Infer non-empty assertion from count with variable

[AndrolGenhald]

Comparing count() to integer literal and integer range variables should cause a non-empty assertion.

https://psalm.dev/r/ad7cd85058
https://psalm.dev/r/cd657ad3a6
https://psalm.dev/r/e706d0612e

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/ad7cd85058

<?php

$c = 1;
/** @var list<int> */
$arr = [1];
assert(count($arr) === $c);
/** @psalm-check-type-exact $arr = non-empty-list<int> */;

Psalm output (using commit 8b7bc07):

ERROR: CheckType - 7:58 - Checked variable $arr = non-empty-list<int> does not match $arr = list<int>

https://psalm.dev/r/cd657ad3a6

<?php

/** @var int<1, max> */
$c = 1;
/** @var list<int> */
$arr = [1];
assert(count($arr) === $c);
/** @psalm-check-type-exact $arr = non-empty-list<int> */;

Psalm output (using commit 8b7bc07):

ERROR: CheckType - 8:58 - Checked variable $arr = non-empty-list<int> does not match $arr = list<int>

https://psalm.dev/r/e706d0612e

<?php

/** @var int<0, max> */
$c = 1;
/** @var list<int> */
$arr = [1];
assert(count($arr) === $c);
/** @psalm-check-type-exact $arr = list<int> */;

Psalm output (using commit 8b7bc07):

No issues!