Review comments

- Fix typo
- Add docstring
- Remove spurious test output file

src/librustc/hir/map/mod.rs

@@ -632,6 +632,28 @@ impl<'hir> Map<'hir> {
         }
     }
 
+    /// Retrieve the NodeId for `id`'s enclosing method, unless there's a
+    /// `while` or `loop` before reacing it, as block tail returns are not
+    /// available in them.
+    ///
+    /// ```
+    /// fn foo(x: usize) -> bool {
+    ///     if x == 1 {
+    ///         true  // `get_return_block` gets passed the `id` corresponding
+    ///     } else {  // to this, it will return `foo`'s `NodeId`.
+    ///         false
+    ///     }
+    /// }
+    /// ```
+    ///
+    /// ```
+    /// fn foo(x: usize) -> bool {
+    ///     loop {
+    ///         true  // `get_return_block` gets passed the `id` corresponding
+    ///     }         // to this, it will return `None`.
+    ///     false
+    /// }
+    /// ```
     pub fn get_return_block(&self, id: NodeId) -> Option<NodeId> {
         let match_fn = |node: &Node| {
             match *node {

src/librustc_typeck/check/mod.rs

@@ -4214,7 +4214,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
         ty
     }
 
-    /// Given a `NodeId`, return the `FnDecl` of the method it is enclosed by and wether it is
+    /// Given a `NodeId`, return the `FnDecl` of the method it is enclosed by and whether it is
     /// `fn main` if it is a method, `None` otherwise.
     pub fn get_fn_decl(&self, blk_id: ast::NodeId) -> Option<(hir::FnDecl, bool)> {
         // Get enclosing Fn, if it is a function or a trait method, unless there's a `loop` or
@@ -4227,7 +4227,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
             }) = parent {
                 decl.clone().and_then(|decl| {
                     // This is less than ideal, it will not present the return type span on any
-                    // method called `main`, regardless of wether it is actually the entry point.
+                    // method called `main`, regardless of whether it is actually the entry point.
                     Some((decl, name == Symbol::intern("main")))
                 })
             } else if let Node::NodeTraitItem(&hir::TraitItem {