[ydah]

Currently, negative Int_ and Float_ nodes on the left of ** are printed without parentheses, changing the value of the expression:

$expr = new Pow(new Int_(-5), new Int_(2));
$printer->prettyPrintExpr($expr);
// Before: -5 ** 2   (evaluates to -25)
// After:  (-5) ** 2 (evaluates to 25)

Base	Before	After
new Int_(-5)	-5 ** 2 → -25	(-5) ** 2 → 25
$factory->val(-5)	-5 ** 2 → -25	(-5) ** 2 → 25
new Float_(-1.5)	-1.5 ** 2 → -2.25	(-1.5) ** 2 → 2.25

Apply unary-minus precedence to numeric scalars that print with a leading -. Also check precedence when numeric values are changed in place during format-preserving printing.