I've hit on a bug that is fixed in master[1], and, I believe, in the 3.5.2 tag. Both the 3.5.1.1 and the 3.5.2 tag have been around for 4 and 2 months, respectively, but there haven't been any official releases.
Are those two tags going to get an official release on <
https://github.com/google/protobuf/releases> soon or are those tags placeholders while more work happens? If the latter, I'd love to hear a release date! The bug I ran into is definitely fixed by a recent merge into protobuf, and I'd love to update homebrew's recipe for it instead of installing my own custom one.