Syntax changes from C++11 to C++20(bfilipek.com)

    bool foo() {
        return [](){return false;}();
    }

    bool bar() {
        struct {
            bool orly() {
                return false;
            }
        } a{};
        return a.orly();
    }

    bool bar() {
        struct a {
            static bool orly() {
                return false;
            }
        };
        return a::orly();
    }

    mult<int, double>(x, add<double, double>(y, z));

    mult(x, add(y, z))

    struct foo {
        std::string capture;
        template <class T>
        std::string operator()(T x) {
            return capture + std::to_string(x);
        }
    };