Auto merge of #66610 - alexreg:trait-upcasting-cosmetic, r=Centril

Aggregation of drive-by cosmetic changes for trait-upcasting PR

Cherry-picked from #60900.

As requested by @Centril (and @nikomatsakis, I believe).

r? @Centril

Author: bors

src/librustc/hir/mod.rs

@@ -1919,8 +1919,9 @@ pub enum ImplItemKind {
 /// Bindings like `A: Debug` are represented as a special type `A =
 /// $::Debug` that is understood by the astconv code.
 ///
-/// FIXME(alexreg) -- why have a separate type for the binding case,
-/// wouldn't it be better to make the `ty` field an enum like:
+/// FIXME(alexreg): why have a separate type for the binding case,
+/// wouldn't it be better to make the `ty` field an enum like the
+/// following?
 ///
 /// ```
 /// enum TypeBindingKind {

src/librustc/infer/canonical/canonicalizer.rs

@@ -306,7 +306,7 @@ impl<'cx, 'tcx> TypeFolder<'tcx> for Canonicalizer<'cx, 'tcx> {
         match *r {
             ty::ReLateBound(index, ..) => {
                 if index >= self.binder_index {
-                    bug!("escaping late bound region during canonicalization")
+                    bug!("escaping late-bound region during canonicalization");
                 } else {
                     r
                 }
@@ -336,7 +336,7 @@ impl<'cx, 'tcx> TypeFolder<'tcx> for Canonicalizer<'cx, 'tcx> {
                 .canonicalize_free_region(self, r),
 
             ty::ReClosureBound(..) => {
-                bug!("closure bound region encountered during canonicalization")
+                bug!("closure bound region encountered during canonicalization");
             }
         }
     }
@@ -346,14 +346,14 @@ impl<'cx, 'tcx> TypeFolder<'tcx> for Canonicalizer<'cx, 'tcx> {
             ty::Infer(ty::TyVar(vid)) => {
                 debug!("canonical: type var found with vid {:?}", vid);
                 match self.infcx.unwrap().probe_ty_var(vid) {
-                    // `t` could be a float / int variable: canonicalize that instead
+                    // `t` could be a float / int variable; canonicalize that instead.
                     Ok(t) => {
                         debug!("(resolved to {:?})", t);
                         self.fold_ty(t)
                     }
 
                     // `TyVar(vid)` is unresolved, track its universe index in the canonicalized
-                    // result
+                    // result.
                     Err(mut ui) => {
                         if !self.infcx.unwrap().tcx.sess.opts.debugging_opts.chalk {
                             // FIXME: perf problem described in #55921.

src/librustc/infer/error_reporting/mod.rs

@@ -48,22 +48,24 @@
 use super::lexical_region_resolve::RegionResolutionError;
 use super::region_constraints::GenericKind;
 use super::{InferCtxt, RegionVariableOrigin, SubregionOrigin, TypeTrace, ValuePairs};
-use crate::infer::{self, SuppressRegionErrors};
 
 use crate::hir;
 use crate::hir::def_id::DefId;
 use crate::hir::Node;
+use crate::infer::{self, SuppressRegionErrors};
 use crate::infer::opaque_types;
 use crate::middle::region;
-use crate::traits::{IfExpressionCause, MatchExpressionArmCause, ObligationCause};
-use crate::traits::{ObligationCauseCode};
+use crate::traits::{
+    IfExpressionCause, MatchExpressionArmCause, ObligationCause, ObligationCauseCode,
+};
 use crate::ty::error::TypeError;
 use crate::ty::{self, subst::{Subst, SubstsRef}, Region, Ty, TyCtxt, TypeFoldable};
+
 use errors::{Applicability, DiagnosticBuilder, DiagnosticStyledString};
-use std::{cmp, fmt};
+use rustc_error_codes::*;
 use syntax_pos::{Pos, Span};
 
-use rustc_error_codes::*;
+use std::{cmp, fmt};
 
 mod note;
 
@@ -1270,7 +1272,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
     }
 
     /// When encountering a case where `.as_ref()` on a `Result` or `Option` would be appropriate,
-    /// suggest it.
+    /// suggests it.
     fn suggest_as_ref_where_appropriate(
         &self,
         span: Span,

src/librustc/infer/outlives/obligations.rs

@@ -221,7 +221,7 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
 }
 
 /// The `TypeOutlives` struct has the job of "lowering" a `T: 'a`
-/// obligation into a series of `'a: 'b` constraints and "verifys", as
+/// obligation into a series of `'a: 'b` constraints and "verify"s, as
 /// described on the module comment. The final constraints are emitted
 /// via a "delegate" of type `D` -- this is usually the `infcx`, which
 /// accrues them into the `region_obligations` code, but for NLL we

src/librustc/mir/interpret/pointer.rs

@@ -1,11 +1,12 @@
-use std::fmt::{self, Display};
-use std::convert::TryFrom;
+use super::{AllocId, InterpResult};
 
 use crate::mir;
 use crate::ty::layout::{self, HasDataLayout, Size};
+
 use rustc_macros::HashStable;
 
-use super::{AllocId, InterpResult};
+use std::convert::TryFrom;
+use std::fmt::{self, Display};
 
 /// Used by `check_in_alloc` to indicate context of check
 #[derive(Debug, Copy, Clone, RustcEncodable, RustcDecodable, HashStable)]
@@ -74,8 +75,8 @@ pub trait PointerArithmetic: layout::HasDataLayout {
     fn overflowing_signed_offset(&self, val: u64, i: i128) -> (u64, bool) {
         // FIXME: is it possible to over/underflow here?
         if i < 0 {
-            // Trickery to ensure that i64::min_value() works fine: compute n = -i.
-            // This formula only works for true negative values, it overflows for zero!
+            // Trickery to ensure that `i64::min_value()` works fine: compute `n = -i`.
+            // This formula only works for true negative values; it overflows for zero!
             let n = u64::max_value() - (i as u64) + 1;
             let res = val.overflowing_sub(n);
             self.truncate_to_ptr(res)
@@ -105,7 +106,7 @@ impl<T: layout::HasDataLayout> PointerArithmetic for T {}
 ///
 /// Defaults to the index based and loosely coupled `AllocId`.
 ///
-/// Pointer is also generic over the `Tag` associated with each pointer,
+/// `Pointer` is also generic over the `Tag` associated with each pointer,
 /// which is used to do provenance tracking during execution.
 #[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd,
          RustcEncodable, RustcDecodable, Hash, HashStable)]
@@ -129,7 +130,7 @@ impl<Id: fmt::Debug> fmt::Debug for Pointer<(), Id> {
     }
 }
 
-/// Produces a `Pointer` which points to the beginning of the `Allocation`.
+/// Produces a `Pointer` that points to the beginning of the `Allocation`.
 impl From<AllocId> for Pointer {
     #[inline(always)]
     fn from(alloc_id: AllocId) -> Self {

src/librustc/session/config.rs

@@ -1203,7 +1203,7 @@ options! {CodegenOptions, CodegenSetter, basic_codegen_options,
     force_frame_pointers: Option<bool> = (None, parse_opt_bool, [TRACKED],
         "force use of the frame pointers"),
     debug_assertions: Option<bool> = (None, parse_opt_bool, [TRACKED],
-        "explicitly enable the cfg(debug_assertions) directive"),
+        "explicitly enable the `cfg(debug_assertions)` directive"),
     inline_threshold: Option<usize> = (None, parse_opt_uint, [TRACKED],
         "set the threshold for inlining a function (default: 225)"),
     panic: Option<PanicStrategy> = (None, parse_panic_strategy,