Deduplicate supertrait_def_ids code

compiler/rustc_trait_selection/src/solve/trait_goals.rs

@@ -1,7 +1,5 @@
 //! Dealing with trait goals, i.e. `T: Trait<'a, U>`.
 
-use crate::traits::supertrait_def_ids;
-
 use super::assembly::structural_traits::AsyncCallableRelevantTypes;
 use super::assembly::{self, structural_traits, Candidate};
 use super::{EvalCtxt, GoalSource, SolverMode};
@@ -837,7 +835,8 @@ impl<'tcx> EvalCtxt<'_, InferCtxt<'tcx>> {
         let a_auto_traits: FxIndexSet<DefId> = a_data
             .auto_traits()
             .chain(a_data.principal_def_id().into_iter().flat_map(|principal_def_id| {
-                supertrait_def_ids(self.interner(), principal_def_id)
+                self.interner()
+                    .supertrait_def_ids(principal_def_id)
                     .filter(|def_id| self.interner().trait_is_auto(*def_id))
             }))
             .collect();

compiler/rustc_trait_selection/src/traits/mod.rs

@@ -65,10 +65,7 @@ pub use self::structural_normalize::StructurallyNormalizeExt;
 pub use self::util::elaborate;
 pub use self::util::{expand_trait_aliases, TraitAliasExpander, TraitAliasExpansionInfo};
 pub use self::util::{get_vtable_index_of_object_method, impl_item_is_final, upcast_choices};
-pub use self::util::{
-    supertrait_def_ids, supertraits, transitive_bounds, transitive_bounds_that_define_assoc_item,
-    SupertraitDefIds,
-};
+pub use self::util::{supertraits, transitive_bounds, transitive_bounds_that_define_assoc_item};
 pub use self::util::{with_replaced_escaping_bound_vars, BoundVarReplacer, PlaceholderReplacer};
 
 pub use rustc_infer::traits::*;

compiler/rustc_trait_selection/src/traits/object_safety.rs

@@ -45,7 +45,8 @@ pub fn hir_ty_lowering_object_safety_violations(
     trait_def_id: DefId,
 ) -> Vec<ObjectSafetyViolation> {
     debug_assert!(tcx.generics_of(trait_def_id).has_self);
-    let violations = traits::supertrait_def_ids(tcx, trait_def_id)
+    let violations = tcx
+        .supertrait_def_ids(trait_def_id)
         .map(|def_id| predicates_reference_self(tcx, def_id, true))
         .filter(|spans| !spans.is_empty())
         .map(ObjectSafetyViolation::SupertraitSelf)
@@ -59,7 +60,7 @@ fn object_safety_violations(tcx: TyCtxt<'_>, trait_def_id: DefId) -> &'_ [Object
     debug!("object_safety_violations: {:?}", trait_def_id);
 
     tcx.arena.alloc_from_iter(
-        traits::supertrait_def_ids(tcx, trait_def_id)
+        tcx.supertrait_def_ids(trait_def_id)
             .flat_map(|def_id| object_safety_violations_for_trait(tcx, def_id)),
     )
 }

compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs

@@ -1004,7 +1004,8 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                     let a_auto_traits: FxIndexSet<DefId> = a_data
                         .auto_traits()
                         .chain(principal_def_id_a.into_iter().flat_map(|principal_def_id| {
-                            util::supertrait_def_ids(self.tcx(), principal_def_id)
+                            self.tcx()
+                                .supertrait_def_ids(principal_def_id)
                                 .filter(|def_id| self.tcx().trait_is_auto(*def_id))
                         }))
                         .collect();

compiler/rustc_trait_selection/src/traits/select/mod.rs

@@ -2591,8 +2591,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
         let a_auto_traits: FxIndexSet<DefId> = a_data
             .auto_traits()
             .chain(a_data.principal_def_id().into_iter().flat_map(|principal_def_id| {
-                util::supertrait_def_ids(tcx, principal_def_id)
-                    .filter(|def_id| tcx.trait_is_auto(*def_id))
+                tcx.supertrait_def_ids(principal_def_id).filter(|def_id| tcx.trait_is_auto(*def_id))
             }))
             .collect();
 

compiler/rustc_trait_selection/src/traits/util.rs

@@ -2,7 +2,7 @@ use std::collections::BTreeMap;
 
 use super::NormalizeExt;
 use super::{ObligationCause, PredicateObligation, SelectionContext};
-use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
+use rustc_data_structures::fx::FxIndexMap;
 use rustc_errors::Diag;
 use rustc_hir::def_id::DefId;
 use rustc_infer::infer::{InferCtxt, InferOk};
@@ -161,43 +161,6 @@ impl<'tcx> Iterator for TraitAliasExpander<'tcx> {
     }
 }
 
-///////////////////////////////////////////////////////////////////////////
-// Iterator over def-IDs of supertraits
-///////////////////////////////////////////////////////////////////////////
-
-pub struct SupertraitDefIds<'tcx> {
-    tcx: TyCtxt<'tcx>,
-    stack: Vec<DefId>,
-    visited: FxHashSet<DefId>,
-}
-
-pub fn supertrait_def_ids(tcx: TyCtxt<'_>, trait_def_id: DefId) -> SupertraitDefIds<'_> {
-    SupertraitDefIds {
-        tcx,
-        stack: vec![trait_def_id],
-        visited: Some(trait_def_id).into_iter().collect(),
-    }
-}
-
-impl Iterator for SupertraitDefIds<'_> {
-    type Item = DefId;
-
-    fn next(&mut self) -> Option<DefId> {
-        let def_id = self.stack.pop()?;
-        let predicates = self.tcx.super_predicates_of(def_id);
-        let visited = &mut self.visited;
-        self.stack.extend(
-            predicates
-                .predicates
-                .iter()
-                .filter_map(|(pred, _)| pred.as_trait_clause())
-                .map(|trait_ref| trait_ref.def_id())
-                .filter(|&super_def_id| visited.insert(super_def_id)),
-        );
-        Some(def_id)
-    }
-}
-
 ///////////////////////////////////////////////////////////////////////////
 // Other
 ///////////////////////////////////////////////////////////////////////////