Thread `Constness` through selection

6 files changed, 17 insertions, 15 deletions

diff --git a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
index d2556c44fb4..ca3369b8f1e 100644
--- a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
@@ -350,11 +350,11 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
         // Micro-optimization: filter out predicates relating to different traits.
         let matching_bounds =
-            all_bounds.filter(|p| p.def_id() == stack.obligation.predicate.def_id());
+            all_bounds.filter(|p| p.value.def_id() == stack.obligation.predicate.def_id());
 
         // Keep only those bounds which may apply, and propagate overflow if it occurs.
         for bound in matching_bounds {
-            let wc = self.evaluate_where_clause(stack, bound)?;
+            let wc = self.evaluate_where_clause(stack, bound.value)?;
             if wc.may_apply() {
                 candidates.vec.push(ParamCandidate(bound));
             }
diff --git a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
index 7c155c7684e..a42c8021346 100644
--- a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
@@ -8,6 +8,7 @@
 //! https://rustc-dev-guide.rust-lang.org/traits/resolution.html#confirmation
 use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_hir::lang_items::LangItem;
+use rustc_hir::Constness;
 use rustc_index::bit_set::GrowableBitSet;
 use rustc_infer::infer::InferOk;
 use rustc_infer::infer::LateBoundRegionConversionTime::HigherRankedType;
@@ -55,8 +56,8 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
             }
 
             ParamCandidate(param) => {
-                let obligations = self.confirm_param_candidate(obligation, param);
-                Ok(ImplSource::Param(obligations))
+                let obligations = self.confirm_param_candidate(obligation, param.value);
+                Ok(ImplSource::Param(obligations, param.constness))
             }
 
             ImplCandidate(impl_def_id) => {
@@ -70,7 +71,8 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
             ProjectionCandidate(idx) => {
                 let obligations = self.confirm_projection_candidate(obligation, idx)?;
-                Ok(ImplSource::Param(obligations))
+                // FIXME(jschievink): constness
+                Ok(ImplSource::Param(obligations, Constness::NotConst))
             }
 
             ObjectCandidate(idx) => {
@@ -106,7 +108,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 // This indicates something like `Trait + Send: Send`. In this case, we know that
                 // this holds because that's what the object type is telling us, and there's really
                 // no additional obligations to prove and no types in particular to unify, etc.
-                Ok(ImplSource::Param(Vec::new()))
+                Ok(ImplSource::Param(Vec::new(), Constness::NotConst))
             }
 
             BuiltinUnsizeCandidate => {
@@ -151,7 +153,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
             obligations.extend(self.infcx.commit_if_ok(|_| {
                 self.infcx
                     .at(&obligation.cause, obligation.param_env)
-                    .sup(placeholder_trait_predicate.trait_ref.to_poly_trait_ref(), candidate)
+                    .sup(placeholder_trait_predicate.trait_ref.to_poly_trait_ref(), candidate.value)
                     .map(|InferOk { obligations, .. }| obligations)
                     .map_err(|_| Unimplemented)
             })?);
diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs
index 05ff9a6fb9c..63870d97146 100644
--- a/compiler/rustc_trait_selection/src/traits/select/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs
@@ -1354,11 +1354,11 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 | TraitAliasCandidate(..)
                 | ObjectCandidate(_)
                 | ProjectionCandidate(_),
-            ) => !is_global(cand),
+            ) => !is_global(&cand.value),
             (ObjectCandidate(_) | ProjectionCandidate(_), ParamCandidate(ref cand)) => {
                 // Prefer these to a global where-clause bound
                 // (see issue #50825).
-                is_global(cand)
+                is_global(&cand.value)
             }
             (
                 ImplCandidate(_)
@@ -1373,7 +1373,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
             ) => {
                 // Prefer these to a global where-clause bound
                 // (see issue #50825).
-                is_global(cand) && other.evaluation.must_apply_modulo_regions()
+                is_global(&cand.value) && other.evaluation.must_apply_modulo_regions()
             }
 
             (ProjectionCandidate(i), ProjectionCandidate(j))
diff --git a/compiler/rustc_trait_selection/src/traits/specialize/mod.rs b/compiler/rustc_trait_selection/src/traits/specialize/mod.rs
index 512591960f5..0133a961c11 100644
--- a/compiler/rustc_trait_selection/src/traits/specialize/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/specialize/mod.rs
@@ -498,8 +498,8 @@ fn to_pretty_impl_header(tcx: TyCtxt<'_>, impl_def_id: DefId) -> Option<String>
 
     for (p, _) in predicates {
         if let Some(poly_trait_ref) = p.to_opt_poly_trait_ref() {
-            if Some(poly_trait_ref.def_id()) == sized_trait {
-                types_without_default_bounds.remove(poly_trait_ref.self_ty().skip_binder());
+            if Some(poly_trait_ref.value.def_id()) == sized_trait {
+                types_without_default_bounds.remove(poly_trait_ref.value.self_ty().skip_binder());
                 continue;
             }
         }
diff --git a/compiler/rustc_trait_selection/src/traits/util.rs b/compiler/rustc_trait_selection/src/traits/util.rs
index 2430620323f..ab4a81c7d15 100644
--- a/compiler/rustc_trait_selection/src/traits/util.rs
+++ b/compiler/rustc_trait_selection/src/traits/util.rs
@@ -125,7 +125,7 @@ impl<'tcx> TraitAliasExpander<'tcx> {
         let items = predicates.predicates.iter().rev().filter_map(|(pred, span)| {
             pred.subst_supertrait(tcx, &trait_ref)
                 .to_opt_poly_trait_ref()
-                .map(|trait_ref| item.clone_and_push(trait_ref, *span))
+                .map(|trait_ref| item.clone_and_push(trait_ref.value, *span))
         });
         debug!("expand_trait_aliases: items={:?}", items.clone());
 
@@ -182,7 +182,7 @@ impl Iterator for SupertraitDefIds<'tcx> {
                 .predicates
                 .iter()
                 .filter_map(|(pred, _)| pred.to_opt_poly_trait_ref())
-                .map(|trait_ref| trait_ref.def_id())
+                .map(|trait_ref| trait_ref.value.def_id())
                 .filter(|&super_def_id| visited.insert(super_def_id)),
         );
         Some(def_id)
diff --git a/compiler/rustc_trait_selection/src/traits/wf.rs b/compiler/rustc_trait_selection/src/traits/wf.rs
index e5a792f229d..5bcb16d21e0 100644
--- a/compiler/rustc_trait_selection/src/traits/wf.rs
+++ b/compiler/rustc_trait_selection/src/traits/wf.rs
@@ -294,7 +294,7 @@ impl<'a, 'tcx> WfPredicates<'a, 'tcx> {
             let mut cause = cause.clone();
             if let Some(parent_trait_ref) = obligation.predicate.to_opt_poly_trait_ref() {
                 let derived_cause = traits::DerivedObligationCause {
-                    parent_trait_ref,
+                    parent_trait_ref: parent_trait_ref.value,
                     parent_code: Rc::new(obligation.cause.code.clone()),
                 };
                 cause.make_mut().code =