Rule for safely prepare for upgrade to new version of PHP

[eduard-sukharev]

The pre-condition: the project uses PHP version it needs to migrate from. For the sake of discussion let's upgrade from 7.1 to 8.0.
The problem: While rector provides a broad set of useful refactoring rules which are helpful when you want to make your project be more up-to-date with all the blows and whistles of 8.0, it doesn't provide "a strict minimum" set of rules to apply before switching to new version. all I actually want is to safely upgrade and with minimal edits make sure the project won't break.
The solution: set of rules like UP_TO_PHP_80_BARE_MINIMUM to only fix those.

[staabm]

Your question highly depends on the codebase.

I would recommend adding a PHP8.0 PHPStan check, and pick rector rules based on the PHPStan errors you get

[eduard-sukharev]

but isn't rector supposed to be a tool to help one migrate easier to new versions of php? isn't easier imply safer?

[samsonasik]

You can do step by step, use LevelSetList::UP_TO_PHP_53 first, yes, start with lowest version, verify, repeat, exclude rule you don't want.

The rules you want to skip will always depends on your needs.

[samsonasik]

You can create your own custom collection of rules, then do

$rectorConfig->import(__DIR__ . '/your-collection/collection.php')`

[rjmccluskey]

I agree with @eduard-sukharev. It would be nice to have a list of rules that only fix breaking changes between php versions. Or some way to easily parse those in documentation so I can create my custom list of rules.

[CViniciusSDias]

I also understand what @eduard-sukharev means. I would love to be able to run Rector on my PHP 7.2 project to upgrade it to 8.x, but only run the rules that are necessary for my code to run sucessfully.

I love the rules that improve and modernize my code, but on huge and older projects, if the number of changes is smaller, it's easier to get the project approved. :-)

[staabm]

You should always run one rule at a time. The Sets are actually only useful to reorganize the rector config file after you ran each rule individually (and you commit'ed and review'ed each rules changes individually)

[eduard-sukharev]

One rule at a time or all at once does not matter in this case: we seek for a set of rules for safe upgrade. We do not want to do the same manual "safe rule" set selection for each project. Yes, I am ok with running rule by rule, one at a time, but I would really love to have some predefined set of rules over which I would iterate. It's not like a set of safe rules forces us to apply them all at once, the same way UP_TO_* set of rules does not force us to apply them at once, but rather a convenient collection of rules to be applied.

[gkakosouris]

This is a very sensible request. I would argue that it would greatly add to rector's usefulness with older, large codebases.