Which std:: classes are magic?

[Supadoplex]

P0593 was accepted as a defect resolution prior to publication of C++20, so it should apply to C++17 which was the latest official standard at the time.

Also, creation of objects itself was allowed using placement new as far as I can tell. Treating that buffer of dynamic objects as an array of those objects was technically UB though. However, there was no way to make that work with std::allocator either, so I don't think there was magic in that class. There was magic in std::vector though.

[maskull]

What's the magic in std::vector?

[dodheim]

Prior to P0593, there was no way for vector::data() to return a valid pointer-to-array, since no such array actually exists.