std::optional<T>::~optional
From cppreference.com
                    
                                        
                    
                    
                                                            
                    |   ~optional();  | 
 (since C++17)  (constexpr since C++20)  | 
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If the object contains a value and the type T is not trivially destructible (see std::is_trivially_destructible), destroys the contained value by calling its destructor, as if by value().T::~T().
Otherwise, does nothing.
Notes
If T is trivially-destructible, then this destructor is also trivial, so std::optional<T> is also trivially-destructible.
| Feature-test macro | Value | Std | Feature | 
|---|---|---|---|
__cpp_lib_optional | 
202106L | (C++20) (DR20)  | 
Fully constexpr | 
Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior | 
|---|---|---|---|
| P2231R1 | C++20 | the destructor was not constexpr while non-trivial destructors can be constexpr in C++20 | made constexpr |