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In which cases when using smart pointers will the delete operator not be called for the object?

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Answer from AI

In case of cyclic dependencies between objects managed by std::shared_ptr.
When using std::unique_ptr with a custom deleter that does not call delete.
When using std::shared_ptr with a custom deleter that does not call delete.
When passing std::shared_ptr or std::unique_ptr to a function or structure that stores a "raw" pointer to the object but does not manage its lifetime.
When using std::weak_ptr, which does not increase the reference count and does not own the object.
If an exception is thrown during the creation of an object or std::shared_ptr before the completion of the std::shared_ptr constructor. In this case, std::shared_ptr may not be fully constructed, and memory management could be incorrect.
When using std::unique_ptr with transfer of ownership (e.g., via std::move) to another std::unique_ptr, and the original unique_ptr goes out of scope. delete will be called for the new owner.
If the smart pointer has not gone out of scope and has not been explicitly reset (reset()).
When using std::unique_ptr or std::shared_ptr to manage memory allocated with non-standard allocators or functions (e.g., malloc), if a custom deleter is not provided. The standard delete will be called, which can lead to undefined behavior.