Do not treat vtable supertraits as distinct when bound with different bound vars

compiler-errors · compiler-errors · commit 571eba5e83cf · 2025-01-11T18:53:43.000Z
diff --git a/compiler/rustc_codegen_cranelift/src/constant.rs b/compiler/rustc_codegen_cranelift/src/constant.rs
@@ -245,7 +245,10 @@ pub(crate) fn data_id_for_vtable<'tcx>(
     ty: Ty<'tcx>,
     trait_ref: Option<Binder<'tcx, ExistentialTraitRef<'tcx>>>,
 ) -> DataId {
-    let alloc_id = tcx.vtable_allocation((ty, trait_ref));
+    let alloc_id = tcx.vtable_allocation((
+        ty,
+        trait_ref.map(|principal| tcx.instantiate_bound_regions_with_erased(principal)),
+    ));
     data_id_for_alloc_id(cx, module, alloc_id, Mutability::Not)
 }
 
diff --git a/compiler/rustc_codegen_gcc/src/common.rs b/compiler/rustc_codegen_gcc/src/common.rs
@@ -229,7 +229,12 @@ impl<'gcc, 'tcx> ConstCodegenMethods<'tcx> for CodegenCx<'gcc, 'tcx> {
                     GlobalAlloc::VTable(ty, dyn_ty) => {
                         let alloc = self
                             .tcx
-                            .global_alloc(self.tcx.vtable_allocation((ty, dyn_ty.principal())))
+                            .global_alloc(self.tcx.vtable_allocation((
+                                ty,
+                                dyn_ty.principal().map(|principal| {
+                                    self.tcx.instantiate_bound_regions_with_erased(principal)
+                                }),
+                            )))
                             .unwrap_memory();
                         let init = const_alloc_to_gcc(self, alloc);
                         self.static_addr_of(init, alloc.inner().align, None)
diff --git a/compiler/rustc_codegen_llvm/src/common.rs b/compiler/rustc_codegen_llvm/src/common.rs
@@ -308,7 +308,12 @@ impl<'ll, 'tcx> ConstCodegenMethods<'tcx> for CodegenCx<'ll, 'tcx> {
                     GlobalAlloc::VTable(ty, dyn_ty) => {
                         let alloc = self
                             .tcx
-                            .global_alloc(self.tcx.vtable_allocation((ty, dyn_ty.principal())))
+                            .global_alloc(self.tcx.vtable_allocation((
+                                ty,
+                                dyn_ty.principal().map(|principal| {
+                                    self.tcx.instantiate_bound_regions_with_erased(principal)
+                                }),
+                            )))
                             .unwrap_memory();
                         let init = const_alloc_to_llvm(self, alloc, /*static*/ false);
                         let value = self.static_addr_of(init, alloc.inner().align, None);
diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs b/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs
@@ -1406,7 +1406,7 @@ fn build_vtable_type_di_node<'ll, 'tcx>(
 
     let vtable_entries = if let Some(poly_trait_ref) = poly_trait_ref {
         let trait_ref = poly_trait_ref.with_self_ty(tcx, ty);
-        let trait_ref = tcx.erase_regions(trait_ref);
+        let trait_ref = tcx.erase_regions(tcx.instantiate_bound_regions_with_erased(trait_ref));
 
         tcx.vtable_entries(trait_ref)
     } else {
diff --git a/compiler/rustc_codegen_ssa/src/meth.rs b/compiler/rustc_codegen_ssa/src/meth.rs
@@ -96,24 +96,28 @@ fn dyn_trait_in_self(ty: Ty<'_>) -> Option<ty::PolyExistentialTraitRef<'_>> {
 pub(crate) fn get_vtable<'tcx, Cx: CodegenMethods<'tcx>>(
     cx: &Cx,
     ty: Ty<'tcx>,
-    trait_ref: Option<ty::PolyExistentialTraitRef<'tcx>>,
+    poly_trait_ref: Option<ty::PolyExistentialTraitRef<'tcx>>,
 ) -> Cx::Value {
     let tcx = cx.tcx();
 
     // Check the cache.
-    if let Some(&val) = cx.vtables().borrow().get(&(ty, trait_ref)) {
+    if let Some(&val) = cx.vtables().borrow().get(&(ty, poly_trait_ref)) {
         return val;
     }
 
+    // FIXME(trait_upcasting): Take a non-higher-ranked vtable as arg.
+    let trait_ref =
+        poly_trait_ref.map(|trait_ref| tcx.instantiate_bound_regions_with_erased(trait_ref));
+
     let vtable_alloc_id = tcx.vtable_allocation((ty, trait_ref));
     let vtable_allocation = tcx.global_alloc(vtable_alloc_id).unwrap_memory();
     let vtable_const = cx.const_data_from_alloc(vtable_allocation);
     let align = cx.data_layout().pointer_align.abi;
     let vtable = cx.static_addr_of(vtable_const, align, Some("vtable"));
 
-    cx.apply_vcall_visibility_metadata(ty, trait_ref, vtable);
-    cx.create_vtable_debuginfo(ty, trait_ref, vtable);
-    cx.vtables().borrow_mut().insert((ty, trait_ref), vtable);
+    cx.apply_vcall_visibility_metadata(ty, poly_trait_ref, vtable);
+    cx.create_vtable_debuginfo(ty, poly_trait_ref, vtable);
+    cx.vtables().borrow_mut().insert((ty, poly_trait_ref), vtable);
     vtable
 }
 
diff --git a/compiler/rustc_const_eval/src/interpret/cast.rs b/compiler/rustc_const_eval/src/interpret/cast.rs
@@ -419,8 +419,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                         self.tcx.supertrait_vtable_slot((src_pointee_ty, dest_pointee_ty));
                     let vtable_entries = self.vtable_entries(data_a.principal(), ty);
                     if let Some(entry_idx) = vptr_entry_idx {
-                        let Some(&ty::VtblEntry::TraitVPtr(upcast_trait_ref)) =
-                            vtable_entries.get(entry_idx)
+                        let Some(&ty::VtblEntry::TraitVPtr(_)) = vtable_entries.get(entry_idx)
                         else {
                             span_bug!(
                                 self.cur_span(),
@@ -429,13 +428,6 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                                 dest_pointee_ty
                             );
                         };
-                        let erased_trait_ref = upcast_trait_ref
-                            .map_bound(|r| ty::ExistentialTraitRef::erase_self_ty(*self.tcx, r));
-                        assert!(
-                            data_b
-                                .principal()
-                                .is_some_and(|b| self.eq_in_param_env(erased_trait_ref, b))
-                        );
                     } else {
                         // In this case codegen would keep using the old vtable. We don't want to do
                         // that as it has the wrong trait. The reason codegen can do this is that
diff --git a/compiler/rustc_const_eval/src/interpret/traits.rs b/compiler/rustc_const_eval/src/interpret/traits.rs
@@ -54,7 +54,8 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
     ) -> &'tcx [VtblEntry<'tcx>] {
         if let Some(trait_) = trait_ {
             let trait_ref = trait_.with_self_ty(*self.tcx, dyn_ty);
-            let trait_ref = self.tcx.erase_regions(trait_ref);
+            let trait_ref =
+                self.tcx.erase_regions(self.tcx.instantiate_bound_regions_with_erased(trait_ref));
             self.tcx.vtable_entries(trait_ref)
         } else {
             TyCtxt::COMMON_VTABLE_ENTRIES
diff --git a/compiler/rustc_hir_analysis/src/collect/dump.rs b/compiler/rustc_hir_analysis/src/collect/dump.rs
@@ -123,7 +123,7 @@ pub(crate) fn vtables<'tcx>(tcx: TyCtxt<'tcx>) {
                     );
                     continue;
                 };
-                tcx.vtable_entries(ty::Binder::dummy(trait_ref))
+                tcx.vtable_entries(trait_ref)
             }
             hir::ItemKind::TyAlias(_, _) => {
                 let ty = tcx.type_of(def_id).instantiate_identity();
@@ -149,7 +149,7 @@ pub(crate) fn vtables<'tcx>(tcx: TyCtxt<'tcx>) {
                 };
                 if let Some(principal) = data.principal() {
                     tcx.vtable_entries(
-                        principal.map_bound(|principal| principal.with_self_ty(tcx, ty)),
+                        tcx.instantiate_bound_regions_with_erased(principal).with_self_ty(tcx, ty),
                     )
                 } else {
                     TyCtxt::COMMON_VTABLE_ENTRIES
diff --git a/compiler/rustc_middle/src/query/keys.rs b/compiler/rustc_middle/src/query/keys.rs
@@ -95,7 +95,7 @@ impl<'tcx> Key for mir::interpret::GlobalId<'tcx> {
     }
 }
 
-impl<'tcx> Key for (Ty<'tcx>, Option<ty::PolyExistentialTraitRef<'tcx>>) {
+impl<'tcx> Key for (Ty<'tcx>, Option<ty::ExistentialTraitRef<'tcx>>) {
     type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, _: TyCtxt<'_>) -> Span {
diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs
@@ -1435,9 +1435,9 @@ rustc_queries! {
         desc { |tcx| "finding all existential vtable entries for trait `{}`", tcx.def_path_str(key) }
     }
 
-    query vtable_entries(key: ty::PolyTraitRef<'tcx>)
+    query vtable_entries(key: ty::TraitRef<'tcx>)
                         -> &'tcx [ty::VtblEntry<'tcx>] {
-        desc { |tcx| "finding all vtable entries for trait `{}`", tcx.def_path_str(key.def_id()) }
+        desc { |tcx| "finding all vtable entries for trait `{}`", tcx.def_path_str(key.def_id) }
     }
 
     query first_method_vtable_slot(key: ty::TraitRef<'tcx>) -> usize {
@@ -1449,7 +1449,7 @@ rustc_queries! {
             key.1, key.0 }
     }
 
-    query vtable_allocation(key: (Ty<'tcx>, Option<ty::PolyExistentialTraitRef<'tcx>>)) -> mir::interpret::AllocId {
+    query vtable_allocation(key: (Ty<'tcx>, Option<ty::ExistentialTraitRef<'tcx>>)) -> mir::interpret::AllocId {
         desc { |tcx| "vtable const allocation for <{} as {}>",
             key.0,
             key.1.map(|trait_ref| format!("{trait_ref}")).unwrap_or("_".to_owned())
diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
@@ -849,7 +849,12 @@ where
                     }
 
                     let mk_dyn_vtable = |principal: Option<ty::PolyExistentialTraitRef<'tcx>>| {
-                        let min_count = ty::vtable_min_entries(tcx, principal);
+                        let min_count = ty::vtable_min_entries(
+                            tcx,
+                            principal.map(|principal| {
+                                tcx.instantiate_bound_regions_with_erased(principal)
+                            }),
+                        );
                         Ty::new_imm_ref(
                             tcx,
                             tcx.lifetimes.re_static,
diff --git a/compiler/rustc_middle/src/ty/vtable.rs b/compiler/rustc_middle/src/ty/vtable.rs
@@ -4,7 +4,7 @@ use rustc_ast::Mutability;
 use rustc_macros::HashStable;
 
 use crate::mir::interpret::{AllocId, Allocation, CTFE_ALLOC_SALT, Pointer, Scalar, alloc_range};
-use crate::ty::{self, Instance, PolyTraitRef, Ty, TyCtxt};
+use crate::ty::{self, Instance, TraitRef, Ty, TyCtxt};
 
 #[derive(Clone, Copy, PartialEq, HashStable)]
 pub enum VtblEntry<'tcx> {
@@ -19,7 +19,7 @@ pub enum VtblEntry<'tcx> {
     /// dispatchable associated function
     Method(Instance<'tcx>),
     /// pointer to a separate supertrait vtable, can be used by trait upcasting coercion
-    TraitVPtr(PolyTraitRef<'tcx>),
+    TraitVPtr(TraitRef<'tcx>),
 }
 
 impl<'tcx> fmt::Debug for VtblEntry<'tcx> {
@@ -56,15 +56,15 @@ pub const COMMON_VTABLE_ENTRIES_ALIGN: usize = 2;
 // function is an accurate approximation. We verify this when actually computing the vtable below.
 pub(crate) fn vtable_min_entries<'tcx>(
     tcx: TyCtxt<'tcx>,
-    trait_ref: Option<ty::PolyExistentialTraitRef<'tcx>>,
+    trait_ref: Option<ty::ExistentialTraitRef<'tcx>>,
 ) -> usize {
     let mut count = TyCtxt::COMMON_VTABLE_ENTRIES.len();
     let Some(trait_ref) = trait_ref else {
         return count;
     };
 
     // This includes self in supertraits.
-    for def_id in tcx.supertrait_def_ids(trait_ref.def_id()) {
+    for def_id in tcx.supertrait_def_ids(trait_ref.def_id) {
         count += tcx.own_existential_vtable_entries(def_id).len();
     }
 
@@ -80,7 +80,7 @@ pub(crate) fn vtable_min_entries<'tcx>(
 /// initial contents.)
 pub(super) fn vtable_allocation_provider<'tcx>(
     tcx: TyCtxt<'tcx>,
-    key: (Ty<'tcx>, Option<ty::PolyExistentialTraitRef<'tcx>>),
+    key: (Ty<'tcx>, Option<ty::ExistentialTraitRef<'tcx>>),
 ) -> AllocId {
     let (ty, poly_trait_ref) = key;
 
@@ -115,7 +115,7 @@ pub(super) fn vtable_allocation_provider<'tcx>(
 
     for (idx, entry) in vtable_entries.iter().enumerate() {
         let idx: u64 = u64::try_from(idx).unwrap();
-        let scalar = match entry {
+        let scalar = match *entry {
             VtblEntry::MetadataDropInPlace => {
                 if ty.needs_drop(tcx, ty::TypingEnv::fully_monomorphized()) {
                     let instance = ty::Instance::resolve_drop_in_place(tcx, ty);
@@ -131,13 +131,12 @@ pub(super) fn vtable_allocation_provider<'tcx>(
             VtblEntry::Vacant => continue,
             VtblEntry::Method(instance) => {
                 // Prepare the fn ptr we write into the vtable.
-                let fn_alloc_id = tcx.reserve_and_set_fn_alloc(*instance, CTFE_ALLOC_SALT);
+                let fn_alloc_id = tcx.reserve_and_set_fn_alloc(instance, CTFE_ALLOC_SALT);
                 let fn_ptr = Pointer::from(fn_alloc_id);
                 Scalar::from_pointer(fn_ptr, &tcx)
             }
             VtblEntry::TraitVPtr(trait_ref) => {
-                let super_trait_ref = trait_ref
-                    .map_bound(|trait_ref| ty::ExistentialTraitRef::erase_self_ty(tcx, trait_ref));
+                let super_trait_ref = ty::ExistentialTraitRef::erase_self_ty(tcx, trait_ref);
                 let supertrait_alloc_id = tcx.vtable_allocation((ty, Some(super_trait_ref)));
                 let vptr = Pointer::from(supertrait_alloc_id);
                 Scalar::from_pointer(vptr, &tcx)
diff --git a/compiler/rustc_monomorphize/src/collector.rs b/compiler/rustc_monomorphize/src/collector.rs
@@ -1138,11 +1138,12 @@ fn create_mono_items_for_vtable_methods<'tcx>(
         bug!("create_mono_items_for_vtable_methods: {trait_ty:?} not a trait type");
     };
     if let Some(principal) = trait_ty.principal() {
-        let poly_trait_ref = principal.with_self_ty(tcx, impl_ty);
-        assert!(!poly_trait_ref.has_escaping_bound_vars());
+        let trait_ref =
+            tcx.instantiate_bound_regions_with_erased(principal.with_self_ty(tcx, impl_ty));
+        assert!(!trait_ref.has_escaping_bound_vars());
 
         // Walk all methods of the trait, including those of its supertraits
-        let entries = tcx.vtable_entries(poly_trait_ref);
+        let entries = tcx.vtable_entries(trait_ref);
         debug!(?entries);
         let methods = entries
             .iter()
@@ -1197,7 +1198,12 @@ fn collect_alloc<'tcx>(tcx: TyCtxt<'tcx>, alloc_id: AllocId, output: &mut MonoIt
             }
         }
         GlobalAlloc::VTable(ty, dyn_ty) => {
-            let alloc_id = tcx.vtable_allocation((ty, dyn_ty.principal()));
+            let alloc_id = tcx.vtable_allocation((
+                ty,
+                dyn_ty
+                    .principal()
+                    .map(|principal| tcx.instantiate_bound_regions_with_erased(principal)),
+            ));
             collect_alloc(tcx, alloc_id, output)
         }
     }
diff --git a/compiler/rustc_smir/src/rustc_smir/context.rs b/compiler/rustc_smir/src/rustc_smir/context.rs
@@ -751,7 +751,9 @@ impl<'tcx> Context for TablesWrapper<'tcx> {
         let tcx = tables.tcx;
         let alloc_id = tables.tcx.vtable_allocation((
             ty.internal(&mut *tables, tcx),
-            trait_ref.internal(&mut *tables, tcx),
+            trait_ref
+                .internal(&mut *tables, tcx)
+                .map(|principal| tcx.instantiate_bound_regions_with_erased(principal)),
         ));
         Some(alloc_id.stable(&mut *tables))
     }
diff --git a/compiler/rustc_trait_selection/src/traits/vtable.rs b/compiler/rustc_trait_selection/src/traits/vtable.rs
diff --git a/tests/ui/traits/trait-upcasting/multiple-supertraits-modulo-binder-vtable.stderr b/tests/ui/traits/trait-upcasting/multiple-supertraits-modulo-binder-vtable.stderr
diff --git a/tests/ui/traits/trait-upcasting/multiple-supertraits-modulo-binder.rs b/tests/ui/traits/trait-upcasting/multiple-supertraits-modulo-binder.rs
diff --git a/tests/ui/traits/trait-upcasting/multiple-supertraits-modulo-binder.run.stdout b/tests/ui/traits/trait-upcasting/multiple-supertraits-modulo-binder.run.stdout

Original file line number	Diff line number	Diff line change
`@@ -95,7 +95,7 @@ impl<'tcx> Key for mir::interpret::GlobalId<'tcx> {`
`95`	`95`	`}`
`96`	`96`	`}`
`97`	`97`
`98`		`-impl<'tcx> Key for (Ty<'tcx>, Option<ty::PolyExistentialTraitRef<'tcx>>) {`
	`98`	`+impl<'tcx> Key for (Ty<'tcx>, Option<ty::ExistentialTraitRef<'tcx>>) {`
`99`	`99`	`type Cache<V> = DefaultCache<Self, V>;`
`100`	`100`
`101`	`101`	`fn default_span(&self, _: TyCtxt<'_>) -> Span {`
Original file line number	Diff line number	Diff line change
`@@ -1435,9 +1435,9 @@ rustc_queries! {`
`1435`	`1435`	desc { \|tcx\| "finding all existential vtable entries for trait `{}`", tcx.def_path_str(key) }
`1436`	`1436`	`}`
`1437`	`1437`
`1438`		`- query vtable_entries(key: ty::PolyTraitRef<'tcx>)`
	`1438`	`+ query vtable_entries(key: ty::TraitRef<'tcx>)`
`1439`	`1439`	`-> &'tcx [ty::VtblEntry<'tcx>] {`
`1440`		- desc { \|tcx\| "finding all vtable entries for trait `{}`", tcx.def_path_str(key.def_id()) }
	`1440`	+ desc { \|tcx\| "finding all vtable entries for trait `{}`", tcx.def_path_str(key.def_id) }
`1441`	`1441`	`}`
`1442`	`1442`
`1443`	`1443`	`query first_method_vtable_slot(key: ty::TraitRef<'tcx>) -> usize {`
`@@ -1449,7 +1449,7 @@ rustc_queries! {`
`1449`	`1449`	`key.1, key.0 }`
`1450`	`1450`	`}`
`1451`	`1451`
`1452`		`- query vtable_allocation(key: (Ty<'tcx>, Option<ty::PolyExistentialTraitRef<'tcx>>)) -> mir::interpret::AllocId {`
	`1452`	`+ query vtable_allocation(key: (Ty<'tcx>, Option<ty::ExistentialTraitRef<'tcx>>)) -> mir::interpret::AllocId {`
`1453`	`1453`	`desc { \|tcx\| "vtable const allocation for <{} as {}>",`
`1454`	`1454`	`key.0,`
`1455`	`1455`	`key.1.map(\|trait_ref\| format!("{trait_ref}")).unwrap_or("_".to_owned())`