How to use Rector to only detect deprecated/changed PHP core methods for PHP 8 upgrade?

[ukenpachi]

Hi, I’m new to Rector and would really appreciate some guidance.

I have a large project that I’ve been maintaining for 18–22 years. It’s currently running on PHP 7.4, and I want to upgrade it to PHP 8. The codebase is quite complex, so my first step is to identify only the core PHP methods or classes that have changed, been deprecated, or could potentially break in PHP 8.

So far, my Rector config looks like this:

<?php
declare(strict_types=1);

use Rector\Config\RectorConfig;
use Rector\Set\ValueObject\SetList;

return static function (RectorConfig $rectorConfig): void {
    $rectorConfig->sets([
        SetList::PHP_80,
    ]);
};

When I run this, Rector suggests more than 45,000 changes and recommendations. That’s overwhelming to handle at once, so instead I’d like to:

• Only generate a list of deprecated/changed PHP methods and classes
• Focus on things that would break the upgrade to PHP 8

Is this possible with Rector, and if so, how should I configure it?

Thanks in advance for your help!

[TomasVotruba]

Hey, welcome to Rector community.

Before you start using Rector, setup coding standard first. We use https://github.com/easy-coding-standard/easy-coding-standard, but you can use any tool.

Apply PSR-12 first, to standardize spacing, indents, etc. Rector is using php-parser that works with AST (abstract syntax tree). It doesn't know tokens (spaces, indents, brackets), so using coding standard tool to "tidy" after Rector is crutial.

Then, try to run Rector with first lowest set possibe. 5.3, then 5.4, 5.5, 5.6 etc. Going one PHP version at at time will give you more precise control on what Rector is changing: https://getrector.com/documentation/integration-to-new-project#content-3-one-php-set-at-a-time

[ukenpachi]

Hey, welcome to Rector community.

Before you start using Rector, setup coding standard first. We use https://github.com/easy-coding-standard/easy-coding-standard, but you can use any tool.

Apply PSR-12 first, to standardize spacing, indents, etc. Rector is using php-parser that works with AST (abstract syntax tree). It doesn't know tokens (spaces, indents, brackets), so using coding standard tool to "tidy" after Rector is crutial.

Then, try to run Rector with first lowest set possibe. 5.3, then 5.4, 5.5, 5.6 etc. Going one PHP version at at time will give you more precise control on what Rector is changing: https://getrector.com/documentation/integration-to-new-project#content-3-one-php-set-at-a-time

Thanks for the reply. I did have a look at this during the past 3-4 weeks of using rector, however I am struggling to get the result I want which is to give me a list of methods/functions which my project is using and it has changed or remove in the upgraded php version.