Avoid sorting by DefId for necessary_variants()

Dylan-DPC-zz · Mar 28, 2021 · a0957c9 · a0957c9
1 parent 8cd7d86
commit a0957c9
Showing 1 changed file with 5 additions and 2 deletions.
diff --git a/compiler/rustc_hir/src/pat_util.rs b/compiler/rustc_hir/src/pat_util.rs
@@ -1,6 +1,7 @@
 use crate::def::{CtorOf, DefKind, Res};
 use crate::def_id::DefId;
 use crate::hir::{self, HirId, PatKind};
+use rustc_data_structures::stable_set::FxHashSet;
 use rustc_span::symbol::Ident;
 use rustc_span::Span;
 
@@ -138,8 +139,10 @@ impl hir::Pat<'_> {
             }
             _ => true,
         });
-        variants.sort();
-        variants.dedup();
+        // We remove duplicates by inserting into a `FxHashSet` to avoid re-ordering
+        // the bounds
+        let mut duplicates = FxHashSet::default();
+        variants.retain(|def_id| duplicates.insert(*def_id));
         variants
     }