From 8f4b918c5bfc539402b774d6e51d5bb0b8874d21 Mon Sep 17 00:00:00 2001
From: Victor Zverovich <victor.zverovich@gmail.com>
Date: Wed, 12 Jul 2017 13:24:51 -0400
Subject: [PATCH] Check argument index

---
 fmt/format.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fmt/format.h b/fmt/format.h
index d552abfc..b2a8995e 100644
--- a/fmt/format.h
+++ b/fmt/format.h
@@ -1626,10 +1626,12 @@ class basic_args {
       uint64_t num_args = -signed_types;
       return index < num_args ? args_[index] : format_arg();
     }
-    if (index > internal::MAX_PACKED_ARGS)
-      return format_arg();
     format_arg arg;
+    if (index > internal::MAX_PACKED_ARGS)
+      return arg;
     arg.type_ = type(index);
+    if (arg.type_ == internal::NONE)
+      return arg;
     internal::value<Context> &val = arg.value_;
     val = values_[index];
     return arg;