property assignment bug with union and int ranges

[staabm]

this should not error https://psalm.dev/r/808fd263bd

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/808fd263bd

<?php

/**
 * @return -1|positive-int
 */
function getInt():int {
    if (rand(0,1)) {
        return 234;
    }
    return -1;
}

class C {
    /** @var positive-int|null */
    private $p;
    
    function doFoo():void {
        $i = getInt();
        if ($i === -1) {
            $i = null;
        }
        $this->p = $i;
    }
}

Psalm output (using commit ef3b018):

ERROR: InvalidPropertyAssignmentValue - 22:20 - $this->p with declared type 'int<1, max>|null' cannot be assigned type 'int<0, max>|null'

[jack-worman]

Simplified: https://psalm.dev/r/4998359b55

The root issue seems to be -1|positive-int getting wrongly converted to int<-1, max>.
Technically it isn't wrong, just more general than it needs to be.

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/4998359b55

<?php

/**
 * @return -1|positive-int
 */
function foo(): int { return random_int(0, 1) ? -1 : 1; }

$a = foo();

/** @psalm-trace $a */

Psalm output (using commit ef3b018):

INFO: Trace - 10:23 - $a: int<-1, max>

INFO: UnusedVariable - 8:1 - $a is never referenced or the value is not used