From 1009c21ad7b1db366a5c600946652cc490598ec1 Mon Sep 17 00:00:00 2001
From: Lenny222 <github@kudling.de>
Date: Fri, 24 May 2013 21:32:30 +0200
Subject: [PATCH] show options for -W help and -W

---
 src/librustc/driver/driver.rs | 2 +-
 src/librustc/rustc.rc         | 7 ++++++-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/librustc/driver/driver.rs b/src/librustc/driver/driver.rs
index a7cc90f473d4b..75731cf4dc62d 100644
--- a/src/librustc/driver/driver.rs
+++ b/src/librustc/driver/driver.rs
@@ -811,7 +811,7 @@ pub fn optgroups() -> ~[getopts::groups::OptGroup] {
                           for detail)", "FEATURE"),
   optopt("", "android-cross-path",
          "The path to the Android NDK", "PATH"),
-  optmulti("W", "warn",
+  optflagopt("W", "warn",
                         "Set lint warnings", "OPT"),
   optmulti("A", "allow",
                         "Set lint allowed", "OPT"),
diff --git a/src/librustc/rustc.rc b/src/librustc/rustc.rc
index 2b392efaa859c..056b4a9a49ef9 100644
--- a/src/librustc/rustc.rc
+++ b/src/librustc/rustc.rc
@@ -228,9 +228,14 @@ pub fn run_compiler(args: &~[~str], demitter: diagnostic::Emitter) {
         return;
     }
 
+    // Display the available lint options if "-W help" or only "-W" is given.
     let lint_flags = vec::append(getopts::opt_strs(matches, "W"),
                                  getopts::opt_strs(matches, "warn"));
-    if lint_flags.contains(&~"help") {
+
+    let show_lint_options = lint_flags.contains(&~"help") ||
+        (opt_present(matches, "W") && lint_flags.is_empty());
+
+    if show_lint_options {
         describe_warnings();
         return;
     }