From 48fe97835b35023b9fb1668b73d6baa421b70755 Mon Sep 17 00:00:00 2001
From: Victor Zverovich <victor.zverovich@gmail.com>
Date: Sun, 2 Oct 2016 09:36:40 -0700
Subject: [PATCH] Add format_arg::operator bool

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

diff --git a/fmt/format.h b/fmt/format.h
index d5249326..27137d4d 100644
--- a/fmt/format.h
+++ b/fmt/format.h
@@ -1031,6 +1031,8 @@ struct Value {
 // allow storage in internal::MemoryBuffer.
 struct format_arg : internal::Value {
   Type type;
+
+  explicit operator bool() const noexcept { return type != NONE; }
 };
 
 namespace internal {