From b3011dd711ea8bf4bcb04d96aff814863eff3973 Mon Sep 17 00:00:00 2001
From: varkor <github@varkor.com>
Date: Thu, 28 Mar 2019 01:45:50 +0000
Subject: [PATCH 1/3] Visit ItemKind::Impl for dead code lint

---
 src/librustc/middle/dead.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/librustc/middle/dead.rs b/src/librustc/middle/dead.rs
index f12367a89bb..cd1fa8763c3 100644
--- a/src/librustc/middle/dead.rs
+++ b/src/librustc/middle/dead.rs
@@ -172,6 +172,7 @@ impl<'a, 'tcx> MarkSymbolVisitor<'a, 'tcx> {
                     | hir::ItemKind::Ty(..)
                     | hir::ItemKind::Static(..)
                     | hir::ItemKind::Existential(..)
+                    | hir::ItemKind::Impl(..)
                     | hir::ItemKind::Const(..) => {
                         intravisit::walk_item(self, &item);
                     }

From 40db5756b435d2e67a834475833f4752486672e0 Mon Sep 17 00:00:00 2001
From: varkor <github@varkor.com>
Date: Thu, 28 Mar 2019 01:47:39 +0000
Subject: [PATCH 2/3] Add a regression test for #47131

---
 src/test/ui/dead-code-impl.rs | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)
 create mode 100644 src/test/ui/dead-code-impl.rs

diff --git a/src/test/ui/dead-code-impl.rs b/src/test/ui/dead-code-impl.rs
new file mode 100644
index 00000000000..84829c98e57
--- /dev/null
+++ b/src/test/ui/dead-code-impl.rs
@@ -0,0 +1,17 @@
+// run-pass
+
+#![deny(dead_code)]
+
+pub struct GenericFoo<T>(T);
+
+type Foo = GenericFoo<u32>;
+
+impl Foo {
+    fn bar(self) -> u8 {
+        0
+    }
+}
+
+fn main() {
+    println!("{}", GenericFoo(0).bar());
+}

From 8cdfad91539dea8c9ec7d22c08f40e42e25e6ff0 Mon Sep 17 00:00:00 2001
From: varkor <github@varkor.com>
Date: Thu, 28 Mar 2019 23:33:17 +0000
Subject: [PATCH 3/3] Walk all items for dead_code lint by default

---
 src/librustc/middle/dead.rs | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/src/librustc/middle/dead.rs b/src/librustc/middle/dead.rs
index cd1fa8763c3..dd080d9ee26 100644
--- a/src/librustc/middle/dead.rs
+++ b/src/librustc/middle/dead.rs
@@ -73,7 +73,7 @@ impl<'a, 'tcx> MarkSymbolVisitor<'a, 'tcx> {
             Def::Const(_) | Def::AssociatedConst(..) | Def::TyAlias(_) => {
                 self.check_def_id(def.def_id());
             }
-            _ if self.in_pat => (),
+            _ if self.in_pat => {},
             Def::PrimTy(..) | Def::SelfTy(..) | Def::SelfCtor(..) |
             Def::Local(..) | Def::Upvar(..) => {}
             Def::Ctor(ctor_def_id, CtorOf::Variant, ..) => {
@@ -91,6 +91,7 @@ impl<'a, 'tcx> MarkSymbolVisitor<'a, 'tcx> {
                     self.check_def_id(variant_id);
                 }
             }
+            Def::ToolMod | Def::NonMacroAttr(..) | Def::Err => {}
             _ => {
                 self.check_def_id(def.def_id());
             }
@@ -166,17 +167,13 @@ impl<'a, 'tcx> MarkSymbolVisitor<'a, 'tcx> {
                     }
                     hir::ItemKind::Enum(..) => {
                         self.inherited_pub_visibility = item.vis.node.is_pub();
+
                         intravisit::walk_item(self, &item);
                     }
-                    hir::ItemKind::Fn(..)
-                    | hir::ItemKind::Ty(..)
-                    | hir::ItemKind::Static(..)
-                    | hir::ItemKind::Existential(..)
-                    | hir::ItemKind::Impl(..)
-                    | hir::ItemKind::Const(..) => {
+                    hir::ItemKind::ForeignMod(..) => {}
+                    _ => {
                         intravisit::walk_item(self, &item);
                     }
-                    _ => ()
                 }
             }
             Node::TraitItem(trait_item) => {
@@ -188,7 +185,7 @@ impl<'a, 'tcx> MarkSymbolVisitor<'a, 'tcx> {
             Node::ForeignItem(foreign_item) => {
                 intravisit::walk_foreign_item(self, &foreign_item);
             }
-            _ => ()
+            _ => {}
         }
         self.repr_has_repr_c = had_repr_c;
         self.inherited_pub_visibility = had_inherited_pub_visibility;