fix and improve module:

* export public documented API
* don't export `namespace detail`
* add `std.h` into module
* add missing namespace qualification in `xchar.h`
* fix call to `detail::get_iterator` in `xchar.h`
* fix ambiguous overload of `detail::isfinite` in `chrono.h`

include/fmt/args.h

@@ -59,6 +59,7 @@ class dynamic_arg_list {
   }
 };
 }  // namespace detail
+FMT_BEGIN_EXPORT
 
 /**
   \rst
@@ -229,6 +230,7 @@ class dynamic_format_arg_store
   }
 };
 
+FMT_END_EXPORT
 FMT_END_NAMESPACE
 
 #endif  // FMT_ARGS_H_

include/fmt/chrono.h

@@ -1666,7 +1666,7 @@ struct chrono_format_checker : null_chrono_spec_handler<chrono_format_checker> {
   FMT_CONSTEXPR void on_duration_unit() {}
 };
 
-template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
+template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value && has_isfinite<T>::value)>
 inline bool isfinite(T) {
   return true;
 }

include/fmt/core.h

@@ -258,6 +258,7 @@ FMT_GCC_PRAGMA("GCC optimize(\"Og\")")
 #endif
 
 FMT_BEGIN_NAMESPACE
+FMT_BEGIN_EXPORT
 
 // Implementations of enable_if_t and other metafunctions for older systems.
 template <bool B, typename T = void>
@@ -295,6 +296,7 @@ inline auto format_as(std::byte b) -> unsigned char {
 }
 #endif
 
+FMT_END_EXPORT
 namespace detail {
 // Suppresses "unused variable" warnings with the method described in
 // https://herbsutter.com/2009/10/18/mailbag-shutting-up-compiler-warnings/.
@@ -386,6 +388,7 @@ FMT_CONSTEXPR inline auto is_utf8() -> bool {
                          uchar(section[1]) == 0xA7);
 }
 }  // namespace detail
+FMT_BEGIN_EXPORT
 
 /**
   An implementation of ``std::basic_string_view`` for pre-C++17. It provides a
@@ -502,6 +505,7 @@ using string_view = basic_string_view<char>;
 template <typename T> struct is_char : std::false_type {};
 template <> struct is_char<char> : std::true_type {};
 
+FMT_END_EXPORT
 namespace detail {
 
 // A base class for compile-time strings.
@@ -635,6 +639,7 @@ struct error_handler {
   }
 };
 }  // namespace detail
+FMT_BEGIN_EXPORT
 
 /** String's character type. */
 template <typename S> using char_t = typename detail::char_t_impl<S>::type;
@@ -713,6 +718,7 @@ template <typename Char> class basic_format_parse_context {
 
 using format_parse_context = basic_format_parse_context<char>;
 
+FMT_END_EXPORT
 namespace detail {
 // A parse context with extra data used only in compile-time checks.
 template <typename Char>
@@ -752,6 +758,7 @@ class compile_parse_context : public basic_format_parse_context<Char> {
   }
 };
 }  // namespace detail
+FMT_BEGIN_EXPORT
 
 template <typename Char>
 FMT_CONSTEXPR void basic_format_parse_context<Char>::do_check_arg_id(int id) {
@@ -799,6 +806,7 @@ struct is_contiguous<std::basic_string<Char>> : std::true_type {};
 
 class appender;
 
+FMT_END_EXPORT
 namespace detail {
 
 template <typename Context, typename T>
@@ -1476,6 +1484,7 @@ enum { max_packed_args = 62 / packed_arg_bits };
 enum : unsigned long long { is_unpacked_bit = 1ULL << 63 };
 enum : unsigned long long { has_named_args_bit = 1ULL << 62 };
 }  // namespace detail
+FMT_BEGIN_EXPORT
 
 // An output iterator that appends to a buffer.
 // It is used to reduce symbol sizes for the common case.
@@ -1594,6 +1603,7 @@ FMT_CONSTEXPR FMT_INLINE auto visit_format_arg(
   return vis(monostate());
 }
 
+FMT_END_EXPORT
 namespace detail {
 
 template <typename Char, typename InputIt>
@@ -1710,6 +1720,7 @@ FMT_CONSTEXPR inline auto make_arg(T&& value) -> basic_format_arg<Context> {
   return make_arg<Context>(value);
 }
 }  // namespace detail
+FMT_BEGIN_EXPORT
 
 // Formatting context.
 template <typename OutputIt, typename Char> class basic_format_context {
@@ -1998,6 +2009,7 @@ enum type FMT_ENUM_UNDERLYING_TYPE(unsigned char){none, minus, plus, space};
 }
 using sign_t = sign::type;
 
+FMT_END_EXPORT
 namespace detail {
 
 // Workaround an array initialization issue in gcc 4.8.
@@ -2024,6 +2036,7 @@ template <typename Char> struct fill_t {
   }
 };
 }  // namespace detail
+FMT_BEGIN_EXPORT
 
 enum class presentation_type : unsigned char {
   none,
@@ -2068,6 +2081,7 @@ template <typename Char = char> struct format_specs {
         localized(false) {}
 };
 
+FMT_END_EXPORT
 namespace detail {
 
 enum class arg_id_kind { none, index, name };

include/fmt/std.h

@@ -73,6 +73,7 @@ inline void write_escaped_path<std::filesystem::path::value_type>(
 }
 
 }  // namespace detail
+FMT_BEGIN_EXPORT
 
 template <typename Char>
 struct formatter<std::filesystem::path, Char>
@@ -91,16 +92,20 @@ struct formatter<std::filesystem::path, Char>
         basic_string_view<Char>(quoted.data(), quoted.size()), ctx);
   }
 };
+FMT_END_EXPORT
 FMT_END_NAMESPACE
 #endif
 
 FMT_BEGIN_NAMESPACE
+FMT_BEGIN_EXPORT
 template <typename Char>
 struct formatter<std::thread::id, Char> : basic_ostream_formatter<Char> {};
+FMT_END_EXPORT
 FMT_END_NAMESPACE
 
 #ifdef __cpp_lib_optional
 FMT_BEGIN_NAMESPACE
+FMT_BEGIN_EXPORT
 template <typename T, typename Char>
 struct formatter<std::optional<T>, Char,
                  std::enable_if_t<is_formattable<T, Char>::value>> {
@@ -139,11 +144,13 @@ struct formatter<std::optional<T>, Char,
     return detail::write(out, ')');
   }
 };
+FMT_END_EXPORT
 FMT_END_NAMESPACE
 #endif  // __cpp_lib_optional
 
 #ifdef __cpp_lib_variant
 FMT_BEGIN_NAMESPACE
+FMT_BEGIN_EXPORT
 template <typename Char> struct formatter<std::monostate, Char> {
   template <typename ParseContext>
   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
@@ -159,7 +166,7 @@ template <typename Char> struct formatter<std::monostate, Char> {
   }
 };
 
-namespace detail {
+FMT_BEGIN_DETAIL_NAMESPACE
 
 template <typename T>
 using variant_index_sequence =
@@ -191,8 +198,7 @@ auto write_variant_alternative(OutputIt out, const T& v) -> OutputIt {
     return write<Char>(out, v);
 }
 
-}  // namespace detail
-
+FMT_END_DETAIL_NAMESPACE
 template <typename T> struct is_variant_like {
   static constexpr const bool value = detail::is_variant_like_<T>::value;
 };
@@ -231,11 +237,12 @@ struct formatter<
     return out;
   }
 };
+FMT_END_EXPORT
 FMT_END_NAMESPACE
 #endif  // __cpp_lib_variant
 
 FMT_BEGIN_NAMESPACE
-
+FMT_BEGIN_EXPORT
 template <typename Char> struct formatter<std::error_code, Char> {
   template <typename ParseContext>
   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
@@ -338,6 +345,7 @@ struct formatter<
     return out;
   }
 };
+FMT_END_EXPORT
 FMT_END_NAMESPACE
 
 #endif  // FMT_STD_H_

include/fmt/xchar.h

@@ -170,7 +170,7 @@ inline auto vformat_to(
   auto&& buf = detail::get_buffer<Char>(out);
   vformat_to(buf, detail::to_string_view(format_str), args,
              detail::locale_ref(loc));
-  return detail::get_iterator(buf);
+  return detail::get_iterator(buf, out);
 }
 
 template <
@@ -181,7 +181,7 @@ template <
 inline auto format_to(OutputIt out, const Locale& loc, const S& format_str,
                       Args&&... args) ->
     typename std::enable_if<enable, OutputIt>::type {
-  return vformat_to(out, loc, to_string_view(format_str),
+  return vformat_to(out, loc, detail::to_string_view(format_str),
                     fmt::make_format_args<buffer_context<Char>>(args...));
 }
 

src/fmt.cc

@@ -14,19 +14,25 @@ module;
 #include <cstring>
 #include <ctime>
 #include <exception>
+#include <filesystem>
+#include <fstream>
 #include <functional>
 #include <iterator>
 #include <limits>
 #include <locale>
 #include <memory>
+#include <optional>
 #include <ostream>
 #include <stdexcept>
 #include <string>
 #include <string_view>
 #include <system_error>
+#include <thread>
 #include <type_traits>
 #include <utility>
+#include <variant>
 #include <vector>
+#include <version>
 
 #if _MSC_VER
 #  include <intrin.h>
@@ -75,6 +81,7 @@ export module fmt;
 #include "fmt/os.h"
 #include "fmt/printf.h"
 #include "fmt/xchar.h"
+#include "fmt/std.h"
 
 // gcc doesn't yet implement private module fragments
 #if !FMT_GCC_VERSION