module RbSys::Mkmf

def env_vars(builder)
  lines = []
  if (cc = env_or_makefile_config("CC", builder)) && find_executable(cc)
    lines << assign_stmt("CC", cc)
  end
  if (cxx = env_or_makefile_config("CXX", builder)) && find_executable(cxx)
    lines << assign_stmt("CXX", cxx)
  end
  if (ar = env_or_makefile_config("AR", builder)) && find_executable(ar)
    lines << assign_stmt("AR", ar)
  end
  lines += builder.build_env.map { |k, v| env_line(k, v) }
  lines.compact.join("\n")
end