Boolean match in strict binary operands mode emits an error

[danog]

https://psalm.dev/r/e58299f88a

ERROR: RedundantIdentityWithTrue - a.php:8:13 - The "=== true" part of this comparison is redundant (see https://psalm.dev/228)
            $item instanceof a => 'a',


ERROR: RedundantIdentityWithTrue - a.php:9:13 - The "=== true" part of this comparison is redundant (see https://psalm.dev/228)
            $item instanceof b => 'b',

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/e58299f88a

<?php

class a {}
class b {}

function a(object $item): string {
          return match (true) {
            $item instanceof a => 'a',
            $item instanceof b => 'b',
          };
}

Psalm output (using commit 028ac7f):

No issues!

[orklah]

Do you have this error on another version of Psalm? The snippet seems fine as is

[danog]

This error is happening on upstream master, but the strictBinaryOperands="true" config flag must be set (can't do that in the website).

[orklah]

Ok :)

The fix should just be to check whether $conditional is a VirtualNotIdentical here:

psalm/src/Psalm/Internal/Analyzer/Statements/Expression/AssertionFinder.php

Line 2141 in 9071e87

&& !$var_type->from_docblock

And there is another with VirtualIdentical in the same file

[danog]

Hmm, isn't it a bit hacky?
Couldn't we miss some legit issue, maybe generated by some plugin which relies on virtual AST?
I was thinking of introducing a context property, instead...

[orklah]

Well, I introduced Virtual nodes exactly for this kind of reason (I was creating a plugin and I needed to differentiate between real code nodes and Virtual nodes created by Psalm for easier analysis. See #5215). So here, Psalm is creating a virtual node with === instead of a match expression so just by checking that, you can deduce it's not really a code that's in the file so it shouldn't be considered as unnecessary