Fake closures (or first-class callables) don't reference the correct static variables

[dktapps]

Calling a first-class callable is identical in behaviour to calling the function directly, and shares the same static variables.

pthreads doesn't currently respect this, and each copied first-class callable ends up with its own copy of the static variables, breaking behaviour.

class A{
    public static function test() : void{
        static $a = 0;
        $a++;
        var_dump("a = $a");
    }
}

function test(\Closure $fcc) : void{
    $fcc();
    A::test();
}

$fcc = \Closure::fromCallable([A::class, 'test']);
test($fcc);
echo "end\n";
$t = new class($fcc) extends \Thread{
    private \Closure $fcc;

    public function __construct(\Closure $fcc){
        $this->fcc = $fcc;
    }

    public function run() : void{
        test($this->fcc);
    }
};
$t->start();
$t->join();

This should output

string(5) "a = 1"
string(5) "a = 2"
end
string(5) "a = 1"
string(5) "a = 2"

but actually outputs

string(5) "a = 1"
string(5) "a = 2"
end
string(5) "a = 1"
string(5) "a = 1"

[dktapps]

Turns out that fake closures may also refer to other closures, where the behaviour is similar (the original closure's static variables are shared with the fake closure created by Closure::fromCallable()).