Psalm misidentifies type with type juggling

[kamil-tekiela]

https://psalm.dev/r/c831c824de

According to type juggling rules false == 0 so the condition ensures that $var is not false. Yet, Psalm complains that the variable might be false.

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/c831c824de

<?php

/** @return int|false */
function a()
{
	return rand(0,1) ? false : 1;
}

$var = a();
if($var != 0){
	$var += 1;
}

Psalm output (using commit 9943efb):

ERROR: PossiblyFalseOperand - 11:2 - Left operand cannot be falsable, got false|int

INFO: UnusedVariable - 11:2 - $var is never referenced or the value is not used

[orklah]

Psalm has limited support of assertions with ==. This could probably be improved, even if the rules in PHP are a pain.

Also related: #1712