Parentheses incorrectly removed from functions defined and called on the same line

This code, which recursively computes the 10th Fibonacci number:

$result = ($fib = function($n) use (&$fib) {
    return $n <= 1 ? $n : $fib($n - 1) + $fib($n - 2);
})(10);

is incorrectly simplified to this:

$result = $fib = function ($n) use (&$fib) {
    return $n <= 1 ? $n : $fib($n - 1) + $fib($n - 2);
}(10);

removing the parentheses leads to incorrect code.

Start by reproducing the reported PHP example with the formatter and compare its output with the expected parenthesized form. Trace the PHP printer logic responsible for formatting an assignment containing an immediately invoked function, then add a regression test demonstrating that the parentheses remain when the function is defined and called on the same line.