T|bool turns into bool|int|string instead of bool|int

[canvural]

Hello 👋🏽

I'm not sure if this is a bug or I misunderstood something so opening a discussion first.

I have the following piece of code:

<?php declare(strict_types = 1);

/** @template T of array-key */
class Foo {
	/** @return T|bool */
	public function doFoo() {} // @phpstan-ignore-line
}

/** @var Foo<int> $foo */
$foo = new Foo;

\PHPStan\Testing\assertType('bool|int', $foo->doFoo());

// Working

/** @template T */
class Bar {
	/** @return T|bool */
	public function doBar() {} // @phpstan-ignore-line
}

/** @var Bar<int> $bar */
$bar = new Bar;

\PHPStan\Testing\assertType('bool|int', $bar->doBar());

and here is the playground link: https://phpstan.org/r/289ebb3c-74d8-4227-8a51-51fbc251c3c7

Am I wrong to expect bool|int on line 12? 🤔