Remove unnecessary sorts in rustc_hir_analysis.

This is an attempt to gain the performance loss after the PR #131140.
Here the related objects are `IndexSet` so do not require a sort to stay stable.

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -531,7 +531,7 @@ fn check_gat_where_clauses(tcx: TyCtxt<'_>, trait_def_id: LocalDefId) {
         debug!(?required_bounds);
         let param_env = tcx.param_env(gat_def_id);
 
-        let mut unsatisfied_bounds: Vec<_> = required_bounds
+        let unsatisfied_bounds: Vec<_> = required_bounds
             .into_iter()
             .filter(|clause| match clause.kind().skip_binder() {
                 ty::ClauseKind::RegionOutlives(ty::OutlivesPredicate(a, b)) => {
@@ -552,9 +552,6 @@ fn check_gat_where_clauses(tcx: TyCtxt<'_>, trait_def_id: LocalDefId) {
             .map(|clause| clause.to_string())
             .collect();
 
-        // We sort so that order is predictable
-        unsatisfied_bounds.sort();
-
         if !unsatisfied_bounds.is_empty() {
             let plural = pluralize!(unsatisfied_bounds.len());
             let suggestion = format!(

compiler/rustc_hir_analysis/src/coherence/inherent_impls_overlap.rs

@@ -319,9 +319,7 @@ impl<'tcx> InherentOverlapChecker<'tcx> {
             // List of connected regions is built. Now, run the overlap check
             // for each pair of impl blocks in the same connected region.
             for region in connected_regions.into_iter().flatten() {
-                let mut impl_blocks =
-                    region.impl_blocks.into_iter().collect::<SmallVec<[usize; 8]>>();
-                impl_blocks.sort_unstable();
+                let impl_blocks = region.impl_blocks.into_iter().collect::<SmallVec<[usize; 8]>>();
                 for (i, &impl1_items_idx) in impl_blocks.iter().enumerate() {
                     let &(&impl1_def_id, impl_items1) = &impls_items[impl1_items_idx];
                     res = res.and(self.check_for_duplicate_items_in_impl(impl1_def_id));