Return type is only added to an interface but implementations are skipped

[mxr576]

TL;DR Can missing (union) return typehint be added to Foo class not just FooContract by Rector automatically?

I was playing around with Rector to try to update our (Drupal) codebase from PHP 7.4 and 8.1 and based on what I saw, Rector could only add union return type to an interface but not to those classes that implements the interface which lead to fatal error. What am I missing? (It looks like having @inheritDoc or {@inheritdoc} on Foo::do() does not change anything.)

<?php

interface FooContract {

  /**
   * @return Bar|Baz
   */
  public function do();
}

class Foo implements FooContract {

  public function do() {
    return new Bar();
  }

}

final class Bar {

}

final class Baz {

}

[mxr576]

@TomasVotruba Hi, sorry for the direct ping but can you share some insights about how/if this should work?

[mxr576]

Thanks for the tips, with the help of TYPE_ rules, Rector also updated return type on classes, not just on interfaces.
My config is:

  $rectorConfig->sets([
    LevelSetList::UP_TO_PHP_81,
    SetList::TYPE_DECLARATION,
    SetList::TYPE_DECLARATION_STRICT, // Not strictly necessary for the expected behavior (pun intended).
  ]);

Although I am still not entirely sure what is going on:

1. Is it an expected behavior that LevelSetList::UP_TO_PHP_81 is not enough for updating a PHP 7.4 codebase to PHP 8.1?
2. Why the above configuration still does nothing on Demo? https://getrector.org/demo/a8850128-2236-408b-94d4-a1cc14041638 (This is the reason why I shared screenshots too.)
3. (Could be unrelated/false positive) Some implementation of the interface (on the screenshot) still did not get the proper union type... needs investigation.

[samsonasik]

You need to return new Bar(); instead of Bar();:

-return Bar();
+return new Bar();

ref https://getrector.org/demo/c6b942b4-2cdb-4ac7-b5e5-e8f3c77a62ad

[mxr576]

Aaaaahhhhh.... 🤦

Does it also mean that when a class method's return type is refactored, the "inherited (union) return type" is not considered, rather only the possible return values that the given implementation can produce? 🤔

https://getrector.org/demo/e820f7df-429f-46eb-9532-32a241802a9e

[samsonasik]

You may looking for AddReturnTypeDeclarationRector for that https://getrector.org/demo/c7564af9-c139-4cab-9f94-95ab1716c6a1

[mxr576]

That is also a viable option indeed. Thx!

[mxr576]

So for the record the actual solution is something like:
https://getrector.org/demo/923fc431-82bd-424a-b1a5-1e72bdaf161b
or
https://getrector.org/demo/e820f7df-429f-46eb-9532-32a241802a9e
or
https://getrector.org/demo/c7564af9-c139-4cab-9f94-95ab1716c6a1