MakeMakefile#egrep_cpp

# File tmp/rubies/ruby-4.1.0-preview1/lib/mkmf.rb, line 927
def egrep_cpp(pat, src, opt = "", &b)
  src = create_tmpsrc(src, &b)
  xpopen(cpp_command('', opt)) do |f|
    if Regexp === pat
      puts("    ruby -ne 'print if #{pat.inspect}'")
      !f.grep(pat) {|l|
        puts "#{f.lineno}: #{l}"
      }.empty?
    else
      puts("    egrep '#{pat}'")
      system("egrep", pat, in: f)
    end
  end
ensure
  MakeMakefile.rm_f "#{CONFTEST}*"
  log_src(src)
end