CLIUsage.externStdUsage
struct CLIUsage
enum externStdUsage = 
"Available C++ standards:
  =[h|help|?]           List information on all available choices
  =c++98                Sets `__traits(getTargetInfo, \"cppStd\")` to `199711`
  =c++11                Sets `__traits(getTargetInfo, \"cppStd\")` to `201103`
  =c++14                Sets `__traits(getTargetInfo, \"cppStd\")` to `201402`
  =c++17                Sets `__traits(getTargetInfo, \"cppStd\")` to `201703`
  =c++20                Sets `__traits(getTargetInfo, \"cppStd\")` to `202002`
";
  
		dmd cli CLIUsage 
		manifest constantsstatic functions 
	 
	
Options supported by -extern-std