Avoid fetching the opaque type origin when only "is this in the defining scope" is actually needed

compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs

@@ -730,8 +730,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             for ty in ret_ty.walk() {
                 if let ty::GenericArgKind::Type(ty) = ty.unpack()
                     && let ty::Alias(ty::Opaque, ty::AliasTy { def_id, .. }) = *ty.kind()
-                    && let Some(def_id) = def_id.as_local()
+                    && self.can_define_opaque_ty(def_id)
-                    && self.opaque_type_origin(def_id).is_some()
                 {
                     return None;
                 }

compiler/rustc_infer/src/infer/mod.rs

@@ -244,7 +244,7 @@ pub struct InferCtxt<'tcx> {
     pub tcx: TyCtxt<'tcx>,
 
     /// The `DefIds` of the opaque types that may have their hidden types constrained.
-    pub defining_opaque_types: &'tcx ty::List<LocalDefId>,
+    defining_opaque_types: &'tcx ty::List<LocalDefId>,
 
     /// Whether this inference context should care about region obligations in
     /// the root universe. Most notably, this is used during hir typeck as region
@@ -1232,6 +1232,12 @@ impl<'tcx> InferCtxt<'tcx> {
         self.inner.borrow().opaque_type_storage.opaque_types.clone()
     }
 
+    #[inline(always)]
+    pub fn can_define_opaque_ty(&self, id: impl Into<DefId>) -> bool {
+        let Some(id) = id.into().as_local() else { return false };
+        self.defining_opaque_types.contains(&id)
+    }
+
     pub fn ty_to_string(&self, t: Ty<'tcx>) -> String {
         self.resolve_vars_if_possible(t).to_string()
     }

compiler/rustc_infer/src/infer/opaque_types/mod.rs

@@ -4,7 +4,6 @@ use crate::errors::OpaqueHiddenTypeDiag;
 use crate::infer::{InferCtxt, InferOk};
 use crate::traits::{self, PredicateObligation};
 use hir::def_id::{DefId, LocalDefId};
-use hir::OpaqueTyOrigin;
 use rustc_data_structures::fx::FxIndexMap;
 use rustc_data_structures::sync::Lrc;
 use rustc_hir as hir;
@@ -54,16 +53,13 @@ impl<'tcx> InferCtxt<'tcx> {
         }
 
         let mut obligations = vec![];
-        let replace_opaque_type = |def_id: DefId| {
-            def_id.as_local().is_some_and(|def_id| self.opaque_type_origin(def_id).is_some())
-        };
         let value = value.fold_with(&mut BottomUpFolder {
             tcx: self.tcx,
             lt_op: |lt| lt,
             ct_op: |ct| ct,
             ty_op: |ty| match *ty.kind() {
                 ty::Alias(ty::Opaque, ty::AliasTy { def_id, .. })
-                    if replace_opaque_type(def_id) && !ty.has_escaping_bound_vars() =>
+                    if self.can_define_opaque_ty(def_id) && !ty.has_escaping_bound_vars() =>
                 {
                     let def_span = self.tcx.def_span(def_id);
                     let span = if span.contains(def_span) { def_span } else { span };
@@ -140,7 +136,7 @@ impl<'tcx> InferCtxt<'tcx> {
                 //     let x = || foo(); // returns the Opaque assoc with `foo`
                 // }
                 // ```
-                if self.opaque_type_origin(def_id).is_none() {
+                if !self.can_define_opaque_ty(def_id) {
                     return None;
                 }
 
@@ -150,8 +146,8 @@ impl<'tcx> InferCtxt<'tcx> {
                     // no one encounters it in practice.
                     // It does occur however in `fn fut() -> impl Future<Output = i32> { async { 42 } }`,
                     // where it is of no concern, so we only check for TAITs.
-                    if let Some(OpaqueTyOrigin::TyAlias { .. }) =
+                    if self.can_define_opaque_ty(b_def_id)
-                        b_def_id.as_local().and_then(|b_def_id| self.opaque_type_origin(b_def_id))
+                        && self.tcx.is_type_alias_impl_trait(b_def_id)
                     {
                         self.tcx.dcx().emit_err(OpaqueHiddenTypeDiag {
                             span: cause.span,
@@ -363,15 +359,6 @@ impl<'tcx> InferCtxt<'tcx> {
             op: |r| self.member_constraint(opaque_type_key, span, concrete_ty, r, &choice_regions),
         });
     }
-
-    /// Returns the origin of the opaque type `def_id` if we're currently
-    /// in its defining scope.
-    #[instrument(skip(self), level = "trace", ret)]
-    pub fn opaque_type_origin(&self, def_id: LocalDefId) -> Option<OpaqueTyOrigin> {
-        let origin = self.tcx.opaque_type_origin(def_id);
-
-        self.defining_opaque_types.contains(&def_id).then_some(origin)
-    }
 }
 
 /// Visitor that requires that (almost) all regions in the type visited outlive

compiler/rustc_trait_selection/src/solve/eval_ctxt/mod.rs

@@ -1,5 +1,5 @@
 use rustc_data_structures::stack::ensure_sufficient_stack;
-use rustc_hir::def_id::{DefId, LocalDefId};
+use rustc_hir::def_id::DefId;
 use rustc_infer::infer::at::ToTrace;
 use rustc_infer::infer::canonical::CanonicalVarValues;
 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
@@ -935,8 +935,8 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
         }
     }
 
-    pub(super) fn can_define_opaque_ty(&self, def_id: LocalDefId) -> bool {
+    pub(super) fn can_define_opaque_ty(&self, def_id: impl Into<DefId>) -> bool {
-        self.infcx.opaque_type_origin(def_id).is_some()
+        self.infcx.can_define_opaque_ty(def_id)
     }
 
     pub(super) fn insert_hidden_type(

compiler/rustc_trait_selection/src/solve/trait_goals.rs

@@ -155,10 +155,7 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> {
         if let ty::Alias(ty::Opaque, opaque_ty) = goal.predicate.self_ty().kind() {
             if matches!(goal.param_env.reveal(), Reveal::All)
                 || matches!(ecx.solver_mode(), SolverMode::Coherence)
-                || opaque_ty
+                || ecx.can_define_opaque_ty(opaque_ty.def_id)
-                    .def_id
-                    .as_local()
-                    .is_some_and(|def_id| ecx.can_define_opaque_ty(def_id))
             {
                 return Err(NoSolution);
             }