src\third_party/s2/s2regioncoverer.h(143): warning C4200: nonstandard extension used : zero-sized array in struct/union
Cannot generate copy-ctor or copy-assignment operator when UDT contains a zero-sized array

This is just a warning and could be suppressed if desired. The Windows builds do not have warning=error so they are not stopped by this. It's nice to get rid of "old" warnings so that new ones stand out more.