[TypeDeclaration] Handle Union with array type on ReturnUnionTypeRector

[samsonasik]

Given the following code:

final class UnionArray
{
    public function run($a, $b)
    {
        if ($a) {
            return null;
        }

        if ($b) {
            return new DateTime('now');
        }

        return [];
    }
}

It currently produce:

-    public function run($a, $b)
+    public function run($a, $b): ?\DateTime

which array should be included.

[samsonasik]

The bug seems on TypeNormalizer::normalizeArrayTypeAndArrayNever()

rector-src/rules/TypeDeclaration/TypeNormalizer.php

Lines 97 to 100 in 49fda93

	// re-create new union types
	if ($countTraversedTypes !== $countCollectedTypes && $countTraversedTypes > 2) {
	return $this->typeFactory->createMixedPassedOrUnionType($collectedTypes);
	}

[samsonasik]

Fixed 🎉

[samsonasik]

this was used by ReturnTypeDeclarationRector which read docblock 20153a9

which now we use native type for return type inferer so it should safe to remove

[samsonasik]

All checks have passed 🎉 @TomasVotruba I am merging it ;)