1 files changed, 125 insertions, 75 deletions

diff --git a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
index 2badd66e3..9358ed612 100644
--- a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
+++ b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
@@ -62,15 +62,16 @@ pub(super) fn predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredic
 /// Returns a list of user-specified type predicates for the definition with ID `def_id`.
 /// N.B., this does not include any implied/inferred constraints.
 #[instrument(level = "trace", skip(tcx), ret)]
-fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
+fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::GenericPredicates<'_> {
     use rustc_hir::*;
 
-    let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
+    let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
     let node = tcx.hir().get(hir_id);
 
     let mut is_trait = None;
     let mut is_default_impl_trait = None;
 
+    // FIXME: Should ItemCtxt take a LocalDefId?
     let icx = ItemCtxt::new(tcx, def_id);
 
     const NO_GENERICS: &hir::Generics<'_> = hir::Generics::empty();
@@ -99,7 +100,7 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericP
             | ItemKind::Union(_, generics) => generics,
 
             ItemKind::Trait(_, _, generics, ..) | ItemKind::TraitAlias(generics, _) => {
-                is_trait = Some(ty::TraitRef::identity(tcx, def_id));
+                is_trait = Some(ty::TraitRef::identity(tcx, def_id.to_def_id()));
                 generics
             }
             ItemKind::OpaqueTy(OpaqueTy { generics, .. }) => generics,
@@ -124,7 +125,7 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericP
     // on a trait we need to add in the supertrait bounds and bounds found on
     // associated types.
     if let Some(_trait_ref) = is_trait {
-        predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().cloned());
+        predicates.extend(tcx.implied_predicates_of(def_id).predicates.iter().cloned());
     }
 
     // In default impls, we can assume that the self type implements
@@ -253,7 +254,7 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericP
     }
 
     if tcx.features().generic_const_exprs {
-        predicates.extend(const_evaluatable_predicates_of(tcx, def_id.expect_local()));
+        predicates.extend(const_evaluatable_predicates_of(tcx, def_id));
     }
 
     let mut predicates: Vec<_> = predicates.into_iter().collect();
@@ -392,18 +393,18 @@ pub(super) fn trait_explicit_predicates_and_bounds(
     def_id: LocalDefId,
 ) -> ty::GenericPredicates<'_> {
     assert_eq!(tcx.def_kind(def_id), DefKind::Trait);
-    gather_explicit_predicates_of(tcx, def_id.to_def_id())
+    gather_explicit_predicates_of(tcx, def_id)
 }
 
 pub(super) fn explicit_predicates_of<'tcx>(
     tcx: TyCtxt<'tcx>,
-    def_id: DefId,
+    def_id: LocalDefId,
 ) -> ty::GenericPredicates<'tcx> {
     let def_kind = tcx.def_kind(def_id);
     if let DefKind::Trait = def_kind {
         // Remove bounds on associated types from the predicates, they will be
         // returned by `explicit_item_bounds`.
-        let predicates_and_bounds = tcx.trait_explicit_predicates_and_bounds(def_id.expect_local());
+        let predicates_and_bounds = tcx.trait_explicit_predicates_and_bounds(def_id);
         let trait_identity_substs = InternalSubsts::identity_for_item(tcx, def_id);
 
         let is_assoc_item_ty = |ty: Ty<'tcx>| {
@@ -418,7 +419,8 @@ pub(super) fn explicit_predicates_of<'tcx>(
             //   supertrait).
             if let ty::Alias(ty::Projection, projection) = ty.kind() {
                 projection.substs == trait_identity_substs
-                    && tcx.associated_item(projection.def_id).container_id(tcx) == def_id
+                    && tcx.associated_item(projection.def_id).container_id(tcx)
+                        == def_id.to_def_id()
             } else {
                 false
             }
@@ -449,7 +451,7 @@ pub(super) fn explicit_predicates_of<'tcx>(
         }
     } else {
         if matches!(def_kind, DefKind::AnonConst) && tcx.lazy_normalization() {
-            let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
+            let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
             let parent_def_id = tcx.hir().get_parent_item(hir_id);
 
             if let Some(defaulted_param_def_id) =
@@ -532,89 +534,136 @@ pub(super) fn explicit_predicates_of<'tcx>(
     }
 }
 
+#[derive(Copy, Clone, Debug)]
+pub enum PredicateFilter {
+    /// All predicates may be implied by the trait
+    All,
+
+    /// Only traits that reference `Self: ..` are implied by the trait
+    SelfOnly,
+
+    /// Only traits that reference `Self: ..` and define an associated type
+    /// with the given ident are implied by the trait
+    SelfThatDefines(Ident),
+}
+
 /// Ensures that the super-predicates of the trait with a `DefId`
 /// of `trait_def_id` are converted and stored. This also ensures that
 /// the transitive super-predicates are converted.
 pub(super) fn super_predicates_of(
     tcx: TyCtxt<'_>,
-    trait_def_id: DefId,
+    trait_def_id: LocalDefId,
+) -> ty::GenericPredicates<'_> {
+    implied_predicates_with_filter(tcx, trait_def_id.to_def_id(), PredicateFilter::SelfOnly)
+}
+
+pub(super) fn super_predicates_that_define_assoc_type(
+    tcx: TyCtxt<'_>,
+    (trait_def_id, assoc_name): (DefId, Ident),
+) -> ty::GenericPredicates<'_> {
+    implied_predicates_with_filter(tcx, trait_def_id, PredicateFilter::SelfThatDefines(assoc_name))
+}
+
+pub(super) fn implied_predicates_of(
+    tcx: TyCtxt<'_>,
+    trait_def_id: LocalDefId,
 ) -> ty::GenericPredicates<'_> {
-    tcx.super_predicates_that_define_assoc_type((trait_def_id, None))
+    if tcx.is_trait_alias(trait_def_id.to_def_id()) {
+        implied_predicates_with_filter(tcx, trait_def_id.to_def_id(), PredicateFilter::All)
+    } else {
+        tcx.super_predicates_of(trait_def_id)
+    }
 }
 
 /// Ensures that the super-predicates of the trait with a `DefId`
 /// of `trait_def_id` are converted and stored. This also ensures that
 /// the transitive super-predicates are converted.
-pub(super) fn super_predicates_that_define_assoc_type(
+pub(super) fn implied_predicates_with_filter(
     tcx: TyCtxt<'_>,
-    (trait_def_id, assoc_name): (DefId, Option<Ident>),
+    trait_def_id: DefId,
+    filter: PredicateFilter,
 ) -> ty::GenericPredicates<'_> {
-    if trait_def_id.is_local() {
-        debug!("local trait");
-        let trait_hir_id = tcx.hir().local_def_id_to_hir_id(trait_def_id.expect_local());
-
-        let Node::Item(item) = tcx.hir().get(trait_hir_id) else {
-            bug!("trait_node_id {} is not an item", trait_hir_id);
-        };
+    let Some(trait_def_id) = trait_def_id.as_local() else {
+        // if `assoc_name` is None, then the query should've been redirected to an
+        // external provider
+        assert!(matches!(filter, PredicateFilter::SelfThatDefines(_)));
+        return tcx.super_predicates_of(trait_def_id);
+    };
 
-        let (generics, bounds) = match item.kind {
-            hir::ItemKind::Trait(.., generics, supertraits, _) => (generics, supertraits),
-            hir::ItemKind::TraitAlias(generics, supertraits) => (generics, supertraits),
-            _ => span_bug!(item.span, "super_predicates invoked on non-trait"),
-        };
+    let trait_hir_id = tcx.hir().local_def_id_to_hir_id(trait_def_id);
 
-        let icx = ItemCtxt::new(tcx, trait_def_id);
+    let Node::Item(item) = tcx.hir().get(trait_hir_id) else {
+        bug!("trait_node_id {} is not an item", trait_hir_id);
+    };
 
-        // Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`.
-        let self_param_ty = tcx.types.self_param;
-        let superbounds1 = if let Some(assoc_name) = assoc_name {
-            icx.astconv().compute_bounds_that_match_assoc_type(self_param_ty, bounds, assoc_name)
-        } else {
-            icx.astconv().compute_bounds(self_param_ty, bounds)
-        };
+    let (generics, bounds) = match item.kind {
+        hir::ItemKind::Trait(.., generics, supertraits, _) => (generics, supertraits),
+        hir::ItemKind::TraitAlias(generics, supertraits) => (generics, supertraits),
+        _ => span_bug!(item.span, "super_predicates invoked on non-trait"),
+    };
 
-        let superbounds1 = superbounds1.predicates();
-
-        // Convert any explicit superbounds in the where-clause,
-        // e.g., `trait Foo where Self: Bar`.
-        // In the case of trait aliases, however, we include all bounds in the where-clause,
-        // so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>`
-        // as one of its "superpredicates".
-        let is_trait_alias = tcx.is_trait_alias(trait_def_id);
-        let superbounds2 = icx.type_parameter_bounds_in_generics(
-            generics,
-            item.owner_id.def_id,
-            self_param_ty,
-            OnlySelfBounds(!is_trait_alias),
-            assoc_name,
-        );
+    let icx = ItemCtxt::new(tcx, trait_def_id);
+
+    let self_param_ty = tcx.types.self_param;
+    let (superbounds, where_bounds_that_match) = match filter {
+        PredicateFilter::All => (
+            // Convert the bounds that follow the colon (or equal in trait aliases)
+            icx.astconv().compute_bounds(self_param_ty, bounds),
+            // Also include all where clause bounds
+            icx.type_parameter_bounds_in_generics(
+                generics,
+                item.owner_id.def_id,
+                self_param_ty,
+                OnlySelfBounds(false),
+                None,
+            ),
+        ),
+        PredicateFilter::SelfOnly => (
+            // Convert the bounds that follow the colon (or equal in trait aliases)
+            icx.astconv().compute_bounds(self_param_ty, bounds),
+            // Include where clause bounds for `Self`
+            icx.type_parameter_bounds_in_generics(
+                generics,
+                item.owner_id.def_id,
+                self_param_ty,
+                OnlySelfBounds(true),
+                None,
+            ),
+        ),
+        PredicateFilter::SelfThatDefines(assoc_name) => (
+            // Convert the bounds that follow the colon (or equal) that reference the associated name
+            icx.astconv().compute_bounds_that_match_assoc_type(self_param_ty, bounds, assoc_name),
+            // Include where clause bounds for `Self` that reference the associated name
+            icx.type_parameter_bounds_in_generics(
+                generics,
+                item.owner_id.def_id,
+                self_param_ty,
+                OnlySelfBounds(true),
+                Some(assoc_name),
+            ),
+        ),
+    };
 
-        // Combine the two lists to form the complete set of superbounds:
-        let superbounds = &*tcx.arena.alloc_from_iter(superbounds1.into_iter().chain(superbounds2));
-        debug!(?superbounds);
+    // Combine the two lists to form the complete set of superbounds:
+    let implied_bounds = &*tcx
+        .arena
+        .alloc_from_iter(superbounds.predicates().into_iter().chain(where_bounds_that_match));
+    debug!(?implied_bounds);
 
+    // Now require that immediate supertraits are converted,
+    // which will, in turn, reach indirect supertraits.
+    if matches!(filter, PredicateFilter::SelfOnly) {
         // Now require that immediate supertraits are converted,
         // which will, in turn, reach indirect supertraits.
-        if assoc_name.is_none() {
-            // Now require that immediate supertraits are converted,
-            // which will, in turn, reach indirect supertraits.
-            for &(pred, span) in superbounds {
-                debug!("superbound: {:?}", pred);
-                if let ty::PredicateKind::Clause(ty::Clause::Trait(bound)) =
-                    pred.kind().skip_binder()
-                {
-                    tcx.at(span).super_predicates_of(bound.def_id());
-                }
+        for &(pred, span) in implied_bounds {
+            debug!("superbound: {:?}", pred);
+            if let ty::PredicateKind::Clause(ty::Clause::Trait(bound)) = pred.kind().skip_binder() {
+                tcx.at(span).super_predicates_of(bound.def_id());
             }
         }
-
-        ty::GenericPredicates { parent: None, predicates: superbounds }
-    } else {
-        // if `assoc_name` is None, then the query should've been redirected to an
-        // external provider
-        assert!(assoc_name.is_some());
-        tcx.super_predicates_of(trait_def_id)
     }
+
+    ty::GenericPredicates { parent: None, predicates: implied_bounds }
 }
 
 /// Returns the predicates defined on `item_def_id` of the form
@@ -622,7 +671,7 @@ pub(super) fn super_predicates_that_define_assoc_type(
 #[instrument(level = "trace", skip(tcx))]
 pub(super) fn type_param_predicates(
     tcx: TyCtxt<'_>,
-    (item_def_id, def_id, assoc_name): (DefId, LocalDefId, Ident),
+    (item_def_id, def_id, assoc_name): (LocalDefId, LocalDefId, Ident),
 ) -> ty::GenericPredicates<'_> {
     use rustc_hir::*;
 
@@ -637,21 +686,21 @@ pub(super) fn type_param_predicates(
     let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(def_id));
 
     // Don't look for bounds where the type parameter isn't in scope.
-    let parent = if item_def_id == param_owner.to_def_id() {
+    let parent = if item_def_id == param_owner {
         None
     } else {
-        tcx.generics_of(item_def_id).parent
+        tcx.generics_of(item_def_id).parent.map(|def_id| def_id.expect_local())
     };
 
     let mut result = parent
         .map(|parent| {
             let icx = ItemCtxt::new(tcx, parent);
-            icx.get_type_parameter_bounds(DUMMY_SP, def_id.to_def_id(), assoc_name)
+            icx.get_type_parameter_bounds(DUMMY_SP, def_id, assoc_name)
         })
         .unwrap_or_default();
     let mut extend = None;
 
-    let item_hir_id = tcx.hir().local_def_id_to_hir_id(item_def_id.expect_local());
+    let item_hir_id = tcx.hir().local_def_id_to_hir_id(item_def_id);
     let ast_generics = match tcx.hir().get(item_hir_id) {
         Node::TraitItem(item) => &item.generics,
 
@@ -673,7 +722,8 @@ pub(super) fn type_param_predicates(
                 ItemKind::Trait(_, _, generics, ..) => {
                     // Implied `Self: Trait` and supertrait bounds.
                     if param_id == item_hir_id {
-                        let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id);
+                        let identity_trait_ref =
+                            ty::TraitRef::identity(tcx, item_def_id.to_def_id());
                         extend =
                             Some((identity_trait_ref.without_const().to_predicate(tcx), item.span));
                     }