Remove a fixme

pcwalton says this is right, and it looks right to me too.

Closes #4731

src/librustc/middle/check_match.rs

@@ -673,7 +673,6 @@ fn specialize(cx: &MatchCheckCtxt,
 
                     DefFn(..) |
                     DefStruct(..) => {
-                        // FIXME #4731: Is this right? --pcw
                         let new_args;
                         match args {
                             Some(args) => new_args = args,

src/test/compile-fail/struct-pattern-match-useless.rs

@@ -0,0 +1,23 @@
+// Copyright 2014 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.
+
+struct Foo {
+    x: int,
+    y: int,
+}
+
+pub fn main() {
+    let a = Foo { x: 1, y: 2 };
+    match a {
+        Foo { x: x, y: y } => (),
+        Foo { .. } => () //~ ERROR unreachable pattern
+    }
+
+}

src/test/run-pass/struct-pattern-matching.rs

@@ -1,4 +1,4 @@
-// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
 // file at the top-level directory of this distribution and at
 // http://rust-lang.org/COPYRIGHT.
 //
@@ -18,4 +18,8 @@ pub fn main() {
     match a {
         Foo { x: x, y: y } => println!("yes, {}, {}", x, y)
     }
+
+    match a {
+        Foo { .. } => ()
+    }
 }