Null wrongly added as possible variable value

[MoonE]

Psalm adds null as a possible value to a variable that never gets assigned null.
After the comparison $as value according to psalm is -1|null

<?php

$a = -1;
if ($a !== null) {
}
echo $a;

Obviously the if block serves no purpose here. However the same problem occurred in a more complex function where an int variable was compared to an int|null variable.

https://psalm.dev/r/1502d48747

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/1502d48747

<?php

$a = -1;
if ($a !== null) {
}

echo $a;

Psalm output (using commit 12ddd03):

ERROR: RedundantCondition - 4:5 - int can never contain null

[weirdan]

https://psalm.dev/r/27a443b1bf

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/27a443b1bf

<?php
function f(): int {
    $a = -1;
    /** @psalm-suppress RedundantCondition */
    if ($a !== null) {}
    return $a; 
}

Psalm output (using commit 12ddd03):

ERROR: NullableReturnStatement - 6:12 - The declared return type 'int' for f is not nullable, but the function returns '-1|null'

ERROR: InvalidNullableReturnType - 2:15 - The declared return type 'int' for f is not nullable, but 'int|null' contains null

[othercorey]

Is this the same behavior as #9348?

[weirdan]

It certainly looks similar.

[weirdan]

I thought this was a recently introduced issue, but it's not. It was broken since at least 3.4.0