message: make array constructor explicit
diff: @@ -122,7 +122,7 @@ public:
  *
  * @param exec the Executor where the array data is allocated
  */
  - Array(std::shared_ptr<const Executor> exec) noexcept
  + explicit Array(std::shared_ptr<const Executor> exec) noexcept
  : num_elems_(0),
  data_(nullptr, default_deleter{exec}),
  exec_(std::move(exec))
  