Review changes

Author: WaffleLapkin

compiler/rustc_lint/src/builtin.rs

@@ -581,7 +581,7 @@ impl<'tcx> LateLintPass<'tcx> for MissingDoc {
 
     fn check_impl_item(&mut self, cx: &LateContext<'_>, impl_item: &hir::ImplItem<'_>) {
         let context = method_context(cx, impl_item.owner_id.def_id);
-        
+
         match context {
             // If the method is an impl for a trait, don't doc.
             MethodLateContext::TraitImpl => return,

compiler/rustc_middle/src/mir/mod.rs

@@ -416,7 +416,7 @@ impl<'tcx> Body<'tcx> {
         (self.arg_count + 1..self.local_decls.len()).filter_map(move |index| {
             let local = Local::new(index);
             let decl = &self.local_decls[local];
-            if decl.is_user_variable() && decl.mutability.is_mut() { Some(local) } else { None }
+            (decl.is_user_variable() && decl.mutability.is_mut()).then(|| local)
         })
     }
 

compiler/rustc_middle/src/mir/pretty.rs

@@ -580,7 +580,7 @@ fn write_scope_tree(
             continue;
         }
 
-        let mut_str = if local_decl.mutability.is_mut() { "mut " } else { "" };
+        let mut_str = local_decl.mutability.prefix_str();
 
         let mut indented_decl =
             format!("{0:1$}let {2}{3:?}: {4:?}", INDENT, indent, mut_str, local, local_decl.ty);

compiler/rustc_save_analysis/src/sig.rs

@@ -768,9 +768,8 @@ impl<'hir> Sig for hir::ForeignItem<'hir> {
             }
             hir::ForeignItemKind::Static(ref ty, m) => {
                 let mut text = "static ".to_owned();
-                if m.is_mut() {
-                    text.push_str("mut ");
-                }
+                text.push_str(m.prefix_str());
+
                 let name = self.ident.to_string();
                 let defs = vec![SigElement {
                     id: id_from_def_id(self.owner_id.to_def_id()),