From 4774d5d9a112563b86e8294f6fb76dcee6577d25 Mon Sep 17 00:00:00 2001
From: Sean Patrick Santos <SeanPatrickSantos@gmail.com>
Date: Thu, 30 Apr 2015 21:46:37 -0600
Subject: [PATCH] Allow `T::C` syntax in match patterns to refer to
 trait-assosociated constants.

---
 src/librustc_resolve/lib.rs                          | 7 +++++--
 src/test/run-pass/associated-const-match-patterns.rs | 4 ++++
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/librustc_resolve/lib.rs b/src/librustc_resolve/lib.rs
index 447230ada2230..38ab0a8c5ed0d 100644
--- a/src/librustc_resolve/lib.rs
+++ b/src/librustc_resolve/lib.rs
@@ -2528,8 +2528,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                                 // If anything ends up here entirely resolved,
                                 // it's an error. If anything ends up here
                                 // partially resolved, that's OK, because it may
-                                // be a `T::CONST` that typeck will resolve to
-                                // an inherent impl.
+                                // be a `T::CONST` that typeck will resolve.
                                 if path_res.depth == 0 {
                                     self.resolve_error(
                                         path.span,
@@ -2537,6 +2536,10 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                                                  token::get_ident(
                                                      path.segments.last().unwrap().identifier)));
                                 } else {
+                                    let const_name = path.segments.last().unwrap()
+                                                         .identifier.name;
+                                    let traits = self.get_traits_containing_item(const_name);
+                                    self.trait_map.insert(pattern.id, traits);
                                     self.record_def(pattern.id, path_res);
                                 }
                             }
diff --git a/src/test/run-pass/associated-const-match-patterns.rs b/src/test/run-pass/associated-const-match-patterns.rs
index eeaacbf9dcc78..62e90d7a6e22b 100644
--- a/src/test/run-pass/associated-const-match-patterns.rs
+++ b/src/test/run-pass/associated-const-match-patterns.rs
@@ -41,6 +41,10 @@ fn main() {
         _ => false,
     });
     // Trait impl
+    assert!(match Bar::Var1 {
+        Foo::THEBAR => true,
+        _ => false,
+    });
     assert!(match Bar::Var1 {
         <Foo>::THEBAR => true,
         _ => false,