Work around an apparent Visual Studio compiler bug.

src/lol/math/polynomial.h

@@ -229,7 +229,7 @@ struct polynomial
                 return array<T> { solutions[0] - k };
 
             // if root of the derivative is also root of the current polynomial, we have a double root.
-            for (auto root : polynomial<T>{c, T(2)*b, T(3)*a}.roots())
+            for (auto root : (polynomial<T>{ c, T(2) * b, T(3) * a }).roots())
                 if (eval(root) == T(0))
                     return array<T> { (solutions[0] + solutions[2]) / T(2) - k,
                                       solutions[1] - k };