From 73201fd675e6d7d6f1ab6c116a360a39a593de93 Mon Sep 17 00:00:00 2001
From: Leo Testard <leo.testard@gmail.com>
Date: Sat, 7 Feb 2015 13:14:17 +0100
Subject: [PATCH] Make the live code analysis visit method declarations.

The live code analysis only visited the function's body when visiting a
method, and not the FnDecl and the generics, resulting in code to be
incorrectly marked as unused when it only appeared in the generics, the
arguments, or the return type, whereas the same code in non-method
functions was correctly detected as used. Fixes #20343.
---
 src/librustc/middle/dead.rs      |  2 +-
 src/test/run-pass/issue-20343.rs | 38 ++++++++++++++++++++++++++++++++
 2 files changed, 39 insertions(+), 1 deletion(-)
 create mode 100644 src/test/run-pass/issue-20343.rs

diff --git a/src/librustc/middle/dead.rs b/src/librustc/middle/dead.rs
index 90d26f0f6bf..cf680871dcf 100644
--- a/src/librustc/middle/dead.rs
+++ b/src/librustc/middle/dead.rs
@@ -234,7 +234,7 @@ fn visit_node(&mut self, node: &ast_map::Node) {
             ast_map::NodeImplItem(impl_item) => {
                 match *impl_item {
                     ast::MethodImplItem(ref method) => {
-                        visit::walk_block(self, method.pe_body());
+                        visit::walk_method_helper(self, method);
                     }
                     ast::TypeImplItem(_) => {}
                 }
diff --git a/src/test/run-pass/issue-20343.rs b/src/test/run-pass/issue-20343.rs
new file mode 100644
index 00000000000..79034a4a4a6
--- /dev/null
+++ b/src/test/run-pass/issue-20343.rs
@@ -0,0 +1,38 @@
+// Copyright 2015 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.
+
+// Regression test for Issue #20343.
+
+#![deny(dead_code)]
+
+struct B { b: u32 }
+struct C;
+struct D;
+
+trait T<A> {}
+impl<A> T<A> for () {}
+
+impl B {
+    // test for unused code in arguments
+    fn foo(B { b }: B) -> u32 { b }
+
+    // test for unused code in return type
+    fn bar() -> C { unsafe { ::std::mem::transmute(()) } }
+
+    // test for unused code in generics
+    fn baz<A: T<D>>() {}
+}
+
+pub fn main() {
+    let b = B { b: 3 };
+    B::foo(b);
+    B::bar();
+    B::baz::<()>();
+}