Merge from rustc

8 files changed, 339 insertions, 43 deletions

diff --git a/compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs b/compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs
index d279590d45a..53300c95fa7 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs
@@ -2294,7 +2294,7 @@ impl<'tcx> ObligationCause<'tcx> {
                 {
                     FailureCode::Error0644
                 }
-                TypeError::IntrinsicCast => FailureCode::Error0308,
+                TypeError::IntrinsicCast | TypeError::ForceInlineCast => FailureCode::Error0308,
                 _ => FailureCode::Error0308,
             },
         }
@@ -2360,8 +2360,11 @@ impl<'tcx> ObligationCause<'tcx> {
                 {
                     ObligationCauseFailureCode::ClosureSelfref { span }
                 }
+                TypeError::ForceInlineCast => {
+                    ObligationCauseFailureCode::CantCoerceForceInline { span, subdiags }
+                }
                 TypeError::IntrinsicCast => {
-                    ObligationCauseFailureCode::CantCoerce { span, subdiags }
+                    ObligationCauseFailureCode::CantCoerceIntrinsic { span, subdiags }
                 }
                 _ => ObligationCauseFailureCode::Generic { span, subdiags },
             },
diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
index f9a30408326..405c26b5b3b 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
@@ -27,7 +27,7 @@ use rustc_middle::ty::{
     self, ToPolyTraitRef, TraitRef, Ty, TyCtxt, TypeFoldable, TypeVisitableExt, Upcast,
 };
 use rustc_middle::{bug, span_bug};
-use rustc_span::{BytePos, DUMMY_SP, Span, Symbol, sym};
+use rustc_span::{BytePos, DUMMY_SP, STDLIB_STABLE_CRATES, Span, Symbol, sym};
 use tracing::{debug, instrument};
 
 use super::on_unimplemented::{AppendConstMessage, OnUnimplementedNote};
@@ -114,7 +114,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                         //
                         // We rely on a few heuristics to identify cases where this root
                         // obligation is more important than the leaf obligation:
-                        let (main_trait_predicate, o) = if let ty::PredicateKind::Clause(
+                        let (main_trait_predicate, main_obligation) = if let ty::PredicateKind::Clause(
                             ty::ClauseKind::Trait(root_pred)
                         ) = root_obligation.predicate.kind().skip_binder()
                             && !leaf_trait_predicate.self_ty().skip_binder().has_escaping_bound_vars()
@@ -199,7 +199,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                             notes,
                             parent_label,
                             append_const_msg,
-                        } = self.on_unimplemented_note(main_trait_predicate, o, &mut long_ty_file);
+                        } = self.on_unimplemented_note(main_trait_predicate, main_obligation, &mut long_ty_file);
 
                         let have_alt_message = message.is_some() || label.is_some();
                         let is_try_conversion = self.is_try_conversion(span, main_trait_ref.def_id());
@@ -520,7 +520,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                             match obligation.cause.span.ctxt().outer_expn_data().macro_def_id {
                                 Some(macro_def_id) => {
                                     let crate_name = tcx.crate_name(macro_def_id.krate);
-                                    crate_name == sym::std || crate_name == sym::core
+                                    STDLIB_STABLE_CRATES.contains(&crate_name)
                                 }
                                 None => false,
                             };
@@ -538,23 +538,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                     }
 
                     ty::PredicateKind::Clause(ty::ClauseKind::HostEffect(predicate)) => {
-                        // FIXME(const_trait_impl): We should recompute the predicate with `~const`
-                        // if it's `const`, and if it holds, explain that this bound only
-                        // *conditionally* holds. If that fails, we should also do selection
-                        // to drill this down to an impl or built-in source, so we can
-                        // point at it and explain that while the trait *is* implemented,
-                        // that implementation is not const.
-                        let err_msg = self.get_standard_error_message(
-                            bound_predicate.rebind(ty::TraitPredicate {
-                                trait_ref: predicate.trait_ref,
-                                polarity: ty::PredicatePolarity::Positive,
-                            }),
-                            None,
-                            Some(predicate.constness),
-                            None,
-                            String::new(),
-                        );
-                        struct_span_code_err!(self.dcx(), span, E0277, "{}", err_msg)
+                        self.report_host_effect_error(bound_predicate.rebind(predicate), obligation.param_env, span)
                     }
 
                     ty::PredicateKind::Subtype(predicate) => {
@@ -753,7 +737,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                     applied_do_not_recommend = true;
                 }
             }
-            if let Some((parent_cause, _parent_pred)) = base_cause.parent() {
+            if let Some(parent_cause) = base_cause.parent() {
                 base_cause = parent_cause.clone();
             } else {
                 break;
@@ -763,6 +747,41 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
         applied_do_not_recommend
     }
 
+    fn report_host_effect_error(
+        &self,
+        predicate: ty::Binder<'tcx, ty::HostEffectPredicate<'tcx>>,
+        param_env: ty::ParamEnv<'tcx>,
+        span: Span,
+    ) -> Diag<'a> {
+        // FIXME(const_trait_impl): We should recompute the predicate with `~const`
+        // if it's `const`, and if it holds, explain that this bound only
+        // *conditionally* holds. If that fails, we should also do selection
+        // to drill this down to an impl or built-in source, so we can
+        // point at it and explain that while the trait *is* implemented,
+        // that implementation is not const.
+        let trait_ref = predicate.map_bound(|predicate| ty::TraitPredicate {
+            trait_ref: predicate.trait_ref,
+            polarity: ty::PredicatePolarity::Positive,
+        });
+        let err_msg = self.get_standard_error_message(
+            trait_ref,
+            None,
+            Some(predicate.constness()),
+            None,
+            String::new(),
+        );
+        let mut diag = struct_span_code_err!(self.dcx(), span, E0277, "{}", err_msg);
+        if !self.predicate_may_hold(&Obligation::new(
+            self.tcx,
+            ObligationCause::dummy(),
+            param_env,
+            trait_ref,
+        )) {
+            diag.downgrade_to_delayed_bug();
+        }
+        diag
+    }
+
     fn emit_specialized_closure_kind_error(
         &self,
         obligation: &PredicateObligation<'tcx>,
@@ -778,7 +797,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                 trait_ref.skip_binder().args.type_at(1).to_opt_closure_kind()
             && !found_kind.extends(expected_kind)
         {
-            if let Some((_, Some(parent))) = obligation.cause.code().parent() {
+            if let Some((_, Some(parent))) = obligation.cause.code().parent_with_predicate() {
                 // If we have a derived obligation, then the parent will be a `AsyncFn*` goal.
                 trait_ref = parent.to_poly_trait_ref();
             } else if let &ObligationCauseCode::FunctionArg { arg_hir_id, .. } =
@@ -926,7 +945,8 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
         let Some(typeck) = &self.typeck_results else {
             return false;
         };
-        let Some((ObligationCauseCode::QuestionMark, Some(y))) = obligation.cause.code().parent()
+        let Some((ObligationCauseCode::QuestionMark, Some(y))) =
+            obligation.cause.code().parent_with_predicate()
         else {
             return false;
         };
@@ -1179,7 +1199,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
 
         let mut code = obligation.cause.code();
         let mut pred = obligation.predicate.as_trait_clause();
-        while let Some((next_code, next_pred)) = code.parent() {
+        while let Some((next_code, next_pred)) = code.parent_with_predicate() {
             if let Some(pred) = pred {
                 self.enter_forall(pred, |pred| {
                     diag.note(format!(
@@ -2095,7 +2115,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
         let mut code = obligation.cause.code();
         let mut trait_pred = trait_predicate;
         let mut peeled = false;
-        while let Some((parent_code, parent_trait_pred)) = code.parent() {
+        while let Some((parent_code, parent_trait_pred)) = code.parent_with_predicate() {
             code = parent_code;
             if let Some(parent_trait_pred) = parent_trait_pred {
                 trait_pred = parent_trait_pred;
diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs
index 007a220ae69..9d85ca1dd4d 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs
@@ -464,7 +464,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
 
             // Get the root obligation, since the leaf obligation we have may be unhelpful (#87437)
             let mut real_trait_pred = trait_pred;
-            while let Some((parent_code, parent_trait_pred)) = code.parent() {
+            while let Some((parent_code, parent_trait_pred)) = code.parent_with_predicate() {
                 code = parent_code;
                 if let Some(parent_trait_pred) = parent_trait_pred {
                     real_trait_pred = parent_trait_pred;
@@ -1447,7 +1447,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
         let mut span = obligation.cause.span;
         let mut trait_pred = trait_pred;
         let mut code = obligation.cause.code();
-        while let Some((c, Some(parent_trait_pred))) = code.parent() {
+        while let Some((c, Some(parent_trait_pred))) = code.parent_with_predicate() {
             // We want the root obligation, in order to detect properly handle
             // `for _ in &mut &mut vec![] {}`.
             code = c;
@@ -3470,6 +3470,59 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                     )
                 });
             }
+            ObligationCauseCode::ImplDerivedHost(ref data) => {
+                let self_ty =
+                    self.resolve_vars_if_possible(data.derived.parent_host_pred.self_ty());
+                let msg = format!(
+                    "required for `{self_ty}` to implement `{} {}`",
+                    data.derived.parent_host_pred.skip_binder().constness,
+                    data.derived
+                        .parent_host_pred
+                        .map_bound(|pred| pred.trait_ref)
+                        .print_only_trait_path(),
+                );
+                match tcx.hir().get_if_local(data.impl_def_id) {
+                    Some(Node::Item(hir::Item {
+                        kind: hir::ItemKind::Impl(hir::Impl { of_trait, self_ty, .. }),
+                        ..
+                    })) => {
+                        let mut spans = vec![self_ty.span];
+                        spans.extend(of_trait.as_ref().map(|t| t.path.span));
+                        let mut spans: MultiSpan = spans.into();
+                        spans.push_span_label(data.span, "unsatisfied trait bound introduced here");
+                        err.span_note(spans, msg);
+                    }
+                    _ => {
+                        err.note(msg);
+                    }
+                }
+                ensure_sufficient_stack(|| {
+                    self.note_obligation_cause_code(
+                        body_id,
+                        err,
+                        data.derived.parent_host_pred,
+                        param_env,
+                        &data.derived.parent_code,
+                        obligated_types,
+                        seen_requirements,
+                        long_ty_file,
+                    )
+                });
+            }
+            ObligationCauseCode::BuiltinDerivedHost(ref data) => {
+                ensure_sufficient_stack(|| {
+                    self.note_obligation_cause_code(
+                        body_id,
+                        err,
+                        data.parent_host_pred,
+                        param_env,
+                        &data.parent_code,
+                        obligated_types,
+                        seen_requirements,
+                        long_ty_file,
+                    )
+                });
+            }
             ObligationCauseCode::WellFormedDerived(ref data) => {
                 let parent_trait_ref = self.resolve_vars_if_possible(data.parent_trait_pred);
                 let parent_predicate = parent_trait_ref;
diff --git a/compiler/rustc_trait_selection/src/errors.rs b/compiler/rustc_trait_selection/src/errors.rs
index a8fddff4e4a..53a4e5031c6 100644
--- a/compiler/rustc_trait_selection/src/errors.rs
+++ b/compiler/rustc_trait_selection/src/errors.rs
@@ -1729,8 +1729,15 @@ pub enum ObligationCauseFailureCode {
         #[primary_span]
         span: Span,
     },
-    #[diag(trait_selection_oc_cant_coerce, code = E0308)]
-    CantCoerce {
+    #[diag(trait_selection_oc_cant_coerce_force_inline, code = E0308)]
+    CantCoerceForceInline {
+        #[primary_span]
+        span: Span,
+        #[subdiagnostic]
+        subdiags: Vec<TypeErrorAdditionalDiags>,
+    },
+    #[diag(trait_selection_oc_cant_coerce_intrinsic, code = E0308)]
+    CantCoerceIntrinsic {
         #[primary_span]
         span: Span,
         #[subdiagnostic]
diff --git a/compiler/rustc_trait_selection/src/infer.rs b/compiler/rustc_trait_selection/src/infer.rs
index ee708564a80..f373706b296 100644
--- a/compiler/rustc_trait_selection/src/infer.rs
+++ b/compiler/rustc_trait_selection/src/infer.rs
@@ -47,6 +47,12 @@ impl<'tcx> InferCtxt<'tcx> {
         traits::type_known_to_meet_bound_modulo_regions(self, param_env, ty, copy_def_id)
     }
 
+    fn type_is_clone_modulo_regions(&self, param_env: ty::ParamEnv<'tcx>, ty: Ty<'tcx>) -> bool {
+        let ty = self.resolve_vars_if_possible(ty);
+        let clone_def_id = self.tcx.require_lang_item(LangItem::Clone, None);
+        traits::type_known_to_meet_bound_modulo_regions(self, param_env, ty, clone_def_id)
+    }
+
     fn type_is_sized_modulo_regions(&self, param_env: ty::ParamEnv<'tcx>, ty: Ty<'tcx>) -> bool {
         let lang_item = self.tcx.require_lang_item(LangItem::Sized, None);
         traits::type_known_to_meet_bound_modulo_regions(self, param_env, ty, lang_item)
diff --git a/compiler/rustc_trait_selection/src/solve/fulfill.rs b/compiler/rustc_trait_selection/src/solve/fulfill.rs
index 2b2623a050e..7db0f2bb5a7 100644
--- a/compiler/rustc_trait_selection/src/solve/fulfill.rs
+++ b/compiler/rustc_trait_selection/src/solve/fulfill.rs
@@ -10,9 +10,9 @@ use rustc_infer::traits::{
     self, FromSolverError, MismatchedProjectionTypes, Obligation, ObligationCause,
     ObligationCauseCode, PredicateObligation, PredicateObligations, SelectionError, TraitEngine,
 };
-use rustc_middle::bug;
 use rustc_middle::ty::error::{ExpectedFound, TypeError};
 use rustc_middle::ty::{self, TyCtxt};
+use rustc_middle::{bug, span_bug};
 use rustc_next_trait_solver::solve::{GenerateProofTree, HasChanged, SolverDelegateEvalExt as _};
 use tracing::{instrument, trace};
 
@@ -258,6 +258,23 @@ fn fulfillment_error_for_no_solution<'tcx>(
                 MismatchedProjectionTypes { err: TypeError::Mismatch },
             )
         }
+        ty::PredicateKind::Clause(ty::ClauseKind::ConstArgHasType(ct, expected_ty)) => {
+            let ct_ty = match ct.kind() {
+                ty::ConstKind::Unevaluated(uv) => {
+                    infcx.tcx.type_of(uv.def).instantiate(infcx.tcx, uv.args)
+                }
+                ty::ConstKind::Param(param_ct) => param_ct.find_ty_from_env(obligation.param_env),
+                _ => span_bug!(
+                    obligation.cause.span,
+                    "ConstArgHasWrongType failed but we don't know how to compute type"
+                ),
+            };
+            FulfillmentErrorCode::Select(SelectionError::ConstArgHasWrongType {
+                ct,
+                ct_ty,
+                expected_ty,
+            })
+        }
         ty::PredicateKind::NormalizesTo(..) => {
             FulfillmentErrorCode::Project(MismatchedProjectionTypes { err: TypeError::Mismatch })
         }
@@ -413,6 +430,7 @@ impl<'tcx> BestObligation<'tcx> {
                                     matches!(
                                         nested_goal.source(),
                                         GoalSource::ImplWhereBound
+                                            | GoalSource::AliasBoundConstCondition
                                             | GoalSource::InstantiateHigherRanked
                                             | GoalSource::AliasWellFormed
                                     ) && match self.consider_ambiguities {
@@ -474,8 +492,11 @@ impl<'tcx> ProofTreeVisitor<'tcx> for BestObligation<'tcx> {
         // for normalizes-to.
         let pred_kind = goal.goal().predicate.kind();
         let child_mode = match pred_kind.skip_binder() {
-            ty::PredicateKind::Clause(ty::ClauseKind::Trait(parent_trait_pred)) => {
-                ChildMode::Trait(pred_kind.rebind(parent_trait_pred))
+            ty::PredicateKind::Clause(ty::ClauseKind::Trait(pred)) => {
+                ChildMode::Trait(pred_kind.rebind(pred))
+            }
+            ty::PredicateKind::Clause(ty::ClauseKind::HostEffect(pred)) => {
+                ChildMode::Host(pred_kind.rebind(pred))
             }
             ty::PredicateKind::NormalizesTo(normalizes_to)
                 if matches!(
@@ -504,7 +525,7 @@ impl<'tcx> ProofTreeVisitor<'tcx> for BestObligation<'tcx> {
 
             let obligation;
             match (child_mode, nested_goal.source()) {
-                (ChildMode::Trait(_), GoalSource::Misc) => {
+                (ChildMode::Trait(_) | ChildMode::Host(_), GoalSource::Misc) => {
                     continue;
                 }
                 (ChildMode::Trait(parent_trait_pred), GoalSource::ImplWhereBound) => {
@@ -517,11 +538,25 @@ impl<'tcx> ProofTreeVisitor<'tcx> for BestObligation<'tcx> {
                     ));
                     impl_where_bound_count += 1;
                 }
+                (
+                    ChildMode::Host(parent_host_pred),
+                    GoalSource::ImplWhereBound | GoalSource::AliasBoundConstCondition,
+                ) => {
+                    obligation = make_obligation(derive_host_cause(
+                        tcx,
+                        candidate.kind(),
+                        self.obligation.cause.clone(),
+                        impl_where_bound_count,
+                        parent_host_pred,
+                    ));
+                    impl_where_bound_count += 1;
+                }
                 // Skip over a higher-ranked predicate.
                 (_, GoalSource::InstantiateHigherRanked) => {
                     obligation = self.obligation.clone();
                 }
-                (ChildMode::PassThrough, _) | (_, GoalSource::AliasWellFormed) => {
+                (ChildMode::PassThrough, _)
+                | (_, GoalSource::AliasWellFormed | GoalSource::AliasBoundConstCondition) => {
                     obligation = make_obligation(self.obligation.cause.clone());
                 }
             }
@@ -575,6 +610,10 @@ enum ChildMode<'tcx> {
     // and skip all `GoalSource::Misc`, which represent useless obligations
     // such as alias-eq which may not hold.
     Trait(ty::PolyTraitPredicate<'tcx>),
+    // Try to derive an `ObligationCause::{ImplDerived,BuiltinDerived}`,
+    // and skip all `GoalSource::Misc`, which represent useless obligations
+    // such as alias-eq which may not hold.
+    Host(ty::Binder<'tcx, ty::HostEffectPredicate<'tcx>>),
     // Skip trying to derive an `ObligationCause` from this obligation, and
     // report *all* sub-obligations as if they came directly from the parent
     // obligation.
@@ -616,3 +655,52 @@ fn derive_cause<'tcx>(
     };
     cause
 }
+
+fn derive_host_cause<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    candidate_kind: inspect::ProbeKind<TyCtxt<'tcx>>,
+    mut cause: ObligationCause<'tcx>,
+    idx: usize,
+    parent_host_pred: ty::Binder<'tcx, ty::HostEffectPredicate<'tcx>>,
+) -> ObligationCause<'tcx> {
+    match candidate_kind {
+        inspect::ProbeKind::TraitCandidate {
+            source: CandidateSource::Impl(impl_def_id),
+            result: _,
+        } => {
+            if let Some((_, span)) = tcx
+                .predicates_of(impl_def_id)
+                .instantiate_identity(tcx)
+                .into_iter()
+                .chain(tcx.const_conditions(impl_def_id).instantiate_identity(tcx).into_iter().map(
+                    |(trait_ref, span)| {
+                        (
+                            trait_ref.to_host_effect_clause(
+                                tcx,
+                                parent_host_pred.skip_binder().constness,
+                            ),
+                            span,
+                        )
+                    },
+                ))
+                .nth(idx)
+            {
+                cause =
+                    cause.derived_host_cause(parent_host_pred, |derived| {
+                        ObligationCauseCode::ImplDerivedHost(Box::new(
+                            traits::ImplDerivedHostCause { derived, impl_def_id, span },
+                        ))
+                    })
+            }
+        }
+        inspect::ProbeKind::TraitCandidate {
+            source: CandidateSource::BuiltinImpl(..),
+            result: _,
+        } => {
+            cause =
+                cause.derived_host_cause(parent_host_pred, ObligationCauseCode::BuiltinDerivedHost);
+        }
+        _ => {}
+    };
+    cause
+}
diff --git a/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs b/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs
index 15eb5d74cbf..446f9eaa348 100644
--- a/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs
+++ b/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs
@@ -79,7 +79,7 @@ pub fn is_const_evaluatable<'tcx>(
                     Err(
                         EvaluateConstErr::EvaluationFailure(e)
                         | EvaluateConstErr::InvalidConstParamTy(e),
-                    ) => Err(NotConstEvaluatable::Error(e.into())),
+                    ) => Err(NotConstEvaluatable::Error(e)),
                     Ok(_) => Ok(()),
                 }
             }
@@ -140,7 +140,7 @@ pub fn is_const_evaluatable<'tcx>(
             }
             Err(
                 EvaluateConstErr::EvaluationFailure(e) | EvaluateConstErr::InvalidConstParamTy(e),
-            ) => Err(NotConstEvaluatable::Error(e.into())),
+            ) => Err(NotConstEvaluatable::Error(e)),
             Ok(_) => Ok(()),
         }
     }
diff --git a/compiler/rustc_trait_selection/src/traits/effects.rs b/compiler/rustc_trait_selection/src/traits/effects.rs
index 91484ef99db..b32909efe0b 100644
--- a/compiler/rustc_trait_selection/src/traits/effects.rs
+++ b/compiler/rustc_trait_selection/src/traits/effects.rs
@@ -1,6 +1,8 @@
-use rustc_hir as hir;
+use rustc_hir::{self as hir, LangItem};
 use rustc_infer::infer::{BoundRegionConversionTime, DefineOpaqueTypes};
-use rustc_infer::traits::{ImplSource, Obligation, PredicateObligation};
+use rustc_infer::traits::{
+    ImplDerivedHostCause, ImplSource, Obligation, ObligationCauseCode, PredicateObligation,
+};
 use rustc_middle::span_bug;
 use rustc_middle::ty::fast_reject::DeepRejectCtxt;
 use rustc_middle::ty::{self, TypingMode};
@@ -46,6 +48,12 @@ pub fn evaluate_host_effect_obligation<'tcx>(
         Err(EvaluationFailure::NoSolution) => {}
     }
 
+    match evaluate_host_effect_from_builtin_impls(selcx, obligation) {
+        Ok(result) => return Ok(result),
+        Err(EvaluationFailure::Ambiguous) => return Err(EvaluationFailure::Ambiguous),
+        Err(EvaluationFailure::NoSolution) => {}
+    }
+
     match evaluate_host_effect_from_selection_candiate(selcx, obligation) {
         Ok(result) => return Ok(result),
         Err(EvaluationFailure::Ambiguous) => return Err(EvaluationFailure::Ambiguous),
@@ -226,6 +234,104 @@ fn evaluate_host_effect_from_item_bounds<'tcx>(
     }
 }
 
+fn evaluate_host_effect_from_builtin_impls<'tcx>(
+    selcx: &mut SelectionContext<'_, 'tcx>,
+    obligation: &HostEffectObligation<'tcx>,
+) -> Result<ThinVec<PredicateObligation<'tcx>>, EvaluationFailure> {
+    match selcx.tcx().as_lang_item(obligation.predicate.def_id()) {
+        Some(LangItem::Destruct) => evaluate_host_effect_for_destruct_goal(selcx, obligation),
+        _ => Err(EvaluationFailure::NoSolution),
+    }
+}
+
+// NOTE: Keep this in sync with `const_conditions_for_destruct` in the new solver.
+fn evaluate_host_effect_for_destruct_goal<'tcx>(
+    selcx: &mut SelectionContext<'_, 'tcx>,
+    obligation: &HostEffectObligation<'tcx>,
+) -> Result<ThinVec<PredicateObligation<'tcx>>, EvaluationFailure> {
+    let tcx = selcx.tcx();
+    let destruct_def_id = tcx.require_lang_item(LangItem::Destruct, None);
+    let self_ty = obligation.predicate.self_ty();
+
+    let const_conditions = match *self_ty.kind() {
+        // An ADT is `~const Destruct` only if all of the fields are,
+        // *and* if there is a `Drop` impl, that `Drop` impl is also `~const`.
+        ty::Adt(adt_def, args) => {
+            let mut const_conditions: ThinVec<_> = adt_def
+                .all_fields()
+                .map(|field| ty::TraitRef::new(tcx, destruct_def_id, [field.ty(tcx, args)]))
+                .collect();
+            match adt_def.destructor(tcx).map(|dtor| dtor.constness) {
+                // `Drop` impl exists, but it's not const. Type cannot be `~const Destruct`.
+                Some(hir::Constness::NotConst) => return Err(EvaluationFailure::NoSolution),
+                // `Drop` impl exists, and it's const. Require `Ty: ~const Drop` to hold.
+                Some(hir::Constness::Const) => {
+                    let drop_def_id = tcx.require_lang_item(LangItem::Drop, None);
+                    let drop_trait_ref = ty::TraitRef::new(tcx, drop_def_id, [self_ty]);
+                    const_conditions.push(drop_trait_ref);
+                }
+                // No `Drop` impl, no need to require anything else.
+                None => {}
+            }
+            const_conditions
+        }
+
+        ty::Array(ty, _) | ty::Pat(ty, _) | ty::Slice(ty) => {
+            thin_vec![ty::TraitRef::new(tcx, destruct_def_id, [ty])]
+        }
+
+        ty::Tuple(tys) => {
+            tys.iter().map(|field_ty| ty::TraitRef::new(tcx, destruct_def_id, [field_ty])).collect()
+        }
+
+        // Trivially implement `~const Destruct`
+        ty::Bool
+        | ty::Char
+        | ty::Int(..)
+        | ty::Uint(..)
+        | ty::Float(..)
+        | ty::Str
+        | ty::RawPtr(..)
+        | ty::Ref(..)
+        | ty::FnDef(..)
+        | ty::FnPtr(..)
+        | ty::Never
+        | ty::Infer(ty::InferTy::FloatVar(_) | ty::InferTy::IntVar(_))
+        | ty::Error(_) => thin_vec![],
+
+        // Coroutines and closures could implement `~const Drop`,
+        // but they don't really need to right now.
+        ty::Closure(_, _)
+        | ty::CoroutineClosure(_, _)
+        | ty::Coroutine(_, _)
+        | ty::CoroutineWitness(_, _) => return Err(EvaluationFailure::NoSolution),
+
+        // FIXME(unsafe_binders): Unsafe binders could implement `~const Drop`
+        // if their inner type implements it.
+        ty::UnsafeBinder(_) => return Err(EvaluationFailure::NoSolution),
+
+        ty::Dynamic(..) | ty::Param(_) | ty::Alias(..) | ty::Placeholder(_) | ty::Foreign(_) => {
+            return Err(EvaluationFailure::NoSolution);
+        }
+
+        ty::Bound(..)
+        | ty::Infer(ty::TyVar(_) | ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
+            panic!("unexpected type `{self_ty:?}`")
+        }
+    };
+
+    Ok(const_conditions
+        .into_iter()
+        .map(|trait_ref| {
+            obligation.with(
+                tcx,
+                ty::Binder::dummy(trait_ref)
+                    .to_host_effect_clause(tcx, obligation.predicate.constness),
+            )
+        })
+        .collect())
+}
+
 fn evaluate_host_effect_from_selection_candiate<'tcx>(
     selcx: &mut SelectionContext<'_, 'tcx>,
     obligation: &HostEffectObligation<'tcx>,
@@ -248,9 +354,22 @@ fn evaluate_host_effect_from_selection_candiate<'tcx>(
                         tcx.const_conditions(impl_.impl_def_id)
                             .instantiate(tcx, impl_.args)
                             .into_iter()
-                            .map(|(trait_ref, _)| {
-                                obligation.with(
+                            .map(|(trait_ref, span)| {
+                                Obligation::new(
                                     tcx,
+                                    obligation.cause.clone().derived_host_cause(
+                                        ty::Binder::dummy(obligation.predicate),
+                                        |derived| {
+                                            ObligationCauseCode::ImplDerivedHost(Box::new(
+                                                ImplDerivedHostCause {
+                                                    derived,
+                                                    impl_def_id: impl_.impl_def_id,
+                                                    span,
+                                                },
+                                            ))
+                                        },
+                                    ),
+                                    obligation.param_env,
                                     trait_ref
                                         .to_host_effect_clause(tcx, obligation.predicate.constness),
                                 )