Fix formatting

Ensure the PDB files are output into the same directory and with the same name
as the static library when using Visual Studio.

Resolves fmtlib#3701.

.github/dependabot.yml

@@ -3,6 +3,6 @@ updates:
   - package-ecosystem: "github-actions" # Necessary to update action hashs	
     directory: "/"
     schedule:
-      interval: "weekly"
+      interval: "monthly"
     # Allow up to 3 opened pull requests for github-actions versions
     open-pull-requests-limit: 3

.github/workflows/doc.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-20.04
 
     steps:
-    - uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # v3.5.3
+    - uses: actions/checkout@8ade135a41bc03ea155e62e844d188df1ea18608 # v4.1.0
 
     - name: Add ubuntu mirrors
       run: |

.github/workflows/linux.yml

@@ -57,7 +57,7 @@ jobs:
           - shared: -DBUILD_SHARED_LIBS=ON
 
     steps:
-    - uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # v3.5.3
+    - uses: actions/checkout@8ade135a41bc03ea155e62e844d188df1ea18608 # v4.1.0
 
     - name: Set timezone
       run: sudo timedatectl set-timezone 'Asia/Yekaterinburg'

.github/workflows/macos.yml

@@ -22,7 +22,7 @@ jobs:
     runs-on: '${{ matrix.os }}'
 
     steps:
-    - uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # v3.5.3
+    - uses: actions/checkout@8ade135a41bc03ea155e62e844d188df1ea18608 # v4.1.0
 
     - name: Set timezone
       run: sudo systemsetup -settimezone 'Asia/Yekaterinburg'

.github/workflows/scorecard.yml

@@ -29,12 +29,12 @@ jobs:
 
     steps:
       - name: "Checkout code"
-        uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # v3.5.3
+        uses: actions/checkout@8ade135a41bc03ea155e62e844d188df1ea18608 # v4.1.0
         with:
           persist-credentials: false
 
       - name: "Run analysis"
-        uses: ossf/scorecard-action@08b4669551908b1024bb425080c797723083c031 # v2.2.0
+        uses: ossf/scorecard-action@0864cf19026789058feabb7e87baa5f140aac736 # v2.3.1
         with:
           results_file: results.sarif
           results_format: sarif
@@ -60,6 +60,6 @@ jobs:
 
       # Upload the results to GitHub's code scanning dashboard.
       - name: "Upload to code-scanning"
-        uses: github/codeql-action/upload-sarif@a09933a12a80f87b87005513f0abb1494c27a716 # v2.21.4
+        uses: github/codeql-action/upload-sarif@74483a38d39275f33fcff5f35b679b5ca4a26a99 # v2.22.5
         with:
           sarif_file: results.sarif

.github/workflows/windows.yml

@@ -41,7 +41,7 @@ jobs:
             standard: 20
 
     steps:
-    - uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # v3.5.3
+    - uses: actions/checkout@8ade135a41bc03ea155e62e844d188df1ea18608 # v4.1.0
 
     - name: Set timezone
       run: tzutil /s "Ekaterinburg Standard Time"
@@ -88,7 +88,7 @@ jobs:
         release: false
         msystem: ${{matrix.sys}}
         pacboy: cc:p cmake:p ninja:p lld:p
-    - uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # v3.5.3
+    - uses: actions/checkout@8ade135a41bc03ea155e62e844d188df1ea18608 # v4.1.0
     - name: Configure
       run: cmake -B ../build -DBUILD_SHARED_LIBS=ON -DCMAKE_BUILD_TYPE=Debug
       env: { LDFLAGS: -fuse-ld=lld }

CMakeLists.txt

@@ -1,9 +1,9 @@
-cmake_minimum_required(VERSION 3.8...3.26)
+cmake_minimum_required(VERSION 3.8...3.28)
 
 # Fallback for using newer policies on CMake <3.12.
-if(${CMAKE_VERSION} VERSION_LESS 3.12)
+if (${CMAKE_VERSION} VERSION_LESS 3.12)
   cmake_policy(VERSION ${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION})
-endif()
+endif ()
 
 # Determine if fmt is built as a subproject (using add_subdirectory)
 # or if it is the master project.
@@ -26,7 +26,7 @@ endfunction()
 
 # DEPRECATED! Should be merged into add_module_library.
 function(enable_module target)
-  if (MSVC)
+  if (MSVC AND CMAKE_VERSION VERSION_LESS 3.28)
     set(BMI ${CMAKE_CURRENT_BINARY_DIR}/${target}.ifc)
     target_compile_options(${target}
       PRIVATE /interface /ifcOutput ${BMI}
@@ -65,7 +65,7 @@ function(add_module_library name)
   # `std` is affected by CMake options and may be higher than C++20.
   get_target_property(std ${name} CXX_STANDARD)
 
-  if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+  if (CMAKE_CXX_COMPILER_ID MATCHES "Clang" AND CMAKE_VERSION VERSION_LESS 3.28)
     set(pcms)
     foreach (src ${sources})
       get_filename_component(pcm ${src} NAME_WE)
@@ -103,7 +103,12 @@ function(add_module_library name)
         DEPENDS ${pcm})
     endforeach ()
   endif ()
-  target_sources(${name} PRIVATE ${sources})
+  if (CMAKE_VERSION VERSION_LESS 3.28)
+    target_sources(${name} PRIVATE ${sources})
+  else ()
+    target_sources(${name} PUBLIC FILE_SET fmt_module TYPE CXX_MODULES
+                   FILES ${sources})
+  endif ()
 endfunction()
 
 include(CMakeParseArguments)
@@ -162,10 +167,10 @@ set(FMT_SYSTEM_HEADERS_ATTRIBUTE "")
 if (FMT_SYSTEM_HEADERS)
   set(FMT_SYSTEM_HEADERS_ATTRIBUTE SYSTEM)
 endif ()
-if(CMAKE_SYSTEM_NAME STREQUAL "MSDOS")
+if (CMAKE_SYSTEM_NAME STREQUAL "MSDOS")
   set(FMT_TEST OFF)
   message(STATUS "MSDOS is incompatible with gtest")
-endif()
+endif ()
 
 # Get version from core.h
 file(READ include/fmt/core.h core_h)
@@ -283,7 +288,7 @@ if (FMT_OS)
 endif ()
 
 add_module_library(fmt src/fmt.cc FALLBACK
-                   ${FMT_SOURCES} ${FMT_HEADERS} README.rst ChangeLog.rst
+                   ${FMT_SOURCES} ${FMT_HEADERS} README.rst ChangeLog.md
                    IF FMT_MODULE)
 add_library(fmt::fmt ALIAS fmt)
 if (FMT_MODULE)
@@ -312,7 +317,15 @@ set(FMT_DEBUG_POSTFIX d CACHE STRING "Debug library postfix.")
 set_target_properties(fmt PROPERTIES
   VERSION ${FMT_VERSION} SOVERSION ${CPACK_PACKAGE_VERSION_MAJOR}
   PUBLIC_HEADER "${FMT_HEADERS}"
-  DEBUG_POSTFIX "${FMT_DEBUG_POSTFIX}")
+  DEBUG_POSTFIX "${FMT_DEBUG_POSTFIX}"
+
+  # Workaround for Visual Studio 2017:
+  # Ensure the .pdb is created with the same name and in the same directory
+  # as the .lib. Newer VS versions already do this by default, but there is no
+  # harm in setting it for those too. Ignored by other generators.
+  COMPILE_PDB_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}"
+  COMPILE_PDB_NAME "fmt"
+  COMPILE_PDB_NAME_DEBUG "fmt${FMT_DEBUG_POSTFIX}")
 
 # Set FMT_LIB_NAME for pkg-config fmt.pc. We cannot use the OUTPUT_NAME target
 # property because it's not set by default.
@@ -326,7 +339,7 @@ if (BUILD_SHARED_LIBS)
 endif ()
 if (FMT_SAFE_DURATION_CAST)
   target_compile_definitions(fmt PUBLIC FMT_SAFE_DURATION_CAST)
-endif()
+endif ()
 
 add_library(fmt-header-only INTERFACE)
 add_library(fmt::fmt-header-only ALIAS fmt-header-only)
@@ -334,7 +347,8 @@ add_library(fmt::fmt-header-only ALIAS fmt-header-only)
 target_compile_definitions(fmt-header-only INTERFACE FMT_HEADER_ONLY=1)
 target_compile_features(fmt-header-only INTERFACE cxx_std_11)
 
-target_include_directories(fmt-header-only ${FMT_SYSTEM_HEADERS_ATTRIBUTE} INTERFACE
+target_include_directories(fmt-header-only
+  ${FMT_SYSTEM_HEADERS_ATTRIBUTE} INTERFACE
   $<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/include>
   $<INSTALL_INTERFACE:${FMT_INC_DIR}>)
 
@@ -384,8 +398,16 @@ if (FMT_INSTALL)
           LIBRARY DESTINATION ${FMT_LIB_DIR}
           ARCHIVE DESTINATION ${FMT_LIB_DIR}
           PUBLIC_HEADER DESTINATION "${FMT_INC_DIR}/fmt"
+          FILE_SET fmt_module DESTINATION "${FMT_LIB_DIR}/cxx/miu"
           RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
 
+  if (FMT_MODULE AND CMAKE_VERSION VERSION_GREATER_EQUAL 3.28)
+    # Install format.cc and os.cc which are included by the fmt.cc module
+    # interface file.
+    install(FILES src/format.cc src/os.cc
+            DESTINATION "${FMT_LIB_DIR}/cxx/miu/src")
+  endif ()
+
   # Use a namespace because CMake provides better diagnostics for namespaced
   # imported targets.
   export(TARGETS ${INSTALL_TARGETS} NAMESPACE fmt::

README.rst

@@ -46,7 +46,8 @@ Features
 * Simple `format API <https://fmt.dev/latest/api.html>`_ with positional arguments
   for localization
 * Implementation of `C++20 std::format
-  <https://en.cppreference.com/w/cpp/utility/format>`__
+  <https://en.cppreference.com/w/cpp/utility/format>`__ and `C++23 std::print
+  <https://en.cppreference.com/w/cpp/io/print>`__
 * `Format string syntax <https://fmt.dev/latest/syntax.html>`_ similar to Python's
   `format <https://docs.python.org/3/library/stdtypes.html#str.format>`_
 * Fast IEEE 754 floating-point formatter with correct rounding, shortness and
@@ -92,7 +93,7 @@ Examples
 .. code:: c++
 
     #include <fmt/core.h>
-    
+
     int main() {
       fmt::print("Hello, world!\n");
     }
@@ -177,15 +178,15 @@ This can be `5 to 9 times faster than fprintf
       fmt::print(fg(fmt::color::crimson) | fmt::emphasis::bold,
                  "Hello, {}!\n", "world");
       fmt::print(fg(fmt::color::floral_white) | bg(fmt::color::slate_gray) |
-                 fmt::emphasis::underline, "Hello, {}!\n", "мир");
+                 fmt::emphasis::underline, "Olá, {}!\n", "Mundo");
       fmt::print(fg(fmt::color::steel_blue) | fmt::emphasis::italic,
-                 "Hello, {}!\n", "世界");
+                 "你好{}！\n", "世界");
     }
 
-Output on a modern terminal:
+Output on a modern terminal with Unicode support:
 
-.. image:: https://user-images.githubusercontent.com/
-           576385/88485597-d312f600-cf2b-11ea-9cbe-61f535a86e28.png
+.. image:: https://github.com/fmtlib/fmt/assets/
+           576385/2a93c904-d6fa-4aa6-b453-2618e1c327d7
 
 Benchmarks
 ----------
@@ -294,7 +295,7 @@ Then you can run the speed test::
 or the bloat test::
 
     $ make bloat-test
-    
+
 Migrating code
 --------------
 
@@ -315,13 +316,13 @@ Projects using this library
   an open-source library for mathematical programming
 
 * `Aseprite <https://github.com/aseprite/aseprite>`_:
-  animated sprite editor & pixel art tool 
+  animated sprite editor & pixel art tool
 
 * `AvioBook <https://www.aviobook.aero/en>`_: a comprehensive aircraft
   operations suite
-  
+
 * `Blizzard Battle.net <https://battle.net/>`_: an online gaming platform
-  
+
 * `Celestia <https://celestia.space/>`_: real-time 3D visualization of space
 
 * `Ceph <https://ceph.com/>`_: a scalable distributed storage system
@@ -330,7 +331,7 @@ Projects using this library
 
 * `ClickHouse <https://github.com/ClickHouse/ClickHouse>`_: an analytical database
   management system
-  
+
 * `Contour <https://github.com/contour-terminal/contour/>`_: a modern terminal emulator
 
 * `CUAUV <https://cuauv.org/>`_: Cornell University's autonomous underwater
@@ -391,7 +392,7 @@ Projects using this library
 
 * `quasardb <https://www.quasardb.net/>`_: a distributed, high-performance,
   associative database
-  
+
 * `Quill <https://github.com/odygrd/quill>`_: asynchronous low-latency logging library
 
 * `QKW <https://github.com/ravijanjam/qkw>`_: generalizing aliasing to simplify
@@ -521,7 +522,7 @@ License
 -------
 
 {fmt} is distributed under the MIT `license
-<https://github.com/fmtlib/fmt/blob/master/LICENSE.rst>`_.
+<https://github.com/fmtlib/fmt/blob/master/LICENSE>`_.
 
 Documentation License
 ---------------------
@@ -543,3 +544,10 @@ See `Contributors <https://github.com/fmtlib/fmt/graphs/contributors>`_ and
 `Releases <https://github.com/fmtlib/fmt/releases>`_ for some of the names.
 Let us know if your contribution is not listed or mentioned incorrectly and
 we'll make it right.
+
+Security Policy
+---------------
+
+To report a security issue, please disclose it at `security advisory <https://github.com/fmtlib/fmt/security/advisories/new>`_.
+
+This project is maintained by a team of volunteers on a reasonable-effort basis. As such, please give us at least 90 days to work on a fix before public exposure.

doc/api.rst

@@ -49,6 +49,10 @@ checked at compile time in C++20. To pass a runtime format string wrap it in
 
 *args* is an argument list representing objects to be formatted.
 
+I/O errors are reported as `std::system_error
+<https://en.cppreference.com/w/cpp/error/system_error>`_ exceptions unless
+specified otherwise.
+
 .. _format:
 
 .. doxygenfunction:: format(format_string<T...> fmt, T&&... args) -> std::string
@@ -104,7 +108,7 @@ with the same format specifiers. The ``format_as`` function should take an
 object of your type and return an object of a formattable type. It should be
 defined in the same namespace as your type.
 
-Example (https://godbolt.org/z/r7vvGE1v7)::
+Example (https://godbolt.org/z/nvME4arz8)::
 
   #include <fmt/format.h>
 
@@ -119,67 +123,13 @@ Example (https://godbolt.org/z/r7vvGE1v7)::
     fmt::print("{}\n", kevin_namespacy::film::se7en); // prints "7"
   }
 
-Using the specialization API is more complex but gives you full control over
-parsing and formatting. To use this method specialize the ``formatter`` struct
-template for your type and implement ``parse`` and ``format`` methods.
-For example::
+Using specialization is more complex but gives you full control over parsing and
+formatting. To use this method specialize the ``formatter`` struct template for
+your type and implement ``parse`` and ``format`` methods.
 
-  #include <fmt/core.h>
-
-  struct point {
-    double x, y;
-  };
-
-  template <> struct fmt::formatter<point> {
-    // Presentation format: 'f' - fixed, 'e' - exponential.
-    char presentation = 'f';
-
-    // Parses format specifications of the form ['f' | 'e'].
-    constexpr auto parse(format_parse_context& ctx) -> format_parse_context::iterator {
-      // [ctx.begin(), ctx.end()) is a character range that contains a part of
-      // the format string starting from the format specifications to be parsed,
-      // e.g. in
-      //
-      //   fmt::format("{:f} - point of interest", point{1, 2});
-      //
-      // the range will contain "f} - point of interest". The formatter should
-      // parse specifiers until '}' or the end of the range. In this example
-      // the formatter should parse the 'f' specifier and return an iterator
-      // pointing to '}'.
-      
-      // Please also note that this character range may be empty, in case of
-      // the "{}" format string, so therefore you should check ctx.begin()
-      // for equality with ctx.end().
-
-      // Parse the presentation format and store it in the formatter:
-      auto it = ctx.begin(), end = ctx.end();
-      if (it != end && (*it == 'f' || *it == 'e')) presentation = *it++;
-
-      // Check if reached the end of the range:
-      if (it != end && *it != '}') throw_format_error("invalid format");
-
-      // Return an iterator past the end of the parsed range:
-      return it;
-    }
-
-    // Formats the point p using the parsed format specification (presentation)
-    // stored in this formatter.
-    auto format(const point& p, format_context& ctx) const -> format_context::iterator {
-      // ctx.out() is an output iterator to write to.
-      return presentation == 'f'
-                ? fmt::format_to(ctx.out(), "({:.1f}, {:.1f})", p.x, p.y)
-                : fmt::format_to(ctx.out(), "({:.1e}, {:.1e})", p.x, p.y);
-    }
-  };
-
-Then you can pass objects of type ``point`` to any formatting function::
-
-  point p = {1, 2};
-  std::string s = fmt::format("{:f}", p);
-  // s == "(1.0, 2.0)"
-
-You can also reuse existing formatters via inheritance or composition, for
-example::
+The recommended way of defining a formatter is by reusing an existing one via
+inheritance or composition. This way you can support standard format specifiers
+without implementing them yourself. For example::
 
   // color.h:
   #include <fmt/core.h>
@@ -207,9 +157,9 @@ example::
   }
 
 Note that ``formatter<string_view>::format`` is defined in ``fmt/format.h`` so
-it has to be included in the source file.
-Since ``parse`` is inherited from ``formatter<string_view>`` it will recognize
-all string format specifications, for example
+it has to be included in the source file. Since ``parse`` is inherited from
+``formatter<string_view>`` it will recognize all string format specifications,
+for example
 
 .. code-block:: c++
 
@@ -217,6 +167,64 @@ all string format specifications, for example
 
 will return ``"      blue"``.
 
+The experimental ``nested_formatter`` provides an easy way applying a formatter
+to one or more subobjects.
+
+For example::
+
+  #include <fmt/format.h>
+
+  struct point {
+    double x, y;
+  };
+
+  template <>
+  struct fmt::formatter<point> : nested_formatter<double> {
+    auto format(point p, format_context& ctx) const {
+      return write_padded(ctx, [=](auto out) {
+        return format_to(out, "({}, {})", nested(p.x), nested(p.y));
+      });
+    }
+  };
+
+  int main() {
+    fmt::print("[{:>20.2f}]", point{1, 2});
+  }
+
+prints::
+
+  [          (1.00, 2.00)]
+
+Notice that fill, align and width are applied to the whole object which is the
+recommended behavior while the remaining specifiers apply to elements.
+
+In general the formatter has the following form::
+
+  template <> struct fmt::formatter<T> {
+    // Parses format specifiers and stores them in the formatter.
+    //
+    // [ctx.begin(), ctx.end()) is a, possibly empty, character range that
+    // contains a part of the format string starting from the format
+    // specifications to be parsed, e.g. in
+    //
+    //   fmt::format("{:f} continued", ...);
+    //
+    // the range will contain "f} continued". The formatter should parse
+    // specifiers until '}' or the end of the range. In this example the
+    // formatter should parse the 'f' specifier and return an iterator
+    // pointing to '}'.
+    constexpr auto parse(format_parse_context& ctx)
+      -> format_parse_context::iterator;
+
+    // Formats value using the parsed format specification stored in this
+    // formatter and writes the output to ctx.out().
+    auto format(const T& value, format_context& ctx) const
+      -> format_context::iterator;
+  };
+
+It is recommended to at least support fill, align and width that apply to the
+whole object and have the same semantics as in standard formatters.
+
 You can also write a formatter for a hierarchy of classes::
 
   // demo.h:

doc/build.py

@@ -4,7 +4,7 @@
 import errno, os, re, sys
 from subprocess import check_call, CalledProcessError, Popen, PIPE, STDOUT
 
-versions = ['1.0.0', '1.1.0', '2.0.0', '3.0.2', '4.0.0', '4.1.0', '5.0.0', '5.1.0', '5.2.0', '5.2.1', '5.3.0', '6.0.0', '6.1.0', '6.1.1', '6.1.2', '6.2.0', '6.2.1', '7.0.0', '7.0.1', '7.0.2', '7.0.3', '7.1.0', '7.1.1', '7.1.2', '7.1.3', '8.0.0', '8.0.1', '8.1.0', '8.1.1', '9.0.0', '9.1.0', '10.0.0', '10.1.0', '10.1.1']
+versions = ['1.0.0', '1.1.0', '2.0.0', '3.0.2', '4.0.0', '4.1.0', '5.0.0', '5.1.0', '5.2.0', '5.2.1', '5.3.0', '6.0.0', '6.1.0', '6.1.1', '6.1.2', '6.2.0', '6.2.1', '7.0.0', '7.0.1', '7.0.2', '7.0.3', '7.1.0', '7.1.1', '7.1.2', '7.1.3', '8.0.0', '8.0.1', '8.1.0', '8.1.1', '9.0.0', '9.1.0', '10.0.0', '10.1.0', '10.1.1', '10.1.1']
 
 class Pip:
   def __init__(self, venv_dir):

doc/usage.rst

@@ -134,6 +134,44 @@ For ``build2`` newcomers or to get more details and use cases, you can read the
 ``build2``
 `toolchain introduction <https://build2.org/build2-toolchain/doc/build2-toolchain-intro.xhtml>`_.
 
+Usage with Meson
+================
+
+`Meson's WrapDB <https://mesonbuild.com/Wrapdb-projects.html>` includes a ``fmt``
+package, which repackages fmt to be built by Meson as a subproject.
+
+**Usage:**
+
+- Install the ``fmt`` subproject from the WrapDB by running::
+
+    meson wrap install fmt
+
+  from the root of your project.
+
+- In your project's ``meson.build`` file, add an entry for the new subproject::
+
+    fmt = subproject('fmt')
+    fmt_dep = fmt.get_variable('fmt_dep')
+
+- Include the new dependency object to link with fmt::
+
+    my_build_target = executable('name', 'src/main.cc', dependencies: [fmt_dep])
+
+**Options:**
+
+If desired, ``fmt`` may be built as a static library, or as a header-only
+library.
+
+For a static build, use the following subproject definition::
+
+  fmt = subproject('fmt', default_options: 'default_library=static')
+  fmt_dep = fmt.get_variable('fmt_dep')
+
+For the header-only version, use::
+
+  fmt = subproject('fmt')
+  fmt_dep = fmt.get_variable('fmt_header_only_dep')
+
 Building the Documentation
 ==========================
 

include/fmt/chrono.h

@@ -336,8 +336,6 @@ template <typename CodeUnit> struct codecvt_result {
   CodeUnit buf[max_size];
   CodeUnit* end;
 };
-template <typename CodeUnit>
-constexpr const size_t codecvt_result<CodeUnit>::max_size;
 
 template <typename CodeUnit>
 void write_codecvt(codecvt_result<CodeUnit>& out, string_view in_buf,
@@ -584,8 +582,9 @@ template <typename Period> FMT_CONSTEXPR inline const char* get_units() {
   if (std::is_same<Period, std::tera>::value) return "Ts";
   if (std::is_same<Period, std::peta>::value) return "Ps";
   if (std::is_same<Period, std::exa>::value) return "Es";
-  if (std::is_same<Period, std::ratio<60>>::value) return "m";
+  if (std::is_same<Period, std::ratio<60>>::value) return "min";
   if (std::is_same<Period, std::ratio<3600>>::value) return "h";
+  if (std::is_same<Period, std::ratio<86400>>::value) return "d";
   return nullptr;
 }
 

include/fmt/color.h

@@ -427,9 +427,10 @@ template <typename Char> inline void reset_color(buffer<Char>& buffer) {
   buffer.append(reset_color.begin(), reset_color.end());
 }
 
-template <typename T> struct styled_arg {
+template <typename T> struct styled_arg : detail::view {
   const T& value;
   text_style style;
+  styled_arg(const T& v, text_style s) : value(v), style(s) {}
 };
 
 template <typename Char>

include/fmt/core.h

@@ -18,7 +18,7 @@
 #include <type_traits>
 
 // The fmt library version in the form major * 10000 + minor * 100 + patch.
-#define FMT_VERSION 100100
+#define FMT_VERSION 100101
 
 #if defined(__clang__) && !defined(__ibmxl__)
 #  define FMT_CLANG_VERSION (__clang_major__ * 100 + __clang_minor__)
@@ -185,18 +185,20 @@
 #  define FMT_END_EXPORT
 #endif
 
+#if FMT_GCC_VERSION || FMT_CLANG_VERSION
+#  define FMT_VISIBILITY(value) __attribute__((visibility(value)))
+#else
+#  define FMT_VISIBILITY(value)
+#endif
+
 #if !defined(FMT_HEADER_ONLY) && defined(_WIN32)
-#  ifdef FMT_LIB_EXPORT
+#  if defined(FMT_LIB_EXPORT)
 #    define FMT_API __declspec(dllexport)
 #  elif defined(FMT_SHARED)
 #    define FMT_API __declspec(dllimport)
 #  endif
-#else
-#  if defined(FMT_LIB_EXPORT) || defined(FMT_SHARED)
-#    if defined(__GNUC__) || defined(__clang__)
-#      define FMT_API __attribute__((visibility("default")))
-#    endif
-#  endif
+#elif defined(FMT_LIB_EXPORT) || defined(FMT_SHARED)
+#  define FMT_API FMT_VISIBILITY("default")
 #endif
 #ifndef FMT_API
 #  define FMT_API
@@ -263,7 +265,9 @@ template <typename T>
 using remove_const_t = typename std::remove_const<T>::type;
 template <typename T>
 using remove_cvref_t = typename std::remove_cv<remove_reference_t<T>>::type;
-template <typename T> struct type_identity { using type = T; };
+template <typename T> struct type_identity {
+  using type = T;
+};
 template <typename T> using type_identity_t = typename type_identity<T>::type;
 template <typename T>
 using underlying_t = typename std::underlying_type<T>::type;
@@ -1504,7 +1508,9 @@ FMT_CONSTEXPR auto copy_str(R&& rng, OutputIt out) -> OutputIt {
 
 #if FMT_GCC_VERSION && FMT_GCC_VERSION < 500
 // A workaround for gcc 4.8 to make void_t work in a SFINAE context.
-template <typename...> struct void_t_impl { using type = void; };
+template <typename...> struct void_t_impl {
+  using type = void;
+};
 template <typename... T> using void_t = typename void_t_impl<T...>::type;
 #else
 template <typename...> using void_t = void;
@@ -2300,9 +2306,12 @@ FMT_CONSTEXPR FMT_INLINE auto parse_format_specs(
     dynamic_format_specs<Char>& specs;
     type arg_type;
 
-    FMT_CONSTEXPR auto operator()(pres type, int set) -> const Char* {
-      if (!in(arg_type, set)) throw_format_error("invalid format specifier");
-      specs.type = type;
+    FMT_CONSTEXPR auto operator()(pres pres_type, int set) -> const Char* {
+      if (!in(arg_type, set)) {
+        if (arg_type == type::none_type) return begin;
+        throw_format_error("invalid format specifier");
+      }
+      specs.type = pres_type;
       return begin + 1;
     }
   } parse_presentation_type{begin, specs, arg_type};
@@ -2319,6 +2328,7 @@ FMT_CONSTEXPR FMT_INLINE auto parse_format_specs(
     case '+':
     case '-':
     case ' ':
+      if (arg_type == type::none_type) return begin;
       enter_state(state::sign, in(arg_type, sint_set | float_set));
       switch (c) {
       case '+':
@@ -2334,14 +2344,17 @@ FMT_CONSTEXPR FMT_INLINE auto parse_format_specs(
       ++begin;
       break;
     case '#':
+      if (arg_type == type::none_type) return begin;
       enter_state(state::hash, is_arithmetic_type(arg_type));
       specs.alt = true;
       ++begin;
       break;
     case '0':
       enter_state(state::zero);
-      if (!is_arithmetic_type(arg_type))
+      if (!is_arithmetic_type(arg_type)) {
+        if (arg_type == type::none_type) return begin;
         throw_format_error("format specifier requires numeric argument");
+      }
       if (specs.align == align::none) {
         // Ignore 0 if align is specified for compatibility with std::format.
         specs.align = align::numeric;
@@ -2363,12 +2376,14 @@ FMT_CONSTEXPR FMT_INLINE auto parse_format_specs(
       begin = parse_dynamic_spec(begin, end, specs.width, specs.width_ref, ctx);
       break;
     case '.':
+      if (arg_type == type::none_type) return begin;
       enter_state(state::precision,
                   in(arg_type, float_set | string_set | cstring_set));
       begin = parse_precision(begin, end, specs.precision, specs.precision_ref,
                               ctx);
       break;
     case 'L':
+      if (arg_type == type::none_type) return begin;
       enter_state(state::locale, is_arithmetic_type(arg_type));
       specs.localized = true;
       ++begin;
@@ -2541,8 +2556,8 @@ FMT_CONSTEXPR auto parse_format_specs(ParseContext& ctx)
       decltype(arg_mapper<context>().map(std::declval<const T&>())),
       typename strip_named_arg<T>::type>;
 #if defined(__cpp_if_constexpr)
-  if constexpr (std::is_default_constructible_v<
-                    formatter<mapped_type, char_type>>) {
+  if constexpr (std::is_default_constructible<
+                    formatter<mapped_type, char_type>>::value) {
     return formatter<mapped_type, char_type>().parse(ctx);
   } else {
     type_is_unformattable_for<T, char_type> _;
@@ -2667,7 +2682,9 @@ template <typename Char = char> struct vformat_args {
   using type = basic_format_args<
       basic_format_context<std::back_insert_iterator<buffer<Char>>, Char>>;
 };
-template <> struct vformat_args<char> { using type = format_args; };
+template <> struct vformat_args<char> {
+  using type = format_args;
+};
 
 // Use vformat_args and avoid type_identity to keep symbols short.
 template <typename Char>

include/fmt/format-inl.h

@@ -18,7 +18,7 @@
 #  include <locale>
 #endif
 
-#ifdef _WIN32
+#if defined(_WIN32) && !defined(FMT_WINDOWS_NO_WCHAR)
 #  include <io.h>  // _isatty
 #endif
 
@@ -73,9 +73,8 @@ FMT_FUNC void report_error(format_func func, int error_code,
 }
 
 // A wrapper around fwrite that throws on error.
-inline void fwrite_fully(const void* ptr, size_t size, size_t count,
-                         FILE* stream) {
-  size_t written = std::fwrite(ptr, size, count, stream);
+inline void fwrite_fully(const void* ptr, size_t count, FILE* stream) {
+  size_t written = std::fwrite(ptr, 1, count, stream);
   if (written < count)
     FMT_THROW(system_error(errno, FMT_STRING("cannot write to file")));
 }
@@ -985,8 +984,7 @@ template <> struct cache_accessor<double> {
       {0xe0accfa875af45a7, 0x93eb1b80a33b8606},
       {0x8c6c01c9498d8b88, 0xbc72f130660533c4},
       {0xaf87023b9bf0ee6a, 0xeb8fad7c7f8680b5},
-      { 0xdb68c2ca82ed2a05,
-        0xa67398db9f6820e2 }
+      {0xdb68c2ca82ed2a05, 0xa67398db9f6820e2}
 #else
       {0xff77b1fcbebcdc4f, 0x25e8e89c13bb0f7b},
       {0xce5d73ff402d98e3, 0xfb0a3d212dc81290},
@@ -1132,7 +1130,7 @@ FMT_INLINE int remove_trailing_zeros(uint32_t& n, int s = 0) noexcept {
   FMT_ASSERT(n != 0, "");
   // Modular inverse of 5 (mod 2^32): (mod_inv_5 * 5) mod 2^32 = 1.
   constexpr uint32_t mod_inv_5 = 0xcccccccd;
-  constexpr uint32_t mod_inv_25 = 0xc28f5c29; // = mod_inv_5 * mod_inv_5
+  constexpr uint32_t mod_inv_25 = 0xc28f5c29;  // = mod_inv_5 * mod_inv_5
 
   while (true) {
     auto q = rotr(n * mod_inv_25, 2);
@@ -1168,7 +1166,7 @@ FMT_INLINE int remove_trailing_zeros(uint64_t& n) noexcept {
 
   // If n is not divisible by 10^8, work with n itself.
   constexpr uint64_t mod_inv_5 = 0xcccccccccccccccd;
-  constexpr uint64_t mod_inv_25 = 0x8f5c28f5c28f5c29; // = mod_inv_5 * mod_inv_5
+  constexpr uint64_t mod_inv_25 = 0x8f5c28f5c28f5c29;  // mod_inv_5 * mod_inv_5
 
   int s = 0;
   while (true) {
@@ -1426,33 +1424,38 @@ FMT_FUNC std::string vformat(string_view fmt, format_args args) {
 }
 
 namespace detail {
-#ifndef _WIN32
-FMT_FUNC bool write_console(std::FILE*, string_view) { return false; }
+#if !defined(_WIN32) || defined(FMT_WINDOWS_NO_WCHAR)
+FMT_FUNC bool write_console(int, string_view) { return false; }
 #else
 using dword = conditional_t<sizeof(long) == 4, unsigned long, unsigned>;
 extern "C" __declspec(dllimport) int __stdcall WriteConsoleW(  //
     void*, const void*, dword, dword*, void*);
 
-FMT_FUNC bool write_console(std::FILE* f, string_view text) {
-  auto fd = _fileno(f);
-  if (!_isatty(fd)) return false;
+FMT_FUNC bool write_console(int fd, string_view text) {
   auto u16 = utf8_to_utf16(text);
-  auto written = dword();
   return WriteConsoleW(reinterpret_cast<void*>(_get_osfhandle(fd)), u16.c_str(),
-                       static_cast<uint32_t>(u16.size()), &written, nullptr) != 0;
+                       static_cast<dword>(u16.size()), nullptr, nullptr) != 0;
 }
+#endif
 
+#ifdef _WIN32
 // Print assuming legacy (non-Unicode) encoding.
 FMT_FUNC void vprint_mojibake(std::FILE* f, string_view fmt, format_args args) {
   auto buffer = memory_buffer();
-  detail::vformat_to(buffer, fmt,
-                     basic_format_args<buffer_context<char>>(args));
-  fwrite_fully(buffer.data(), 1, buffer.size(), f);
+  detail::vformat_to(buffer, fmt, args);
+  fwrite_fully(buffer.data(), buffer.size(), f);
 }
 #endif
 
 FMT_FUNC void print(std::FILE* f, string_view text) {
-  if (!write_console(f, text)) fwrite_fully(text.data(), 1, text.size(), f);
+#ifdef _WIN32
+  int fd = _fileno(f);
+  if (_isatty(fd)) {
+    std::fflush(f);
+    if (write_console(fd, text)) return;
+  }
+#endif
+  fwrite_fully(text.data(), text.size(), f);
 }
 }  // namespace detail
 

include/fmt/format.h

@@ -93,10 +93,11 @@
 #  define FMT_NO_UNIQUE_ADDRESS
 #endif
 
-#if FMT_GCC_VERSION || defined(__clang__)
-#  define FMT_VISIBILITY(value) __attribute__((visibility(value)))
+// Visibility when compiled as a shared library/object.
+#if defined(FMT_LIB_EXPORT) || defined(FMT_SHARED)
+#  define FMT_SO_VISIBILITY(value) FMT_VISIBILITY(value)
 #else
-#  define FMT_VISIBILITY(value)
+#  define FMT_SO_VISIBILITY(value)
 #endif
 
 #ifdef __has_builtin
@@ -152,7 +153,10 @@ FMT_END_NAMESPACE
 
 #ifndef FMT_USE_USER_DEFINED_LITERALS
 // EDG based compilers (Intel, NVIDIA, Elbrus, etc), GCC and MSVC support UDLs.
-#  if (FMT_HAS_FEATURE(cxx_user_literals) || FMT_GCC_VERSION >= 407 || \
+//
+// GCC before 4.9 requires a space in `operator"" _a` which is invalid in later
+// compiler versions.
+#  if (FMT_HAS_FEATURE(cxx_user_literals) || FMT_GCC_VERSION >= 409 || \
        FMT_MSC_VERSION >= 1900) &&                                     \
       (!defined(__EDG_VERSION__) || __EDG_VERSION__ >= /* UDL feature */ 480)
 #    define FMT_USE_USER_DEFINED_LITERALS 1
@@ -1034,7 +1038,7 @@ struct is_contiguous<basic_memory_buffer<T, SIZE, Allocator>> : std::true_type {
 
 FMT_END_EXPORT
 namespace detail {
-FMT_API bool write_console(std::FILE* f, string_view text);
+FMT_API bool write_console(int fd, string_view text);
 FMT_API void print(std::FILE*, string_view);
 }  // namespace detail
 
@@ -1046,7 +1050,7 @@ FMT_BEGIN_EXPORT
 #endif
 
 /** An error reported from a formatting function. */
-class FMT_VISIBILITY("default") format_error : public std::runtime_error {
+class FMT_SO_VISIBILITY("default") format_error : public std::runtime_error {
  public:
   using std::runtime_error::runtime_error;
 };
@@ -1394,7 +1398,7 @@ FMT_CONSTEXPR inline auto format_uint(It out, UInt value, int num_digits,
     return out;
   }
   // Buffer should be large enough to hold all digits (digits / BASE_BITS + 1).
-  char buffer[num_bits<UInt>() / BASE_BITS + 1];
+  char buffer[num_bits<UInt>() / BASE_BITS + 1] = {};
   format_uint<BASE_BITS>(buffer, value, num_digits, upper);
   return detail::copy_str_noinline<Char>(buffer, buffer + num_digits, out);
 }
@@ -1736,29 +1740,6 @@ FMT_CONSTEXPR inline fp operator*(fp x, fp y) {
   return {multiply(x.f, y.f), x.e + y.e + 64};
 }
 
-template <typename T = void> struct basic_data {
-  // For checking rounding thresholds.
-  // The kth entry is chosen to be the smallest integer such that the
-  // upper 32-bits of 10^(k+1) times it is strictly bigger than 5 * 10^k.
-  static constexpr uint32_t fractional_part_rounding_thresholds[8] = {
-      2576980378U,  // ceil(2^31 + 2^32/10^1)
-      2190433321U,  // ceil(2^31 + 2^32/10^2)
-      2151778616U,  // ceil(2^31 + 2^32/10^3)
-      2147913145U,  // ceil(2^31 + 2^32/10^4)
-      2147526598U,  // ceil(2^31 + 2^32/10^5)
-      2147487943U,  // ceil(2^31 + 2^32/10^6)
-      2147484078U,  // ceil(2^31 + 2^32/10^7)
-      2147483691U   // ceil(2^31 + 2^32/10^8)
-  };
-};
-// This is a struct rather than an alias to avoid shadowing warnings in gcc.
-struct data : basic_data<> {};
-
-#if FMT_CPLUSPLUS < 201703L
-template <typename T>
-constexpr uint32_t basic_data<T>::fractional_part_rounding_thresholds[];
-#endif
-
 template <typename T, bool doublish = num_bits<T>() == num_bits<double>()>
 using convert_float_result =
     conditional_t<std::is_same<T, float>::value || doublish, double, T>;
@@ -1977,11 +1958,12 @@ auto write_escaped_string(OutputIt out, basic_string_view<Char> str)
 
 template <typename Char, typename OutputIt>
 auto write_escaped_char(OutputIt out, Char v) -> OutputIt {
+  Char v_array[1] = {v};
   *out++ = static_cast<Char>('\'');
   if ((needs_escape(static_cast<uint32_t>(v)) && v != static_cast<Char>('"')) ||
       v == static_cast<Char>('\'')) {
     out = write_escaped_cp(
-        out, find_escape_result<Char>{&v, &v + 1, static_cast<uint32_t>(v)});
+        out, find_escape_result<Char>{v_array, v_array + 1, static_cast<uint32_t>(v)});
   } else {
     *out++ = v;
   }
@@ -3029,7 +3011,7 @@ class bigint {
     bigits_.resize(to_unsigned(num_bigits + exp_difference));
     for (int i = num_bigits - 1, j = i + exp_difference; i >= 0; --i, --j)
       bigits_[j] = bigits_[i];
-    std::uninitialized_fill_n(bigits_.data(), exp_difference, 0);
+    std::uninitialized_fill_n(bigits_.data(), exp_difference, 0u);
     exp_ -= exp_difference;
   }
 
@@ -3178,8 +3160,10 @@ FMT_CONSTEXPR20 inline void format_dragon(basic_fp<uint128_t> value,
       }
       if (buf[0] == overflow) {
         buf[0] = '1';
-        if ((flags & dragon::fixed) != 0) buf.push_back('0');
-        else ++exp10;
+        if ((flags & dragon::fixed) != 0)
+          buf.push_back('0');
+        else
+          ++exp10;
       }
       return;
     }
@@ -3276,6 +3260,17 @@ FMT_CONSTEXPR20 void format_hexfloat(Float value, int precision,
   format_hexfloat(static_cast<double>(value), precision, specs, buf);
 }
 
+constexpr uint32_t fractional_part_rounding_thresholds(int index) {
+  // For checking rounding thresholds.
+  // The kth entry is chosen to be the smallest integer such that the
+  // upper 32-bits of 10^(k+1) times it is strictly bigger than 5 * 10^k.
+  // It is equal to ceil(2^31 + 2^32/10^(k + 1)).
+  // These are stored in a string literal because we cannot have static arrays
+  // in constexpr functions and non-static ones are poorly optimized.
+  return U"\x9999999a\x828f5c29\x80418938\x80068db9\x8000a7c6\x800010c7"
+         U"\x800001ae\x8000002b"[index];
+}
+
 template <typename Float>
 FMT_CONSTEXPR20 auto format_float(Float value, int precision, float_specs specs,
                                   buffer<char>& buf) -> int {
@@ -3480,12 +3475,12 @@ FMT_CONSTEXPR20 auto format_float(Float value, int precision, float_specs specs,
           //    fractional part is strictly larger than 1/2.
           if (precision < 9) {
             uint32_t fractional_part = static_cast<uint32_t>(prod);
-            should_round_up = fractional_part >=
-                                  data::fractional_part_rounding_thresholds
-                                      [8 - number_of_digits_to_print] ||
-                              ((fractional_part >> 31) &
-                               ((digits & 1) | (second_third_subsegments != 0) |
-                                has_more_segments)) != 0;
+            should_round_up =
+                fractional_part >= fractional_part_rounding_thresholds(
+                                       8 - number_of_digits_to_print) ||
+                ((fractional_part >> 31) &
+                 ((digits & 1) | (second_third_subsegments != 0) |
+                  has_more_segments)) != 0;
           }
           // Rounding at the subsegment boundary.
           // In this case, the fractional part is at least 1/2 if and only if
@@ -3520,12 +3515,12 @@ FMT_CONSTEXPR20 auto format_float(Float value, int precision, float_specs specs,
             // of 19 digits, so in this case the third segment should be
             // consisting of a genuine digit from the input.
             uint32_t fractional_part = static_cast<uint32_t>(prod);
-            should_round_up = fractional_part >=
-                                  data::fractional_part_rounding_thresholds
-                                      [8 - number_of_digits_to_print] ||
-                              ((fractional_part >> 31) &
-                               ((digits & 1) | (third_subsegment != 0) |
-                                has_more_segments)) != 0;
+            should_round_up =
+                fractional_part >= fractional_part_rounding_thresholds(
+                                       8 - number_of_digits_to_print) ||
+                ((fractional_part >> 31) &
+                 ((digits & 1) | (third_subsegment != 0) |
+                  has_more_segments)) != 0;
           }
           // Rounding at the subsegment boundary.
           else {
@@ -3757,8 +3752,11 @@ template <typename Char, typename OutputIt, typename T,
 FMT_CONSTEXPR auto write(OutputIt out, const T& value)
     -> enable_if_t<mapped_type_constant<T, Context>::value == type::custom_type,
                    OutputIt> {
+  auto formatter = typename Context::template formatter_type<T>();
+  auto parse_ctx = typename Context::parse_context_type({});
+  formatter.parse(parse_ctx);
   auto ctx = Context(out, {}, {});
-  return typename Context::template formatter_type<T>().format(value, ctx);
+  return formatter.format(value, ctx);
 }
 
 // An argument visitor that formats the argument and writes it via the output
@@ -4198,6 +4196,59 @@ template <typename T> struct formatter<group_digits_view<T>> : formatter<T> {
   }
 };
 
+template <typename T> struct nested_view {
+  const formatter<T>* fmt;
+  const T* value;
+};
+
+template <typename T> struct formatter<nested_view<T>> {
+  FMT_CONSTEXPR auto parse(format_parse_context& ctx) -> const char* {
+    return ctx.begin();
+  }
+  auto format(nested_view<T> view, format_context& ctx) const
+      -> decltype(ctx.out()) {
+    return view.fmt->format(*view.value, ctx);
+  }
+};
+
+template <typename T> struct nested_formatter {
+ private:
+  int width_;
+  detail::fill_t<char> fill_;
+  align_t align_ : 4;
+  formatter<T> formatter_;
+
+ public:
+  constexpr nested_formatter() : width_(0), align_(align_t::none) {}
+
+  FMT_CONSTEXPR auto parse(format_parse_context& ctx) -> const char* {
+    auto specs = detail::dynamic_format_specs<char>();
+    auto it = parse_format_specs(ctx.begin(), ctx.end(), specs, ctx,
+                                 detail::type::none_type);
+    width_ = specs.width;
+    fill_ = specs.fill;
+    align_ = specs.align;
+    ctx.advance_to(it);
+    return formatter_.parse(ctx);
+  }
+
+  template <typename F>
+  auto write_padded(format_context& ctx, F write) const -> decltype(ctx.out()) {
+    if (width_ == 0) return write(ctx.out());
+    auto buf = memory_buffer();
+    write(std::back_inserter(buf));
+    auto specs = format_specs<>();
+    specs.width = width_;
+    specs.fill = fill_;
+    specs.align = align_;
+    return detail::write(ctx.out(), string_view(buf.data(), buf.size()), specs);
+  }
+
+  auto nested(const T& value) const -> nested_view<T> {
+    return nested_view<T>{&formatter_, &value};
+  }
+};
+
 // DEPRECATED! join_view will be moved to ranges.h.
 template <typename It, typename Sentinel, typename Char = char>
 struct join_view : detail::view {
@@ -4426,7 +4477,7 @@ template <detail_exported::fixed_string Str> constexpr auto operator""_a() {
   return detail::udl_arg<char_t, sizeof(Str.data) / sizeof(char_t), Str>();
 }
 #  else
-constexpr auto operator"" _a(const char* s, size_t) -> detail::udl_arg<char> {
+constexpr auto operator""_a(const char* s, size_t) -> detail::udl_arg<char> {
   return {s};
 }
 #  endif

include/fmt/os.h

@@ -13,12 +13,14 @@
 #include <cstdio>
 #include <system_error>  // std::system_error
 
-#if defined __APPLE__ || defined(__FreeBSD__)
-#  include <xlocale.h>  // for LC_NUMERIC_MASK on OS X
-#endif
-
 #include "format.h"
 
+#if defined __APPLE__ || defined(__FreeBSD__)
+#  if FMT_HAS_INCLUDE(<xlocale.h>)
+#    include <xlocale.h>  // for LC_NUMERIC_MASK on OS X
+#  endif
+#endif
+
 #ifndef FMT_USE_FCNTL
 // UWP doesn't provide _pipe.
 #  if FMT_HAS_INCLUDE("winapifamily.h")
@@ -46,6 +48,7 @@
 
 // Calls to system functions are wrapped in FMT_SYSTEM for testability.
 #ifdef FMT_SYSTEM
+#  define FMT_HAS_SYSTEM
 #  define FMT_POSIX_CALL(call) FMT_SYSTEM(call)
 #else
 #  define FMT_SYSTEM(call) ::call
@@ -419,7 +422,7 @@ class FMT_API ostream {
     output to the file.
    */
   template <typename... T> void print(format_string<T...> fmt, T&&... args) {
-    vformat_to(detail::buffer_appender<char>(buffer_), fmt,
+    vformat_to(std::back_inserter(buffer_), fmt,
                fmt::make_format_args(args...));
   }
 };

include/fmt/ostream.h

@@ -10,11 +10,12 @@
 
 #include <fstream>  // std::filebuf
 
-#if defined(_WIN32) && defined(__GLIBCXX__)
-#  include <ext/stdio_filebuf.h>
-#  include <ext/stdio_sync_filebuf.h>
-#elif defined(_WIN32) && defined(_LIBCPP_VERSION)
-#  include <__std_stream>
+#ifdef _WIN32
+#  ifdef __GLIBCXX__
+#    include <ext/stdio_filebuf.h>
+#    include <ext/stdio_sync_filebuf.h>
+#  endif
+#  include <io.h>
 #endif
 
 #include "format.h"
@@ -37,31 +38,34 @@ class file_access {
 template class file_access<file_access_tag, std::filebuf,
                            &std::filebuf::_Myfile>;
 auto get_file(std::filebuf&) -> FILE*;
-#elif defined(_WIN32) && defined(_LIBCPP_VERSION)
-template class file_access<file_access_tag, std::__stdoutbuf<char>,
-                           &std::__stdoutbuf<char>::__file_>;
-auto get_file(std::__stdoutbuf<char>&) -> FILE*;
 #endif
 
 inline bool write_ostream_unicode(std::ostream& os, fmt::string_view data) {
+  FILE* f = nullptr;
 #if FMT_MSC_VERSION
   if (auto* buf = dynamic_cast<std::filebuf*>(os.rdbuf()))
-    if (FILE* f = get_file(*buf)) return write_console(f, data);
-#elif defined(_WIN32) && defined(__GLIBCXX__)
-  auto* rdbuf = os.rdbuf();
-  FILE* c_file;
-  if (auto* sfbuf = dynamic_cast<__gnu_cxx::stdio_sync_filebuf<char>*>(rdbuf))
-    c_file = sfbuf->file();
-  else if (auto* fbuf = dynamic_cast<__gnu_cxx::stdio_filebuf<char>*>(rdbuf))
-    c_file = fbuf->file();
+    f = get_file(*buf);
+  else
+    return false;
+#elif defined(_WIN32) && defined(__GLIBCXX__)
+  auto* rdbuf = os.rdbuf();
+  if (auto* sfbuf = dynamic_cast<__gnu_cxx::stdio_sync_filebuf<char>*>(rdbuf))
+    f = sfbuf->file();
+  else if (auto* fbuf = dynamic_cast<__gnu_cxx::stdio_filebuf<char>*>(rdbuf))
+    f = fbuf->file();
   else
     return false;
-  if (c_file) return write_console(c_file, data);
-#elif defined(_WIN32) && defined(_LIBCPP_VERSION)
-  if (auto* buf = dynamic_cast<std::__stdoutbuf<char>*>(os.rdbuf()))
-    if (FILE* f = get_file(*buf)) return write_console(f, data);
 #else
-  ignore_unused(os, data);
+  ignore_unused(os, data, f);
+#endif
+#ifdef _WIN32
+  if (f) {
+    int fd = _fileno(f);
+    if (_isatty(fd)) {
+      os.flush();
+      return write_console(fd, data);
+    }
+  }
 #endif
   return false;
 }
@@ -98,7 +102,9 @@ void format_value(buffer<Char>& buf, const T& value,
   output.exceptions(std::ios_base::failbit | std::ios_base::badbit);
 }
 
-template <typename T> struct streamed_view { const T& value; };
+template <typename T> struct streamed_view {
+  const T& value;
+};
 
 }  // namespace detail
 
@@ -140,7 +146,7 @@ struct formatter<detail::streamed_view<T>, Char>
   \endrst
  */
 template <typename T>
-auto streamed(const T& value) -> detail::streamed_view<T> {
+constexpr auto streamed(const T& value) -> detail::streamed_view<T> {
   return {value};
 }
 

include/fmt/printf.h

@@ -16,13 +16,19 @@
 FMT_BEGIN_NAMESPACE
 FMT_BEGIN_EXPORT
 
-template <typename T> struct printf_formatter { printf_formatter() = delete; };
+template <typename T> struct printf_formatter {
+  printf_formatter() = delete;
+};
 
 template <typename Char> class basic_printf_context {
  private:
   detail::buffer_appender<Char> out_;
   basic_format_args<basic_printf_context> args_;
 
+  static_assert(std::is_same<Char, char>::value ||
+                    std::is_same<Char, wchar_t>::value,
+                "Unsupported code unit type.");
+
  public:
   using char_type = Char;
   using parse_context_type = basic_format_parse_context<Char>;
@@ -102,7 +108,9 @@ struct is_zero_int {
 
 template <typename T> struct make_unsigned_or_bool : std::make_unsigned<T> {};
 
-template <> struct make_unsigned_or_bool<bool> { using type = bool; };
+template <> struct make_unsigned_or_bool<bool> {
+  using type = bool;
+};
 
 template <typename T, typename Context> class arg_converter {
  private:

include/fmt/ranges.h

@@ -1,13 +1,9 @@
-// Formatting library for C++ - experimental range support
+// Formatting library for C++ - range and tuple support
 //
-// Copyright (c) 2012 - present, Victor Zverovich
+// Copyright (c) 2012 - present, Victor Zverovich and {fmt} contributors
 // All rights reserved.
 //
 // For the license information refer to format.h.
-//
-// Copyright (c) 2018 - present, Remotion (Igor Schulz)
-// All Rights Reserved
-// {fmt} support for ranges, containers and types tuple interface.
 
 #ifndef FMT_RANGES_H_
 #define FMT_RANGES_H_

include/fmt/std.h

@@ -64,38 +64,29 @@ FMT_BEGIN_NAMESPACE
 
 namespace detail {
 
-template <typename Char> auto get_path_string(const std::filesystem::path& p) {
-  return p.string<Char>();
+template <typename Char, typename PathChar> auto get_path_string(
+  const std::filesystem::path& p, const std::basic_string<PathChar>& native) {
+  if constexpr (std::is_same_v<Char, char> && std::is_same_v<PathChar, wchar_t>)
+    return to_utf8<wchar_t>(native, to_utf8_error_policy::replace);
+  else
+    return p.string<Char>();
 }
 
-template <typename Char>
+template <typename Char, typename PathChar>
 void write_escaped_path(basic_memory_buffer<Char>& quoted,
-                        const std::filesystem::path& p) {
-  write_escaped_string<Char>(std::back_inserter(quoted), p.string<Char>());
-}
-
-#  ifdef _WIN32
-template <>
-inline auto get_path_string<char>(const std::filesystem::path& p) {
-  return to_utf8<wchar_t>(p.native(), to_utf8_error_policy::replace);
-}
-
-template <>
-inline void write_escaped_path<char>(memory_buffer& quoted,
-                                     const std::filesystem::path& p) {
-  auto buf = basic_memory_buffer<wchar_t>();
-  write_escaped_string<wchar_t>(std::back_inserter(buf), p.native());
-  bool valid = to_utf8<wchar_t>::convert(quoted, {buf.data(), buf.size()});
-  FMT_ASSERT(valid, "invalid utf16");
-}
-#  endif  // _WIN32
-
-template <>
-inline void write_escaped_path<std::filesystem::path::value_type>(
-    basic_memory_buffer<std::filesystem::path::value_type>& quoted,
-    const std::filesystem::path& p) {
-  write_escaped_string<std::filesystem::path::value_type>(
-      std::back_inserter(quoted), p.native());
+                        const std::filesystem::path& p,
+                        const std::basic_string<PathChar>& native) {
+  if constexpr (std::is_same_v<Char, char> && std::is_same_v<PathChar, wchar_t>) {
+    auto buf = basic_memory_buffer<wchar_t>();
+    write_escaped_string<wchar_t>(std::back_inserter(buf), native);
+    bool valid = to_utf8<wchar_t>::convert(quoted, {buf.data(), buf.size()});
+    FMT_ASSERT(valid, "invalid utf16");
+  } else if constexpr (std::is_same_v<Char, PathChar>) {
+    write_escaped_string<std::filesystem::path::value_type>(
+        std::back_inserter(quoted), native);
+  } else {
+    write_escaped_string<Char>(std::back_inserter(quoted), p.string<Char>());
+  }
 }
 
 }  // namespace detail
@@ -131,11 +122,11 @@ template <typename Char> struct formatter<std::filesystem::path, Char> {
     detail::handle_dynamic_spec<detail::width_checker>(specs.width, width_ref_,
                                                        ctx);
     if (!debug_) {
-      auto s = detail::get_path_string<Char>(p);
+      auto s = detail::get_path_string<Char>(p, p.native());
       return detail::write(ctx.out(), basic_string_view<Char>(s), specs);
     }
     auto quoted = basic_memory_buffer<Char>();
-    detail::write_escaped_path(quoted, p);
+    detail::write_escaped_path(quoted, p, p.native());
     return detail::write(ctx.out(),
                          basic_string_view<Char>(quoted.data(), quoted.size()),
                          specs);
@@ -145,6 +136,32 @@ FMT_END_NAMESPACE
 #endif
 
 FMT_BEGIN_NAMESPACE
+FMT_EXPORT
+template <std::size_t N, typename Char>
+struct formatter<std::bitset<N>, Char> : nested_formatter<string_view> {
+ private:
+  // Functor because C++11 doesn't support generic lambdas.
+  struct writer {
+    const std::bitset<N>& bs;
+
+    template <typename OutputIt>
+    FMT_CONSTEXPR OutputIt operator()(OutputIt out) {
+      for (auto pos = N; pos > 0; --pos) {
+        out = detail::write<Char>(out, bs[pos - 1] ? Char('1') : Char('0'));
+      }
+
+      return out;
+    }
+  };
+
+ public:
+  template <typename FormatContext>
+  auto format(const std::bitset<N>& bs, FormatContext& ctx) const
+      -> decltype(ctx.out()) {
+    return write_padded(ctx, writer{bs});
+  }
+};
+
 FMT_EXPORT
 template <typename Char>
 struct formatter<std::thread::id, Char> : basic_ostream_formatter<Char> {};
@@ -451,15 +468,14 @@ struct formatter<std::atomic<T>, Char,
 #ifdef __cpp_lib_atomic_flag_test
 FMT_EXPORT
 template <typename Char>
-struct formatter<std::atomic_flag, Char>
-    : formatter<bool, Char> {
+struct formatter<std::atomic_flag, Char> : formatter<bool, Char> {
   template <typename FormatContext>
   auto format(const std::atomic_flag& v, FormatContext& ctx) const
       -> decltype(ctx.out()) {
     return formatter<bool, Char>::format(v.test(), ctx);
   }
 };
-#endif // __cpp_lib_atomic_flag_test
+#endif  // __cpp_lib_atomic_flag_test
 
 FMT_END_NAMESPACE
 #endif  // FMT_STD_H_

src/fmt.cc

@@ -63,8 +63,6 @@ module;
 #  if defined(__GLIBCXX__)
 #    include <ext/stdio_filebuf.h>
 #    include <ext/stdio_sync_filebuf.h>
-#  elif defined(_LIBCPP_VERSION)
-#    include <__std_stream>
 #  endif
 #  define WIN32_LEAN_AND_MEAN
 #  include <windows.h>

src/os.cc

@@ -18,8 +18,8 @@
 #  include <sys/stat.h>
 #  include <sys/types.h>
 
-#  ifdef _WRS_KERNEL   // VxWorks7 kernel
-#    include <ioLib.h> // getpagesize
+#  ifdef _WRS_KERNEL    // VxWorks7 kernel
+#    include <ioLib.h>  // getpagesize
 #  endif
 
 #  ifndef _WIN32
@@ -182,10 +182,14 @@ void buffered_file::close() {
 }
 
 int buffered_file::descriptor() const {
-#ifdef fileno  // fileno is a macro on OpenBSD so we cannot use FMT_POSIX_CALL.
-  int fd = fileno(file_);
-#else
+#if !defined(fileno)
   int fd = FMT_POSIX_CALL(fileno(file_));
+#elif defined(FMT_HAS_SYSTEM)
+  // fileno is a macro on OpenBSD so we cannot use FMT_POSIX_CALL.
+#  define FMT_DISABLE_MACRO
+  int fd = FMT_SYSTEM(fileno FMT_DISABLE_MACRO(file_));
+#else
+  int fd = fileno(file_);
 #endif
   if (fd == -1)
     FMT_THROW(system_error(errno, FMT_STRING("cannot get file descriptor")));

support/manage.py

@@ -231,7 +231,7 @@ def release(args):
 
     # Convert changelog from RST to GitHub-flavored Markdown and get the
     # version.
-    changelog = 'ChangeLog.rst'
+    changelog = 'ChangeLog.md'
     changelog_path = os.path.join(fmt_repo.dir, changelog)
     import rst2md
     changes, version = rst2md.convert(changelog_path)

support/rst2md.py

@@ -1,166 +0,0 @@
-#!/usr/bin/env python
-# reStructuredText (RST) to GitHub-flavored Markdown converter
-
-import re, sys
-from docutils import core, nodes, writers
-
-
-def is_github_ref(node):
-    return re.match('https://github.com/.*/(issues|pull)/.*', node['refuri'])
-
-
-class Translator(nodes.NodeVisitor):
-    def __init__(self, document):
-        nodes.NodeVisitor.__init__(self, document)
-        self.output = ''
-        self.indent = 0
-        self.preserve_newlines = False
-
-    def write(self, text):
-        self.output += text.replace('\n', '\n' + ' ' * self.indent)
-
-    def visit_document(self, node):
-        pass
-
-    def depart_document(self, node):
-        pass
-
-    def visit_section(self, node):
-        pass
-
-    def depart_section(self, node):
-        # Skip all sections except the first one.
-        raise nodes.StopTraversal
-
-    def visit_title(self, node):
-        self.version = re.match(r'(\d+\.\d+\.\d+).*', node.children[0]).group(1)
-        raise nodes.SkipChildren
-
-    def visit_title_reference(self, node):
-        raise Exception(node)
-
-    def depart_title(self, node):
-        pass
-
-    def visit_Text(self, node):
-        if not self.preserve_newlines:
-            node = node.replace('\n', ' ')
-        self.write(node)
-
-    def depart_Text(self, node):
-        pass
-
-    def visit_bullet_list(self, node):
-        pass
-
-    def depart_bullet_list(self, node):
-        pass
-
-    def visit_list_item(self, node):
-        self.write('* ')
-        self.indent += 2
-
-    def depart_list_item(self, node):
-        self.indent -= 2
-        self.write('\n\n')
-
-    def visit_paragraph(self, node):
-        self.write('\n\n')
-
-    def depart_paragraph(self, node):
-        pass
-
-    def visit_reference(self, node):
-        if not is_github_ref(node):
-            self.write('[')
-
-    def depart_reference(self, node):
-        if not is_github_ref(node):
-            self.write('](' + node['refuri'] + ')')
-
-    def visit_target(self, node):
-        pass
-
-    def depart_target(self, node):
-        pass
-
-    def visit_literal(self, node):
-        self.write('`')
-
-    def depart_literal(self, node):
-        self.write('`')
-
-    def visit_literal_block(self, node):
-        self.write('\n\n```')
-        if 'c++' in node['classes']:
-            self.write('c++')
-        self.write('\n')
-        self.preserve_newlines = True
-
-    def depart_literal_block(self, node):
-        self.write('\n```\n')
-        self.preserve_newlines = False
-
-    def visit_inline(self, node):
-        pass
-
-    def depart_inline(self, node):
-        pass
-
-    def visit_image(self, node):
-        self.write('![](' + node['uri'] + ')')
-
-    def depart_image(self, node):
-        pass
-
-    def write_row(self, row, widths):
-        for i, entry in enumerate(row):
-            text = entry[0][0] if len(entry) > 0 else ''
-            if i != 0:
-                self.write('|')
-            self.write('{:{}}'.format(text, widths[i]))
-        self.write('\n')
-
-    def visit_table(self, node):
-        table = node.children[0]
-        colspecs = table[:-2]
-        thead = table[-2]
-        tbody = table[-1]
-        widths = [int(cs['colwidth']) for cs in colspecs]
-        sep = '|'.join(['-' * w for w in widths]) + '\n'
-        self.write('\n\n')
-        self.write_row(thead[0], widths)
-        self.write(sep)
-        for row in tbody:
-            self.write_row(row, widths)
-        raise nodes.SkipChildren
-
-    def depart_table(self, node):
-        pass
-
-    def visit_system_message(self, node):
-        pass
-
-    def depart_system_message(self, node):
-        pass
-
-
-class MDWriter(writers.Writer):
-    """GitHub-flavored markdown writer"""
-
-    supported = ('md',)
-    """Formats this writer supports."""
-
-    def translate(self):
-        translator = Translator(self.document)
-        self.document.walkabout(translator)
-        self.output = (translator.output, translator.version)
-
-
-def convert(rst_path):
-    """Converts RST file to Markdown."""
-    return core.publish_file(source_path=rst_path, writer=MDWriter())
-
-
-if __name__ == '__main__':
-    convert(sys.argv[1])

test/CMakeLists.txt

@@ -175,7 +175,12 @@ if (FMT_PEDANTIC)
 endif ()
 
 # These tests are disabled on Windows because they take too long.
-if (FMT_PEDANTIC AND NOT WIN32)
+# They are disabled on GCC < 4.9 because it can not parse UDLs without
+# a space after `operator""` but that is an incorrect syntax for any more
+# modern compiler.
+if (FMT_PEDANTIC AND NOT WIN32 AND NOT (
+    CMAKE_CXX_COMPILER_ID MATCHES "GNU" AND
+    CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.9))
   # Test if incorrect API usages produce compilation error.
   add_test(compile-error-test ${CMAKE_CTEST_COMMAND}
     --build-and-test

test/chrono-test.cc

@@ -454,8 +454,11 @@ TEST(chrono_test, format_default) {
             fmt::format("{}", std::chrono::duration<int, std::peta>(42)));
   EXPECT_EQ("42Es",
             fmt::format("{}", std::chrono::duration<int, std::exa>(42)));
-  EXPECT_EQ("42m", fmt::format("{}", std::chrono::minutes(42)));
+  EXPECT_EQ("42min", fmt::format("{}", std::chrono::minutes(42)));
   EXPECT_EQ("42h", fmt::format("{}", std::chrono::hours(42)));
+#  if defined(__cpp_lib_chrono) && __cpp_lib_chrono >= 201907L
+  EXPECT_EQ("42d", fmt::format("{}", std::chrono::days(42)));
+#  endif
   EXPECT_EQ(
       "42[15]s",
       fmt::format("{}", std::chrono::duration<int, std::ratio<15, 1>>(42)));
@@ -740,21 +743,20 @@ TEST(chrono_test, unsigned_duration) {
 }
 
 TEST(chrono_test, weekday) {
-  auto loc = get_locale("ru_RU.UTF-8");
+  auto loc = get_locale("es_ES.UTF-8");
   std::locale::global(loc);
-  auto mon = fmt::weekday(1);
+  auto sat = fmt::weekday(6);
 
   auto tm = std::tm();
-  tm.tm_wday = static_cast<int>(mon.c_encoding());
+  tm.tm_wday = static_cast<int>(sat.c_encoding());
 
-  EXPECT_EQ(fmt::format("{}", mon), "Mon");
-  EXPECT_EQ(fmt::format("{:%a}", tm), "Mon");
+  EXPECT_EQ(fmt::format("{}", sat), "Sat");
+  EXPECT_EQ(fmt::format("{:%a}", tm), "Sat");
 
   if (loc != std::locale::classic()) {
-    EXPECT_THAT((std::vector<std::string>{"пн", "Пн", "пнд", "Пнд"}),
-                Contains(fmt::format(loc, "{:L}", mon)));
-    EXPECT_THAT((std::vector<std::string>{"пн", "Пн", "пнд", "Пнд"}),
-                Contains(fmt::format(loc, "{:%a}", tm)));
+    auto saturdays = std::vector<std::string>{"sáb", "sá."};
+    EXPECT_THAT(saturdays, Contains(fmt::format(loc, "{:L}", sat)));
+    EXPECT_THAT(saturdays, Contains(fmt::format(loc, "{:%a}", tm)));
   }
 }
 

test/format-impl-test.cc

@@ -351,7 +351,7 @@ TEST(format_impl_test, write_dragon_even) {
   if (!FMT_MSC_VERSION) EXPECT_EQ(s, "33554450");
 }
 
-#ifdef _WIN32
+#if defined(_WIN32) && !defined(FMT_WINDOWS_NO_WCHAR)
 #  include <windows.h>
 
 TEST(format_impl_test, write_console_signature) {

test/format-test.cc

@@ -443,6 +443,10 @@ TEST(memory_buffer_test, max_size_allocator_overflow) {
   EXPECT_THROW(buffer.resize(161), std::exception);
 }
 
+TEST(format_test, exception_from_lib) {
+  EXPECT_THROW_MSG(fmt::throw_format_error("test"), format_error, "test");
+}
+
 TEST(format_test, escape) {
   EXPECT_EQ("{", fmt::format("{{"));
   EXPECT_EQ("before {", fmt::format("before {{"));
@@ -1775,6 +1779,26 @@ TEST(format_test, group_digits_view) {
   EXPECT_EQ(fmt::format("{:8}", fmt::group_digits(1000)), "   1,000");
 }
 
+#ifdef __cpp_generic_lambdas
+struct point {
+  double x, y;
+};
+
+FMT_BEGIN_NAMESPACE
+template <> struct formatter<point> : nested_formatter<double> {
+  auto format(point p, format_context& ctx) const -> decltype(ctx.out()) {
+    return write_padded(ctx, [this, p](auto out) -> decltype(out) {
+      return fmt::format_to(out, "({}, {})", nested(p.x), nested(p.y));
+    });
+  }
+};
+FMT_END_NAMESPACE
+
+TEST(format_test, nested_formatter) {
+  EXPECT_EQ(fmt::format("{:>16.2f}", point{1, 2}), "    (1.00, 2.00)");
+}
+#endif  // __cpp_generic_lambdas
+
 enum test_enum { foo, bar };
 auto format_as(test_enum e) -> int { return e; }
 

test/ranges-test.cc

@@ -1,13 +1,9 @@
-// Formatting library for C++ - the core API
+// Formatting library for C++ - ranges tests
 //
-// Copyright (c) 2012 - present, Victor Zverovich
+// Copyright (c) 2012 - present, Victor Zverovich and {fmt} contributors
 // All rights reserved.
 //
 // For the license information refer to format.h.
-//
-// Copyright (c) 2018 - present, Remotion (Igor Schulz)
-// All Rights Reserved
-// {fmt} support for ranges, containers and types tuple interface.
 
 #include "fmt/ranges.h"
 
@@ -63,13 +59,18 @@ TEST(ranges_test, format_vector) {
   EXPECT_EQ(fmt::format("{:n:n:}", vvc), "a, b, c, a, b, c");
 }
 
-TEST(ranges_test, format_vector2) {
+TEST(ranges_test, format_nested_vector) {
   auto v = std::vector<std::vector<int>>{{1, 2}, {3, 5}, {7, 11}};
   EXPECT_EQ(fmt::format("{}", v), "[[1, 2], [3, 5], [7, 11]]");
   EXPECT_EQ(fmt::format("{:::#x}", v), "[[0x1, 0x2], [0x3, 0x5], [0x7, 0xb]]");
   EXPECT_EQ(fmt::format("{:n:n:#x}", v), "0x1, 0x2, 0x3, 0x5, 0x7, 0xb");
 }
 
+TEST(ranges_test, to_string_vector) {
+  auto v = std::vector<std::string>{"a", "b", "c"};
+  EXPECT_EQ(fmt::to_string(v), "[\"a\", \"b\", \"c\"]");
+}
+
 TEST(ranges_test, format_map) {
   auto m = std::map<std::string, int>{{"one", 1}, {"two", 2}};
   EXPECT_EQ(fmt::format("{}", m), "{\"one\": 1, \"two\": 2}");
@@ -83,7 +84,7 @@ TEST(ranges_test, format_set) {
 
 // Models std::flat_set close enough to test if no ambiguous lookup of a
 // formatter happens due to the flat_set type matching is_set and
-// is_container_adaptor_like
+// is_container_adaptor_like.
 template <typename T> class flat_set {
  public:
   using key_type = T;
@@ -95,11 +96,11 @@ template <typename T> class flat_set {
   template <typename... Ts>
   explicit flat_set(Ts&&... args) : c{std::forward<Ts>(args)...} {}
 
-  iterator begin() { return c.begin(); }
-  const_iterator begin() const { return c.begin(); }
+  auto begin() -> iterator { return c.begin(); }
+  auto end() -> iterator { return c.end(); }
 
-  iterator end() { return c.end(); }
-  const_iterator end() const { return c.end(); }
+  auto begin() const -> const_iterator { return c.begin(); }
+  auto end() const -> const_iterator { return c.end(); }
 
  private:
   std::vector<T> c;
@@ -116,7 +117,6 @@ struct box {
 };
 
 auto begin(const box& b) -> const int* { return &b.value; }
-
 auto end(const box& b) -> const int* { return &b.value + 1; }
 }  // namespace adl
 
@@ -173,11 +173,12 @@ struct tuple_like {
   int i;
   std::string str;
 
-  template <size_t N> fmt::enable_if_t<N == 0, int> get() const noexcept {
+  template <size_t N>
+  auto get() const noexcept -> fmt::enable_if_t<N == 0, int> {
     return i;
   }
   template <size_t N>
-  fmt::enable_if_t<N == 1, fmt::string_view> get() const noexcept {
+  auto get() const noexcept -> fmt::enable_if_t<N == 1, fmt::string_view> {
     return str;
   }
 };
@@ -210,8 +211,8 @@ TEST(ranges_test, format_to) {
 }
 
 template <typename Char> struct path_like {
-  const path_like* begin() const;
-  const path_like* end() const;
+  auto begin() const -> const path_like*;
+  auto end() const -> const path_like*;
 
   operator std::basic_string<Char>() const;
 };
@@ -241,8 +242,8 @@ template <typename T> class non_const_only_range {
   explicit non_const_only_range(Args&&... args)
       : vec(std::forward<Args>(args)...) {}
 
-  const_iterator begin() { return vec.begin(); }
-  const_iterator end() { return vec.end(); }
+  auto begin() -> const_iterator{ return vec.begin(); }
+  auto end() -> const_iterator { return vec.end(); }
 };
 
 template <typename T> class noncopyable_range {
@@ -259,16 +260,16 @@ template <typename T> class noncopyable_range {
   noncopyable_range(noncopyable_range const&) = delete;
   noncopyable_range(noncopyable_range&) = delete;
 
-  iterator begin() { return vec.begin(); }
-  iterator end() { return vec.end(); }
+  auto begin() -> iterator { return vec.begin(); }
+  auto end() -> iterator { return vec.end(); }
 };
 
 TEST(ranges_test, range) {
-  noncopyable_range<int> w(3u, 0);
+  auto&& w = noncopyable_range<int>(3u, 0);
   EXPECT_EQ(fmt::format("{}", w), "[0, 0, 0]");
   EXPECT_EQ(fmt::format("{}", noncopyable_range<int>(3u, 0)), "[0, 0, 0]");
 
-  non_const_only_range<int> x(3u, 0);
+  auto x = non_const_only_range<int>(3u, 0);
   EXPECT_EQ(fmt::format("{}", x), "[0, 0, 0]");
   EXPECT_EQ(fmt::format("{}", non_const_only_range<int>(3u, 0)), "[0, 0, 0]");
 
@@ -343,8 +344,8 @@ bool operator!=(const char* p, zstring_sentinel) { return *p != '\0'; }
 
 struct zstring {
   const char* p;
-  const char* begin() const { return p; }
-  zstring_sentinel end() const { return {}; }
+  auto begin() const -> const char* { return p; }
+  auto end() const -> zstring_sentinel { return {}; }
 };
 
 #  ifdef __cpp_lib_ranges
@@ -358,20 +359,22 @@ struct cpp20_only_range {
 
     iterator() = default;
     iterator(int i) : val(i) {}
-    int operator*() const { return val; }
-    iterator& operator++() {
+    auto operator*() const -> int { return val; }
+    auto operator++() -> iterator&{
       ++val;
       return *this;
     }
     void operator++(int) { ++*this; }
-    bool operator==(const iterator& rhs) const { return val == rhs.val; }
+    auto operator==(const iterator& rhs) const -> bool {
+      return val == rhs.val;
+    }
   };
 
   int lo;
   int hi;
 
-  iterator begin() const { return iterator(lo); }
-  iterator end() const { return iterator(hi); }
+  auto begin() const -> iterator { return iterator(lo); }
+  auto end() const -> iterator { return iterator(hi); }
 };
 
 static_assert(std::input_iterator<cpp20_only_range::iterator>);
@@ -385,12 +388,12 @@ TEST(ranges_test, join_sentinel) {
 }
 
 TEST(ranges_test, join_range) {
-  noncopyable_range<int> w(3u, 0);
+  auto&& w = noncopyable_range<int>(3u, 0);
   EXPECT_EQ(fmt::format("{}", fmt::join(w, ",")), "0,0,0");
   EXPECT_EQ(fmt::format("{}", fmt::join(noncopyable_range<int>(3u, 0), ",")),
             "0,0,0");
 
-  non_const_only_range<int> x(3u, 0);
+  auto x = non_const_only_range<int>(3u, 0);
   EXPECT_EQ(fmt::format("{}", fmt::join(x, ",")), "0,0,0");
   EXPECT_EQ(fmt::format("{}", fmt::join(non_const_only_range<int>(3u, 0), ",")),
             "0,0,0");
@@ -456,10 +459,10 @@ template <typename R> struct fmt_ref_view {
 };
 
 TEST(ranges_test, range_of_range_of_mixed_const) {
-  std::vector<std::vector<int>> v = {{1, 2, 3}, {4, 5}};
+  auto v = std::vector<std::vector<int>>{{1, 2, 3}, {4, 5}};
   EXPECT_EQ(fmt::format("{}", v), "[[1, 2, 3], [4, 5]]");
 
-  fmt_ref_view<decltype(v)> r{&v};
+  auto r = fmt_ref_view<decltype(v)>{&v};
   EXPECT_EQ(fmt::format("{}", r), "[[1, 2, 3], [4, 5]]");
 }
 

test/std-test.cc

@@ -237,6 +237,13 @@ TEST(std_test, format_const_bit_reference) {
   EXPECT_EQ(fmt::format("{} {}", v[0], v[1]), "true false");
 }
 
+TEST(std_test, format_bitset) {
+  auto bs = std::bitset<6>(42);
+  EXPECT_EQ(fmt::format("{}", bs), "101010");
+  EXPECT_EQ(fmt::format("{:0>8}", bs), "00101010");
+  EXPECT_EQ(fmt::format("{:-^12}", bs), "---101010---");
+}
+
 TEST(std_test, format_atomic) {
   std::atomic<bool> b(false);
   EXPECT_EQ(fmt::format("{}", b), "false");

test/util.cc

@@ -37,9 +37,8 @@ std::locale do_get_locale(const char* name) {
 
 std::locale get_locale(const char* name, const char* alt_name) {
   auto loc = do_get_locale(name);
-  if (loc == std::locale::classic() && alt_name) {
+  if (loc == std::locale::classic() && alt_name)
     loc = do_get_locale(alt_name);
-  }
   if (loc == std::locale::classic())
     fmt::print(stderr, "{} locale is missing.\n", name);
   return loc;

test/xchar-test.cc

@@ -102,11 +102,71 @@ struct custom_char {
   template <typename T>
   constexpr custom_char(T val) : value(static_cast<int>(val)) {}
 
-  operator char() const {
+  constexpr operator char() const {
     return value <= 0xff ? static_cast<char>(value) : '\0';
   }
+  constexpr bool operator<(custom_char c) const { return value < c.value; }
 };
 
+namespace std {
+
+template <> struct char_traits<custom_char> {
+  using char_type = custom_char;
+  using int_type = int;
+  using off_type = streamoff;
+  using pos_type = streampos;
+  using state_type = mbstate_t;
+
+  static constexpr void assign(char_type& r, const char_type& a) { r = a; }
+  static constexpr bool eq(char_type a, char_type b) { return a == b; }
+  static constexpr bool lt(char_type a, char_type b) { return a < b; }
+  static FMT_CONSTEXPR int compare(const char_type* s1, const char_type* s2,
+                                   size_t count) {
+    for (; count; count--, s1++, s2++) {
+      if (lt(*s1, *s2)) return -1;
+      if (lt(*s2, *s1)) return 1;
+    }
+    return 0;
+  }
+  static FMT_CONSTEXPR size_t length(const char_type* s) {
+    size_t count = 0;
+    while (!eq(*s++, custom_char(0))) count++;
+    return count;
+  }
+  static const char_type* find(const char_type*, size_t, const char_type&);
+  static FMT_CONSTEXPR char_type* move(char_type* dest, const char_type* src,
+                                       size_t count) {
+    if (count == 0) return dest;
+    char_type* ret = dest;
+    if (src < dest) {
+      dest += count;
+      src += count;
+      for (; count; count--) assign(*--dest, *--src);
+    } else if (src > dest)
+      copy(dest, src, count);
+    return ret;
+  }
+  static FMT_CONSTEXPR char_type* copy(char_type* dest, const char_type* src,
+                                       size_t count) {
+    char_type* ret = dest;
+    for (; count; count--) assign(*dest++, *src++);
+    return ret;
+  }
+  static FMT_CONSTEXPR char_type* assign(char_type* dest, std::size_t count,
+                                         char_type a) {
+    char_type* ret = dest;
+    for (; count; count--) assign(*dest++, a);
+    return ret;
+  }
+  static int_type not_eof(int_type);
+  static char_type to_char_type(int_type);
+  static int_type to_int_type(char_type);
+  static bool eq_int_type(int_type, int_type);
+  static int_type eof();
+};
+
+}  // namespace std
+
 auto to_ascii(custom_char c) -> char { return c; }
 
 FMT_BEGIN_NAMESPACE
@@ -554,17 +614,14 @@ TEST(locale_test, complex) {
 }
 
 TEST(locale_test, chrono_weekday) {
-  auto loc = get_locale("ru_RU.UTF-8", "Russian_Russia.1251");
+  auto loc = get_locale("es_ES.UTF-8", "Spanish_Spain.1252");
   auto loc_old = std::locale::global(loc);
-  auto mon = fmt::weekday(1);
-  EXPECT_EQ(fmt::format(L"{}", mon), L"Mon");
+  auto sat = fmt::weekday(6);
+  EXPECT_EQ(fmt::format(L"{}", sat), L"Sat");
   if (loc != std::locale::classic()) {
-    // {L"\x43F\x43D", L"\x41F\x43D", L"\x43F\x43D\x434", L"\x41F\x43D\x434"}
-    // {L"пн", L"Пн", L"пнд", L"Пнд"}
-    EXPECT_THAT(
-        (std::vector<std::wstring>{L"\x43F\x43D", L"\x41F\x43D",
-                                   L"\x43F\x43D\x434", L"\x41F\x43D\x434"}),
-        Contains(fmt::format(loc, L"{:L}", mon)));
+    // L'\xE1' is 'á'.
+    auto saturdays = std::vector<std::wstring>{L"s\xE1""b", L"s\xE1."};
+    EXPECT_THAT(saturdays, Contains(fmt::format(loc, L"{:L}", sat)));
   }
   std::locale::global(loc_old);
 }