Gem::SpecFetcher#available_specs

# File tmp/rubies/ruby-3.3.0/lib/rubygems/spec_fetcher.rb, line 211
def available_specs(type)
  errors = []
  list = {}

  @sources.each_source do |source|
    names = case type
            when :latest
              tuples_for source, :latest
            when :released
              tuples_for source, :released
            when :complete
              names =
                tuples_for(source, :prerelease, true) +
                tuples_for(source, :released)

              names.sort
            when :abs_latest
              names =
                tuples_for(source, :prerelease, true) +
                tuples_for(source, :latest)

              names.sort
            when :prerelease
              tuples_for(source, :prerelease)
            else
              raise Gem::Exception, "Unknown type - :#{type}"
    end
  rescue Gem::RemoteFetcher::FetchError => e
    errors << Gem::SourceFetchProblem.new(source, e)
  else
    list[source] = names
  end

  [list, errors]
end