Re-implement --help in rustpkg

Fixes #11423

Author: eminence

src/librustpkg/parse_args.rs

@@ -36,7 +36,8 @@ pub struct ParseResult {
 /// Parses command line arguments of rustpkg.
 /// Returns a triplet (command, remaining_args, context)
 pub fn parse_args(args: &[~str]) -> Result<ParseResult, int> {
-    let opts = ~[ getopts::optflag("no-link"),
+    let opts = ~[ getopts::optflag("h"), getopts::optflag("help"),
+                                        getopts::optflag("no-link"),
                                         getopts::optflag("no-trans"),
                  // n.b. Ignores different --pretty options for now
                                         getopts::optflag("pretty"),
@@ -71,6 +72,12 @@ pub fn parse_args(args: &[~str]) -> Result<ParseResult, int> {
     let pretty = matches.opt_present("pretty");
     let emit_llvm = matches.opt_present("emit-llvm");
 
+    if matches.opt_present("h") ||
+       matches.opt_present("help") {
+         usage::general();
+         return Err(0);
+    }
+
     if matches.opt_present("v") ||
        matches.opt_present("version") {
         version(args[0]);