From 4fa28a2e855fc47cea8475000a15e2df24799e12 Mon Sep 17 00:00:00 2001
From: "Felix S. Klock II" <pnkfelix@pnkfx.org>
Date: Tue, 3 Sep 2013 01:58:12 +0200
Subject: [PATCH 1/3] Allow _ param name in trait default method for #8468.

---
 src/libsyntax/parse/parser.rs | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 02af6d23b4415..b939ac109315f 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -347,6 +347,13 @@ impl Drop for Parser {
     fn drop(&self) {}
 }
 
+fn is_plain_ident_or_underscore(t: &token::Token) -> bool {
+    match *t {
+        token::IDENT(_, false) | token::UNDERSCORE => true,
+        _ => false,
+    }
+}
+
 impl Parser {
     // convert a token to a string using self's reader
     pub fn token_to_str(&self, token: &token::Token) -> ~str {
@@ -1242,11 +1249,13 @@ impl Parser {
             _ => 0
         };
 
+        debug!("parser is_named_argument offset:%u", offset);
+
         if offset == 0 {
-            is_plain_ident(&*self.token)
+            is_plain_ident_or_underscore(&*self.token)
                 && self.look_ahead(1, |t| *t == token::COLON)
         } else {
-            self.look_ahead(offset, |t| is_plain_ident(t))
+            self.look_ahead(offset, |t| is_plain_ident_or_underscore(t))
                 && self.look_ahead(offset + 1, |t| *t == token::COLON)
         }
     }
@@ -1256,6 +1265,8 @@ impl Parser {
     pub fn parse_arg_general(&self, require_name: bool) -> arg {
         let is_mutbl = self.eat_keyword(keywords::Mut);
         let pat = if require_name || self.is_named_argument() {
+            debug!("parse_arg_general parse_pat (require_name:%?)",
+                   require_name);
             self.parse_arg_mode();
             let pat = self.parse_pat();
 
@@ -1266,6 +1277,7 @@ impl Parser {
             self.expect(&token::COLON);
             pat
         } else {
+            debug!("parse_arg_general ident_to_pat");
             ast_util::ident_to_pat(self.get_id(),
                                    *self.last_span,
                                    special_idents::invalid)

From ba1f44d24fd740bf9f74f99ffcd4733151b84fab Mon Sep 17 00:00:00 2001
From: "Felix S. Klock II" <pnkfelix@pnkfx.org>
Date: Tue, 3 Sep 2013 01:58:36 +0200
Subject: [PATCH 2/3] Regression test for #8468.

---
 src/test/run-pass/default-method-parsing.rs | 15 +++++++++++++++
 1 file changed, 15 insertions(+)
 create mode 100644 src/test/run-pass/default-method-parsing.rs

diff --git a/src/test/run-pass/default-method-parsing.rs b/src/test/run-pass/default-method-parsing.rs
new file mode 100644
index 0000000000000..ec607102566aa
--- /dev/null
+++ b/src/test/run-pass/default-method-parsing.rs
@@ -0,0 +1,15 @@
+// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+trait Foo {
+    fn m(&self, _:int) { }
+}
+
+fn main() { }

From 1b3cd960decbaad3fc585c4ac4e5ec4dd8ceabc9 Mon Sep 17 00:00:00 2001
From: "Felix S. Klock II" <pnkfelix@pnkfx.org>
Date: Tue, 3 Sep 2013 11:15:41 +0200
Subject: [PATCH 3/3] Incorporate review feedback.  Fix #8468.

---
 src/libsyntax/parse/parser.rs | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index b939ac109315f..14b133b43798c 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -348,10 +348,7 @@ impl Drop for Parser {
 }
 
 fn is_plain_ident_or_underscore(t: &token::Token) -> bool {
-    match *t {
-        token::IDENT(_, false) | token::UNDERSCORE => true,
-        _ => false,
-    }
+    is_plain_ident(t) || *t == token::UNDERSCORE
 }
 
 impl Parser {