The standard says that reading from an uninitialized variable is undefined behavior. However, suppose I want to construct std::array of uninitialized values of user-defined type Z, which is in fact initialized by default. Can one achieve something like the following without causing UB?

   struct Uninitialized{};

   struct Z{
      Z() : x_{} {}
      Z(Uninitialized) {}
      int x_; 
   };

   std::array<Z, 2> A{Z{Uninitialized{}}, Z{Uninitialized{}};

The use case for this would be to identify uninitialized values using sanitizers when working with arrays(without sacrificing initialization of x_ in default constructor of Z).

   auto uz = Z{Uninitialized{}};
   std::array<Z, 5> A{uz, uz, uz, uz, uz};

   // ... some tedious computations where A[4].x_ remains uninitialized 
   // due to incorrect implementation(maybe off-by-1). 

   // ... print A to file
   

I tried running the code above in a somewhat different setting and it worked as expected using Valgrind.