From 28446ef19eebaee31bbbd2706fed29632ee7b7f9 Mon Sep 17 00:00:00 2001
From: Santiago Pastorino <spastorino@gmail.com>
Date: Tue, 24 Nov 2020 17:02:54 -0300
Subject: [PATCH] Inline elaborate_trait_refs_that_define_assoc_type into
 transitive_bounds_that_define_assoc_type

---
 compiler/rustc_infer/src/traits/util.rs | 56 +++++++++++--------------
 1 file changed, 24 insertions(+), 32 deletions(-)

diff --git a/compiler/rustc_infer/src/traits/util.rs b/compiler/rustc_infer/src/traits/util.rs
index b7d6e8f0bf6fd..e084530d17a5e 100644
--- a/compiler/rustc_infer/src/traits/util.rs
+++ b/compiler/rustc_infer/src/traits/util.rs
@@ -90,37 +90,6 @@ pub fn elaborate_trait_refs<'tcx>(
     elaborate_predicates(tcx, predicates)
 }
 
-/// A specialized variant of `elaborate_trait_refs` that only elaborates trait references that may
-/// define the given associated type `assoc_name`. It uses the
-/// `super_predicates_that_define_assoc_type` query to avoid enumerating super-predicates that
-/// aren't related to `assoc_item`.  This is used when resolving types like `Self::Item` or
-/// `T::Item` and helps to avoid cycle errors (see e.g. #35237).
-pub fn elaborate_trait_refs_that_define_assoc_type<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    trait_refs: impl Iterator<Item = ty::PolyTraitRef<'tcx>>,
-    assoc_name: Ident,
-) -> FxHashSet<ty::PolyTraitRef<'tcx>> {
-    let mut stack: Vec<_> = trait_refs.collect();
-    let mut trait_refs = FxHashSet::default();
-
-    while let Some(trait_ref) = stack.pop() {
-        if trait_refs.insert(trait_ref) {
-            let super_predicates =
-                tcx.super_predicates_that_define_assoc_type((trait_ref.def_id(), Some(assoc_name)));
-            for (super_predicate, _) in super_predicates.predicates {
-                let bound_predicate = super_predicate.bound_atom();
-                let subst_predicate = super_predicate
-                    .subst_supertrait(tcx, &bound_predicate.rebind(trait_ref.skip_binder()));
-                if let Some(binder) = subst_predicate.to_opt_poly_trait_ref() {
-                    stack.push(binder.value);
-                }
-            }
-        }
-    }
-
-    trait_refs
-}
-
 pub fn elaborate_predicates<'tcx>(
     tcx: TyCtxt<'tcx>,
     predicates: impl Iterator<Item = ty::Predicate<'tcx>>,
@@ -319,12 +288,35 @@ pub fn transitive_bounds<'tcx>(
     elaborate_trait_refs(tcx, bounds).filter_to_traits()
 }
 
+/// A specialized variant of `elaborate_trait_refs` that only elaborates trait references that may
+/// define the given associated type `assoc_name`. It uses the
+/// `super_predicates_that_define_assoc_type` query to avoid enumerating super-predicates that
+/// aren't related to `assoc_item`.  This is used when resolving types like `Self::Item` or
+/// `T::Item` and helps to avoid cycle errors (see e.g. #35237).
 pub fn transitive_bounds_that_define_assoc_type<'tcx>(
     tcx: TyCtxt<'tcx>,
     bounds: impl Iterator<Item = ty::PolyTraitRef<'tcx>>,
     assoc_name: Ident,
 ) -> FxHashSet<ty::PolyTraitRef<'tcx>> {
-    elaborate_trait_refs_that_define_assoc_type(tcx, bounds, assoc_name)
+    let mut stack: Vec<_> = bounds.collect();
+    let mut trait_refs = FxHashSet::default();
+
+    while let Some(trait_ref) = stack.pop() {
+        if trait_refs.insert(trait_ref) {
+            let super_predicates =
+                tcx.super_predicates_that_define_assoc_type((trait_ref.def_id(), Some(assoc_name)));
+            for (super_predicate, _) in super_predicates.predicates {
+                let bound_predicate = super_predicate.bound_atom();
+                let subst_predicate = super_predicate
+                    .subst_supertrait(tcx, &bound_predicate.rebind(trait_ref.skip_binder()));
+                if let Some(binder) = subst_predicate.to_opt_poly_trait_ref() {
+                    stack.push(binder.value);
+                }
+            }
+        }
+    }
+
+    trait_refs
 }
 
 ///////////////////////////////////////////////////////////////////////////