validate_dependencies

# File lib/rubygems/specification_policy.rb, line 123
  def validate_dependencies # :nodoc:
    # NOTE: see REFACTOR note in Gem::Dependency about types - this might be brittle
    seen = Gem::Dependency::TYPES.inject({}) { |types, type| types.merge({ type => {}}) }

    error_messages = []
    warning_messages = []
    dependencies.each do |dep|
      if prev = seen[dep.type][dep.name]
        error_messages << duplicate dependency on #{dep}, (#{prev.requirement}) use:    add_#{dep.type}_dependency '#{dep.name}', '#{dep.requirement}', '#{prev.requirement}'
      end

      seen[dep.type][dep.name] = dep

      prerelease_dep = dep.requirements_list.any? do |req|
        Gem::Requirement.new(req).prerelease?
      end

      warning_messages << "prerelease dependency on #{dep} is not recommended" if
          prerelease_dep && !version.prerelease?

      open_ended = dep.requirement.requirements.all? do |op, version|
        not version.prerelease? and (op == '>' or op == '>=')
      end

      if open_ended
        op, dep_version = dep.requirement.requirements.first

        segments = dep_version.segments

        base = segments.first 2

        recommendation = if (op == '>' || op == '>=') && segments == [0]
                           "  use a bounded requirement, such as '~> x.y'"
                         else
                           bugfix = if op == '>'
                                      ", '> #{dep_version}'"
                                    elsif op == '>=' and base != segments
                                      ", '>= #{dep_version}'"
                                    end

                           "  if #{dep.name} is semantically versioned, use:\n"                             "    add_#{dep.type}_dependency '#{dep.name}', '~> #{base.join '.'}'#{bugfix}"
                         end

        warning_messages << ["open-ended dependency on #{dep} is not recommended", recommendation].join("\n") + "\n"
      end
    end
    if error_messages.any?
      error error_messages.join
    end
    if warning_messages.any?
      warning_messages.each { |warning_message| warning warning_message }
    end
  end