In some cases we can do a bit better by using
std::min(std::numeric_limits<size_type>::max() / 2, allocator<T>::max_size())

They may help in some cases, particularly on 32-bit platforms.

PiperOrigin-RevId: 471846886
Change-Id: I5bd63de5dd8aec3de6530a33d8904dd6e9bd015e