Simplify sort_by calls

compiler/rustc_hir_typeck/src/method/probe.rs

@@ -1031,7 +1031,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
             .collect();
 
         // Sort them by the name so we have a stable result.
-        names.sort_by(|a, b| a.as_str().partial_cmp(b.as_str()).unwrap());
+        names.sort_by(|a, b| a.as_str().cmp(b.as_str()));
         names
     }
 

compiler/rustc_hir_typeck/src/method/suggest.rs

@@ -42,7 +42,7 @@ use rustc_trait_selection::traits::{
 use super::probe::{AutorefOrPtrAdjustment, IsSuggestion, Mode, ProbeScope};
 use super::{CandidateSource, MethodError, NoMatchData};
 use rustc_hir::intravisit::Visitor;
-use std::cmp::Ordering;
+use std::cmp::{self, Ordering};
 use std::iter;
 
 impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
@@ -2517,7 +2517,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
         if !candidates.is_empty() {
             // Sort from most relevant to least relevant.
-            candidates.sort_by(|a, b| a.cmp(b).reverse());
+            candidates.sort_by_key(|&info| cmp::Reverse(info));
             candidates.dedup();
 
             let param_type = match rcvr_ty.kind() {

compiler/rustc_monomorphize/src/partitioning/merging.rs

@@ -24,7 +24,7 @@ pub fn merge_codegen_units<'tcx>(
     // smallest into each other) we're sure to start off with a deterministic
     // order (sorted by name). This'll mean that if two cgus have the same size
     // the stable sort below will keep everything nice and deterministic.
-    codegen_units.sort_by(|a, b| a.name().as_str().partial_cmp(b.name().as_str()).unwrap());
+    codegen_units.sort_by(|a, b| a.name().as_str().cmp(b.name().as_str()));
 
     // This map keeps track of what got merged into what.
     let mut cgu_contents: FxHashMap<Symbol, Vec<Symbol>> =

compiler/rustc_monomorphize/src/partitioning/mod.rs

@@ -252,7 +252,7 @@ pub fn partition<'tcx>(
         internalization_candidates: _,
     } = post_inlining;
 
-    result.sort_by(|a, b| a.name().as_str().partial_cmp(b.name().as_str()).unwrap());
+    result.sort_by(|a, b| a.name().as_str().cmp(b.name().as_str()));
 
     result
 }

compiler/rustc_parse/src/lexer/diagnostics.rs

@@ -71,7 +71,7 @@ pub fn report_suspicious_mismatch_block(
         .collect();
 
     // sort by `lo`, so the large block spans in the front
-    matched_spans.sort_by(|a, b| a.0.lo().cmp(&b.0.lo()));
+    matched_spans.sort_by_key(|(span, _)| span.lo());
 
     // We use larger block whose identation is well to cover those inner mismatched blocks
     // O(N^2) here, but we are on error reporting path, so it is fine

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -1736,7 +1736,7 @@ impl<'a: 'ast, 'ast, 'tcx> LateResolutionVisitor<'a, '_, 'ast, 'tcx> {
 
         let name = path[path.len() - 1].ident.name;
         // Make sure error reporting is deterministic.
-        names.sort_by(|a, b| a.candidate.as_str().partial_cmp(b.candidate.as_str()).unwrap());
+        names.sort_by(|a, b| a.candidate.as_str().cmp(b.candidate.as_str()));
 
         match find_best_match_for_name(
             &names.iter().map(|suggestion| suggestion.candidate).collect::<Vec<Symbol>>(),

compiler/rustc_session/src/code_stats.rs

@@ -2,7 +2,7 @@ use rustc_data_structures::fx::FxHashSet;
 use rustc_data_structures::sync::Lock;
 use rustc_span::Symbol;
 use rustc_target::abi::{Align, Size};
-use std::cmp::{self, Ordering};
+use std::cmp;
 
 #[derive(Clone, PartialEq, Eq, Hash, Debug)]
 pub struct VariantInfo {
@@ -87,7 +87,7 @@ impl CodeStats {
         // Except for Generators, whose variants are already sorted according to
         // their yield points in `variant_info_for_generator`.
         if kind != DataTypeKind::Generator {
-            variants.sort_by(|info1, info2| info2.size.cmp(&info1.size));
+            variants.sort_by_key(|info| cmp::Reverse(info.size));
         }
         let info = TypeSizeInfo {
             kind,
@@ -107,13 +107,7 @@ impl CodeStats {
 
         // Primary sort: large-to-small.
         // Secondary sort: description (dictionary order)
-        sorted.sort_by(|info1, info2| {
-            // (reversing cmp order to get large-to-small ordering)
-            match info2.overall_size.cmp(&info1.overall_size) {
-                Ordering::Equal => info1.type_description.cmp(&info2.type_description),
-                other => other,
-            }
-        });
+        sorted.sort_by_key(|info| (cmp::Reverse(info.overall_size), &info.type_description));
 
         for info in sorted {
             let TypeSizeInfo { type_description, overall_size, align, kind, variants, .. } = info;