Bug report

• php 8.1.3
• phpstan 1.4.10

1. Did a quick search for gettype switch in issues - nothing stood out as similar (#1330 came close, but that was from 2018, and doesn't appear to be this 'use' case)
2. I'm aware that what I'm doing here is possibly a gross abuse of gettype(), and should probably be doing (and in fact probably will do) something saner here. Nevertheless - reporting this in case I'm not misunderstanding something more fundamental

I'm using a switch gettype($var) and caseing on the return values; the behavior changing depending on what was passed in.

At the point where gettype() has determined (in this example) integer and in that case clause, I'd presume the same behaviour after - say - branching on an is_int() on the same variable. However it seems the result of gettype() here isn't 'remembered,' or at least considered.

Code snippet that reproduces the problem

https://phpstan.org/r/545f326d-f332-4bd1-a5c4-a635edc47575

<?php declare(strict_types = 1);

/**
* Do-nothing function to be called from foo() below
* @param integer $x
* @return integer
*/
function bar(int $x){
	return (rand()%2 == $x)*2;
}

/**
* @param integer|string|array<string> $y
* @return integer
*/
function foo($y){
	switch (gettype($y)){
		case "integer":
			echo bar($y); // 19 Parameter #1 $x of function bar expects int, array<string>|int|string given.
			break;
		case "string":
			// do something with the string
			break;
		case "array":
			// foreach($y as $k => $v), do different stuff with each $v.
			break;
		default:
			/* - */
	}
	return 0;
}

Output

Line | Error
-- | --
19 | Parameter #1 $x of function bar expects int, array<string>\|int\|string given.

Expected output

No error