[libc++] undefined behaviour in std::set/std::map/std::unordered_set/std::unordered_map #102547
Description
I was implementing P3372 (constexpr containers and adaptors) in libc++ and found UB which fails evaluation in ExprConstant.cpp.
It's in these two files:
libcxx/include/__tree
libcxx/include/__hash_table
(link is to the locations of problems)
These are similar issue where a node / bucket is allocated, but NOT constructed, and then a subobject is constructed.