3 files changed, 46 insertions, 45 deletions
diff --git a/compiler/rustc_trait_selection/src/traits/mod.rs b/compiler/rustc_trait_selection/src/traits/mod.rs
index 15081d65682..a5481714e3e 100644
--- a/compiler/rustc_trait_selection/src/traits/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/mod.rs
@@ -65,12 +65,12 @@ pub use self::specialize::{
 pub use self::structural_match::search_for_structural_match_violation;
 pub use self::structural_normalize::StructurallyNormalizeExt;
 pub use self::util::elaborate;
-pub use self::util::{expand_trait_aliases, TraitAliasExpander};
-pub use self::util::{get_vtable_index_of_object_method, impl_item_is_final, upcast_choices};
 pub use self::util::{
-    supertrait_def_ids, supertraits, transitive_bounds, transitive_bounds_that_define_assoc_item,
-    SupertraitDefIds,
+    check_substs_compatible, supertrait_def_ids, supertraits, transitive_bounds,
+    transitive_bounds_that_define_assoc_item, SupertraitDefIds,
 };
+pub use self::util::{expand_trait_aliases, TraitAliasExpander};
+pub use self::util::{get_vtable_index_of_object_method, impl_item_is_final, upcast_choices};
 
 pub use self::chalk_fulfill::FulfillmentContext as ChalkFulfillmentContext;
 
diff --git a/compiler/rustc_trait_selection/src/traits/project.rs b/compiler/rustc_trait_selection/src/traits/project.rs
index de76587c7b9..81b1ecc0d88 100644
--- a/compiler/rustc_trait_selection/src/traits/project.rs
+++ b/compiler/rustc_trait_selection/src/traits/project.rs
@@ -1,5 +1,6 @@
 //! Code for projecting associated types out of trait references.
 
+use super::check_substs_compatible;
 use super::specialization_graph;
 use super::translate_substs;
 use super::util;
@@ -2378,47 +2379,6 @@ fn confirm_impl_candidate<'cx, 'tcx>(
     }
 }
 
-// Verify that the trait item and its implementation have compatible substs lists
-fn check_substs_compatible<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    assoc_item: ty::AssocItem,
-    substs: ty::SubstsRef<'tcx>,
-) -> bool {
-    fn check_substs_compatible_inner<'tcx>(
-        tcx: TyCtxt<'tcx>,
-        generics: &'tcx ty::Generics,
-        args: &'tcx [ty::GenericArg<'tcx>],
-    ) -> bool {
-        if generics.count() != args.len() {
-            return false;
-        }
-
-        let (parent_args, own_args) = args.split_at(generics.parent_count);
-
-        if let Some(parent) = generics.parent
-            && let parent_generics = tcx.generics_of(parent)
-            && !check_substs_compatible_inner(tcx, parent_generics, parent_args) {
-            return false;
-        }
-
-        for (param, arg) in std::iter::zip(&generics.params, own_args) {
-            match (&param.kind, arg.unpack()) {
-                (ty::GenericParamDefKind::Type { .. }, ty::GenericArgKind::Type(_))
-                | (ty::GenericParamDefKind::Lifetime, ty::GenericArgKind::Lifetime(_))
-                | (ty::GenericParamDefKind::Const { .. }, ty::GenericArgKind::Const(_)) => {}
-                _ => return false,
-            }
-        }
-
-        true
-    }
-
-    let generics = tcx.generics_of(assoc_item.def_id);
-    // Chop off any additional substs (RPITIT) substs
-    let substs = &substs[0..generics.count().min(substs.len())];
-    check_substs_compatible_inner(tcx, generics, substs)
-}
-
 fn confirm_impl_trait_in_trait_candidate<'tcx>(
     selcx: &mut SelectionContext<'_, 'tcx>,
     obligation: &ProjectionTyObligation<'tcx>,
diff --git a/compiler/rustc_trait_selection/src/traits/util.rs b/compiler/rustc_trait_selection/src/traits/util.rs
index 906c357e8ca..05a7f3e3b02 100644
--- a/compiler/rustc_trait_selection/src/traits/util.rs
+++ b/compiler/rustc_trait_selection/src/traits/util.rs
@@ -302,3 +302,44 @@ pub enum TupleArgumentsFlag {
     Yes,
     No,
 }
+
+// Verify that the trait item and its implementation have compatible substs lists
+pub fn check_substs_compatible<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    assoc_item: ty::AssocItem,
+    substs: ty::SubstsRef<'tcx>,
+) -> bool {
+    fn check_substs_compatible_inner<'tcx>(
+        tcx: TyCtxt<'tcx>,
+        generics: &'tcx ty::Generics,
+        args: &'tcx [ty::GenericArg<'tcx>],
+    ) -> bool {
+        if generics.count() != args.len() {
+            return false;
+        }
+
+        let (parent_args, own_args) = args.split_at(generics.parent_count);
+
+        if let Some(parent) = generics.parent
+            && let parent_generics = tcx.generics_of(parent)
+            && !check_substs_compatible_inner(tcx, parent_generics, parent_args) {
+            return false;
+        }
+
+        for (param, arg) in std::iter::zip(&generics.params, own_args) {
+            match (&param.kind, arg.unpack()) {
+                (ty::GenericParamDefKind::Type { .. }, ty::GenericArgKind::Type(_))
+                | (ty::GenericParamDefKind::Lifetime, ty::GenericArgKind::Lifetime(_))
+                | (ty::GenericParamDefKind::Const { .. }, ty::GenericArgKind::Const(_)) => {}
+                _ => return false,
+            }
+        }
+
+        true
+    }
+
+    let generics = tcx.generics_of(assoc_item.def_id);
+    // Chop off any additional substs (RPITIT) substs
+    let substs = &substs[0..generics.count().min(substs.len())];
+    check_substs_compatible_inner(tcx, generics, substs)
+}