MRuby::Toolchain.new(:emscripten) do |conf, _params|
  toolchain :gcc, default_command: 'emcc'

  [conf.cc, conf.objc, conf.asm].each do |cc|
    i = cc.flags[1][0].rindex("-Og")
    cc.flags[1][0][i] = "-O3" if i
  end

  conf.archiver.command = "emar"
  conf.exts.executable = '.js'
end