From 5efb24dd2b0a64c8e826c69c70d1fded5e8571a6 Mon Sep 17 00:00:00 2001
From: Victor Zverovich <victor.zverovich@gmail.com>
Date: Fri, 19 Apr 2019 17:02:31 -0700
Subject: [PATCH] Add specialization test

---
 include/fmt/ostream.h |  8 +++++---
 test/ostream-test.cc  | 15 +++++++++++++++
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/include/fmt/ostream.h b/include/fmt/ostream.h
index 8af60c0d..659cbaf3 100644
--- a/include/fmt/ostream.h
+++ b/include/fmt/ostream.h
@@ -112,9 +112,11 @@ struct fallback_formatter<
 
 // Disable conversion to int if T has an overloaded operator<< which is a free
 // function (not a member of std::ostream).
-template <typename T, typename Char> struct convert_to_int<T, Char, void> {
-  static const bool value = convert_to_int<T, Char, int>::value &&
-                            !internal::is_streamable<T, Char>::value;
+template <typename T, typename Char>
+struct convert_to_int<
+    T, Char,
+    typename std::enable_if<internal::is_streamable<T, Char>::value>::type> {
+  static const bool value = false;
 };
 
 template <typename Char>
diff --git a/test/ostream-test.cc b/test/ostream-test.cc
index e60db62d..b566637b 100644
--- a/test/ostream-test.cc
+++ b/test/ostream-test.cc
@@ -6,6 +6,21 @@
 // For the license information refer to format.h.
 
 #define FMT_STRING_ALIAS 1
+#include "fmt/format.h"
+
+struct test {};
+
+// Test that there is no issues with specializations when fmt/ostream.h is
+// included after fmt/format.h.
+namespace fmt {
+template <> struct formatter<test> : formatter<int> {
+  template <typename FormatContext>
+  typename FormatContext::iterator format(const test&, FormatContext& ctx) {
+    return formatter<int>::format(42, ctx);
+  }
+};
+}  // namespace fmt
+
 #include "fmt/ostream.h"
 
 #include <sstream>