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@ondrejmirtes

The PhpStorm stub marks ob_get_contents() as follows:

#[Pure(true)]
function ob_get_contents(): string|false {}

#[Pure(true)] is defined as follows:

class Pure
{
    /**
     * @param bool $mayDependOnGlobalScope Whether the function result may be dependendent on anything except passed variables
     */
    public function __construct(bool $mayDependOnGlobalScope = false)
    {
    }
}

ob_get_contents() is clearly an impure function with state, but it doesn't make sense to write ob_get_contents(); on a separate line. #[Pure(true)] means that.

This is the same as the #2037 vs 2b5b317 conflict about file_get_contents().

According to the current semantics of PHPStan, all #[Pure(true)] should be declared as hasSideEffects => true, but importing them all seems to break many of PHPStan's tests.

Not needed anymore thanks to #3880