[depre] Deprecate ReturnTypeWillChangeRector as discourages from filling correct types, use type declaration set instead

[TomasVotruba]

Looking at this attributes, its goal is to delay filling of correct return type declarations.
Our goal is to upgrade as soon as possible with best code quality available. Postponing adding return types where they should be in the first place does not match our goal.

That's why I'm deprecating this rule. Use type declaration set instead, to compleetely avoid these missed types and increase your type coverage and code quality 👍

[TobiasBg]

Hi @TomasVotruba,

So far, I had

$rector_config->ruleWithConfiguration(
	Rector\Transform\Rector\ClassMethod\ReturnTypeWillChangeRector::class,
	array(
		new Rector\Transform\ValueObject\ClassMethodReference( 'JsonSerializable', 'jsonSerialize' ),
	),
);

in my Rector config, which resulted in #[\ReturnTypeWillChange] being added to the jsonSerialize() method of a class that implements the JsonSerializable interface, when downgrading the file (coming from an external library) to support PHP 7.4 as its minimum version.

This downgrading removes the mixed return type (and adds a type via phpdoc).

When I remove that config, I now get deprecation warnings when running PHPUnit:
Return type of TablePress\PhpOffice\PhpSpreadsheet\Spreadsheet::jsonSerialize() should either be compatible with JsonSerializable::jsonSerialize(): mixed, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice

Obviously, adding mixed won't work in PHP 7.4, so the attribute is needed.

Can you maybe guide me to how I can now achieve this, with this rule being deprecated in Rector? Thanks a lot!

Best wishes,
Tobias

[TomasVotruba]

Hi, thanks for detailed reporting.

We should handle this in downgrade rules then. Can you kick of the PR in the downgrade rules?

[TobiasBg]

Hi @TomasVotruba,

Thanks for your reply!
Unfortunately, I have no clue how to integrate this into a downgrade rule code, so I can't really create PR (assumingly in https://github.com/rectorphp/rector-downgrade-php). :-(
I did create rectorphp/rector#9515 as a tracking issue, I hope that's ok.

Thank you!
Tobias

[TomasVotruba]

That's correct repository. Basically copy pasting the rule there will do for a start :)