From 4a6eadbde0619b249bde5e019d69e3e8afb02260 Mon Sep 17 00:00:00 2001
From: Victor Zverovich <victor.zverovich@gmail.com>
Date: Thu, 3 Dec 2020 08:50:28 -0800
Subject: [PATCH] Make std::byte formattabe (#1981)

---
 include/fmt/format.h | 5 ++++-
 test/format-test.cc  | 7 +++++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/include/fmt/format.h b/include/fmt/format.h
index afcb32f5cf3e..8ec527e6a0a7 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -3538,7 +3538,7 @@ struct formatter<T, Char,
   struct formatter<Type, Char> : formatter<Base, Char> {                      \
     template <typename FormatContext>                                         \
     auto format(Type const& val, FormatContext& ctx) -> decltype(ctx.out()) { \
-      return formatter<Base, Char>::format(val, ctx);                         \
+      return formatter<Base, Char>::format(static_cast<Base>(val), ctx);      \
     }                                                                         \
   }
 
@@ -3552,6 +3552,9 @@ FMT_FORMAT_AS(Char*, const Char*);
 FMT_FORMAT_AS(std::basic_string<Char>, basic_string_view<Char>);
 FMT_FORMAT_AS(std::nullptr_t, const void*);
 FMT_FORMAT_AS(detail::std_string_view<Char>, basic_string_view<Char>);
+#if __cplusplus >= 201703L
+FMT_FORMAT_AS(std::byte, unsigned);
+#endif
 
 template <typename Char>
 struct formatter<void*, Char> : formatter<const void*, Char> {
diff --git a/test/format-test.cc b/test/format-test.cc
index 205997ec827f..bb10460f40f4 100644
--- a/test/format-test.cc
+++ b/test/format-test.cc
@@ -1762,6 +1762,13 @@ TEST(FormatTest, JoinArg) {
 #endif
 }
 
+#if __cplusplus >= 201703L
+TEST(FormatTest, JoinBytes) {
+  std::vector<std::byte> v = {std::byte(1), std::byte(2), std::byte(3)};
+  EXPECT_EQ("1, 2, 3", fmt::format("{}", fmt::join(v, ", ")));
+}
+#endif
+
 template <typename T> std::string str(const T& value) {
   return fmt::format("{}", value);
 }