The tagging code was iterating over bits set in the ID_RECALC_ALL and was casting the flag to IDRecalcFlag. This was triggering an undefined behavior warning in Clang since the bit might not have a corresponding value in the enumerator. The solution is to pre-define all reacalc flags for all bits. While this seems a bit annoying this seems to be the least fragile solution from all suggested ones. Differential Revision: https://developer.blender.org/D15602