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Using placement new and manual call to the destructor. It ensures that C++ objects are correctly handled when creating C++ objects through vlc_object_create<>(), and that their destructors are correctly called when the (C++) object is destroyed. According to the C++ draft standard, the vlc_object_t won't get overwritten by the placement new since (7.1) will apply to the C++ object being allocated and placement-new'ed, which triggers the default initialization of members, and the default initialization of the vlc_object_t member enters the (7.3) case since no constructors exists for the structure. (It's an extern "C" structure). To default-initialize an object of type T means: (7.1) If T is a (possibly cv-qualified) class type ([class]), constructors are considered. The applicable constructors are enumerated ([over.match.ctor]), and the best one for the initializer () is chosen through overload resolution ([over.match]). The constructor thus selected is called, with an empty argument list, to initialize the object. (7.2) If T is an array type, each element is default-initialized. (7.3) Otherwise, no initialization is performed. --: https://eel.is/c++draft/dcl.init#general-7 However, it's not possible to use a zero-initializing placement-new operation.6cfbabfc
