diff --git a/lib/ASTGen/Sources/ASTGen/Exprs.swift b/lib/ASTGen/Sources/ASTGen/Exprs.swift
index 5cddba907844a..97e799c0923b6 100644
--- a/lib/ASTGen/Sources/ASTGen/Exprs.swift
+++ b/lib/ASTGen/Sources/ASTGen/Exprs.swift
@@ -736,6 +736,9 @@ extension ASTGenVisitor {
           additionalTrailingClosures: nil
         )
       ).asExpr
+
+    case .method(_):
+      fatalError("unimplemented")
     }
   }