Use ItemId as a strongly typed index.

clippy_lints/src/lifetimes.rs

@@ -375,7 +375,7 @@ fn visit_ty(&mut self, ty: &'tcx Ty<'_>) {
         match ty.kind {
             TyKind::OpaqueDef(item, _) => {
                 let map = self.cx.tcx.hir();
-                let item = map.expect_item(item.id);
+                let item = map.item(item);
                 walk_item(self, item);
                 walk_ty(self, ty);
             },

clippy_lints/src/manual_async_fn.rs

@@ -102,7 +102,7 @@ fn future_trait_ref<'tcx>(
 ) -> Option<(&'tcx TraitRef<'tcx>, Vec<LifetimeName>)> {
     if_chain! {
         if let TyKind::OpaqueDef(item_id, bounds) = ty.kind;
-        let item = cx.tcx.hir().item(item_id.id);
+        let item = cx.tcx.hir().item(item_id);
         if let ItemKind::OpaqueTy(opaque) = &item.kind;
         if let Some(trait_ref) = opaque.bounds.iter().find_map(|bound| {
             if let GenericBound::Trait(poly, _) = bound {

clippy_lints/src/missing_inline.rs

@@ -107,7 +107,7 @@ fn check_item(&mut self, cx: &LateContext<'tcx>, it: &'tcx hir::Item<'_>) {
                                 // trait method with default body needs inline in case
                                 // an impl is not provided
                                 let desc = "a default trait method";
-                                let item = cx.tcx.hir().expect_trait_item(tit.id.hir_id);
+                                let item = cx.tcx.hir().trait_item(tit.id);
                                 check_missing_inline_attrs(cx, &item.attrs, item.span, desc);
                             }
                         },

clippy_lints/src/utils/author.rs

@@ -130,7 +130,7 @@ fn check_arm(&mut self, cx: &LateContext<'tcx>, arm: &'tcx hir::Arm<'_>) {
     }
 
     fn check_stmt(&mut self, cx: &LateContext<'tcx>, stmt: &'tcx hir::Stmt<'_>) {
-        if !has_attr(cx.sess(), stmt.kind.attrs(|id| cx.tcx.hir().item(id.id))) {
+        if !has_attr(cx.sess(), stmt.kind.attrs(|id| cx.tcx.hir().item(id))) {
             return;
         }
         prelude();

clippy_lints/src/utils/inspector.rs

@@ -109,7 +109,7 @@ fn check_arm(&mut self, cx: &LateContext<'tcx>, arm: &'tcx hir::Arm<'_>) {
     }
 
     fn check_stmt(&mut self, cx: &LateContext<'tcx>, stmt: &'tcx hir::Stmt<'_>) {
-        if !has_attr(cx.sess(), stmt.kind.attrs(|id| cx.tcx.hir().item(id.id))) {
+        if !has_attr(cx.sess(), stmt.kind.attrs(|id| cx.tcx.hir().item(id))) {
             return;
         }
         match stmt.kind {