Reduce symbol sizes and simplify iterator use

test/core-test.cc

@@ -53,10 +53,7 @@ template <typename Char> struct formatter<test_struct, Char> {
     return ctx.begin();
   }
 
-  typedef std::back_insert_iterator<buffer<Char>> iterator;
-
-  auto format(test_struct, basic_format_context<iterator, char>& ctx)
-      -> decltype(ctx.out()) {
+  auto format(test_struct, format_context& ctx) -> decltype(ctx.out()) {
     const Char* test = "test";
     return std::copy_n(test, std::strlen(test), ctx.out());
   }
@@ -377,9 +374,9 @@ struct check_custom {
       test_buffer() : fmt::detail::buffer<char>(data, 0, 10) {}
       void grow(size_t) {}
     } buffer;
-    fmt::detail::buffer<char>& base = buffer;
     fmt::format_parse_context parse_ctx("");
-    fmt::format_context ctx(std::back_inserter(base), fmt::format_args());
+    fmt::format_context ctx{
+      fmt::detail::buffer_appender<char>(buffer), fmt::format_args()};
     h.format(parse_ctx, ctx);
     EXPECT_EQ("test", std::string(buffer.data, buffer.size()));
     return test_result();
@@ -388,8 +385,8 @@ struct check_custom {
 
 TEST(ArgTest, CustomArg) {
   test_struct test;
-  typedef mock_visitor<fmt::basic_format_arg<fmt::format_context>::handle>
-      visitor;
+  using visitor =
+    mock_visitor<fmt::basic_format_arg<fmt::format_context>::handle>;
   testing::StrictMock<visitor> v;
   EXPECT_CALL(v, visit(_)).WillOnce(testing::Invoke(check_custom()));
   fmt::visit_format_arg(v, make_arg<fmt::format_context>(test));

test/custom-formatter-test.cc

@@ -39,10 +39,9 @@ class custom_arg_formatter
 
 std::string custom_vformat(fmt::string_view format_str, fmt::format_args args) {
   fmt::memory_buffer buffer;
-  fmt::detail::buffer<char>& base = buffer;
   // Pass custom argument formatter as a template arg to vwrite.
-  fmt::vformat_to<custom_arg_formatter>(std::back_inserter(base), format_str,
-                                        args);
+  fmt::vformat_to<custom_arg_formatter>(
+    fmt::detail::buffer_appender<char>(buffer), format_str, args);
   return std::string(buffer.data(), buffer.size());
 }
 

test/format

@@ -38,9 +38,9 @@ namespace std {
   
   template<class Out, class charT> class basic_format_context;
   using format_context = basic_format_context<
-    /* unspecified */ std::back_insert_iterator<fmt::detail::buffer<char>>, char>;
+    /* unspecified */ fmt::detail::buffer_appender<char>, char>;
   using wformat_context = basic_format_context<
-    /* unspecified */ std::back_insert_iterator<fmt::detail::buffer<wchar_t>>, wchar_t>;
+    /* unspecified */ fmt::detail::buffer_appender<wchar_t>, wchar_t>;
 
   template<class T, class charT = char> struct formatter {
     formatter() = delete;
@@ -714,7 +714,7 @@ string vformat(string_view fmt, format_args args) {
   fmt::detail::buffer<char>& buf = mbuf;
   using af = detail::arg_formatter<fmt::format_context::iterator, char>;
   detail::format_handler<af, char, format_context>
-    h(std::back_inserter(buf), fmt, args, {});
+    h(fmt::detail::buffer_appender<char>(buf), fmt, args, {});
   fmt::detail::parse_format_string<false>(fmt::to_string_view(fmt), h);
   return to_string(mbuf);
 }

test/format-test.cc

@@ -1844,10 +1844,9 @@ class mock_arg_formatter
 };
 
 static void custom_vformat(fmt::string_view format_str, fmt::format_args args) {
-  fmt::memory_buffer buffer;
-  fmt::detail::buffer<char>& base = buffer;
-  fmt::vformat_to<mock_arg_formatter>(std::back_inserter(base), format_str,
-                                      args);
+  fmt::memory_buffer buf;
+  fmt::vformat_to<mock_arg_formatter>(fmt::detail::buffer_appender<char>(buf),
+                                      format_str, args);
 }
 
 template <typename... Args>

test/ostream-test.cc

@@ -75,8 +75,8 @@ struct test_arg_formatter
 
 TEST(OStreamTest, CustomArg) {
   fmt::memory_buffer buffer;
-  fmt::detail::buffer<char>& base = buffer;
-  fmt::format_context ctx(std::back_inserter(base), fmt::format_args());
+  fmt::format_context ctx(
+    fmt::detail::buffer_appender<char>{buffer}, fmt::format_args());
   fmt::format_specs spec;
   test_arg_formatter af(ctx, spec);
   fmt::visit_format_arg(