From b31d1a75a016dca5d68027647b6b52d739bfd8d7 Mon Sep 17 00:00:00 2001
From: Vladislav Shchapov <vladislav@shchapov.ru>
Date: Sun, 3 Jul 2022 18:42:08 +0500
Subject: [PATCH] Add xchar support for fmt::streamed().

Signed-off-by: Vladislav Shchapov <vladislav@shchapov.ru>
---
 include/fmt/ostream.h |  9 +++++----
 test/xchar-test.cc    | 13 +++++++++++++
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/include/fmt/ostream.h b/include/fmt/ostream.h
index 394d947c..ced05f75 100644
--- a/include/fmt/ostream.h
+++ b/include/fmt/ostream.h
@@ -142,12 +142,13 @@ struct basic_ostream_formatter : formatter<basic_string_view<Char>, Char> {
 
 using ostream_formatter = basic_ostream_formatter<char>;
 
-template <typename T>
-struct formatter<detail::streamed_view<T>> : ostream_formatter {
+template <typename T, typename Char>
+struct formatter<detail::streamed_view<T>, Char>
+    : basic_ostream_formatter<Char> {
   template <typename OutputIt>
   auto format(detail::streamed_view<T> view,
-              basic_format_context<OutputIt, char>& ctx) const -> OutputIt {
-    return ostream_formatter::format(view.value, ctx);
+              basic_format_context<OutputIt, Char>& ctx) const -> OutputIt {
+    return basic_ostream_formatter<Char>::format(view.value, ctx);
   }
 };
 
diff --git a/test/xchar-test.cc b/test/xchar-test.cc
index ea8bc85a..290f5ffa 100644
--- a/test/xchar-test.cc
+++ b/test/xchar-test.cc
@@ -229,6 +229,19 @@ TEST(xchar_test, enum) {
   EXPECT_EQ(L"0", fmt::format(L"{}", unstreamable_enum()));
 }
 
+struct streamable_and_unformattable {};
+
+auto operator<<(std::wostream& os, streamable_and_unformattable)
+    -> std::wostream& {
+  return os << L"foo";
+}
+
+TEST(xchar_test, streamed) {
+  EXPECT_FALSE(fmt::is_formattable<streamable_and_unformattable>());
+  EXPECT_EQ(fmt::format(L"{}", fmt::streamed(streamable_and_unformattable())),
+            L"foo");
+}
+
 TEST(xchar_test, sign_not_truncated) {
   wchar_t format_str[] = {
       L'{', L':',