From 08ca40ea9139b9066843e93e308927dc7bb69819 Mon Sep 17 00:00:00 2001
From: Victor Zverovich <viz@fb.com>
Date: Sun, 22 Mar 2020 07:57:56 -0700
Subject: [PATCH] Detect /utf-8 in MSVC

---
 include/fmt/core.h | 43 +++++++++++++++++++++++++------------------
 1 file changed, 25 insertions(+), 18 deletions(-)

diff --git a/include/fmt/core.h b/include/fmt/core.h
index d1242b59..74b9b08d 100644
--- a/include/fmt/core.h
+++ b/include/fmt/core.h
@@ -240,9 +240,9 @@
 #endif
 
 #ifndef FMT_UNICODE
-#  define FMT_UNICODE 0
+#  define FMT_UNICODE !FMT_MSC_VER
 #endif
-#if FMT_UNICODE
+#if FMT_UNICODE && FMT_MSC_VER
 #  pragma execution_character_set("utf-8")
 #endif
 
@@ -324,6 +324,13 @@ FMT_CONSTEXPR typename std::make_unsigned<Int>::type to_unsigned(Int value) {
   return static_cast<typename std::make_unsigned<Int>::type>(value);
 }
 
+constexpr unsigned char micro[] = "\u00B5";
+
+constexpr bool is_utf8() {
+  return FMT_UNICODE ||
+         (sizeof(micro) == 3 && micro[0] == 0xC2 && micro[1] == 0xB5);
+}
+
 #ifdef __cpp_char8_t
 using char8_type = char8_t;
 #else
@@ -1648,6 +1655,10 @@ typename buffer_context<Char>::iterator vformat_to(
     basic_format_args<buffer_context<type_identity_t<Char>>> args);
 
 FMT_API void vprint_mojibake(std::FILE*, string_view, format_args);
+
+#ifndef _WIN32
+inline void vprint_mojibake(std::FILE*, string_view, format_args) {}
+#endif
 }  // namespace internal
 
 /**
@@ -1738,14 +1749,12 @@ FMT_API void vprint(std::FILE*, string_view, format_args);
 template <typename S, typename... Args,
           FMT_ENABLE_IF(internal::is_string<S>::value)>
 inline void print(std::FILE* f, const S& format_str, Args&&... args) {
-#if !defined(_WIN32) || FMT_UNICODE
-  vprint(f, to_string_view(format_str),
-         internal::make_args_checked<Args...>(format_str, args...));
-#else
-  internal::vprint_mojibake(
-      f, to_string_view(format_str),
-      internal::make_args_checked<Args...>(format_str, args...));
-#endif
+  return internal::is_utf8()
+             ? vprint(f, to_string_view(format_str),
+                      internal::make_args_checked<Args...>(format_str, args...))
+             : internal::vprint_mojibake(
+                   f, to_string_view(format_str),
+                   internal::make_args_checked<Args...>(format_str, args...));
 }
 
 /**
@@ -1762,14 +1771,12 @@ inline void print(std::FILE* f, const S& format_str, Args&&... args) {
 template <typename S, typename... Args,
           FMT_ENABLE_IF(internal::is_string<S>::value)>
 inline void print(const S& format_str, Args&&... args) {
-#if !defined(_WIN32) || FMT_UNICODE
-  vprint(to_string_view(format_str),
-         internal::make_args_checked<Args...>(format_str, args...));
-#else
-  internal::vprint_mojibake(
-      stdout, to_string_view(format_str),
-      internal::make_args_checked<Args...>(format_str, args...));
-#endif
+  return internal::is_utf8()
+             ? vprint(to_string_view(format_str),
+                      internal::make_args_checked<Args...>(format_str, args...))
+             : internal::vprint_mojibake(
+                   stdout, to_string_view(format_str),
+                   internal::make_args_checked<Args...>(format_str, args...));
 }
 FMT_END_NAMESPACE