Find the builtin TypeCanAggregateDestroy in the FacetType for facet values

toolchain/check/convert.cpp

@@ -1225,9 +1225,6 @@ static auto PerformBuiltinConversion(
       // form. We can skip past the whole impl lookup step then and do that
       // here.
       //
-      // See also test:
-      // facet_access_type_converts_back_to_original_facet_value.carbon
-      //
       // TODO: This instruction is going to become a `SymbolicBindingType`, so
       // we'll need to handle that instead.
       auto const_type_inst_id =

toolchain/check/eval_inst.cpp

@@ -210,14 +210,12 @@ auto EvalConstantInst(Context& context, SemIR::FacetValue inst)
   if (auto access =
           context.insts().TryGetAs<SemIR::FacetAccessType>(inst.type_inst_id)) {
     auto bind_id = access->facet_value_inst_id;
-    auto bind = context.insts().Get(bind_id);
-    if (bind.Is<SemIR::BindSymbolicName>()) {
-      // If the FacetTypes are the same, then the FacetValue didn't add/remove
-      // any witnesses.
-      if (bind.type_id() == inst.type_id) {
-        return ConstantEvalResult::Existing(
-            context.constant_values().Get(bind_id));
-      }
+    auto bind = context.insts().TryGetAs<SemIR::BindSymbolicName>(bind_id);
+    // If the FacetTypes are the same, then the FacetValue didn't add/remove
+    // any witnesses.
+    if (bind.has_value() && bind->type_id == inst.type_id) {
+      return ConstantEvalResult::Existing(
+          context.constant_values().Get(bind_id));
     }
   }
 

toolchain/check/impl_lookup.cpp

@@ -545,8 +545,19 @@ static auto GetOrAddLookupImplWitness(Context& context, SemIR::LocId loc_id,
 // Returns true if the `Self` should impl `Destroy`.
 static auto TypeCanDestroy(Context& context,
                            SemIR::ConstantId query_self_const_id) -> bool {
-  auto inst = context.insts().Get(
-      context.constant_values().GetInstId(query_self_const_id));
+  auto inst = context.insts().Get(context.constant_values().GetInstId(
+      GetCanonicalizedFacetOrTypeValue(context, query_self_const_id)));
+
+  // For facet values, look if the FacetType provides the same.
+  if (auto facet_type =
+          context.types().TryGetAs<SemIR::FacetType>(inst.type_id())) {
+    const auto& info = context.facet_types().Get(facet_type->facet_type_id);
+    if (info.builtin_constraint_mask.HasAnyOf(
+            SemIR::BuiltinConstraintMask::TypeCanDestroy)) {
+      return true;
+    }
+  }
+
   CARBON_KIND_SWITCH(inst) {
     case CARBON_KIND(SemIR::ClassType class_type): {
       auto class_info = context.classes().Get(class_type.class_id);

toolchain/check/testdata/builtins/type/can_destroy.carbon

@@ -38,6 +38,21 @@ fn G() {
   //@dump-sem-ir-end
 }
 
+// --- symbolic.carbon
+library "[[@TEST_NAME]]";
+
+interface Z {}
+
+fn CanDestroy() -> type = "type.can_destroy";
+
+fn G(U:! CanDestroy()) {}
+
+fn F(T:! Z & CanDestroy()) {
+  // Requires a conversion (and thus impl lookup into `T`) since `T` and `U`
+  // have different (but compatible) facet types.
+  G(T);
+}
+
 // --- fail_incomplete.carbon
 library "[[@TEST_NAME]]";