Normalize caller bounds

compiler/rustc_infer/src/infer/outlives/obligations.rs

@@ -68,8 +68,9 @@ use crate::infer::{
 use crate::traits::{ObligationCause, ObligationCauseCode};
 use rustc_data_structures::undo_log::UndoLogs;
 use rustc_middle::mir::ConstraintCategory;
-use rustc_middle::ty::GenericArgKind;
 use rustc_middle::ty::{self, GenericArgsRef, Region, Ty, TyCtxt, TypeVisitableExt};
+use rustc_middle::ty::{GenericArgKind, ToPredicate};
+use rustc_span::DUMMY_SP;
 use smallvec::smallvec;
 
 use super::env::OutlivesEnvironment;
@@ -131,6 +132,25 @@ impl<'tcx> InferCtxt<'tcx> {
     ) -> Result<(), (E, SubregionOrigin<'tcx>)> {
         assert!(!self.in_snapshot(), "cannot process registered region obligations in a snapshot");
 
+        let normalized_caller_bounds: Vec<_> = outlives_env
+            .param_env
+            .caller_bounds()
+            .iter()
+            .filter_map(|clause| {
+                let bound_clause = clause.kind();
+                let ty::ClauseKind::TypeOutlives(outlives) = bound_clause.skip_binder() else {
+                    return None;
+                };
+                Some(deeply_normalize_ty(outlives.0).map(|ty| {
+                    bound_clause
+                        .rebind(ty::ClauseKind::TypeOutlives(ty::OutlivesPredicate(ty, outlives.1)))
+                        .to_predicate(self.tcx)
+                }))
+            })
+            // FIXME: How do we accurately report an error here :(
+            .try_collect()
+            .map_err(|e| (e, SubregionOrigin::AscribeUserTypeProvePredicate(DUMMY_SP)))?;
+
         let my_region_obligations = self.take_registered_region_obligations();
 
         for RegionObligation { sup_type, sub_region, origin } in my_region_obligations {
@@ -142,7 +162,7 @@ impl<'tcx> InferCtxt<'tcx> {
                 self.tcx,
                 outlives_env.region_bound_pairs(),
                 None,
-                outlives_env.param_env,
+                &normalized_caller_bounds,
             );
             let category = origin.to_constraint_category();
             outlives.type_must_outlive(origin, sup_type, sub_region, category);
@@ -196,7 +216,7 @@ where
         tcx: TyCtxt<'tcx>,
         region_bound_pairs: &'cx RegionBoundPairs<'tcx>,
         implicit_region_bound: Option<ty::Region<'tcx>>,
-        param_env: ty::ParamEnv<'tcx>,
+        caller_bounds: &'cx [ty::Clause<'tcx>],
     ) -> Self {
         Self {
             delegate,
@@ -205,7 +225,7 @@ where
                 tcx,
                 region_bound_pairs,
                 implicit_region_bound,
-                param_env,
+                caller_bounds,
             ),
         }
     }

compiler/rustc_infer/src/infer/outlives/verify.rs

@@ -23,7 +23,7 @@ pub struct VerifyBoundCx<'cx, 'tcx> {
     /// Outside of borrowck the only way to prove `T: '?0` is by
     /// setting  `'?0` to `'empty`.
     implicit_region_bound: Option<ty::Region<'tcx>>,
-    param_env: ty::ParamEnv<'tcx>,
+    caller_bounds: &'cx [ty::Clause<'tcx>],
 }
 
 impl<'cx, 'tcx> VerifyBoundCx<'cx, 'tcx> {
@@ -31,9 +31,9 @@ impl<'cx, 'tcx> VerifyBoundCx<'cx, 'tcx> {
         tcx: TyCtxt<'tcx>,
         region_bound_pairs: &'cx RegionBoundPairs<'tcx>,
         implicit_region_bound: Option<ty::Region<'tcx>>,
-        param_env: ty::ParamEnv<'tcx>,
+        caller_bounds: &'cx [ty::Clause<'tcx>],
     ) -> Self {
-        Self { tcx, region_bound_pairs, implicit_region_bound, param_env }
+        Self { tcx, region_bound_pairs, implicit_region_bound, caller_bounds }
     }
 
     #[instrument(level = "debug", skip(self))]
@@ -219,8 +219,8 @@ impl<'cx, 'tcx> VerifyBoundCx<'cx, 'tcx> {
         // To start, collect bounds from user environment. Note that
         // parameter environments are already elaborated, so we don't
         // have to worry about that.
-        let c_b = self.param_env.caller_bounds();
-        let param_bounds = self.collect_outlives_from_clause_list(erased_ty, c_b.into_iter());
+        let param_bounds =
+            self.collect_outlives_from_clause_list(erased_ty, self.caller_bounds.iter().copied());
 
         // Next, collect regions we scraped from the well-formedness
         // constraints in the fn signature. To do that, we walk the list

compiler/rustc_infer/src/lib.rs

@@ -21,6 +21,7 @@
 #![feature(extend_one)]
 #![feature(let_chains)]
 #![feature(if_let_guard)]
+#![feature(iterator_try_collect)]
 #![feature(min_specialization)]
 #![feature(try_blocks)]
 #![recursion_limit = "512"] // For rustdoc