Rector: [Downgrade] PHP 8.0 union types to doc types

[TomasVotruba]

See https://github.com/rectorphp/rector/issues/4051

[leoloso]

Hey @TomasVotruba if you want, I can already handle this issue, because I can use the same abstract classes from the other issues I just implemented:

To downgrade type unions, I can just inherit from AbstractDowngradeParamTypeDeclarationRector and AbstractDowngradeReturnTypeDeclarationRector, and set shouldSkip as !($property->type instanceof UnionType).

In addition, I can extract class AbstractDowngradeTypedPropertyRector from DowngradeTypedPropertyRector, and from there create DowngradeTypeUnionTypedPropertyRector.

I've seen you've done plenty of changes in the associated PR, including adding PHP 8.0 to the matrix. We could then decouple this issue into 2 issues:

• Adding support for PHP 8.0
• Downgrading the type union

Then, we could have this issue only handle the first part "Adding support for PHP 8.0" (removing file DowngradeUnionTypeToDocBlockRector from the PR), and possibly you can already merge it to master.

And then, I can create a new issue for "Downgrading the type union", and submit a PR with the 3 new rules:

• DowngradeTypeUnionTypedPropertyRector
• DowngradeParamTypeUnionDeclarationRector
• DowngradeReturnTypeUnionDeclarationRector

What do you think?

[TomasVotruba]

Hi @leoloso,

thanks for detailed plan. I love how you prepare a path and fill my possible questions with answers :+1:

Please, go for it

[leoloso]

Great! So please take care of converting this issue and PR to "Adding support for PHP 8.0". After it's merged, I can then submit PRs with PHP 8 code

[TomasVotruba]

This issue can remain as it is, since we often close them very quickly.
Just close it with union PRs.

[leoloso]

I'm not concerned with this issue, but with PR #4082 since it integrates PHP 8.0 to the CI, so I need that merged before I can submit another PR with PHP 8 code...

Or you mean that I should also work on that same branch, downgrade-union? There are conflicting files there, and I wouldn't be able to solve that.

[TomasVotruba]

That is not neccessary as it can take weeks or months to merge.
There are many 3rd party blockres we don't control.

E.g. see https://github.com/rectorphp/rector/runs/1051205204

Better make a standalone branch and PR. We'll have to code in the dark untill PHP 8 is supported in all Rector dependencies

[leoloso]

Ok