Add default init

Author: kuznetsss

include/xrpl/basics/Mutex.hpp

@@ -101,7 +101,7 @@ template <typename ProtectedDataType, typename MutexType = std::mutex>
 class Mutex
 {
     mutable MutexType mutex_;
-    ProtectedDataType data_;
+    ProtectedDataType data_{};
 
 public:
     Mutex() = default;

src/tests/libxrpl/basics/Mutex.cpp

@@ -2,11 +2,11 @@
 
 #include <gtest/gtest.h>
 
+#include <memory>
 #include <mutex>
 #include <shared_mutex>
 #include <string>
 #include <vector>
-#include <memory>
 
 using namespace xrpl;
 
@@ -56,6 +56,13 @@ TEST_F(MutexDirectConstructionTest, default_constructor)
     EXPECT_TRUE(lock->empty());
 }
 
+TEST_F(MutexDirectConstructionTest, default_initialization)
+{
+    Mutex<int> m;
+    auto lock = m.lock();
+    EXPECT_EQ(*lock, 0);
+}
+
 TEST_F(MutexDirectConstructionTest, constructor_with_value)
 {
     Mutex<int> m(42);