diff --git a/gcc/rust/ast/rust-ast-dump.cc b/gcc/rust/ast/rust-ast-dump.cc
index 9393f957aa2eb99eaba3a1ae319bd37f58ea6666..a37d5addbc4c7ccadc22e40cc337abe69eb76b30 100644
--- a/gcc/rust/ast/rust-ast-dump.cc
+++ b/gcc/rust/ast/rust-ast-dump.cc
@@ -1661,6 +1661,9 @@ Dump::visit (SliceType &type)
 void
 Dump::visit (InferredType &)
 {
+  // Syntax:
+  //    _
+
   stream << "_";
 }