From c5979d564e1ec40c383eaca610c8aa7cca1733a4 Mon Sep 17 00:00:00 2001
From: Yuval Gamzon-Kapeller <yuvalgamzon@gmail.com>
Date: Sun, 7 Feb 2021 10:19:17 +0200
Subject: [PATCH] Fix fmt::localtime formatting not working in wide-char string
 contexts

---
 include/fmt/chrono.h |  3 ++-
 test/chrono-test.cc  | 24 ++++++++++++++++++------
 2 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/include/fmt/chrono.h b/include/fmt/chrono.h
index 4b9aeeb1..1b71131d 100644
--- a/include/fmt/chrono.h
+++ b/include/fmt/chrono.h
@@ -413,7 +413,8 @@ struct formatter<std::chrono::time_point<std::chrono::system_clock>, Char>
 };
 
 template <typename Char> struct formatter<std::tm, Char> {
-  FMT_CONSTEXPR auto parse(format_parse_context& ctx) -> decltype(ctx.begin()) {
+  template <typename ParseContext>
+  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
     auto it = ctx.begin();
     if (it != ctx.end() && *it == ':') ++it;
     auto end = it;
diff --git a/test/chrono-test.cc b/test/chrono-test.cc
index 6c4ff6da..e56b2bfe 100644
--- a/test/chrono-test.cc
+++ b/test/chrono-test.cc
@@ -95,17 +95,29 @@ TEST(TimeTest, GMTime) {
   EXPECT_TRUE(EqualTime(tm, fmt::gmtime(t)));
 }
 
-TEST(TimeTest, TimePoint) {
-  std::chrono::system_clock::time_point point =
-      std::chrono::system_clock::now();
-
+TEST(TimeTest, FormatTM) {
+  auto point = std::chrono::system_clock::now();
   std::time_t t = std::chrono::system_clock::to_time_t(point);
   std::tm tm = *std::localtime(&t);
   char strftime_output[256];
   std::strftime(strftime_output, sizeof(strftime_output),
-                "It is %Y-%m-%d %H:%M:%S", &tm);
+                "%Y-%m-%d %H:%M:%S", &tm);
+  EXPECT_EQ(strftime_output, fmt::format("{:%Y-%m-%d %H:%M:%S}", tm));
+  auto wstrftime_output = std::wstring();
+  std::copy(strftime_output, strftime_output + strlen(strftime_output),
+            std::back_inserter(wstrftime_output));
+  EXPECT_EQ(wstrftime_output,
+            fmt::format(L"{:%Y-%m-%d %H:%M:%S}", tm));
+}
 
-  EXPECT_EQ(strftime_output, fmt::format("It is {:%Y-%m-%d %H:%M:%S}", point));
+TEST(TimeTest, TimePoint) {
+  auto point = std::chrono::system_clock::now();
+  std::time_t t = std::chrono::system_clock::to_time_t(point);
+  std::tm tm = *std::localtime(&t);
+  char strftime_output[256];
+  std::strftime(strftime_output, sizeof(strftime_output),
+                "%Y-%m-%d %H:%M:%S", &tm);
+  EXPECT_EQ(strftime_output, fmt::format("{:%Y-%m-%d %H:%M:%S}", point));
 }
 
 #define EXPECT_TIME(spec, time, duration)                 \