Auto merge of #38051 - sanxiyn:unused-type-alias-3, r=eddyb

 Warn unused type aliases, reimplemented

Reimplementation of #37631. Fix #37455.

Author: bors

src/librustc/middle/dead.rs

@@ -86,20 +86,7 @@ impl<'a, 'tcx> MarkSymbolVisitor<'a, 'tcx> {
         }
     }
 
-    fn handle_definition(&mut self, id: ast::NodeId, def: Def) {
-        // If `bar` is a trait item, make sure to mark Foo as alive in `Foo::bar`
-        match def {
-            Def::AssociatedTy(..) | Def::Method(_) | Def::AssociatedConst(_)
-            if self.tcx.trait_of_item(def.def_id()).is_some() => {
-                if let Some(substs) = self.tcx.tables().item_substs.get(&id) {
-                    if let ty::TyAdt(tyid, _) = substs.substs.type_at(0).sty {
-                        self.check_def_id(tyid.did);
-                    }
-                }
-            }
-            _ => {}
-        }
-
+    fn handle_definition(&mut self, def: Def) {
         match def {
             Def::Const(_) | Def::AssociatedConst(..) => {
                 self.check_def_id(def.def_id());
@@ -241,7 +228,7 @@ impl<'a, 'tcx> Visitor<'tcx> for MarkSymbolVisitor<'a, 'tcx> {
         match expr.node {
             hir::ExprPath(ref qpath @ hir::QPath::TypeRelative(..)) => {
                 let def = self.tcx.tables().qpath_def(qpath, expr.id);
-                self.handle_definition(expr.id, def);
+                self.handle_definition(def);
             }
             hir::ExprMethodCall(..) => {
                 self.lookup_and_handle_method(expr.id);
@@ -281,7 +268,7 @@ impl<'a, 'tcx> Visitor<'tcx> for MarkSymbolVisitor<'a, 'tcx> {
             }
             PatKind::Path(ref qpath @ hir::QPath::TypeRelative(..)) => {
                 let def = self.tcx.tables().qpath_def(qpath, pat.id);
-                self.handle_definition(pat.id, def);
+                self.handle_definition(def);
             }
             _ => ()
         }
@@ -291,8 +278,8 @@ impl<'a, 'tcx> Visitor<'tcx> for MarkSymbolVisitor<'a, 'tcx> {
         self.ignore_non_const_paths = false;
     }
 
-    fn visit_path(&mut self, path: &'tcx hir::Path, id: ast::NodeId) {
-        self.handle_definition(id, path.def);
+    fn visit_path(&mut self, path: &'tcx hir::Path, _: ast::NodeId) {
+        self.handle_definition(path.def);
         intravisit::walk_path(self, path);
     }
 }
@@ -426,6 +413,7 @@ impl<'a, 'tcx> DeadVisitor<'a, 'tcx> {
             hir::ItemStatic(..)
             | hir::ItemConst(..)
             | hir::ItemFn(..)
+            | hir::ItemTy(..)
             | hir::ItemEnum(..)
             | hir::ItemStruct(..)
             | hir::ItemUnion(..) => true,

src/librustc_data_structures/graph/tests.rs

@@ -11,8 +11,6 @@
 use graph::*;
 use std::fmt::Debug;
 
-type TestNode = Node<&'static str>;
-type TestEdge = Edge<&'static str>;
 type TestGraph = Graph<&'static str, &'static str>;
 
 fn create_graph() -> TestGraph {

src/librustc_trans/back/msvc/registry.rs

@@ -12,7 +12,7 @@ use std::io;
 use std::ffi::{OsString, OsStr};
 use std::os::windows::prelude::*;
 use std::ptr;
-use libc::{c_void, c_long};
+use libc::c_long;
 
 pub type DWORD = u32;
 type LPCWSTR = *const u16;
@@ -38,8 +38,6 @@ pub enum __HKEY__ {}
 pub type HKEY = *mut __HKEY__;
 pub type PHKEY = *mut HKEY;
 pub type REGSAM = DWORD;
-pub type LPWSTR = *mut u16;
-pub type PFILETIME = *mut c_void;
 
 #[link(name = "advapi32")]
 extern "system" {

src/libstd/sys/windows/c.rs

@@ -47,7 +47,9 @@ pub type CHAR = c_char;
 pub type HCRYPTPROV = LONG_PTR;
 pub type ULONG_PTR = c_ulonglong;
 pub type ULONG = c_ulong;
+#[cfg(target_arch = "x86_64")]
 pub type ULONGLONG = u64;
+#[cfg(target_arch = "x86_64")]
 pub type DWORDLONG = ULONGLONG;
 
 pub type LPBOOL = *mut BOOL;
@@ -66,7 +68,6 @@ pub type LPVOID = *mut c_void;
 pub type LPWCH = *mut WCHAR;
 pub type LPWIN32_FIND_DATAW = *mut WIN32_FIND_DATAW;
 pub type LPWSADATA = *mut WSADATA;
-pub type LPWSAPROTOCOLCHAIN = *mut WSAPROTOCOLCHAIN;
 pub type LPWSAPROTOCOL_INFO = *mut WSAPROTOCOL_INFO;
 pub type LPWSTR = *mut WCHAR;
 pub type LPFILETIME = *mut FILETIME;
@@ -311,8 +312,6 @@ pub struct WSADATA {
     pub szSystemStatus: [u8; WSASYS_STATUS_LEN + 1],
 }
 
-pub type WSAEVENT = HANDLE;
-
 #[repr(C)]
 pub struct WSAPROTOCOL_INFO {
     pub dwServiceFlags1: DWORD,

src/test/compile-fail/issue-32119.rs

@@ -9,6 +9,7 @@
 // except according to those terms.
 
 #![feature(rustc_attrs)]
+#![allow(dead_code)]
 
 pub type T = ();
 mod foo { pub use super::T; }

src/test/compile-fail/lint-dead-code-type-alias.rs

@@ -0,0 +1,20 @@
+// Copyright 2016 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.
+
+#![deny(dead_code)]
+
+type Used = u8;
+type Unused = u8; //~ ERROR type alias is never used
+
+fn id(x: Used) -> Used { x }
+
+fn main() {
+    id(0);
+}

src/test/compile-fail/macro-tt-matchers.rs

@@ -9,6 +9,7 @@
 // except according to those terms.
 
 #![feature(rustc_attrs)]
+#![allow(dead_code)]
 
 macro_rules! foo {
     ($x:tt) => (type Alias = $x<i32>;)

src/tools/cargotest/main.rs

@@ -24,7 +24,7 @@ struct Test {
 const TEST_REPOS: &'static [Test] = &[Test {
                                           name: "cargo",
                                           repo: "https://github.com/rust-lang/cargo",
-                                          sha: "806e3c368a15f618244a3b4e918bf77f9c403fd0",
+                                          sha: "b7be4f2ef2cf743492edc6dfb55d087ed88f2d76",
                                           lock: None,
                                       },
                                       Test {