Make `associated_items` query return a slice

11 files changed, 25 insertions, 31 deletions

diff --git a/src/librustc/query/mod.rs b/src/librustc/query/mod.rs
index d1bccb961c4..7cb1f3aa0e8 100644
--- a/src/librustc/query/mod.rs
+++ b/src/librustc/query/mod.rs
@@ -323,7 +323,7 @@ rustc_queries! {
         query associated_item(_: DefId) -> ty::AssocItem {}
 
         /// Collects the associated items defined on a trait or impl.
-        query associated_items(key: DefId) -> ty::AssocItemsIterator<'tcx> {
+        query associated_items(key: DefId) -> &'tcx [ty::AssocItem] {
             desc { |tcx| "collecting associated items of {}", tcx.def_path_str(key) }
         }
 
diff --git a/src/librustc/traits/mod.rs b/src/librustc/traits/mod.rs
index 50068b89687..9e6e6047b35 100644
--- a/src/librustc/traits/mod.rs
+++ b/src/librustc/traits/mod.rs
@@ -539,6 +539,7 @@ fn vtable_methods<'tcx>(
     tcx.arena.alloc_from_iter(supertraits(tcx, trait_ref).flat_map(move |trait_ref| {
         let trait_methods = tcx
             .associated_items(trait_ref.def_id())
+            .iter()
             .filter(|item| item.kind == ty::AssocKind::Method);
 
         // Now list each method's DefId and InternalSubsts (for within its trait).
diff --git a/src/librustc/traits/object_safety.rs b/src/librustc/traits/object_safety.rs
index d0dbfe73c91..3c886ce7f3e 100644
--- a/src/librustc/traits/object_safety.rs
+++ b/src/librustc/traits/object_safety.rs
@@ -212,6 +212,7 @@ fn object_safety_violations_for_trait(
     // Check methods for violations.
     let mut violations: Vec<_> = tcx
         .associated_items(trait_def_id)
+        .iter()
         .filter(|item| item.kind == ty::AssocKind::Method)
         .filter_map(|item| {
             object_safety_violation_for_method(tcx, trait_def_id, &item)
@@ -277,6 +278,7 @@ fn object_safety_violations_for_trait(
 
     violations.extend(
         tcx.associated_items(trait_def_id)
+            .iter()
             .filter(|item| item.kind == ty::AssocKind::Const)
             .map(|item| ObjectSafetyViolation::AssocConst(item.ident.name, item.ident.span)),
     );
@@ -632,7 +634,9 @@ fn object_ty_for_trait<'tcx>(
 
     let mut associated_types = traits::supertraits(tcx, ty::Binder::dummy(trait_ref))
         .flat_map(|super_trait_ref| {
-            tcx.associated_items(super_trait_ref.def_id()).map(move |item| (super_trait_ref, item))
+            tcx.associated_items(super_trait_ref.def_id())
+                .iter()
+                .map(move |item| (super_trait_ref, item))
         })
         .filter(|(_, item)| item.kind == ty::AssocKind::Type)
         .collect::<Vec<_>>();
diff --git a/src/librustc/traits/project.rs b/src/librustc/traits/project.rs
index fffcf66075f..8ea990d1e93 100644
--- a/src/librustc/traits/project.rs
+++ b/src/librustc/traits/project.rs
@@ -1436,7 +1436,7 @@ fn assoc_ty_def(
         {
             return specialization_graph::NodeItem {
                 node: specialization_graph::Node::Impl(impl_def_id),
-                item,
+                item: *item,
             };
         }
     }
diff --git a/src/librustc/traits/types/specialization_graph.rs b/src/librustc/traits/types/specialization_graph.rs
index 3086850db6d..36a84369d4a 100644
--- a/src/librustc/traits/types/specialization_graph.rs
+++ b/src/librustc/traits/types/specialization_graph.rs
@@ -81,7 +81,7 @@ impl<'tcx> Node {
     }
 
     /// Iterate over the items defined directly by the given (impl or trait) node.
-    pub fn items(&self, tcx: TyCtxt<'tcx>) -> ty::AssocItemsIterator<'tcx> {
+    pub fn items(&self, tcx: TyCtxt<'tcx>) -> &'tcx [ty::AssocItem] {
         tcx.associated_items(self.def_id())
     }
 
@@ -98,8 +98,10 @@ impl<'tcx> Node {
     ) -> Option<ty::AssocItem> {
         use crate::ty::AssocKind::*;
 
-        tcx.associated_items(self.def_id()).find(move |impl_item| {
-            match (trait_item_kind, impl_item.kind) {
+        tcx.associated_items(self.def_id())
+            .iter()
+            .find(move |impl_item| {
+                match (trait_item_kind, impl_item.kind) {
                 | (Const, Const)
                 | (Method, Method)
                 | (Type, Type)
@@ -112,7 +114,8 @@ impl<'tcx> Node {
                 | (OpaqueTy, _)
                 => false,
             }
-        })
+            })
+            .copied()
     }
 
     pub fn def_id(&self) -> DefId {
diff --git a/src/librustc/traits/wf.rs b/src/librustc/traits/wf.rs
index 9fa3c874779..c44d45e7580 100644
--- a/src/librustc/traits/wf.rs
+++ b/src/librustc/traits/wf.rs
@@ -166,7 +166,7 @@ impl<'a, 'tcx> WfPredicates<'a, 'tcx> {
         let extend_cause_with_original_assoc_item_obligation =
             |cause: &mut traits::ObligationCause<'_>,
              pred: &ty::Predicate<'_>,
-             trait_assoc_items: ty::AssocItemsIterator<'_>| {
+             trait_assoc_items: &[ty::AssocItem]| {
                 let trait_item = tcx
                     .hir()
                     .as_local_hir_id(trait_ref.def_id)
@@ -283,6 +283,7 @@ impl<'a, 'tcx> WfPredicates<'a, 'tcx> {
                         ) = (&proj.skip_binder().self_ty().kind, item.map(|i| &i.kind))
                         {
                             if let Some((impl_item, trait_assoc_item)) = trait_assoc_items
+                                .iter()
                                 .filter(|i| i.def_id == *item_def_id)
                                 .next()
                                 .and_then(|trait_assoc_item| {
@@ -325,7 +326,7 @@ impl<'a, 'tcx> WfPredicates<'a, 'tcx> {
                 extend_cause_with_original_assoc_item_obligation(
                     &mut cause,
                     &pred,
-                    trait_assoc_items.clone(),
+                    trait_assoc_items,
                 );
                 traits::Obligation::new(cause, param_env, pred)
             });
diff --git a/src/librustc/ty/adjustment.rs b/src/librustc/ty/adjustment.rs
index db034d1618c..f4006a1cd40 100644
--- a/src/librustc/ty/adjustment.rs
+++ b/src/librustc/ty/adjustment.rs
@@ -122,6 +122,7 @@ impl<'tcx> OverloadedDeref<'tcx> {
         };
         let method_def_id = tcx
             .associated_items(trait_def_id.unwrap())
+            .iter()
             .find(|m| m.kind == ty::AssocKind::Method)
             .unwrap()
             .def_id;
diff --git a/src/librustc/ty/instance.rs b/src/librustc/ty/instance.rs
index 51a18f8eae2..c7f19513f66 100644
--- a/src/librustc/ty/instance.rs
+++ b/src/librustc/ty/instance.rs
@@ -376,6 +376,7 @@ impl<'tcx> Instance<'tcx> {
         let fn_once = tcx.lang_items().fn_once_trait().unwrap();
         let call_once = tcx
             .associated_items(fn_once)
+            .iter()
             .find(|it| it.kind == ty::AssocKind::Method)
             .unwrap()
             .def_id;
diff --git a/src/librustc/ty/mod.rs b/src/librustc/ty/mod.rs
index 2538322431e..62dc02eaa03 100644
--- a/src/librustc/ty/mod.rs
+++ b/src/librustc/ty/mod.rs
@@ -2705,14 +2705,15 @@ impl<'tcx> TyCtxt<'tcx> {
             .for_each(|&body_id| f(self.hir().body_owner_def_id(body_id)));
     }
 
-    pub fn provided_trait_methods(self, id: DefId) -> Vec<AssocItem> {
+    pub fn provided_trait_methods(self, id: DefId) -> Vec<&'tcx AssocItem> {
         self.associated_items(id)
+            .iter()
             .filter(|item| item.kind == AssocKind::Method && item.defaultness.has_value())
             .collect()
     }
 
     pub fn trait_relevant_for_never(self, did: DefId) -> bool {
-        self.associated_items(did).any(|item| item.relevant_for_never())
+        self.associated_items(did).iter().any(|item| item.relevant_for_never())
     }
 
     pub fn opt_item_name(self, def_id: DefId) -> Option<Ident> {
@@ -2974,25 +2975,6 @@ impl<'tcx> TyCtxt<'tcx> {
     }
 }
 
-#[derive(Copy, Clone, HashStable)]
-pub struct AssocItemsIterator<'tcx> {
-    pub items: &'tcx [AssocItem],
-}
-
-impl<'tcx> Iterator for AssocItemsIterator<'tcx> {
-    type Item = AssocItem;
-
-    #[inline]
-    fn next(&mut self) -> Option<AssocItem> {
-        if let Some((first, rest)) = self.items.split_first() {
-            self.items = rest;
-            Some(*first)
-        } else {
-            None
-        }
-    }
-}
-
 #[derive(Clone, HashStable)]
 pub struct AdtSizedConstraint<'tcx>(pub &'tcx [Ty<'tcx>]);
 
diff --git a/src/librustc/ty/sty.rs b/src/librustc/ty/sty.rs
index 4c5bc3debde..0718853b1df 100644
--- a/src/librustc/ty/sty.rs
+++ b/src/librustc/ty/sty.rs
@@ -1066,6 +1066,7 @@ impl<'tcx> ProjectionTy<'tcx> {
     ) -> ProjectionTy<'tcx> {
         let item_def_id = tcx
             .associated_items(trait_ref.def_id)
+            .iter()
             .find(|item| {
                 item.kind == ty::AssocKind::Type
                     && tcx.hygienic_eq(item_name, item.ident, trait_ref.def_id)
diff --git a/src/librustc/ty/util.rs b/src/librustc/ty/util.rs
index 4dfff85d531..5d5fa4090c8 100644
--- a/src/librustc/ty/util.rs
+++ b/src/librustc/ty/util.rs
@@ -355,7 +355,7 @@ impl<'tcx> TyCtxt<'tcx> {
         let mut dtor_did = None;
         let ty = self.type_of(adt_did);
         self.for_each_relevant_impl(drop_trait, ty, |impl_did| {
-            if let Some(item) = self.associated_items(impl_did).next() {
+            if let Some(item) = self.associated_items(impl_did).first() {
                 if validate(self, impl_did).is_ok() {
                     dtor_did = Some(item.def_id);
                 }