Remove #![allow(rustc::potential_query_instability)] from rustc_infer

Change reported_violations to use IndexSet

It is being used to iterate and to insert, without a lot of lookups
so hopefully it won't be a perf hit

Change MiniGraph.nodes to use IndexSet

It is being used to iterate and to insert, without performing lookups
so hopefully it won't be a perf hit

Change RegionConstraintData.givens to a FxIndexSet

This might result in a perf hit. Remove was being used in `givens`,
and `FxIndexSet` doesn't allow calling remove without losing the
fixed iteration order. So it was necessary to change remove to
`shift_remove`, but this method is slower.

Change OpaqueTypesVisitor to use stable sets and maps

This could also be a perf hit.

Make TraitObject visitor use a stable set

1 files changed, 4 insertions, 4 deletions

diff --git a/compiler/rustc_borrowck/src/diagnostics/region_errors.rs b/compiler/rustc_borrowck/src/diagnostics/region_errors.rs
index 15230718dc0..1db7ef032b1 100644
--- a/compiler/rustc_borrowck/src/diagnostics/region_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/region_errors.rs
@@ -2,7 +2,7 @@
 #![deny(rustc::diagnostic_outside_of_impl)]
 //! Error reporting machinery for lifetime errors.
 
-use rustc_data_structures::fx::FxHashSet;
+use rustc_data_structures::fx::FxIndexSet;
 use rustc_errors::{Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed, MultiSpan};
 use rustc_hir::def_id::DefId;
 use rustc_hir::intravisit::Visitor;
@@ -276,7 +276,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
     fn get_impl_ident_and_self_ty_from_trait(
         &self,
         def_id: DefId,
-        trait_objects: &FxHashSet<DefId>,
+        trait_objects: &FxIndexSet<DefId>,
     ) -> Option<(Ident, &'tcx hir::Ty<'tcx>)> {
         let tcx = self.infcx.tcx;
         match tcx.hir().get_if_local(def_id) {
@@ -830,7 +830,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
         };
         debug!(?param);
 
-        let mut visitor = TraitObjectVisitor(FxHashSet::default());
+        let mut visitor = TraitObjectVisitor(FxIndexSet::default());
         visitor.visit_ty(param.param_ty);
 
         let Some((ident, self_ty)) =
@@ -843,7 +843,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
     fn suggest_constrain_dyn_trait_in_impl(
         &self,
         err: &mut Diagnostic,
-        found_dids: &FxHashSet<DefId>,
+        found_dids: &FxIndexSet<DefId>,
         ident: Ident,
         self_ty: &hir::Ty<'_>,
     ) -> bool {