diff --git a/compiler/rustc_infer/src/infer/error_reporting/mod.rs b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
index 58c3aa362ea..7a0db820c9c 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/mod.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
@@ -1704,13 +1704,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
if let ty::Opaque(def_id, substs) = ty.kind() {
let future_trait = self.tcx.require_lang_item(LangItem::Future, None);
// Future::Output
- let item_def_id = self
- .tcx
- .associated_items(future_trait)
- .in_definition_order()
- .next()
- .unwrap()
- .def_id;
+ let item_def_id = self.tcx.associated_item_def_ids(future_trait)[0];
let bounds = self.tcx.explicit_item_bounds(*def_id);
diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs
index e57075ed338..5e807b2f55c 100644
--- a/compiler/rustc_middle/src/ty/sty.rs
+++ b/compiler/rustc_middle/src/ty/sty.rs
@@ -2086,10 +2086,10 @@ impl<'tcx> TyS<'tcx> {
ty::Generator(_, substs, _) => substs.as_generator().discr_ty(tcx),
ty::Param(_) | ty::Projection(_) | ty::Opaque(..) | ty::Infer(ty::TyVar(_)) => {
- let assoc_items =
- tcx.associated_items(tcx.lang_items().discriminant_kind_trait().unwrap());
- let discriminant_def_id = assoc_items.in_definition_order().next().unwrap().def_id;
- tcx.mk_projection(discriminant_def_id, tcx.mk_substs([self.into()].iter()))
+ let assoc_items = tcx.associated_item_def_ids(
+ tcx.require_lang_item(hir::LangItem::DiscriminantKind, None),
+ );
+ tcx.mk_projection(assoc_items[0], tcx.intern_substs(&[self.into()]))
}
ty::Bool
diff --git a/compiler/rustc_middle/src/ty/util.rs b/compiler/rustc_middle/src/ty/util.rs
index 6b287445ff0..6e7acb244d1 100644
--- a/compiler/rustc_middle/src/ty/util.rs
+++ b/compiler/rustc_middle/src/ty/util.rs
@@ -325,9 +325,9 @@ impl<'tcx> TyCtxt<'tcx> {
let ty = self.type_of(adt_did);
let (did, constness) = self.find_map_relevant_impl(drop_trait, ty, |impl_did| {
- if let Some(item) = self.associated_items(impl_did).in_definition_order().next() {
+ if let Some(item_id) = self.associated_item_def_ids(impl_did).first() {
if validate(self, impl_did).is_ok() {
- return Some((item.def_id, self.impl_constness(impl_did)));
+ return Some((*item_id, self.impl_constness(impl_did)));
}
}
None
diff --git a/compiler/rustc_mir_dataflow/src/elaborate_drops.rs b/compiler/rustc_mir_dataflow/src/elaborate_drops.rs
index 7607ccc3aba..11856f6e047 100644
--- a/compiler/rustc_mir_dataflow/src/elaborate_drops.rs
+++ b/compiler/rustc_mir_dataflow/src/elaborate_drops.rs
@@ -604,7 +604,7 @@ where
debug!("destructor_call_block({:?}, {:?})", self, succ);
let tcx = self.tcx();
let drop_trait = tcx.require_lang_item(LangItem::Drop, None);
- let drop_fn = tcx.associated_items(drop_trait).in_definition_order().next().unwrap();
+ let drop_fn = tcx.associated_item_def_ids(drop_trait)[0];
let ty = self.place_ty(self.place);
let substs = tcx.mk_substs_trait(ty, &[]);
@@ -624,12 +624,7 @@ where
)],
terminator: Some(Terminator {
kind: TerminatorKind::Call {
- func: Operand::function_handle(
- tcx,
- drop_fn.def_id,
- substs,
- self.source_info.span,
- ),
+ func: Operand::function_handle(tcx, drop_fn, substs, self.source_info.span),
args: vec![Operand::Move(Place::from(ref_place))],
destination: Some((unit_temp, succ)),
cleanup: unwind.into_option(),
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
index 7d9568e0ca3..bdec7163cd9 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
@@ -2471,13 +2471,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
obligation.param_env,
);
- let item_def_id = self
- .tcx
- .associated_items(future_trait)
- .in_definition_order()
- .next()
- .unwrap()
- .def_id;
+ let item_def_id = self.tcx.associated_item_def_ids(future_trait)[0];
// `<T as Future>::Output`
let projection_ty = ty::ProjectionTy {
// `T`
diff --git a/compiler/rustc_typeck/src/check/closure.rs b/compiler/rustc_typeck/src/check/closure.rs
index f7accbb430c..4a41552a5fb 100644
--- a/compiler/rustc_typeck/src/check/closure.rs
+++ b/compiler/rustc_typeck/src/check/closure.rs
@@ -257,8 +257,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
if is_gen {
// Check that we deduce the signature from the `<_ as std::ops::Generator>::Return`
// associated item and not yield.
- let return_assoc_item =
- self.tcx.associated_items(gen_trait).in_definition_order().nth(1).unwrap().def_id;
+ let return_assoc_item = self.tcx.associated_item_def_ids(gen_trait)[1];
if return_assoc_item != projection.projection_def_id() {
debug!("deduce_sig_from_projection: not return assoc item of generator");
return None;
@@ -694,8 +693,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
// The `Future` trait has only one associted item, `Output`,
// so check that this is what we see.
- let output_assoc_item =
- self.tcx.associated_items(future_trait).in_definition_order().next().unwrap().def_id;
+ let output_assoc_item = self.tcx.associated_item_def_ids(future_trait)[0];
if output_assoc_item != predicate.projection_ty.item_def_id {
span_bug!(
cause_span,
diff --git a/compiler/rustc_typeck/src/check/intrinsic.rs b/compiler/rustc_typeck/src/check/intrinsic.rs
index b0cb8443bfb..6314f2aba4e 100644
--- a/compiler/rustc_typeck/src/check/intrinsic.rs
+++ b/compiler/rustc_typeck/src/check/intrinsic.rs
@@ -324,9 +324,10 @@ pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {
sym::unlikely => (0, vec![tcx.types.bool], tcx.types.bool),
sym::discriminant_value => {
- let assoc_items =
- tcx.associated_items(tcx.lang_items().discriminant_kind_trait().unwrap());
- let discriminant_def_id = assoc_items.in_definition_order().next().unwrap().def_id;
+ let assoc_items = tcx.associated_item_def_ids(
+ tcx.require_lang_item(hir::LangItem::DiscriminantKind, None),
+ );
+ let discriminant_def_id = assoc_items[0];
let br = ty::BoundRegion { var: ty::BoundVar::from_u32(0), kind: ty::BrAnon(0) };
(