Remove some impl_trait_ref usages

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -245,7 +245,7 @@ pub(super) fn check_item<'tcx>(
         // won't be allowed unless there's an *explicit* implementation of `Send`
         // for `T`
         hir::ItemKind::Impl(ref impl_) => {
-            crate::impl_wf_check::check_impl_wf(tcx, def_id)?;
+            crate::impl_wf_check::check_impl_wf(tcx, def_id, impl_.of_trait.is_some())?;
             let mut res = Ok(());
             if let Some(of_trait) = impl_.of_trait {
                 let header = tcx.impl_trait_header(def_id).unwrap();

compiler/rustc_hir_analysis/src/collect/predicates_of.rs

@@ -350,9 +350,12 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen
     // before uses of `U`. This avoids false ambiguity errors
     // in trait checking. See `setup_constraining_predicates`
     // for details.
-    if let Node::Item(&Item { kind: ItemKind::Impl { .. }, .. }) = node {
+    if let Node::Item(&Item { kind: ItemKind::Impl(impl_), .. }) = node {
         let self_ty = tcx.type_of(def_id).instantiate_identity();
-        let trait_ref = tcx.impl_trait_ref(def_id).map(ty::EarlyBinder::instantiate_identity);
+        let trait_ref = impl_
+            .of_trait
+            .is_some()
+            .then(|| tcx.impl_trait_ref(def_id).unwrap().instantiate_identity());
         cgp::setup_constraining_predicates(
             tcx,
             &mut predicates,
@@ -460,11 +463,12 @@ fn const_evaluatable_predicates_of<'tcx>(
     }
 
     if let hir::Node::Item(item) = node
-        && let hir::ItemKind::Impl(_) = item.kind
+        && let hir::ItemKind::Impl(impl_) = item.kind
     {
-        if let Some(of_trait) = tcx.impl_trait_ref(def_id) {
+        if impl_.of_trait.is_some() {
             debug!("visit impl trait_ref");
-            of_trait.instantiate_identity().visit_with(&mut collector);
+            let trait_ref = tcx.impl_trait_ref(def_id).unwrap();
+            trait_ref.instantiate_identity().visit_with(&mut collector);
         }
 
         debug!("visit self_ty");

compiler/rustc_hir_analysis/src/impl_wf_check.rs

@@ -56,6 +56,7 @@ mod min_specialization;
 pub(crate) fn check_impl_wf(
     tcx: TyCtxt<'_>,
     impl_def_id: LocalDefId,
+    of_trait: bool,
 ) -> Result<(), ErrorGuaranteed> {
     debug_assert_matches!(tcx.def_kind(impl_def_id), DefKind::Impl { .. });
 
@@ -63,9 +64,9 @@ pub(crate) fn check_impl_wf(
     // since unconstrained type/const params cause ICEs in projection, so we want to
     // detect those specifically and project those to `TyKind::Error`.
     let mut res = tcx.ensure_ok().enforce_impl_non_lifetime_params_are_constrained(impl_def_id);
-    res = res.and(enforce_impl_lifetime_params_are_constrained(tcx, impl_def_id));
+    res = res.and(enforce_impl_lifetime_params_are_constrained(tcx, impl_def_id, of_trait));
 
-    if tcx.features().min_specialization() {
+    if of_trait && tcx.features().min_specialization() {
         res = res.and(check_min_specialization(tcx, impl_def_id));
     }
     res
@@ -74,6 +75,7 @@ pub(crate) fn check_impl_wf(
 pub(crate) fn enforce_impl_lifetime_params_are_constrained(
     tcx: TyCtxt<'_>,
     impl_def_id: LocalDefId,
+    of_trait: bool,
 ) -> Result<(), ErrorGuaranteed> {
     let impl_self_ty = tcx.type_of(impl_def_id).instantiate_identity();
 
@@ -83,7 +85,8 @@ pub(crate) fn enforce_impl_lifetime_params_are_constrained(
 
     let impl_generics = tcx.generics_of(impl_def_id);
     let impl_predicates = tcx.predicates_of(impl_def_id);
-    let impl_trait_ref = tcx.impl_trait_ref(impl_def_id).map(ty::EarlyBinder::instantiate_identity);
+    let impl_trait_ref =
+        of_trait.then(|| tcx.impl_trait_ref(impl_def_id).unwrap().instantiate_identity());
 
     impl_trait_ref.error_reported()?;
 

compiler/rustc_hir_analysis/src/impl_wf_check/min_specialization.rs

@@ -93,7 +93,7 @@ pub(super) fn check_min_specialization(
 }
 
 fn parent_specialization_node(tcx: TyCtxt<'_>, impl1_def_id: LocalDefId) -> Option<Node> {
-    let trait_ref = tcx.impl_trait_ref(impl1_def_id)?;
+    let trait_ref = tcx.impl_trait_ref(impl1_def_id).unwrap();
     let trait_def = tcx.trait_def(trait_ref.skip_binder().def_id);
 
     let impl2_node = trait_def.ancestors(tcx, impl1_def_id.to_def_id()).ok()?.nth(1)?;

compiler/rustc_hir_typeck/src/method/confirm.rs

@@ -18,8 +18,8 @@ use rustc_middle::ty::adjustment::{
     Adjust, Adjustment, AllowTwoPhase, AutoBorrow, AutoBorrowMutability, PointerCoercion,
 };
 use rustc_middle::ty::{
-    self, GenericArgs, GenericArgsRef, GenericParamDefKind, Ty, TyCtxt, TypeFoldable,
-    TypeVisitableExt, UserArgs,
+    self, AssocContainer, GenericArgs, GenericArgsRef, GenericParamDefKind, Ty, TyCtxt,
+    TypeFoldable, TypeVisitableExt, UserArgs,
 };
 use rustc_middle::{bug, span_bug};
 use rustc_span::{DUMMY_SP, Span};
@@ -272,7 +272,7 @@ impl<'a, 'tcx> ConfirmContext<'a, 'tcx> {
             probe::InherentImplPick => {
                 let impl_def_id = pick.item.container_id(self.tcx);
                 assert!(
-                    self.tcx.impl_trait_ref(impl_def_id).is_none(),
+                    matches!(pick.item.container, AssocContainer::InherentImpl),
                     "impl {impl_def_id:?} is not an inherent impl"
                 );
                 self.fresh_args_for_item(self.span, impl_def_id)

compiler/rustc_middle/src/ty/trait_def.rs

@@ -271,9 +271,7 @@ pub(super) fn traits_provider(tcx: TyCtxt<'_>, _: LocalCrate) -> &[DefId] {
 pub(super) fn trait_impls_in_crate_provider(tcx: TyCtxt<'_>, _: LocalCrate) -> &[DefId] {
     let mut trait_impls = Vec::new();
     for id in tcx.hir_free_items() {
-        if matches!(tcx.def_kind(id.owner_id), DefKind::Impl { .. })
-            && tcx.impl_trait_ref(id.owner_id).is_some()
-        {
+        if tcx.def_kind(id.owner_id) == (DefKind::Impl { of_trait: true }) {
             trait_impls.push(id.owner_id.to_def_id())
         }
     }

compiler/rustc_ty_utils/src/implied_bounds.rs

@@ -42,12 +42,14 @@ fn assumed_wf_types<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> &'tcx [(Ty<'
             ));
             tcx.arena.alloc_slice(&assumed_wf_types)
         }
-        DefKind::Impl { .. } => {
+        DefKind::Impl { of_trait } => {
             // Trait arguments and the self type for trait impls or only the self type for
             // inherent impls.
-            let tys = match tcx.impl_trait_ref(def_id) {
-                Some(trait_ref) => trait_ref.skip_binder().args.types().collect(),
-                None => vec![tcx.type_of(def_id).instantiate_identity()],
+            let tys = if of_trait {
+                let trait_ref = tcx.impl_trait_ref(def_id).unwrap();
+                trait_ref.skip_binder().args.types().collect()
+            } else {
+                vec![tcx.type_of(def_id).instantiate_identity()]
             };
 
             let mut impl_spans = impl_spans(tcx, def_id);

compiler/rustc_ty_utils/src/opaque_types.rs

@@ -62,24 +62,6 @@ impl<'tcx> OpaqueTypeCollector<'tcx> {
         self.span = old;
     }
 
-    fn parent_impl_trait_ref(&self) -> Option<ty::TraitRef<'tcx>> {
-        let parent = self.parent()?;
-        if matches!(self.tcx.def_kind(parent), DefKind::Impl { .. }) {
-            Some(self.tcx.impl_trait_ref(parent)?.instantiate_identity())
-        } else {
-            None
-        }
-    }
-
-    fn parent(&self) -> Option<LocalDefId> {
-        match self.tcx.def_kind(self.item) {
-            DefKind::AssocFn | DefKind::AssocTy | DefKind::AssocConst => {
-                Some(self.tcx.local_parent(self.item))
-            }
-            _ => None,
-        }
-    }
-
     #[instrument(level = "trace", skip(self))]
     fn collect_taits_declared_in_body(&mut self) {
         let body = self.tcx.hir_body_owned_by(self.item).value;
@@ -236,13 +218,13 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for OpaqueTypeCollector<'tcx> {
                 // This avoids having to do normalization of `Self::AssocTy` by only
                 // supporting the case of a method defining opaque types from assoc types
                 // in the same impl block.
-                if let Some(impl_trait_ref) = self.parent_impl_trait_ref() {
+                if let Some(parent) = self.tcx.trait_impl_of_assoc(self.item.to_def_id()) {
+                    let impl_trait_ref =
+                        self.tcx.impl_trait_ref(parent).unwrap().instantiate_identity();
                     // If the trait ref of the associated item and the impl differs,
                     // then we can't use the impl's identity args below, so
                     // just skip.
                     if alias_ty.trait_ref(self.tcx) == impl_trait_ref {
-                        let parent = self.parent().expect("we should have a parent here");
-
                         for &assoc in self.tcx.associated_items(parent).in_definition_order() {
                             trace!(?assoc);
                             if assoc.expect_trait_impl() != Ok(alias_ty.def_id) {