pickup configure arguments defined in ext/**/extconf.rb

pickup.rb

require "ripper"

def show(meth, arg)
  case meth
  when "dir_config"
    puts "--with-#{arg}-dir"
  when "enable_config"
    puts "--enable-#{arg}"
  when "with_config"
    puts "--with-#{arg}"
  end
end

def traverse(sexp, fname = "-")
  method_list = %w"dir_config enable_config with_config"
  parent = sexp
  sexp.each do |s|
    if s.is_a?(Array)
      if s.first == :fcall && Array(method_list).include?(s[1][1])
        show(s[1][1], get_arg(parent[2]))
      elsif s.first == :command && Array(method_list).include?(s[1][1])
        show(s[1][1], get_arg(s[2]))
      else
        traverse(s, fname)
      end
    end
  end
end

def get_arg(sexp)
  case sexp.first
  when :arg_paren, :string_literal
    get_arg(sexp[1])
  when :args_add_block
    get_arg(sexp[1].first)
  when :string_content
    sexp[1][1]
  else
    sexp
  end
end

Dir.glob("ext/**/extconf.rb").each do |extconf|
  src = File.read(extconf)
  extconf = File.dirname(extconf).delete_prefix("mytree/ext/")
  sexp = Ripper.sexp(src, extconf)
  traverse(sexp, extconf)
end

result.txt

--with-dbm-dir
--with-dbm-type
--enable-bundled-libffi
--with-libffi-dir
--with-gdbm-dir
--with-openssl-dir
--with-kerberos-dir
--with-debug
--enable-debug
--with-libyaml-dir
--enable-bundled-libyaml
--with-curses-dir
--with-ncurses-dir
--with-termcap-dir
--with-readline-dir
--enable-libedit
--with-libedit-dir
--enable-ipv6
--with-inet6-dir
--enable-close-fds-by-recvmsg-with-peek
--enable-wide-getaddrinfo
--with-lookup-order-hack
--enable-socks
--with-win32-dir
--with-zlib-dir
--with-os-code