C/C++ Compiler Error: Passing std::vector<T2> to Function Taking std::vector<T1>

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When passing a std::vector<T2> to a function expecting std::vector<T1>, where T2 is derived from T1, the compiler raises an error because std::vector is not covariant. This means that a vector of derived types cannot be treated as a vector of base types directly. While using pointers or references might allow for polymorphic behavior, actual instances in vectors do not support this due to their strict type requirements. To achieve the desired functionality, one must pass a pointer to the vector and ensure that the vector elements are of the same type.
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If I have a function that takes a std::vector< T1 > and I pass it a std::vector< T2 >, where T2 is publicly derived from T1, that should work, why does my compiler complain?
 
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What makes you think that should work? A vector of references or pointers might work; note well that I am not saying it will. A vector of actual instances is a different beast. I would think that this should not work.
 
You have to pass a pointer to the vector, and make sure the vector elements are the same.
 

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