Handle multiple applicable projection candidates

2 files changed, 5 insertions, 4 deletions

diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs
index 240f2c0792c..fc4c343372a 100644
--- a/compiler/rustc_middle/src/query/mod.rs
+++ b/compiler/rustc_middle/src/query/mod.rs
@@ -157,7 +157,7 @@ rustc_queries! {
         }
 
         /// Returns the list of bounds that can be used for
-        /// `SelectionCandidate::ProjectionCandidate` and
+        /// `SelectionCandidate::ProjectionCandidate(_)` and
         /// `ProjectionTyCandidate::TraitDef`.
         /// Specifically this is the bounds written on the trait's type
         /// definition, or those after the `impl` keyword
diff --git a/compiler/rustc_middle/src/traits/select.rs b/compiler/rustc_middle/src/traits/select.rs
index 6ad514c6be2..358ead507b4 100644
--- a/compiler/rustc_middle/src/traits/select.rs
+++ b/compiler/rustc_middle/src/traits/select.rs
@@ -105,9 +105,10 @@ pub enum SelectionCandidate<'tcx> {
     ImplCandidate(DefId),
     AutoImplCandidate(DefId),
 
-    /// This is a trait matching with a projected type as `Self`, and
-    /// we found an applicable bound in the trait definition.
-    ProjectionCandidate,
+    /// This is a trait matching with a projected type as `Self`, and we found
+    /// an applicable bound in the trait definition. The `usize` is an index
+    /// into the list returned by `tcx.item_bounds`.
+    ProjectionCandidate(usize),
 
     /// Implementation of a `Fn`-family trait by one of the anonymous types
     /// generated for a `||` expression.