5 files changed, 29 insertions, 11 deletions
diff --git a/compiler/rustc_infer/src/traits/engine.rs b/compiler/rustc_infer/src/traits/engine.rs
index 736278ba0..b2b985a22 100644
--- a/compiler/rustc_infer/src/traits/engine.rs
+++ b/compiler/rustc_infer/src/traits/engine.rs
@@ -10,7 +10,7 @@ use super::{ObligationCause, PredicateObligation};
 pub trait TraitEngine<'tcx>: 'tcx {
     fn normalize_projection_type(
         &mut self,
-        infcx: &InferCtxt<'_, 'tcx>,
+        infcx: &InferCtxt<'tcx>,
         param_env: ty::ParamEnv<'tcx>,
         projection_ty: ty::ProjectionTy<'tcx>,
         cause: ObligationCause<'tcx>,
@@ -21,7 +21,7 @@ pub trait TraitEngine<'tcx>: 'tcx {
     /// parameters (except for `Self`).
     fn register_bound(
         &mut self,
-        infcx: &InferCtxt<'_, 'tcx>,
+        infcx: &InferCtxt<'tcx>,
         param_env: ty::ParamEnv<'tcx>,
         ty: Ty<'tcx>,
         def_id: DefId,
@@ -41,14 +41,13 @@ pub trait TraitEngine<'tcx>: 'tcx {
 
     fn register_predicate_obligation(
         &mut self,
-        infcx: &InferCtxt<'_, 'tcx>,
+        infcx: &InferCtxt<'tcx>,
         obligation: PredicateObligation<'tcx>,
     );
 
-    fn select_all_or_error(&mut self, infcx: &InferCtxt<'_, 'tcx>) -> Vec<FulfillmentError<'tcx>>;
+    fn select_all_or_error(&mut self, infcx: &InferCtxt<'tcx>) -> Vec<FulfillmentError<'tcx>>;
 
-    fn select_where_possible(&mut self, infcx: &InferCtxt<'_, 'tcx>)
-    -> Vec<FulfillmentError<'tcx>>;
+    fn select_where_possible(&mut self, infcx: &InferCtxt<'tcx>) -> Vec<FulfillmentError<'tcx>>;
 
     fn pending_obligations(&self) -> Vec<PredicateObligation<'tcx>>;
 
@@ -58,7 +57,7 @@ pub trait TraitEngine<'tcx>: 'tcx {
 pub trait TraitEngineExt<'tcx> {
     fn register_predicate_obligations(
         &mut self,
-        infcx: &InferCtxt<'_, 'tcx>,
+        infcx: &InferCtxt<'tcx>,
         obligations: impl IntoIterator<Item = PredicateObligation<'tcx>>,
     );
 }
@@ -66,7 +65,7 @@ pub trait TraitEngineExt<'tcx> {
 impl<'tcx, T: ?Sized + TraitEngine<'tcx>> TraitEngineExt<'tcx> for T {
     fn register_predicate_obligations(
         &mut self,
-        infcx: &InferCtxt<'_, 'tcx>,
+        infcx: &InferCtxt<'tcx>,
         obligations: impl IntoIterator<Item = PredicateObligation<'tcx>>,
     ) {
         for obligation in obligations {
diff --git a/compiler/rustc_infer/src/traits/error_reporting/mod.rs b/compiler/rustc_infer/src/traits/error_reporting/mod.rs
index 95b6c4ce1..f8b5009a5 100644
--- a/compiler/rustc_infer/src/traits/error_reporting/mod.rs
+++ b/compiler/rustc_infer/src/traits/error_reporting/mod.rs
@@ -10,7 +10,7 @@ use rustc_span::Span;
 use std::fmt;
 use std::iter;
 
-impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
+impl<'tcx> InferCtxt<'tcx> {
     pub fn report_extra_impl_obligation(
         &self,
         error_span: Span,
diff --git a/compiler/rustc_infer/src/traits/mod.rs b/compiler/rustc_infer/src/traits/mod.rs
index 4df4de21a..c8600ded9 100644
--- a/compiler/rustc_infer/src/traits/mod.rs
+++ b/compiler/rustc_infer/src/traits/mod.rs
@@ -67,6 +67,14 @@ impl<'tcx> PredicateObligation<'tcx> {
             recursion_depth: self.recursion_depth,
         })
     }
+
+    pub fn without_const(mut self, tcx: TyCtxt<'tcx>) -> PredicateObligation<'tcx> {
+        self.param_env = self.param_env.without_const();
+        if let ty::PredicateKind::Trait(trait_pred) = self.predicate.kind().skip_binder() && trait_pred.is_const_if_const() {
+            self.predicate = tcx.mk_predicate(self.predicate.kind().map_bound(|_| ty::PredicateKind::Trait(trait_pred.without_const())));
+        }
+        self
+    }
 }
 
 impl<'tcx> TraitObligation<'tcx> {
@@ -105,6 +113,8 @@ pub struct FulfillmentError<'tcx> {
 
 #[derive(Clone)]
 pub enum FulfillmentErrorCode<'tcx> {
+    /// Inherently impossible to fulfill; this trait is implemented if and only if it is already implemented.
+    CodeCycle(Vec<Obligation<'tcx, ty::Predicate<'tcx>>>),
     CodeSelectionError(SelectionError<'tcx>),
     CodeProjectionError(MismatchedProjectionTypes<'tcx>),
     CodeSubtypeError(ExpectedFound<Ty<'tcx>>, TypeError<'tcx>), // always comes from a SubtypePredicate
diff --git a/compiler/rustc_infer/src/traits/structural_impls.rs b/compiler/rustc_infer/src/traits/structural_impls.rs
index 573d2d1e3..1c6ab6a08 100644
--- a/compiler/rustc_infer/src/traits/structural_impls.rs
+++ b/compiler/rustc_infer/src/traits/structural_impls.rs
@@ -47,6 +47,7 @@ impl<'tcx> fmt::Debug for traits::FulfillmentErrorCode<'tcx> {
                 write!(f, "CodeConstEquateError({:?}, {:?})", a, b)
             }
             super::CodeAmbiguity => write!(f, "Ambiguity"),
+            super::CodeCycle(ref cycle) => write!(f, "Cycle({:?})", cycle),
         }
     }
 }
diff --git a/compiler/rustc_infer/src/traits/util.rs b/compiler/rustc_infer/src/traits/util.rs
index f5a1edf6d..e12c069dc 100644
--- a/compiler/rustc_infer/src/traits/util.rs
+++ b/compiler/rustc_infer/src/traits/util.rs
@@ -246,6 +246,13 @@ impl<'tcx> Elaborator<'tcx> {
 
                             Component::UnresolvedInferenceVariable(_) => None,
 
+                            Component::Opaque(def_id, substs) => {
+                                let ty = tcx.mk_opaque(def_id, substs);
+                                Some(ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(
+                                    ty, r_min,
+                                )))
+                            }
+
                             Component::Projection(projection) => {
                                 // We might end up here if we have `Foo<<Bar as Baz>::Assoc>: 'a`.
                                 // With this, we can deduce that `<Bar as Baz>::Assoc: 'a`.
@@ -262,8 +269,9 @@ impl<'tcx> Elaborator<'tcx> {
                                 None
                             }
                         })
-                        .map(ty::Binder::dummy)
-                        .map(|predicate_kind| predicate_kind.to_predicate(tcx))
+                        .map(|predicate_kind| {
+                            bound_predicate.rebind(predicate_kind).to_predicate(tcx)
+                        })
                         .filter(|&predicate| visited.insert(predicate))
                         .map(|predicate| {
                             predicate_obligation(