bound_vars -> infer: don't return lt map

compiler/rustc_borrowck/src/type_check/input_output.rs

@@ -60,13 +60,11 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                     // Replace the bound items in the fn sig with fresh
                     // variables, so that they represent the view from
                     // "inside" the closure.
-                    self.infcx
+                    self.infcx.replace_bound_vars_with_fresh_vars(
-                        .replace_bound_vars_with_fresh_vars(
                         body.span,
                         LateBoundRegionConversionTime::FnCall,
                         poly_sig,
                     )
-                        .0
                 },
             );
         }

compiler/rustc_infer/src/infer/higher_ranked/mod.rs

@@ -38,8 +38,7 @@ impl<'a, 'tcx> CombineFields<'a, 'tcx> {
             // with a fresh region variable. These region variables --
             // but no other pre-existing region variables -- can name
             // the placeholders.
-            let (a_prime, _) =
+            let a_prime = self.infcx.replace_bound_vars_with_fresh_vars(span, HigherRankedType, a);
-                self.infcx.replace_bound_vars_with_fresh_vars(span, HigherRankedType, a);
 
             debug!("a_prime={:?}", a_prime);
             debug!("b_prime={:?}", b_prime);

compiler/rustc_infer/src/infer/mod.rs

@@ -1524,7 +1524,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
         span: Span,
         lbrct: LateBoundRegionConversionTime,
         value: ty::Binder<'tcx, T>,
-    ) -> (T, BTreeMap<ty::BoundRegion, ty::Region<'tcx>>)
+    ) -> T
     where
         T: TypeFoldable<'tcx>,
     {
@@ -1553,8 +1553,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                 )
             })
         };
-        let result = self.tcx.replace_bound_vars_uncached(value, fld_r, fld_t, fld_c);
+        self.tcx.replace_bound_vars_uncached(value, fld_r, fld_t, fld_c)
-        (result, region_map)
     }
 
     /// See the [`region_constraints::RegionConstraintCollector::verify_generic_bound`] method.

compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs

@@ -1536,7 +1536,7 @@ impl<'a, 'tcx> InferCtxtPrivExt<'a, 'tcx> for InferCtxt<'a, 'tcx> {
             let bound_predicate = predicate.kind();
             if let ty::PredicateKind::Projection(data) = bound_predicate.skip_binder() {
                 let mut selcx = SelectionContext::new(self);
-                let (data, _) = self.replace_bound_vars_with_fresh_vars(
+                let data = self.replace_bound_vars_with_fresh_vars(
                     obligation.cause.span,
                     infer::LateBoundRegionConversionTime::HigherRankedType,
                     bound_predicate.rebind(data),

compiler/rustc_trait_selection/src/traits/project.rs

@@ -1920,7 +1920,7 @@ fn confirm_param_env_candidate<'cx, 'tcx>(
     let cause = &obligation.cause;
     let param_env = obligation.param_env;
 
-    let (cache_entry, _) = infcx.replace_bound_vars_with_fresh_vars(
+    let cache_entry = infcx.replace_bound_vars_with_fresh_vars(
         cause.span,
         LateBoundRegionConversionTime::HigherRankedType,
         poly_cache_entry,

compiler/rustc_trait_selection/src/traits/select/confirmation.rs

@@ -421,14 +421,11 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         let object_trait_ref = data.principal().unwrap_or_else(|| {
             span_bug!(obligation.cause.span, "object candidate with no principal")
         });
-        let object_trait_ref = self
+        let object_trait_ref = self.infcx.replace_bound_vars_with_fresh_vars(
-            .infcx
-            .replace_bound_vars_with_fresh_vars(
             obligation.cause.span,
             HigherRankedType,
             object_trait_ref,
-            )
+        );
-            .0;
         let object_trait_ref = object_trait_ref.with_self_ty(self.tcx(), self_ty);
 
         let mut nested = vec![];

compiler/rustc_trait_selection/src/traits/select/mod.rs

@@ -1453,7 +1453,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         potentially_unnormalized_candidates: bool,
     ) -> ProjectionMatchesProjection {
         let mut nested_obligations = Vec::new();
-        let (infer_predicate, _) = self.infcx.replace_bound_vars_with_fresh_vars(
+        let infer_predicate = self.infcx.replace_bound_vars_with_fresh_vars(
             obligation.cause.span,
             LateBoundRegionConversionTime::HigherRankedType,
             env_predicate,

compiler/rustc_typeck/src/check/callee.rs

@@ -152,13 +152,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 // fnmut vs fnonce. If so, we have to defer further processing.
                 if self.closure_kind(substs).is_none() {
                     let closure_sig = substs.as_closure().sig();
-                    let closure_sig = self
+                    let closure_sig = self.replace_bound_vars_with_fresh_vars(
-                        .replace_bound_vars_with_fresh_vars(
                         call_expr.span,
                         infer::FnCall,
                         closure_sig,
-                        )
+                    );
-                        .0;
                     let adjustments = self.adjust_steps(autoderef);
                     self.record_deferred_call_resolution(
                         def_id,
@@ -503,8 +501,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         // renormalize the associated types at this point, since they
         // previously appeared within a `Binder<>` and hence would not
         // have been normalized before.
-        let fn_sig =
+        let fn_sig = self.replace_bound_vars_with_fresh_vars(call_expr.span, infer::FnCall, fn_sig);
-            self.replace_bound_vars_with_fresh_vars(call_expr.span, infer::FnCall, fn_sig).0;
         let fn_sig = self.normalize_associated_types_in(call_expr.span, fn_sig);
 
         // Call the generic checker.

compiler/rustc_typeck/src/check/closure.rs

@@ -550,7 +550,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 expected_sigs.liberated_sig.inputs(), // `liberated_sig` is E'.
             ) {
                 // Instantiate (this part of..) S to S', i.e., with fresh variables.
-                let (supplied_ty, _) = self.infcx.replace_bound_vars_with_fresh_vars(
+                let supplied_ty = self.infcx.replace_bound_vars_with_fresh_vars(
                     hir_ty.span,
                     LateBoundRegionConversionTime::FnCall,
                     supplied_sig.inputs().rebind(supplied_ty),
@@ -563,7 +563,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 all_obligations.extend(obligations);
             }
 
-            let (supplied_output_ty, _) = self.infcx.replace_bound_vars_with_fresh_vars(
+            let supplied_output_ty = self.infcx.replace_bound_vars_with_fresh_vars(
                 decl.output.span(),
                 LateBoundRegionConversionTime::FnCall,
                 supplied_sig.output(),

compiler/rustc_typeck/src/check/compare_method.rs

@@ -255,7 +255,7 @@ fn compare_predicate_entailment<'tcx>(
 
         let mut wf_tys = FxHashSet::default();
 
-        let (impl_sig, _) = infcx.replace_bound_vars_with_fresh_vars(
+        let impl_sig = infcx.replace_bound_vars_with_fresh_vars(
             impl_m_span,
             infer::HigherRankedType,
             tcx.fn_sig(impl_m.def_id),

compiler/rustc_typeck/src/check/expr.rs

@@ -561,13 +561,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     // placeholder lifetimes with probing, we just replace higher lifetimes
                     // with fresh vars.
                     let span = args.get(i).map(|a| a.span).unwrap_or(expr.span);
-                    let input = self
+                    let input = self.replace_bound_vars_with_fresh_vars(
-                        .replace_bound_vars_with_fresh_vars(
                         span,
                         infer::LateBoundRegionConversionTime::FnCall,
                         fn_sig.input(i),
-                        )
+                    );
-                        .0;
                     self.require_type_is_sized_deferred(
                         input,
                         span,
@@ -581,13 +579,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             // Also, as we just want to check sizedness, instead of introducing
             // placeholder lifetimes with probing, we just replace higher lifetimes
             // with fresh vars.
-            let output = self
+            let output = self.replace_bound_vars_with_fresh_vars(
-                .replace_bound_vars_with_fresh_vars(
                 expr.span,
                 infer::LateBoundRegionConversionTime::FnCall,
                 fn_sig.output(),
-                )
+            );
-                .0;
             self.require_type_is_sized_deferred(output, expr.span, traits::SizedReturnType);
         }
 

compiler/rustc_typeck/src/check/fn_ctxt/mod.rs

@@ -256,7 +256,7 @@ impl<'a, 'tcx> AstConv<'tcx> for FnCtxt<'a, 'tcx> {
         item_segment: &hir::PathSegment<'_>,
         poly_trait_ref: ty::PolyTraitRef<'tcx>,
     ) -> Ty<'tcx> {
-        let (trait_ref, _) = self.replace_bound_vars_with_fresh_vars(
+        let trait_ref = self.replace_bound_vars_with_fresh_vars(
             span,
             infer::LateBoundRegionConversionTime::AssocTypeProjection(item_def_id),
             poly_trait_ref,

compiler/rustc_typeck/src/check/fn_ctxt/suggestions.rs

@@ -85,7 +85,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             _ => return false,
         };
 
-        let sig = self.replace_bound_vars_with_fresh_vars(expr.span, infer::FnCall, sig).0;
+        let sig = self.replace_bound_vars_with_fresh_vars(expr.span, infer::FnCall, sig);
         let sig = self.normalize_associated_types_in(expr.span, sig);
         if self.can_coerce(sig.output(), expected) {
             let (mut sugg_call, applicability) = if sig.inputs().is_empty() {

compiler/rustc_typeck/src/check/method/confirm.rs

@@ -574,6 +574,6 @@ impl<'a, 'tcx> ConfirmContext<'a, 'tcx> {
     where
         T: TypeFoldable<'tcx>,
     {
-        self.fcx.replace_bound_vars_with_fresh_vars(self.span, infer::FnCall, value).0
+        self.fcx.replace_bound_vars_with_fresh_vars(self.span, infer::FnCall, value)
     }
 }

compiler/rustc_typeck/src/check/method/mod.rs

@@ -462,7 +462,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         // may reference those regions.
         let fn_sig = tcx.bound_fn_sig(def_id);
         let fn_sig = fn_sig.subst(self.tcx, substs);
-        let fn_sig = self.replace_bound_vars_with_fresh_vars(span, infer::FnCall, fn_sig).0;
+        let fn_sig = self.replace_bound_vars_with_fresh_vars(span, infer::FnCall, fn_sig);
 
         let InferOk { value, obligations: o } = if is_op {
             self.normalize_op_associated_types_in_as_infer_ok(span, fn_sig, opt_input_expr)

compiler/rustc_typeck/src/check/method/probe.rs

@@ -905,7 +905,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
                 self.probe(|_| {
                     let substs = self.fresh_substs_for_item(self.span, method.def_id);
                     let fty = fty.subst(self.tcx, substs);
-                    let (fty, _) =
+                    let fty =
                         self.replace_bound_vars_with_fresh_vars(self.span, infer::FnCall, fty);
 
                     if let Some(self_ty) = self_ty {