Generated when trying to lookup a gem to indicate that the gem was found, but that it isn't usable on the current platform.
fetch and install read these and report them to the user to aid in figuring out why a gem couldn't be installed.
append a platform to the list of mismatched platforms.
Platforms are added via this instead of injected via the constructor so that we can loop over a list of mismatches and just add them rather than perform some kind of calculation mismatch summary before creation.
# File ruby-3.1.2/lib/rubygems/errors.rb, line 129 def add_platform(platform) @platforms << platform end