.org/02vqB#v8.5.8

[TomasVotruba]

Good point 👍 We should skip assert-related types

[samsonasik]

Ok, I created PR:

• [DeadCode] Skip assert() enforcement that produce NeverType on NarrowWideUnionReturnTypeRector rector-src#8282