MarkBennett

I was able to get Ruby 2.5.1 building on M1 by following two of the steps in that GH issue...

rbenv/ruby-build#1691 (comment) rbenv/ruby-build#1691 (comment)

I installed readline and openssl with standard brew install.

brew install readline
brew install openssl

fernandoaleman

For MacOS Catalina, visit Install mysql2 on MacOS Catalina

Problem

Installing mysql2 gem errors on MacOS Mojave.

Solution

Make sure openssl is installed on Mac via Homebrew.