Gem::Resolver#versions_for

# File tmp/rubies/ruby-4.1.0-preview1/lib/rubygems/resolver.rb, line 235
def versions_for(package, range = Gem::PubGrub::VersionRange.any)
  @versions_for_cache[package][range] ||= begin
    candidates = range.select_versions(@sorted_versions[package])

    if Gem::PubGrub::Package.root?(package) ||
       (@set.respond_to?(:prerelease) && @set.prerelease) ||
       range_admits_prerelease?(range)
      candidates
    elsif @all_versions[package].any? {|v| !v.prerelease? }
      candidates.reject(&:prerelease?)
    else
      # Only prereleases exist for this gem; fall back to them so
      # dependencies like `>= 1.0` can still be satisfied.
      candidates
    end
  end
end