C++ named requirements: CopyInsertable (since C++11)

Specifies that an object of the type can be copy-constructed in-place by a given allocator.

# Notes

If A is std::allocator, then this will call placement new, as by ::new((void*)p) T(v)(until C++20)std::construct_at(p, v)(since C++20).

Although it is required that customized construct is used when constructing elements of std::basic_string until C++23, all implementations only used the default mechanism. The requirement is corrected by P1072R10 to match existing practice.

# Defect reports