Update docs and format code

Author: JohnTitor

README.md

@@ -27,13 +27,13 @@ repository and compiled from source or installed from
 of the nightly toolchain is supported at any given time.
 
 <!-- NOTE: Keep in sync with nightly date on rust-toolchain. -->
-It's recommended to use `nightly-2021-11-30` toolchain.
-You can install it by using `rustup install nightly-2021-11-30` if you already have rustup.
+It's recommended to use `nightly-2021-12-31` toolchain.
+You can install it by using `rustup install nightly-2021-12-31` if you already have rustup.
 Then you can do:
 
 ```sh
-$ rustup component add rustc-dev llvm-tools-preview --toolchain nightly-2021-11-30
-$ cargo +nightly-2021-11-30 install --git https://github.com/rust-lang/rust-semverver
+$ rustup component add rustc-dev llvm-tools-preview --toolchain nightly-2021-12-31
+$ cargo +nightly-2021-12-31 install --git https://github.com/rust-lang/rust-semverver
 ```
 
 You'd also need `cmake` for some dependencies, and a few common libraries (if you hit

src/mismatch.rs

@@ -198,12 +198,7 @@ impl<'a, 'tcx> TypeRelation<'tcx> for MismatchRelation<'a, 'tcx> {
                 None
             }
             (&TyKind::RawPtr(a_mt), &TyKind::RawPtr(b_mt)) => {
-                let _ = ty::relate::relate_type_and_mut(
-                    self,
-                    a_mt,
-                    b_mt,
-                    a,
-                )?;
+                let _ = ty::relate::relate_type_and_mut(self, a_mt, b_mt, a)?;
                 None
             }
             (&TyKind::Ref(a_r, a_ty, _), &TyKind::Ref(b_r, b_ty, _)) => {

src/translate.rs

@@ -166,7 +166,7 @@ impl<'a, 'tcx> TranslationContext<'a, 'tcx> {
         use rustc_middle::ty::TypeAndMut;
         use rustc_middle::ty::{AdtDef, Binder, ExistentialProjection, ExistentialTraitRef};
 
-        let result = orig.fold_with(&mut BottomUpFolder {
+        orig.fold_with(&mut BottomUpFolder {
             tcx: self.tcx,
             ty_op: |ty| {
                 match *ty.kind() {
@@ -327,8 +327,7 @@ impl<'a, 'tcx> TranslationContext<'a, 'tcx> {
             },
             lt_op: |region| self.translate_region(region),
             ct_op: |konst| konst, // TODO: translate consts
-        });
-        result
+        })
     }
 
     /// Translate a region.

src/traverse.rs

@@ -85,7 +85,7 @@ pub fn run_traversal(tcx: TyCtxt, new: DefId) {
 
     // Pull a module from the queue, with its global visibility.
     while let Some((new_def_id, idents, new_vis)) = mod_queue.pop_front() {
-        for item in tcx.item_children(new_def_id).to_vec() {
+        for item in tcx.item_children(new_def_id).iter().copied() {
             let n_vis = get_vis(new_vis, item);
             match item.res {
                 Def(Mod, n_def_id) => {