Fix type assertion for Arithemtic addition and subtraction

[KevinVanSonsbeek]

Closes #11241

[orklah]

Cool! Seems like an improvement but I'm not sure it fixes everything

Can you check this for example? https://psalm.dev/r/6f97b61d3d

What you did is replace $sum usage by a generic TInt in one of the branches. It's better because it stops assuming we have a literal 1, but the issue is with $sum everywhere I think

We should fix it here if we can
https://github.com/vimeo/psalm/pull/11269/files#diff-38fd2d45971b85013dfc252b81a4d63816a2f0b9e6d15b5168c5878ad2dd65c4R826

I think we need to check what's in $right_type_part instead of assuming we have 1 or -1.
If it's a literal int, the operation is easy to do. If we have something else, we can just assume a generic TInt will be returned for the whole https://github.com/vimeo/psalm/pull/11269/files#diff-38fd2d45971b85013dfc252b81a4d63816a2f0b9e6d15b5168c5878ad2dd65c4R825 branch

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/6f97b61d3d

<?php
        /** @return int<0,5> */
        function intFunc(): int {
            return 5;
        }
        $a = 1;
        $a += intFunc();
/** @psalm-trace $a */;

Psalm output (using commit 38fc844):

INFO: Trace - 8:23 - $a: int<1, 6>

INFO: UnusedVariable - 6:9 - $a is never referenced or the value is not used

INFO: UnusedVariable - 7:9 - $a is never referenced or the value is not used

[KevinVanSonsbeek]

I can't really seem to reproduce the sum issues in other situations.

The example you sent with an int-range is handled in an earlier branch. Same with additions/subtractions that have an TLiteralInt on the right side, and are not inside of a loop.

If i check the right type part, and grab that value if it is a TLiteralInt it actually ends up breaking int-ranges for loops.
ex:

// Replacing the sum assignment with this:
  if ($right_type_part instanceof TLiteralInt) {
      $sum = $right_type_part->value;
  } else {
      $sum = $parent instanceof VirtualPlus ? 1 : -1;
  }

Causes the incrementInLoop test to fail:

-    '$i' => 'int<0, 10>'
-    '$j' => 'int<100, 110>'
+    '$i' => 'int<0, 11>'
+    '$j' => 'int<100, 111>'

Increments in loops also seem to be the only situation where the righthand side is a TLiteralInt from what i can see in the tests present.

Edit: typo

[orklah]

Fair enough! Can you just leave a comment above the $sum initialisation with something like "This seems arbitrary defined as 1/-1, this may need a better handling if there's issues"

Just to facilitate a future debugging :p

Thanks!

[orklah]

Thanks!