fix universal: disable initialization of Required with {} as initializer-list

universal/include/userver/utils/required.hpp

@@ -4,6 +4,7 @@
 /// @brief @copybrief utils::Required
 
 #include <concepts>
+#include <memory>
 #include <string_view>
 #include <type_traits>
 #include <utility>
@@ -31,7 +32,7 @@ class Required final {
     Required() = delete;
 
     /// @brief Construct `T` from a value (conditionally explicit).
-    template <typename U = T>
+    template <typename U>
     requires(!std::same_as<std::decay_t<U>, Required> && std::constructible_from<T, U &&>)
     constexpr explicit(!std::convertible_to<U&&, T>) Required(U&& value)
         : value_(std::forward<U>(value))
@@ -59,10 +60,10 @@ class Required final {
     constexpr T&& operator*() && noexcept { return std::move(value_); }
 
     /// @brief Access members of the contained value.
-    constexpr T* operator->() noexcept USERVER_IMPL_LIFETIME_BOUND { return &value_; }
+    constexpr T* operator->() noexcept USERVER_IMPL_LIFETIME_BOUND { return std::addressof(value_); }
 
     /// @overload
-    constexpr const T* operator->() const noexcept USERVER_IMPL_LIFETIME_BOUND { return &value_; }
+    constexpr const T* operator->() const noexcept USERVER_IMPL_LIFETIME_BOUND { return std::addressof(value_); }
 
     /// @brief Implicit conversion to `T&`.
     constexpr /*implicit*/ operator T&() & noexcept USERVER_IMPL_LIFETIME_BOUND { return value_; }

universal/src/utils/required_test.cpp

@@ -87,6 +87,19 @@ TEST(UtilsRequired, DerefMove) {
     EXPECT_EQ(moved, "move-me");
 }
 
+TEST(UtilsRequired, DerefAddressof) {
+    struct Overloaded {
+        bool used = false;
+        auto operator&() {
+            used = true;
+            return this;
+        }
+    };
+
+    utils::Required<Overloaded> r{false};
+    EXPECT_FALSE(r->used);
+}
+
 TEST(UtilsRequired, Mutate) {
     utils::Required<std::string> r{"initial"};
     *r = "modified";