In MDEV-34973, a few low-level functions were annotated with noexcept, because they can’t throw any exceptions.

Many more rather low-level functions could be annotated to slightly reduce the code footprint. I would be conservative and avoid annotating functions that may invoke something that might throw std::bad_alloc. This would be something that uses a C++ memory allocator, such as some standard template library containers that are instantiated without an allocator template.