Print compiler defines from a macro in Haxe

Main.hx

// Note: Context.getDefines() requires Haxe 3.2 or later
class Main { // example main class

  // - - - - - - - - - - - - - - - - - - - - - - - - - -
  // Just paste this code into one of your classes:
  // - - - - - - - - - - - - - - - - - - - - - - - - - -
  macro public static function get_defines():haxe.macro.Expr {
    var rtn = "Defines ("+
      (haxe.macro.Context.defined("macro")?"macro":"standard")+" pass):\n";
    var defines:Map<String,String> = haxe.macro.Context.getDefines();
    for (key in defines.keys()) {
      rtn += "-D "+key+"="+defines.get(key)+"\n";
    }
    trace(rtn); // compile-time trace
    return {expr: EConst(CString(rtn)) , pos : haxe.macro.Context.currentPos()};
  };
  private static var __invoke_defines = get_defines();
  // - - - - - - - - - - - - - - - - - - - - - - - - - -


  static function main() {
  }
}

output.txt

>haxe Main.hx -main Main -D foo=3
Main.hx:15: Defines (macro pass):
-D haxe_ver=3.2
-D macro=1
-D sys=1
-D foo=3
-D dce=std
-D hxcpp_api_level=321
-D true=1
-D cross=1
-D neko=1
-D haxe3=1

Main.hx:15: Defines (standard pass):
-D haxe_ver=3.2
-D sys=1
-D foo=3
-D dce=std
-D hxcpp_api_level=321
-D true=1
-D cross=1
-D haxe3=1