From 744c2824c5217c5a92dc48a2ff959d36dc8c760d Mon Sep 17 00:00:00 2001
From: Victor Zverovich <victor.zverovich@gmail.com>
Date: Sun, 8 May 2016 09:45:32 -0700
Subject: [PATCH] Fix a clang warning about an undefined template (#318)

---
 fmt/format.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/fmt/format.h b/fmt/format.h
index 5013b810..a31b9dca 100644
--- a/fmt/format.h
+++ b/fmt/format.h
@@ -98,6 +98,7 @@ typedef __int64          intmax_t;
 #endif
 
 #if defined(__clang__) && !defined(FMT_ICC_VERSION)
+# define FMT_CLANG_VERSION (__clang_major__ * 100 + __clang_minor__)
 # pragma clang diagnostic push
 # pragma clang diagnostic ignored "-Wdocumentation"
 #endif
@@ -830,6 +831,14 @@ struct FMT_API BasicData {
   static const char DIGITS[];
 };
 
+#ifndef FMT_USE_EXTERN_TEMPLATES
+# define FMT_USE_EXTERN_TEMPLATES (FMT_CLANG_VERSION >= 209)
+#endif
+
+#if FMT_USE_EXTERN_TEMPLATES
+extern template struct BasicData<void>;
+#endif
+
 typedef BasicData<> Data;
 
 #ifdef FMT_BUILTIN_CLZLL