From 26c6b1c23dd5274b0e2d6d0d7c9a773924641eed Mon Sep 17 00:00:00 2001
From: Victor Zverovich <victor.zverovich@gmail.com>
Date: Thu, 29 Jan 2026 21:30:20 -0800
Subject: [PATCH] Move copy to format.h

---
 include/fmt/base.h   | 58 -------------------------------------------
 include/fmt/format.h | 59 ++++++++++++++++++++++++++++++++++++++++++++
 test/base-test.cc    | 11 ---------
 test/format-test.cc  | 11 +++++++++
 4 files changed, 70 insertions(+), 69 deletions(-)

diff --git a/include/fmt/base.h b/include/fmt/base.h
index 5151232c..d6d32e97 100644
--- a/include/fmt/base.h
+++ b/include/fmt/base.h
@@ -2031,64 +2031,6 @@ template <typename T = char> class counting_buffer : public buffer<T> {
 template <typename T>
 struct is_back_insert_iterator<basic_appender<T>> : std::true_type {};
 
-template <typename OutputIt, typename InputIt, typename = void>
-struct has_back_insert_iterator_container_append : std::false_type {};
-template <typename OutputIt, typename InputIt>
-struct has_back_insert_iterator_container_append<
-    OutputIt, InputIt,
-    void_t<decltype(get_container(std::declval<OutputIt>())
-                        .append(std::declval<InputIt>(),
-                                std::declval<InputIt>()))>> : std::true_type {};
-
-template <typename OutputIt, typename InputIt, typename = void>
-struct has_back_insert_iterator_container_insert_at_end : std::false_type {};
-
-template <typename OutputIt, typename InputIt>
-struct has_back_insert_iterator_container_insert_at_end<
-    OutputIt, InputIt,
-    void_t<decltype(get_container(std::declval<OutputIt>())
-                        .insert(get_container(std::declval<OutputIt>()).end(),
-                                std::declval<InputIt>(),
-                                std::declval<InputIt>()))>> : std::true_type {};
-
-// An optimized version of std::copy with the output value type (T).
-template <typename T, typename InputIt, typename OutputIt,
-          FMT_ENABLE_IF(is_back_insert_iterator<OutputIt>::value&&
-                            has_back_insert_iterator_container_append<
-                                OutputIt, InputIt>::value)>
-FMT_CONSTEXPR auto copy(InputIt begin, InputIt end, OutputIt out) -> OutputIt {
-  get_container(out).append(begin, end);
-  return out;
-}
-
-template <typename T, typename InputIt, typename OutputIt,
-          FMT_ENABLE_IF(is_back_insert_iterator<OutputIt>::value &&
-                        !has_back_insert_iterator_container_append<
-                            OutputIt, InputIt>::value &&
-                        has_back_insert_iterator_container_insert_at_end<
-                            OutputIt, InputIt>::value)>
-FMT_CONSTEXPR auto copy(InputIt begin, InputIt end, OutputIt out) -> OutputIt {
-  auto& c = get_container(out);
-  c.insert(c.end(), begin, end);
-  return out;
-}
-
-template <typename T, typename InputIt, typename OutputIt,
-          FMT_ENABLE_IF(!(is_back_insert_iterator<OutputIt>::value &&
-                          (has_back_insert_iterator_container_append<
-                               OutputIt, InputIt>::value ||
-                           has_back_insert_iterator_container_insert_at_end<
-                               OutputIt, InputIt>::value)))>
-FMT_CONSTEXPR auto copy(InputIt begin, InputIt end, OutputIt out) -> OutputIt {
-  while (begin != end) *out++ = static_cast<T>(*begin++);
-  return out;
-}
-
-template <typename T, typename V, typename OutputIt>
-FMT_CONSTEXPR auto copy(basic_string_view<V> s, OutputIt out) -> OutputIt {
-  return copy<T>(s.begin(), s.end(), out);
-}
-
 template <typename It, typename Enable = std::true_type>
 struct is_buffer_appender : std::false_type {};
 template <typename It>
diff --git a/include/fmt/format.h b/include/fmt/format.h
index 94e964b4..1fd4a59e 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -567,6 +567,65 @@ FMT_CONSTEXPR20 auto fill_n(T* out, Size count, char value) -> T* {
   return out + count;
 }
 
+template <typename OutputIt, typename InputIt, typename = void>
+struct has_back_insert_iterator_container_append : std::false_type {};
+
+template <typename OutputIt, typename InputIt>
+struct has_back_insert_iterator_container_append<
+    OutputIt, InputIt,
+    void_t<decltype(get_container(std::declval<OutputIt>())
+                        .append(std::declval<InputIt>(),
+                                std::declval<InputIt>()))>> : std::true_type {};
+
+template <typename OutputIt, typename InputIt, typename = void>
+struct has_back_insert_iterator_container_insert_at_end : std::false_type {};
+
+template <typename OutputIt, typename InputIt>
+struct has_back_insert_iterator_container_insert_at_end<
+    OutputIt, InputIt,
+    void_t<decltype(get_container(std::declval<OutputIt>())
+                        .insert(get_container(std::declval<OutputIt>()).end(),
+                                std::declval<InputIt>(),
+                                std::declval<InputIt>()))>> : std::true_type {};
+
+// An optimized version of std::copy with the output value type (T).
+template <typename T, typename InputIt, typename OutputIt,
+          FMT_ENABLE_IF(is_back_insert_iterator<OutputIt>::value&&
+                            has_back_insert_iterator_container_append<
+                                OutputIt, InputIt>::value)>
+FMT_CONSTEXPR auto copy(InputIt begin, InputIt end, OutputIt out) -> OutputIt {
+  get_container(out).append(begin, end);
+  return out;
+}
+
+template <typename T, typename InputIt, typename OutputIt,
+          FMT_ENABLE_IF(is_back_insert_iterator<OutputIt>::value &&
+                        !has_back_insert_iterator_container_append<
+                            OutputIt, InputIt>::value &&
+                        has_back_insert_iterator_container_insert_at_end<
+                            OutputIt, InputIt>::value)>
+FMT_CONSTEXPR auto copy(InputIt begin, InputIt end, OutputIt out) -> OutputIt {
+  auto& c = get_container(out);
+  c.insert(c.end(), begin, end);
+  return out;
+}
+
+template <typename T, typename InputIt, typename OutputIt,
+          FMT_ENABLE_IF(!(is_back_insert_iterator<OutputIt>::value &&
+                          (has_back_insert_iterator_container_append<
+                               OutputIt, InputIt>::value ||
+                           has_back_insert_iterator_container_insert_at_end<
+                               OutputIt, InputIt>::value)))>
+FMT_CONSTEXPR auto copy(InputIt begin, InputIt end, OutputIt out) -> OutputIt {
+  while (begin != end) *out++ = static_cast<T>(*begin++);
+  return out;
+}
+
+template <typename T, typename V, typename OutputIt>
+FMT_CONSTEXPR auto copy(basic_string_view<V> s, OutputIt out) -> OutputIt {
+  return copy<T>(s.begin(), s.end(), out);
+}
+
 template <typename OutChar, typename InputIt, typename OutputIt>
 FMT_CONSTEXPR FMT_NOINLINE auto copy_noinline(InputIt begin, InputIt end,
                                               OutputIt out) -> OutputIt {
diff --git a/test/base-test.cc b/test/base-test.cc
index 7f5c5c7b..bf268875 100644
--- a/test/base-test.cc
+++ b/test/base-test.cc
@@ -282,17 +282,6 @@ TEST(base_test, is_back_insert_iterator) {
                std::front_insert_iterator<std::string>>::value);
 }
 
-struct minimal_container {
-  using value_type = char;
-  void push_back(char) {}
-};
-
-TEST(base_test, copy) {
-  minimal_container c;
-  static constexpr char str[] = "a";
-  fmt::detail::copy<char>(str, str + 1, std::back_inserter(c));
-}
-
 TEST(base_test, get_buffer) {
   mock_buffer<char> buffer;
   void* buffer_ptr = &buffer;
diff --git a/test/format-test.cc b/test/format-test.cc
index 4db939a1..9efde149 100644
--- a/test/format-test.cc
+++ b/test/format-test.cc
@@ -196,6 +196,17 @@ TEST(util_test, increment) {
   EXPECT_STREQ("200", s);
 }
 
+struct minimal_container {
+  using value_type = char;
+  void push_back(char) {}
+};
+
+TEST(util_test, copy) {
+  minimal_container c;
+  static constexpr char str[] = "a";
+  fmt::detail::copy<char>(str, str + 1, std::back_inserter(c));
+}
+
 TEST(util_test, parse_nonnegative_int) {
   auto s = fmt::string_view("10000000000");
   auto begin = s.begin(), end = s.end();