1 files changed, 24 insertions, 0 deletions
diff --git a/compiler/rustc_expand/src/placeholders.rs b/compiler/rustc_expand/src/placeholders.rs
index e969f2d4fb5..3a470924c7f 100644
--- a/compiler/rustc_expand/src/placeholders.rs
+++ b/compiler/rustc_expand/src/placeholders.rs
@@ -188,6 +188,19 @@ pub(crate) fn placeholder(
             vis,
             is_placeholder: true,
         }]),
+        AstFragmentKind::WherePredicates => {
+            AstFragment::WherePredicates(smallvec![ast::WherePredicate {
+                attrs: Default::default(),
+                id,
+                span,
+                kind: ast::WherePredicateKind::BoundPredicate(ast::WhereBoundPredicate {
+                    bound_generic_params: Default::default(),
+                    bounded_ty: ty(),
+                    bounds: Default::default(),
+                }),
+                is_placeholder: true,
+            }])
+        }
     }
 }
 
@@ -267,6 +280,17 @@ impl MutVisitor for PlaceholderExpander {
         }
     }
 
+    fn flat_map_where_predicate(
+        &mut self,
+        predicate: ast::WherePredicate,
+    ) -> SmallVec<[ast::WherePredicate; 1]> {
+        if predicate.is_placeholder {
+            self.remove(predicate.id).make_where_predicates()
+        } else {
+            walk_flat_map_where_predicate(self, predicate)
+        }
+    }
+
     fn flat_map_item(&mut self, item: P<ast::Item>) -> SmallVec<[P<ast::Item>; 1]> {
         match item.kind {
             ast::ItemKind::MacCall(_) => self.remove(item.id).make_items(),