Rollup merge of #58562 - dlrobertson:fix_nits, r=alexreg

Fix style nits

Fix style nits discovered in reading code.

r? @alexreg

src/librustc/cfg/construct.rs

@@ -150,9 +150,11 @@ impl<'a, 'tcx> CFGBuilder<'a, 'tcx> {
         }
     }
 
-    fn pats_all<'b, I: Iterator<Item=&'b P<hir::Pat>>>(&mut self,
-                                          pats: I,
-                                          pred: CFGIndex) -> CFGIndex {
+    fn pats_all<'b, I: Iterator<Item=&'b P<hir::Pat>>>(
+        &mut self,
+        pats: I,
+        pred: CFGIndex
+    ) -> CFGIndex {
         //! Handles case where all of the patterns must match.
         pats.fold(pred, |pred, pat| self.pat(&pat, pred))
     }

src/librustc/hir/mod.rs

@@ -964,14 +964,19 @@ pub enum PatKind {
     /// If the `..` pattern fragment is present, then `Option<usize>` denotes its position.
     /// `0 <= position <= subpats.len()`
     Tuple(HirVec<P<Pat>>, Option<usize>),
+
     /// A `box` pattern.
     Box(P<Pat>),
+
     /// A reference pattern (e.g., `&mut (a, b)`).
     Ref(P<Pat>, Mutability),
+
     /// A literal.
     Lit(P<Expr>),
+
     /// A range pattern (e.g., `1...2` or `1..2`).
     Range(P<Expr>, P<Expr>, RangeEnd),
+
     /// `[a, b, ..i, y, z]` is represented as:
     ///     `PatKind::Slice(box [a, b], Some(i), box [y, z])`.
     Slice(HirVec<P<Pat>>, Option<P<Pat>>, HirVec<P<Pat>>),

src/librustc/middle/mem_categorization.rs

@@ -1311,12 +1311,12 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
                     Def::Err => {
                         debug!("access to unresolvable pattern {:?}", pat);
                         return Err(())
-                    },
+                    }
                     Def::Variant(variant_did) |
                     Def::VariantCtor(variant_did, ..) => {
                         self.cat_downcast_if_needed(pat, cmt, variant_did)
-                    },
-                    _ => cmt
+                    }
+                    _ => cmt,
                 };
 
                 for fp in field_pats {
@@ -1347,7 +1347,7 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
                 }
             }
 
-                PatKind::Box(ref subpat) | PatKind::Ref(ref subpat, _) => {
+            PatKind::Box(ref subpat) | PatKind::Ref(ref subpat, _) => {
                 // box p1, &p1, &mut p1.  we can ignore the mutability of
                 // PatKind::Ref since that information is already contained
                 // in the type.

src/librustc/ty/sty.rs

@@ -1167,13 +1167,13 @@ pub type Region<'tcx> = &'tcx RegionKind;
 /// [rustc guide]: https://rust-lang.github.io/rustc-guide/traits/hrtb.html
 #[derive(Clone, PartialEq, Eq, Hash, Copy, RustcEncodable, RustcDecodable, PartialOrd, Ord)]
 pub enum RegionKind {
-    // Region bound in a type or fn declaration which will be
-    // substituted 'early' -- that is, at the same time when type
-    // parameters are substituted.
+    /// Region bound in a type or fn declaration which will be
+    /// substituted 'early' -- that is, at the same time when type
+    /// parameters are substituted.
     ReEarlyBound(EarlyBoundRegion),
 
-    // Region bound in a function scope, which will be substituted when the
-    // function is called.
+    /// Region bound in a function scope, which will be substituted when the
+    /// function is called.
     ReLateBound(DebruijnIndex, BoundRegion),
 
     /// When checking a function body, the types of all arguments and so forth

src/librustc_codegen_llvm/intrinsic.rs

@@ -192,8 +192,7 @@ impl IntrinsicCallMethods<'tcx> for Builder<'a, 'll, 'tcx> {
             "size_of_val" => {
                 let tp_ty = substs.type_at(0);
                 if let OperandValue::Pair(_, meta) = args[0].val {
-                    let (llsize, _) =
-                        glue::size_and_align_of_dst(self, tp_ty, Some(meta));
+                    let (llsize, _) = glue::size_and_align_of_dst(self, tp_ty, Some(meta));
                     llsize
                 } else {
                     self.const_usize(self.size_of(tp_ty).bytes())
@@ -206,8 +205,7 @@ impl IntrinsicCallMethods<'tcx> for Builder<'a, 'll, 'tcx> {
             "min_align_of_val" => {
                 let tp_ty = substs.type_at(0);
                 if let OperandValue::Pair(_, meta) = args[0].val {
-                    let (_, llalign) =
-                        glue::size_and_align_of_dst(self, tp_ty, Some(meta));
+                    let (_, llalign) = glue::size_and_align_of_dst(self, tp_ty, Some(meta));
                     llalign
                 } else {
                     self.const_usize(self.align_of(tp_ty).bytes())

src/librustc_codegen_llvm/type_.rs

@@ -82,7 +82,6 @@ impl BaseTypeMethods<'tcx> for CodegenCx<'ll, 'tcx> {
 
     fn type_i16(&self) -> &'ll Type {
         unsafe {
-
             llvm::LLVMInt16TypeInContext(self.llcx)
         }
     }

src/librustc_mir/build/matches/mod.rs

@@ -338,6 +338,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                 self.schedule_drop_for_binding(var, irrefutable_pat.span, OutsideGuard);
                 block.unit()
             }
+
             _ => {
                 let place = unpack!(block = self.as_place(block, initializer));
                 self.place_into_pattern(block, irrefutable_pat, &place, true)
@@ -534,6 +535,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                     self.visit_bindings(subpattern, pattern_user_ty, f);
                 }
             }
+
             PatternKind::Array {
                 ref prefix,
                 ref slice,
@@ -556,10 +558,13 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                     self.visit_bindings(subpattern, pattern_user_ty.clone().index(), f);
                 }
             }
+
             PatternKind::Constant { .. } | PatternKind::Range { .. } | PatternKind::Wild => {}
+
             PatternKind::Deref { ref subpattern } => {
                 self.visit_bindings(subpattern, pattern_user_ty.deref(), f);
             }
+
             PatternKind::AscribeUserType {
                 ref subpattern,
                 ascription: hair::pattern::Ascription {

src/librustc_mir/build/matches/simplify.rs

@@ -45,10 +45,10 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
         }
     }
 
-    /// Tries to simplify `match_pair`, returning true if
+    /// Tries to simplify `match_pair`, returning `Ok(())` if
     /// successful. If successful, new match pairs and bindings will
     /// have been pushed into the candidate. If no simplification is
-    /// possible, Err is returned and no changes are made to
+    /// possible, `Err` is returned and no changes are made to
     /// candidate.
     fn simplify_match_pair<'pat>(&mut self,
                                  match_pair: MatchPair<'pat, 'tcx>,
@@ -174,7 +174,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                 } else {
                     Err(match_pair)
                 }
-            },
+            }
 
             PatternKind::Array { ref prefix, ref slice, ref suffix } => {
                 self.prefix_slice_suffix(&mut candidate.match_pairs,

src/librustc_mir/build/matches/test.rs

@@ -35,10 +35,9 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                 }
             }
 
-            PatternKind::Constant { .. }
-            if is_switch_ty(match_pair.pattern.ty) => {
-                // for integers, we use a SwitchInt match, which allows
-                // us to handle more cases
+            PatternKind::Constant { .. } if is_switch_ty(match_pair.pattern.ty) => {
+                // For integers, we use a `SwitchInt` match, which allows
+                // us to handle more cases.
                 Test {
                     span: match_pair.pattern.span,
                     kind: TestKind::SwitchInt {
@@ -253,12 +252,12 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
             TestKind::Eq { value, mut ty } => {
                 let val = Operand::Copy(place.clone());
                 let mut expect = self.literal_operand(test.span, ty, value);
-                // Use PartialEq::eq instead of BinOp::Eq
+                // Use `PartialEq::eq` instead of `BinOp::Eq`
                 // (the binop can only handle primitives)
                 let fail = self.cfg.start_new_block();
                 if !ty.is_scalar() {
-                    // If we're using b"..." as a pattern, we need to insert an
-                    // unsizing coercion, as the byte string has the type &[u8; N].
+                    // If we're using `b"..."` as a pattern, we need to insert an
+                    // unsizing coercion, as the byte string has the type `&[u8; N]`.
                     //
                     // We want to do this even when the scrutinee is a reference to an
                     // array, so we can call `<[u8]>::eq` rather than having to find an
@@ -503,6 +502,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                 resulting_candidates[variant_index.as_usize()].push(new_candidate);
                 true
             }
+
             (&TestKind::Switch { .. }, _) => false,
 
             // If we are performing a switch over integers, then this informs integer
@@ -539,7 +539,6 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
 
             (&TestKind::SwitchInt { .. }, _) => false,
 
-
             (&TestKind::Len { len: test_len, op: BinOp::Eq },
              &PatternKind::Slice { ref prefix, ref slice, ref suffix }) => {
                 let pat_len = (prefix.len() + suffix.len()) as u64;

src/librustc_mir/build/matches/util.rs

@@ -13,7 +13,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
         subpatterns.iter()
                    .map(|fieldpat| {
                        let place = place.clone().field(fieldpat.field,
-                                                         fieldpat.pattern.ty);
+                                                       fieldpat.pattern.ty);
                        MatchPair::new(place, &fieldpat.pattern)
                    })
                    .collect()

src/librustc_mir/hair/pattern/_match.rs

@@ -634,8 +634,8 @@ impl<'tcx> Witness<'tcx> {
 /// but is instead bounded by the maximum fixed length of slice patterns in
 /// the column of patterns being analyzed.
 ///
-/// We make sure to omit constructors that are statically impossible. eg for
-/// Option<!> we do not include Some(_) in the returned list of constructors.
+/// We make sure to omit constructors that are statically impossible. E.g., for
+/// `Option<!>`, we do not include `Some(_)` in the returned list of constructors.
 fn all_constructors<'a, 'tcx: 'a>(cx: &mut MatchCheckCtxt<'a, 'tcx>,
                                   pcx: PatternContext<'tcx>)
                                   -> Vec<Constructor<'tcx>>
@@ -1347,7 +1347,7 @@ fn pat_constructors<'tcx>(cx: &mut MatchCheckCtxt<'_, 'tcx>,
 /// This computes the arity of a constructor. The arity of a constructor
 /// is how many subpattern patterns of that constructor should be expanded to.
 ///
-/// For instance, a tuple pattern (_, 42, Some([])) has the arity of 3.
+/// For instance, a tuple pattern `(_, 42, Some([]))` has the arity of 3.
 /// A struct pattern's arity is the number of fields it contains, etc.
 fn constructor_arity(cx: &MatchCheckCtxt<'a, 'tcx>, ctor: &Constructor<'tcx>, ty: Ty<'tcx>) -> u64 {
     debug!("constructor_arity({:#?}, {:?})", ctor, ty);
@@ -1357,7 +1357,7 @@ fn constructor_arity(cx: &MatchCheckCtxt<'a, 'tcx>, ctor: &Constructor<'tcx>, ty
             Slice(length) => length,
             ConstantValue(_) => 0,
             _ => bug!("bad slice pattern {:?} {:?}", ctor, ty)
-        },
+        }
         ty::Ref(..) => 1,
         ty::Adt(adt, _) => {
             adt.variants[ctor.variant_index_for_adt(cx, adt)].fields.len() as u64
@@ -1381,7 +1381,7 @@ fn constructor_sub_pattern_tys<'a, 'tcx: 'a>(cx: &MatchCheckCtxt<'a, 'tcx>,
             Slice(length) => (0..length).map(|_| ty).collect(),
             ConstantValue(_) => vec![],
             _ => bug!("bad slice pattern {:?} {:?}", ctor, ty)
-        },
+        }
         ty::Ref(_, rty, _) => vec![rty],
         ty::Adt(adt, substs) => {
             if adt.is_box() {

src/librustc_mir/hair/pattern/check_match.rs

@@ -375,7 +375,7 @@ fn check_arms<'a, 'tcx>(cx: &mut MatchCheckCtxt<'a, 'tcx>,
                                 },
                                 _ => bug!(),
                             }
-                        },
+                        }
 
                         hir::MatchSource::ForLoopDesugar |
                         hir::MatchSource::Normal => {
@@ -391,7 +391,7 @@ fn check_arms<'a, 'tcx>(cx: &mut MatchCheckCtxt<'a, 'tcx>,
                                 err.span_label(catchall, "matches any value");
                             }
                             err.emit();
-                        },
+                        }
 
                         // Unreachable patterns in try expressions occur when one of the arms
                         // are an uninhabited type. Which is OK.
@@ -436,7 +436,7 @@ fn check_exhaustive<'p, 'a: 'p, 'tcx: 'a>(cx: &mut MatchCheckCtxt<'a, 'tcx>,
                     let (tail, head) = witnesses.split_last().unwrap();
                     let head: Vec<_> = head.iter().map(|w| w.to_string()).collect();
                     format!("`{}` and `{}`", head.join("`, `"), tail)
-                },
+                }
                 _ => {
                     let (head, tail) = witnesses.split_at(LIMIT);
                     let head: Vec<_> = head.iter().map(|w| w.to_string()).collect();
@@ -446,7 +446,7 @@ fn check_exhaustive<'p, 'a: 'p, 'tcx: 'a>(cx: &mut MatchCheckCtxt<'a, 'tcx>,
 
             let label_text = match witnesses.len() {
                 1 => format!("pattern {} not covered", joined_patterns),
-                _ => format!("patterns {} not covered", joined_patterns)
+                _ => format!("patterns {} not covered", joined_patterns),
             };
             create_e0004(cx.tcx.sess, sp,
                             format!("non-exhaustive patterns: {} not covered",
@@ -456,7 +456,7 @@ fn check_exhaustive<'p, 'a: 'p, 'tcx: 'a>(cx: &mut MatchCheckCtxt<'a, 'tcx>,
         }
         NotUseful => {
             // This is good, wildcard pattern isn't reachable
-        },
+        }
         _ => bug!()
     }
 }

src/librustc_mir/hair/pattern/mod.rs

@@ -965,7 +965,7 @@ impl<'a, 'tcx> PatternContext<'a, 'tcx> {
                 PatternKind::Constant {
                     value: cv,
                 }
-            },
+            }
             ty::Adt(adt_def, _) if adt_def.is_union() => {
                 // Matching on union fields is unsafe, we can't hide it in constants
                 self.tcx.sess.span_err(span, "cannot use unions in constant patterns");
@@ -978,7 +978,7 @@ impl<'a, 'tcx> PatternContext<'a, 'tcx> {
                                     self.tcx.item_path_str(adt_def.did));
                 self.tcx.sess.span_err(span, &msg);
                 PatternKind::Wild
-            },
+            }
             ty::Adt(adt_def, substs) if adt_def.is_enum() => {
                 let variant_index = const_variant_index(
                     self.tcx, self.param_env, cv
@@ -993,7 +993,7 @@ impl<'a, 'tcx> PatternContext<'a, 'tcx> {
                     variant_index,
                     subpatterns,
                 }
-            },
+            }
             ty::Adt(adt_def, _) => {
                 let struct_var = adt_def.non_enum_variant();
                 PatternKind::Leaf {
@@ -1018,7 +1018,7 @@ impl<'a, 'tcx> PatternContext<'a, 'tcx> {
                 PatternKind::Constant {
                     value: cv,
                 }
-            },
+            }
         };
 
         Pattern {
@@ -1252,19 +1252,19 @@ pub fn compare_const_vals<'a, 'gcx, 'tcx>(
                 let l = ::rustc_apfloat::ieee::Single::from_bits(a);
                 let r = ::rustc_apfloat::ieee::Single::from_bits(b);
                 l.partial_cmp(&r)
-            },
+            }
             ty::Float(ast::FloatTy::F64) => {
                 let l = ::rustc_apfloat::ieee::Double::from_bits(a);
                 let r = ::rustc_apfloat::ieee::Double::from_bits(b);
                 l.partial_cmp(&r)
-            },
+            }
             ty::Int(_) => {
                 let layout = tcx.layout_of(ty).ok()?;
                 assert!(layout.abi.is_signed());
                 let a = sign_extend(a, layout.size);
                 let b = sign_extend(b, layout.size);
                 Some((a as i128).cmp(&(b as i128)))
-            },
+            }
             _ => Some(a.cmp(&b)),
         }
     }

src/libsyntax/ast.rs

@@ -640,19 +640,26 @@ pub enum PatKind {
     /// If the `..` pattern fragment is present, then `Option<usize>` denotes its position.
     /// `0 <= position <= subpats.len()`.
     Tuple(Vec<P<Pat>>, Option<usize>),
+
     /// A `box` pattern.
     Box(P<Pat>),
+
     /// A reference pattern (e.g., `&mut (a, b)`).
     Ref(P<Pat>, Mutability),
+
     /// A literal.
     Lit(P<Expr>),
+
     /// A range pattern (e.g., `1...2`, `1..=2` or `1..2`).
     Range(P<Expr>, P<Expr>, Spanned<RangeEnd>),
+
     /// `[a, b, ..i, y, z]` is represented as:
     ///     `PatKind::Slice(box [a, b], Some(i), box [y, z])`
     Slice(Vec<P<Pat>>, Option<P<Pat>>, Vec<P<Pat>>),
+
     /// Parentheses in patterns used for grouping (i.e., `(PAT)`).
     Paren(P<Pat>),
+
     /// A macro pattern; pre-expansion.
     Mac(Mac),
 }

src/libsyntax/mut_visit.rs

@@ -1037,7 +1037,7 @@ pub fn noop_visit_pat<T: MutVisitor>(pat: &mut P<Pat>, vis: &mut T) {
             vis.visit_expr(e1);
             vis.visit_expr(e2);
             vis.visit_span(span);
-        },
+        }
         PatKind::Slice(before, slice, after) => {
             visit_vec(before, |pat| vis.visit_pat(pat));
             visit_opt(slice, |slice| vis.visit_pat(slice));

src/libsyntax/parse/parser.rs

@@ -4173,7 +4173,8 @@ impl<'a> Parser<'a> {
                 err.emit();
                 self.bump();
             } else if self.eat(&token::BinOp(token::Or)) {
-                // No op.
+                // This is a No-op. Continue the loop to parse the next
+                // pattern.
             } else {
                 return Ok(pats);
             }