If U is unsigned in destroy_alloc_n, n-- can lead to unsigned integer rollover when n is 0.
This behavior, while trivial and defined, is sufficient to trigger clang's ubsan detector and create excess noise.
/mnt/fscratch0/pub/dependencies/boost/boost/container/detail/copy_move_algo.hpp:966:11: runtime error: unsigned integer overflow: 0 - 1 cannot be represented in type 'unsigned long'
If U is unsigned in destroy_alloc_n, n-- can lead to unsigned integer rollover when n is 0. This behavior, while trivial and defined, is sufficient to trigger clang's ubsan detector and create excess noise.