improve help about options that do nothing and support giving short options together

Author: timfel

graalpython/com.oracle.graal.python.shell/src/com/oracle/graal/python/shell/GraalPythonMain.java

@@ -90,7 +90,6 @@ protected List<String> preprocessArguments(List<String> givenArgs, Map<String, S
             String arg = arguments.get(i);
             switch (arg) {
                 case "-B":
-                    System.out.println("Warning: " + arg + " does nothing on GraalPython.");
                     break;
                 case "-c":
                     i += 1;
@@ -123,7 +122,7 @@ protected List<String> preprocessArguments(List<String> givenArgs, Map<String, S
                     break;
                 case "-O":
                 case "-OO":
-                    System.out.println("Warning: " + arg + " does nothing on GraalPython.");
+                case "-R":
                     break;
                 case "-q":
                     quietFlag = true;
@@ -192,7 +191,13 @@ protected List<String> preprocessArguments(List<String> givenArgs, Map<String, S
                         inputFile = arg;
                         programArgs.add(inputFile);
                         break;
+                    } else if (!arg.startsWith("--") && arg.length() > 2) {
+                        // short arguments can be given together
+                        for (String optionChar : arg.substring(1).split("")) {
+                            arguments.add(i + 1, "-" + optionChar);
+                        }
                     } else {
+                        // possibly a polyglot argument
                         unrecognized.add(arg);
                     }
             }
@@ -494,20 +499,23 @@ protected String getLanguageId() {
     protected void printHelp(OptionCategory maxCategory) {
         print("usage: python [option] ... (-c cmd | file) [arg] ...\n" +
                         "Options and arguments (and corresponding environment variables):\n" +
-                        "-B     : don't write .py[co] files on import; also PYTHONDONTWRITEBYTECODE=x\n" +
+                        "-B     : on CPython, this disables writing .py[co] files on import;\n" +
+                        "         GraalPython does not use bytecode, and thus this flag has no effect\n" +
                         "-c cmd : program passed in as string (terminates option list)\n" +
                         // "-d : debug output from parser; also PYTHONDEBUG=x\n" +
                         "-E     : ignore PYTHON* environment variables (such as PYTHONPATH)\n" +
                         "-h     : print this help message and exit (also --help)\n" +
                         "-i     : inspect interactively after running script; forces a prompt even\n" +
                         "         if stdin does not appear to be a terminal; also PYTHONINSPECT=x\n" +
                         "-m mod : run library module as a script (terminates option list)\n" +
-                        "-O     : optimize generated bytecode slightly; also PYTHONOPTIMIZE=x\n" +
-                        "-OO    : remove doc-strings in addition to the -O optimizations\n" +
-                        // "-R : use a pseudo-random salt to make hash() values of various types
-                        // be\n" +
-                        // " unpredictable between separate invocations of the interpreter, as\n" +
-                        // " a defense against denial-of-service attacks\n" +
+                        "-O     : on CPython, this optimizes generated bytecode slightly;\n" +
+                        "         GraalPython does not use bytecode, and thus this flag has no effect\n" +
+                        "-OO    : remove doc-strings in addition to the -O optimizations;\n" +
+                        "         GraalPython does not use bytecode, and thus this flag has no effect\n" +
+                        "-R     : on CPython, this enables the use of a pseudo-random salt to make\n"+
+                        "         hash()values of various types be unpredictable between separate\n" +
+                        "         invocations of the interpreter, as a defense against denial-of-service\n" +
+                        "         attacks; GraalPython always enables this and the flag has no effect.\n" +
                         // "-Q arg : division options: -Qold (default), -Qwarn, -Qwarnall, -Qnew\n"
                         // +
                         "-q     : don't print version and copyright messages on interactive startup\n" +