cd2cfdeab0
Currently `MEM_delete` frees pointers expecting that they match to the pointers allocated with `MEM_new`, otherwise it can cause undefined behavior when freeing memory(using `--debug-memory` flag breaks in place, if not it can corrupts other data, generating a incorrect back-traces). However polymorphic objects lifetime can be managed by pointer of their most derived type or by any pointer in their ancestor tree that defines a virtual destructor, which sometimes can differ in offset when pointing to the same object. This changes ensures the correct pointer is being freed, by using the pointer to the most derived type (returned by`dynamic_cast<void *>(...);`[0]). ---------- [0] = [dynamic_cast](https://en.cppreference.com/w/cpp/language/dynamic_cast.html): `a) If expression is a pointer to (possibly cv-qualified) void, the result is a pointer to the most derived object pointed to by expression.` ----------- As an example, given the followings structs: ```c++ struct A { int a; virtual ~A() = default; }; struct B { int b; virtual ~B() = default; }; struct Derived : public A , public B { int c; }; std::unique_ptr<A> a_ptr = std::make_unique<Derived>(); std::unique_ptr<B> b_ptr = std::make_unique<Derived>(); ``` Using std smart pointers to manage `Derived` objects can be done with `A` or `B` pointers. However if a `Derived` object memory is managed with `MEM_delete`, using a `B` pointer for freeing the memory currently may silently break Blender, since it don't accounts for the full object memory layout, the `dynamic_cast<void *>(ptr);` cast gives a more safe pointer for freeing the memory. Note that object destruction is successfully handled through the virtual destructor. ---------- This instead could be an assert to ensure polymorphic objects to be deleted as the most derived object type. Pull Request: https://projects.blender.org/blender/blender/pulls/146269
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