Implement non-const Destruct trait in new solver

Author: compiler-errors

compiler/rustc_trait_selection/src/solve/assembly.rs

@@ -209,6 +209,11 @@ pub(super) trait GoalKind<'tcx>: TypeFoldable<TyCtxt<'tcx>> + Copy + Eq {
         ecx: &mut EvalCtxt<'_, 'tcx>,
         goal: Goal<'tcx, Self>,
     ) -> QueryResult<'tcx>;
+
+    fn consider_builtin_destruct_candidate(
+        ecx: &mut EvalCtxt<'_, 'tcx>,
+        goal: Goal<'tcx, Self>,
+    ) -> QueryResult<'tcx>;
 }
 
 impl<'tcx> EvalCtxt<'_, 'tcx> {
@@ -336,6 +341,8 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
             G::consider_builtin_unsize_candidate(self, goal)
         } else if lang_items.discriminant_kind_trait() == Some(trait_def_id) {
             G::consider_builtin_discriminant_kind_candidate(self, goal)
+        } else if lang_items.destruct_trait() == Some(trait_def_id) {
+            G::consider_builtin_destruct_candidate(self, goal)
         } else {
             Err(NoSolution)
         };

compiler/rustc_trait_selection/src/solve/project_goals.rs

@@ -483,6 +483,13 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> {
             ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
         })
     }
+
+    fn consider_builtin_destruct_candidate(
+        _ecx: &mut EvalCtxt<'_, 'tcx>,
+        goal: Goal<'tcx, Self>,
+    ) -> QueryResult<'tcx> {
+        bug!("`Destruct` does not have an associated type: {:?}", goal);
+    }
 }
 
 /// This behavior is also implemented in `rustc_ty_utils` and in the old `project` code.

compiler/rustc_trait_selection/src/solve/trait_goals.rs

@@ -513,6 +513,20 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> {
         // `DiscriminantKind` is automatically implemented for every type.
         ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
     }
+
+    fn consider_builtin_destruct_candidate(
+        ecx: &mut EvalCtxt<'_, 'tcx>,
+        goal: Goal<'tcx, Self>,
+    ) -> QueryResult<'tcx> {
+        if !goal.param_env.is_const() {
+            // `Destruct` is automatically implemented for every type in
+            // non-const environments.
+            ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
+        } else {
+            // FIXME(-Ztrait-solver=next): Implement this when we get const working in the new solver
+            Err(NoSolution)
+        }
+    }
 }
 
 impl<'tcx> EvalCtxt<'_, 'tcx> {

tests/ui/traits/new-solver/destruct.rs

@@ -0,0 +1,13 @@
+// compile-flags: -Ztrait-solver=next
+// check-pass
+
+#![feature(const_trait_impl)]
+
+fn foo(_: impl std::marker::Destruct) {}
+
+struct MyAdt;
+
+fn main() {
+    foo(1);
+    foo(MyAdt);
+}