src: remove NonCopyableMaybe

I added this class in 823d86c in 2018 when we did not yet use `std::optional`. The last uses were removed in 5b9bf39, so remove it. Refs: #24234 Refs: #55368 PR-URL: #58168 Reviewed-By: Colin Ihrig <[email protected]> Reviewed-By: Ruben Bridgewater <[email protected]> Reviewed-By: Juan José Arboleda <[email protected]> Reviewed-By: Gerhard Stöbich <[email protected]> Reviewed-By: Daeyeon Jeong <[email protected]> Reviewed-By: Marco Ippolito <[email protected]> Reviewed-By: Luigi Pinca <[email protected]>

Author: tniessen

src/util.h

@@ -655,38 +655,6 @@ struct MallocedBuffer{
  MallocedBuffer& operator=(const MallocedBuffer&) = delete;
 };
 
-template <typename T>
-classNonCopyableMaybe{
-public:
-NonCopyableMaybe() : empty_(true){}
-explicitNonCopyableMaybe(T&& value)
- : empty_(false),
- value_(std::move(value)){}
-
-boolIsEmpty() const{
-return empty_;
- }
-
-const T* get() const{
-return empty_ ? nullptr : &value_;
- }
-
-const T* operator->() const{
-CHECK(!empty_);
-return &value_;
- }
-
- T&& Release(){
-CHECK_EQ(empty_, false);
- empty_ = true;
-returnstd::move(value_);
- }
-
-private:
-bool empty_;
- T value_;
-};
-
 // Test whether some value can be called with ().
 template <typename T, typename = void>
 structis_callable : std::is_function<T>{};