Fix format_to formatting to wmemory_buffer

include/fmt/format.h

@@ -3457,16 +3457,17 @@ inline wformat_context::iterator vformat_to(
   return vformat_to<arg_formatter<range>>(buf, format_str, args);
 }
 
-template <typename String, typename... Args,
-          std::size_t SIZE = inline_buffer_size>
-inline format_context::iterator format_to(
-    basic_memory_buffer<char, SIZE> &buf, const String &format_str,
+template <
+    typename String, typename... Args,
+    std::size_t SIZE = inline_buffer_size,
+    typename Char = typename internal::format_string_traits<String>::char_type>
+inline typename buffer_context<Char>::type::iterator format_to(
+    basic_memory_buffer<Char, SIZE> &buf, const String &format_str,
     const Args & ... args) {
   internal::check_format_string<Args...>(format_str);
-  typedef typename internal::format_string_traits<String>::char_type char_t;
   return vformat_to(
-        buf, basic_string_view<char_t>(format_str),
-        make_format_args<typename buffer_context<char_t>::type>(args...));
+        buf, basic_string_view<Char>(format_str),
+        make_format_args<typename buffer_context<Char>::type>(args...));
 }
 
 template <typename OutputIt, typename Char = char>

test/format-test.cc

@@ -692,6 +692,9 @@ TEST(FormatToTest, FormatToMemoryBuffer) {
   fmt::basic_memory_buffer<char, 100> buffer;
   fmt::format_to(buffer, "{}", "foo");
   EXPECT_EQ("foo", to_string(buffer));
+  fmt::wmemory_buffer wbuffer;
+  fmt::format_to(wbuffer, L"{}", L"foo");
+  EXPECT_EQ(L"foo", to_string(wbuffer));
 }
 
 TEST(FormatterTest, Escape) {