The definition of PGoauthBearerRequest uses a temporary SOCKTYPE macro to hide the difference between Windows and Berkeley socket handles, since we don't surface pgsocket in our public API. This macro doesn't need to escape the header, because implementers will choose the correct socket type based on their platform, so I #undef'd it immediately after use. I didn't namespace that helper, though, so if anyone else needs a SOCKTYPE macro, libpq-fe.h will now unhelpfully get rid of it. This doesn't seem too far-fetched, given its proximity to existing POSIX macro names. Add a PQ_ prefix to avoid collisions, update and improve the surrounding documentation, and backpatch. Reviewed-by: Chao Li <li.evan.chao@gmail.com> Discussion: https://postgr.es/m/CAOYmi%2BmrGg%2Bn_X2MOLgeWcj3v_M00gR8uz_D7mM8z%3DdX1JYVbg%40mail.gmail.com Backpatch-through: 18