False positive: Binary operation "+" between array()|array(...) and array()|array(...) results in an error.

[schlndh]

Bug report

Phpstan reports an error when concatenating arrays with +. It only seems to happen when the type of the arrays is a union (e.g. $c = ['a' => 5] + ['b' => 6]; does not report an error).

This issue was introduced in 0.12.97, it does not occur in the previous version.

Code snippet that reproduces the problem

https://phpstan.org/r/0fea1806-6978-44a7-b5e9-eed6d2d5660c

Expected output

No errors.

[ondrejmirtes]

/cc @staabm Can you look at this? It's a bit weird to me because the code handling the unions is there https://github.com/phpstan/phpstan-src/blob/2ba9332d29c1acdde0f85a2781308d2e8972f00e/src/Analyser/MutatingScope.php#L1325-L1344 but maybe it's unreachable with the new range math...

You can test this in NodeScopeResolverTest, the operation type should not be ErrorType...

[staabm]

I can have a look at the beginning of next week

[ondrejmirtes]

Fixed by phpstan/phpstan-src#657

[github-actions]

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