super_traits_of is now a query

Author: spastorino

compiler/rustc_middle/src/query/mod.rs

@@ -433,7 +433,13 @@ rustc_queries! {
         /// full predicates are available (note that supertraits have
         /// additional acyclicity requirements).
         query super_predicates_of(key: DefId) -> ty::GenericPredicates<'tcx> {
-            desc { |tcx| "computing the supertraits of `{}`", tcx.def_path_str(key) }
+            desc { |tcx| "computing the super predicates of `{}`", tcx.def_path_str(key) }
+        }
+
+        /// Maps from the `DefId` of a trait to the list of
+        /// all the ancestors super traits.
+        query super_traits_of(key: DefId) -> FxHashSet<DefId> {
+            desc { |tcx| "computing the super traits of `{}`", tcx.def_path_str(key) }
         }
 
         /// Maps from the `DefId` of a trait to the list of

compiler/rustc_typeck/src/astconv/mod.rs

@@ -6,7 +6,6 @@ mod errors;
 mod generics;
 
 use crate::bounds::Bounds;
-use crate::collect::super_traits_of;
 use crate::collect::PlaceholderHirTyCollector;
 use crate::errors::{
     AmbiguousLifetimeBound, MultipleRelaxedDefaultBounds, TraitObjectDeclaredWithNoTraits,
@@ -923,10 +922,10 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
     /// Given the def_id of a Trait `trait_def_id` and the name of an associated item `assoc_name`
     /// returns true if the `trait_def_id` defines an associated item of name `assoc_name`.
     fn trait_may_define_assoc_type(&self, trait_def_id: DefId, assoc_name: Ident) -> bool {
-        super_traits_of(self.tcx(), trait_def_id).any(|trait_did| {
+        self.tcx().super_traits_of(trait_def_id).iter().any(|trait_did| {
             self.tcx()
-                .associated_items(trait_did)
-                .find_by_name_and_kind(self.tcx(), assoc_name, ty::AssocKind::Type, trait_did)
+                .associated_items(*trait_did)
+                .find_by_name_and_kind(self.tcx(), assoc_name, ty::AssocKind::Type, *trait_did)
                 .is_some()
         })
     }

compiler/rustc_typeck/src/collect.rs

@@ -80,6 +80,7 @@ pub fn provide(providers: &mut Providers) {
         projection_ty_from_predicates,
         explicit_predicates_of,
         super_predicates_of,
+        super_traits_of,
         super_predicates_that_define_assoc_type,
         trait_explicit_predicates_and_bounds,
         type_param_predicates,
@@ -653,14 +654,14 @@ impl ItemCtxt<'tcx> {
             hir::GenericBound::Trait(poly_trait_ref, _) => {
                 let trait_ref = &poly_trait_ref.trait_ref;
                 if let Some(trait_did) = trait_ref.trait_def_id() {
-                    super_traits_of(self.tcx, trait_did).any(|trait_did| {
+                    self.tcx.super_traits_of(trait_did).iter().any(|trait_did| {
                         self.tcx
-                            .associated_items(trait_did)
+                            .associated_items(*trait_did)
                             .find_by_name_and_kind(
                                 self.tcx,
                                 assoc_name,
                                 ty::AssocKind::Type,
-                                trait_did,
+                                *trait_did,
                             )
                             .is_some()
                     })
@@ -1125,7 +1126,7 @@ fn super_predicates_that_define_assoc_type(
     }
 }
 
-pub fn super_traits_of(tcx: TyCtxt<'_>, trait_def_id: DefId) -> impl Iterator<Item = DefId> {
+fn super_traits_of(tcx: TyCtxt<'_>, trait_def_id: DefId) -> FxHashSet<DefId> {
     let mut set = FxHashSet::default();
     let mut stack = vec![trait_def_id];
     while let Some(trait_did) = stack.pop() {
@@ -1185,7 +1186,7 @@ pub fn super_traits_of(tcx: TyCtxt<'_>, trait_def_id: DefId) -> impl Iterator<It
         }
     }
 
-    set.into_iter()
+    set
 }
 
 fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> ty::TraitDef {