What does this error mean and how to fix it ?

rabol

I have seen this a few times in my app and was wondering what it means and how to fix it ?

"Special` function 'in_array' should be called in global namespace to allow compiler optimization."

here is a very simple method to demonstrate

    public function testFunction(string $value)
    {
        $arr = [];

        if (in_array($value, $arr)) {
            echo 'found';
        } else {
            echo 'not found';
        }

    }

JakubMisek

rabol, hello,

It's a hint (low-severity refactoring), not an error. It should not be listed in your Problems window either (unless explicitly configured).

It suggests fully qualifying the function name, so PHP can optimize it. Otherwise, if you will have a lot of such functions in your code, it may significantly slow down your program.

We have a blog post about this diagnostic at https://blog.devsense.com/2025/optimize-native-function-invocation/
and a short description at https://docs.devsense.com/vscode/problems/diagnostics/?h=php6616#hint_1

It can be safely ignored, or even removed using the "Do not show" quick action (as on the screenshot above).