Remove invoking of the non-trivial destructor.

json11.cpp

@@ -25,6 +25,8 @@
 #include <cstdlib>
 #include <cstdio>
 #include <limits>
+#include <new>
+#include <utility>
 
 namespace json11 {
 
@@ -46,6 +48,41 @@ struct NullStruct {
     bool operator<(NullStruct) const { return false; }
 };
 
+/* NoDestructor
+ *
+ * Wrapper that makes it easy to create an object of type T with static storage duration that:
+ * - is only constructed on first access
+ * - never invokes the destructor
+ */
+template <typename T>
+class NoDestructor {
+public:
+    template <typename... Args>
+    explicit NoDestructor(Args&&... args) {
+        new (storage_) T(std::forward<Args>(args)...);
+    }
+
+    explicit NoDestructor(const T& x) { new (storage_) T(x); }
+    explicit NoDestructor(T&& x) { new (storage_) T(std::move(x)); }
+
+    NoDestructor(const NoDestructor&) = delete;
+    NoDestructor& operator=(const NoDestructor&) = delete;
+
+    ~NoDestructor() = default;
+
+    const T& operator*() const { return *get(); }
+    T& operator*() { return *get(); }
+
+    const T* operator->() const { return get(); }
+    T* operator->() { return get(); }
+
+    const T* get() const { return reinterpret_cast<const T*>(storage_); }
+    T* get() { return reinterpret_cast<T*>(storage_); }
+
+private:
+    alignas(T) char storage_[sizeof(T)];
+};
+
 /* * * * * * * * * * * * * * * * * * * *
  * Serialization
  */
@@ -236,14 +273,14 @@ struct Statics {
 };
 
 static const Statics & statics() {
-    static const Statics s {};
-    return s;
+    static const NoDestructor<Statics> s;
+    return *s;
 }
 
 static const Json & static_null() {
     // This has to be separate, not in Statics, because Json() accesses statics().null.
-    static const Json json_null;
-    return json_null;
+    static const NoDestructor<Json> json_null;
+    return *json_null;
 }
 
 /* * * * * * * * * * * * * * * * * * * *