depend_rules

# File lib/mkmf.rb, line 2071
  def depend_rules(depend)
    suffixes = []
    depout = []
    cont = implicit = nil
    impconv = proc do
      each_compile_rules {|rule| depout << (rule % implicit[0]) << implicit[1]}
      implicit = nil
    end
    ruleconv = proc do |line|
      if implicit
        if /\A\t/ =~ line
          implicit[1] << line
          next
        else
          impconv[]
        end
      end
      if m = /\A\.(\w+)\.(\w+)(?:\s*:)/.match(line)
        suffixes << m[1] << m[2]
        implicit = [[m[1], m[2]], [m.post_match]]
        next
      elsif RULE_SUBST and /\A(?!\s*\w+\s*=)[$\w][^#]*:/ =~ line
        line.sub!(/\s*\#.*$/, '')
        comment = $&
        line.gsub!(%(\s)(?!\.)([^$(){}+=:\s\\,]+)(?=\s|\z)") {$1 + RULE_SUBST % $2}
        line = line.chomp + comment + "\n" if comment
      end
      depout << line
    end
    depend.each_line do |line|
      line.gsub!(/\.o\b/, ".#{$OBJEXT}")
      line.gsub!(/\{\$\(VPATH\)\}/, "") unless $nmake
      line.gsub!(/\$\((?:hdr|top)dir\)\/config.h/, $config_h)
      line.gsub!(%\$\(hdrdir\)/(?!ruby(?![^:;/\s]))(?=[-\w]+\.h)", '\&ruby/')
      if $nmake && /\A\s*\$\(RM|COPY\)/ =~ line
        line.gsub!(%[-\w\./]{2,}"){$&.tr("/", "\\")}
        line.gsub!(/(\$\((?!RM|COPY)[^:)]+)(?=\))/, '\1:/=\')
      end
      if /(?:^|[^\\])(?:\\\\)*\\$/ =~ line
        (cont ||= []) << line
        next
      elsif cont
        line = (cont << line).join
        cont = nil
      end
      ruleconv.call(line)
    end
    if cont
      ruleconv.call(cont.join)
    elsif implicit
      impconv.call
    end
    unless suffixes.empty?
      depout.unshift(".SUFFIXES: ." + suffixes.uniq.join(" .") + "\n\n")
    end
    if $extconf_h
      depout.unshift("$(OBJS): $(RUBY_EXTCONF_H)\n\n")
      depout.unshift("$(OBJS): $(hdrdir)/ruby/win32.h\n\n") if $mswin or $mingw
    end
    depout.flatten!
    depout
  end