Show lint names

src/librustc/driver/session.rs

@@ -234,6 +234,7 @@ pub impl Session_ {
                  msg: &str) {
         let level = lint::get_lint_settings_level(
             self.lint_settings, lint_mode, expr_id, item_id);
+        let msg = fmt!("%s [-W%s]", msg, lint::get_lint_name(lint_mode));
         self.span_lint_level(level, span, msg);
     }
     fn next_node_id(@self) -> ast::node_id {

src/librustc/middle/lint.rs

@@ -245,6 +245,14 @@ pub fn get_lint_dict() -> LintDict {
     return @map;
 }
 
+pub fn get_lint_name(lint_mode: lint) -> ~str {
+    for lint_table.each |&(name, spec)| {
+        if spec.lint == lint_mode {
+            return name.to_str();
+        }
+    }
+    fail!();
+}
 // This is a highly not-optimal set of data structure decisions.
 type LintModes = @mut SmallIntMap<level>;
 type LintModeMap = @mut HashMap<ast::node_id, LintModes>;