Update version

fails only when FMT_BUILTIN_CTZLL is not defined

CMakeLists.txt

@@ -1,10 +1,8 @@
-cmake_minimum_required(VERSION 3.1.0)
+cmake_minimum_required(VERSION 3.1...3.18)
 
-# Use newer policies if available, up to most recent tested version of CMake.
-if(${CMAKE_VERSION} VERSION_LESS 3.11)
+# Fallback for using newer policies on CMake <3.12.
+if(${CMAKE_VERSION} VERSION_LESS 3.12)
   cmake_policy(VERSION ${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION})
-else()
-  cmake_policy(VERSION 3.11)
 endif()
 
 # Determine if fmt is built as a subproject (using add_subdirectory)
@@ -24,15 +22,23 @@ function(join result_var)
   set(${result_var} "${result}" PARENT_SCOPE)
 endfunction()
 
+include(CMakeParseArguments)
+
 # Sets a cache variable with a docstring joined from multiple arguments:
 #   set(<variable> <value>... CACHE <type> <docstring>...)
 # This allows splitting a long docstring for readability.
 function(set_verbose)
-  cmake_parse_arguments(SET_VERBOSE "" "" "CACHE" ${ARGN})
-  list(GET SET_VERBOSE_CACHE 0 type)
-  list(REMOVE_AT SET_VERBOSE_CACHE 0)
-  join(doc ${SET_VERBOSE_CACHE})
-  set(${SET_VERBOSE_UNPARSED_ARGUMENTS} CACHE ${type} ${doc})
+  # cmake_parse_arguments is broken in CMake 3.4 (cannot parse CACHE) so use
+  # list instead.
+  list(GET ARGN 0 var)
+  list(REMOVE_AT ARGN 0)
+  list(GET ARGN 0 val)
+  list(REMOVE_AT ARGN 0)
+  list(REMOVE_AT ARGN 0)
+  list(GET ARGN 0 type)
+  list(REMOVE_AT ARGN 0)
+  join(doc ${ARGN})
+  set(${var} ${val} CACHE ${type} ${doc})
 endfunction()
 
 # Set the default CMAKE_BUILD_TYPE to Release.
@@ -47,8 +53,8 @@ endif ()
 project(FMT CXX)
 include(GNUInstallDirs)
 set_verbose(FMT_INC_DIR ${CMAKE_INSTALL_INCLUDEDIR} CACHE STRING
-            "Installation directory for include files, a relative path "
-            "that will be joined to ${CMAKE_INSTALL_PREFIX}, or an arbitrary absolute path.")
+            "Installation directory for include files, a relative path that "
+            "will be joined with ${CMAKE_INSTALL_PREFIX} or an absolute path.")
 
 option(FMT_PEDANTIC "Enable extra warnings and expensive tests." OFF)
 option(FMT_WERROR "Halt the compilation with an error on compiler warnings."
@@ -101,11 +107,11 @@ if (CMAKE_CXX_COMPILER_ID MATCHES "GNU")
       -Wold-style-cast -Wundef
       -Wredundant-decls -Wwrite-strings -Wpointer-arith
       -Wcast-qual -Wformat=2 -Wmissing-include-dirs
-      -Wcast-align -Wnon-virtual-dtor
+      -Wcast-align
       -Wctor-dtor-privacy -Wdisabled-optimization
       -Winvalid-pch -Woverloaded-virtual
-      -Wconversion -Wswitch-enum
-      -Wno-ctor-dtor-privacy -Wno-format-nonliteral -Wno-shadow)
+      -Wconversion -Wswitch-enum -Wundef
+      -Wno-ctor-dtor-privacy -Wno-format-nonliteral)
   if (NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.6)
       set(PEDANTIC_COMPILE_FLAGS ${PEDANTIC_COMPILE_FLAGS} -Wnoexcept
          -Wno-dangling-else -Wno-unused-local-typedefs)
@@ -123,8 +129,8 @@ if (CMAKE_CXX_COMPILER_ID MATCHES "GNU")
 endif ()
 
 if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
-  set(PEDANTIC_COMPILE_FLAGS -Wall -Wextra -pedantic -Wconversion
-      -Wno-sign-conversion -Wdeprecated -Wweak-vtables)
+  set(PEDANTIC_COMPILE_FLAGS -Wall -Wextra -pedantic -Wconversion -Wundef
+      -Wdeprecated -Wweak-vtables)
   check_cxx_compiler_flag(-Wzero-as-null-pointer-constant HAS_NULLPTR_WARNING)
   if (HAS_NULLPTR_WARNING)
     set(PEDANTIC_COMPILE_FLAGS ${PEDANTIC_COMPILE_FLAGS}
@@ -193,7 +199,10 @@ if (HAVE_STRTOD_L)
 endif ()
 
 if (MINGW)
-  target_compile_options(fmt PUBLIC "-Wa,-mbig-obj")
+  check_cxx_compiler_flag("Wa,-mbig-obj" FMT_HAS_MBIG_OBJ)
+  if (${FMT_HAS_MBIG_OBJ})
+    target_compile_options(fmt PUBLIC "-Wa,-mbig-obj")
+  endif()
 endif ()
 
 if (FMT_WERROR)
@@ -223,7 +232,8 @@ if (CMAKE_BUILD_TYPE STREQUAL "Debug")
 endif ()
 
 if (BUILD_SHARED_LIBS)
-  if (UNIX AND NOT APPLE AND NOT ${CMAKE_SYSTEM_NAME} MATCHES "SunOS" AND NOT EMSCRIPTEN)
+  if (UNIX AND NOT APPLE AND NOT ${CMAKE_SYSTEM_NAME} MATCHES "SunOS" AND
+      NOT EMSCRIPTEN)
     # Fix rpmlint warning:
     # unused-direct-shlib-dependency /usr/lib/libformat.so.1.1.0 /lib/libm.so.6.
     target_link_libraries(fmt -Wl,--as-needed)
@@ -248,20 +258,22 @@ target_include_directories(fmt-header-only INTERFACE
 if (FMT_INSTALL)
   include(CMakePackageConfigHelpers)
   set_verbose(FMT_CMAKE_DIR ${CMAKE_INSTALL_LIBDIR}/cmake/fmt CACHE STRING
-              "Installation directory for cmake files, a relative path "
-              "that will be joined to ${CMAKE_INSTALL_PREFIX}, or an arbitrary absolute path.")
+              "Installation directory for cmake files, a relative path that "
+              "will be joined with ${CMAKE_INSTALL_PREFIX} or an absolute "
+              "path.")
   set(version_config ${PROJECT_BINARY_DIR}/fmt-config-version.cmake)
   set(project_config ${PROJECT_BINARY_DIR}/fmt-config.cmake)
   set(pkgconfig ${PROJECT_BINARY_DIR}/fmt.pc)
   set(targets_export_name fmt-targets)
 
   set_verbose(FMT_LIB_DIR ${CMAKE_INSTALL_LIBDIR} CACHE STRING
-              "Installation directory for libraries, a relative path "
-              "that will be joined to ${CMAKE_INSTALL_PREFIX}, or an arbitrary absolute path.")
+              "Installation directory for libraries, a relative path that "
+              "will be joined to ${CMAKE_INSTALL_PREFIX} or an absolute path.")
 
   set_verbose(FMT_PKGCONFIG_DIR ${CMAKE_INSTALL_LIBDIR}/pkgconfig CACHE PATH
-              "Installation directory for pkgconfig (.pc) files, a relative path "
-              "that will be joined to ${CMAKE_INSTALL_PREFIX}, or an arbitrary absolute path.")
+              "Installation directory for pkgconfig (.pc) files, a relative "
+              "path that will be joined with ${CMAKE_INSTALL_PREFIX} or an "
+              "absolute path.")
 
   # Generate the version, config and target files into the build directory.
   write_basic_package_version_file(
@@ -318,6 +330,12 @@ endif ()
 # Control fuzzing independent of the unit tests.
 if (FMT_FUZZ)
   add_subdirectory(test/fuzzing)
+
+  # The FMT_FUZZ macro is used to prevent resource exhaustion in fuzzing
+  # mode and make fuzzing practically possible. It is similar to
+  # FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION but uses a different name to
+  # avoid interfering with fuzzing of projects that use {fmt}.
+  # See also https://llvm.org/docs/LibFuzzer.html#fuzzer-friendly-build-mode.
   target_compile_definitions(fmt PUBLIC FMT_FUZZ)
 endif ()
 

CONTRIBUTING.md

@@ -14,4 +14,7 @@ exceptions:
 * snake_case should be used instead of UpperCamelCase for function and type
   names
 
+All documentation must adhere to the [Google Developer Documentation Style
+Guide](https://developers.google.com/style).
+
 Thanks for contributing!

ChangeLog.rst

@@ -1,3 +1,449 @@
+7.1.1 - 2020-11-01
+------------------
+
+* Fixed ABI compatibility with 7.0.x
+  (`#1961 <https://github.com/fmtlib/fmt/issues/1961>`_).
+
+* Added the ``FMT_ARM_ABI_COMPATIBILITY`` macro to work around ABI
+  incompatibility between GCC and Clang on ARM
+  (`#1919 <https://github.com/fmtlib/fmt/issues/1919>`_).
+
+* Worked around a SFINAE bug in GCC 8
+  (`#1957 <https://github.com/fmtlib/fmt/issues/1957>`_).
+
+* Fixed linkage errors when building with GCC's LTO
+  (`#1955 <https://github.com/fmtlib/fmt/issues/1955>`_).
+
+* Fixed a compilation error when building without ``__builtin_clz`` or equivalent
+  (`#1968 <https://github.com/fmtlib/fmt/pull/1968>`_).
+  Thanks `@tohammer (Tobias Hammer) <https://github.com/tohammer>`_.
+
+* Fixed a sign conversion warning
+  (`#1964 <https://github.com/fmtlib/fmt/pull/1964>`_).
+  Thanks `@OptoCloud <https://github.com/OptoCloud>`_.
+
+7.1.0 - 2020-10-25
+------------------
+
+* Switched from `Grisu3
+  <https://www.cs.tufts.edu/~nr/cs257/archive/florian-loitsch/printf.pdf>`_
+  to `Dragonbox <https://github.com/jk-jeon/dragonbox>`_ for the default
+  floating-point formatting which gives the shortest decimal representation
+  with round-trip guarantee and correct rounding
+  (`#1882 <https://github.com/fmtlib/fmt/pull/1882>`_,
+  `#1887 <https://github.com/fmtlib/fmt/pull/1887>`_,
+  `#1894 <https://github.com/fmtlib/fmt/pull/1894>`_). This makes {fmt} up to
+  20-30x faster than common implementations of ``std::ostringstream`` and
+  ``sprintf`` on `dtoa-benchmark <https://github.com/fmtlib/dtoa-benchmark>`_
+  and faster than double-conversion and Ryū:
+
+  .. image:: https://user-images.githubusercontent.com/576385/
+             95684665-11719600-0ba8-11eb-8e5b-972ff4e49428.png
+
+  It is possible to get even better performance at the cost of larger binary
+  size by compiling with the ``FMT_USE_FULL_CACHE_DRAGONBOX`` macro set to 1.
+
+  Thanks `@jk-jeon (Junekey Jeon) <https://github.com/jk-jeon>`_.
+
+* Added an experimental unsynchronized file output API which, together with
+  `format string compilation <https://fmt.dev/latest/api.html#compile-api>`_,
+  can give `5-9 times speed up compared to fprintf
+  <https://www.zverovich.net/2020/08/04/optimal-file-buffer-size.html>`_
+  on common platforms (`godbolt <https://godbolt.org/z/nsTcG8>`__):
+
+  .. code:: c++
+
+     #include <fmt/os.h>
+
+     int main() {
+       auto f = fmt::output_file("guide");
+       f.print("The answer is {}.", 42);
+     }
+
+* Added a formatter for ``std::chrono::time_point<system_clock>``
+  (`#1819 <https://github.com/fmtlib/fmt/issues/1819>`_,
+  `#1837 <https://github.com/fmtlib/fmt/pull/1837>`_). For example
+  (`godbolt <https://godbolt.org/z/c4M6fh>`__):
+
+  .. code:: c++
+
+     #include <fmt/chrono.h>
+
+     int main() {
+       auto now = std::chrono::system_clock::now();
+       fmt::print("The time is {:%H:%M:%S}.\n", now);
+     }
+
+  Thanks `@adamburgess (Adam Burgess) <https://github.com/adamburgess>`_.
+
+* Added support for ranges with non-const ``begin``/``end`` to ``fmt::join``
+  (`#1784 <https://github.com/fmtlib/fmt/issues/1784>`_,
+  `#1786 <https://github.com/fmtlib/fmt/pull/1786>`_). For example
+  (`godbolt <https://godbolt.org/z/jP63Tv>`__):
+
+  .. code:: c++
+
+     #include <fmt/ranges.h>
+     #include <range/v3/view/filter.hpp>
+
+     int main() {
+       using std::literals::string_literals::operator""s;
+       auto strs = std::array{"a"s, "bb"s, "ccc"s};
+       auto range = strs | ranges::views::filter(
+         [] (const std::string &x) { return x.size() != 2; }
+       );
+       fmt::print("{}\n", fmt::join(range, ""));
+     }
+
+  prints "accc".
+
+  Thanks `@tonyelewis (Tony E Lewis) <https://github.com/tonyelewis>`_.
+
+* Added a ``memory_buffer::append`` overload that takes a range
+  (`#1806 <https://github.com/fmtlib/fmt/pull/1806>`_).
+  Thanks `@BRevzin (Barry Revzin) <https://github.com/BRevzin>`_.
+
+* Improved handling of single code units in ``FMT_COMPILE``. For example:
+
+  .. code:: c++
+
+     #include <fmt/compile.h>
+
+     char* f(char* buf) {
+       return fmt::format_to(buf, FMT_COMPILE("x{}"), 42);
+     }
+
+  compiles to just (`godbolt <https://godbolt.org/z/5vncz3>`__):
+
+  .. code:: asm
+
+     _Z1fPc:
+       movb $120, (%rdi)
+       xorl %edx, %edx
+       cmpl $42, _ZN3fmt2v76detail10basic_dataIvE23zero_or_powers_of_10_32E+8(%rip)
+       movl $3, %eax
+       seta %dl
+       subl %edx, %eax
+       movzwl _ZN3fmt2v76detail10basic_dataIvE6digitsE+84(%rip), %edx
+       cltq
+       addq %rdi, %rax
+       movw %dx, -2(%rax)
+       ret
+
+  Here a single ``mov`` instruction writes ``'x'`` (``$120``) to the output
+  buffer.
+
+* Added dynamic width support to format string compilation
+  (`#1809 <https://github.com/fmtlib/fmt/issues/1809>`_).
+
+* Improved error reporting for unformattable types: now you'll get the type name
+  directly in the error message instead of the note:
+
+  .. code:: c++
+
+     #include <fmt/core.h>
+
+     struct how_about_no {};
+
+     int main() {
+       fmt::print("{}", how_about_no());
+     }
+
+  Error (`godbolt <https://godbolt.org/z/GoxM4e>`__):
+
+  ``fmt/core.h:1438:3: error: static_assert failed due to requirement
+  'fmt::v7::formattable<how_about_no>()' "Cannot format an argument.
+  To make type T formattable provide a formatter<T> specialization:
+  https://fmt.dev/latest/api.html#udt"
+  ...``
+
+* Added the `make_args_checked <https://fmt.dev/7.1.0/api.html#argument-lists>`_
+  function template that allows you to write formatting functions with
+  compile-time format string checks and avoid binary code bloat
+  (`godbolt <https://godbolt.org/z/PEf9qr>`__):
+
+  .. code:: c++
+
+     void vlog(const char* file, int line, fmt::string_view format,
+               fmt::format_args args) {
+       fmt::print("{}: {}: ", file, line);
+       fmt::vprint(format, args);
+     }
+
+     template <typename S, typename... Args>
+     void log(const char* file, int line, const S& format, Args&&... args) {
+       vlog(file, line, format,
+           fmt::make_args_checked<Args...>(format, args...));
+     }
+
+     #define MY_LOG(format, ...) \
+       log(__FILE__, __LINE__, FMT_STRING(format), __VA_ARGS__)
+
+     MY_LOG("invalid squishiness: {}", 42);
+
+* Replaced ``snprintf`` fallback with a faster internal IEEE 754 ``float`` and
+  ``double`` formatter for arbitrary precision. For example
+  (`godbolt <https://godbolt.org/z/dPhWvj>`__):
+
+  .. code:: c++
+
+     #include <fmt/core.h>
+
+     int main() {
+       fmt::print("{:.500}\n", 4.9406564584124654E-324);
+     }
+
+  prints
+
+  ``4.9406564584124654417656879286822137236505980261432476442558568250067550727020875186529983636163599237979656469544571773092665671035593979639877479601078187812630071319031140452784581716784898210368871863605699873072305000638740915356498438731247339727316961514003171538539807412623856559117102665855668676818703956031062493194527159149245532930545654440112748012970999954193198940908041656332452475714786901472678015935523861155013480352649347201937902681071074917033322268447533357208324319360923829e-324``.
+
+* Made ``format_to_n`` and ``formatted_size`` part of the `core API
+  <https://fmt.dev/latest/api.html#core-api>`__
+  (`godbolt <https://godbolt.org/z/sPjY1K>`__):
+
+  .. code:: c++
+
+     #include <fmt/core.h>
+
+     int main() {
+       char buffer[10];
+       auto result = fmt::format_to_n(buffer, sizeof(buffer), "{}", 42);
+     }
+
+* Added ``fmt::format_to_n`` overload with format string compilation
+  (`#1764 <https://github.com/fmtlib/fmt/issues/1764>`_,
+  `#1767 <https://github.com/fmtlib/fmt/pull/1767>`_,
+  `#1869 <https://github.com/fmtlib/fmt/pull/1869>`_). For example
+  (`godbolt <https://godbolt.org/z/93h86q>`__):
+
+  .. code:: c++
+
+     #include <fmt/compile.h>
+
+     int main() {
+       char buffer[8];
+       fmt::format_to_n(buffer, sizeof(buffer), FMT_COMPILE("{}"), 42);
+     }
+
+  Thanks `@Kurkin (Dmitry Kurkin) <https://github.com/Kurkin>`_,
+  `@alexezeder (Alexey Ochapov) <https://github.com/alexezeder>`_.
+
+* Added ``fmt::format_to`` overload that take ``text_style``
+  (`#1593 <https://github.com/fmtlib/fmt/issues/1593>`_,
+  `#1842 <https://github.com/fmtlib/fmt/issues/1842>`_,
+  `#1843 <https://github.com/fmtlib/fmt/pull/1843>`_). For example
+  (`godbolt <https://godbolt.org/z/91153r>`__):
+
+  .. code:: c++
+
+     #include <fmt/color.h>
+
+     int main() {
+       std::string out;
+       fmt::format_to(std::back_inserter(out),
+                      fmt::emphasis::bold | fg(fmt::color::red),
+                      "The answer is {}.", 42);
+     }
+
+  Thanks `@Naios (Denis Blank) <https://github.com/Naios>`_.
+
+* Made the ``#`` specifier emit trailing zeros in addition to the decimal point
+  (`#1797 <https://github.com/fmtlib/fmt/issues/1797>`_). For example
+  (`godbolt <https://godbolt.org/z/bhdcW9>`__):
+
+  .. code:: c++
+
+     #include <fmt/core.h>
+
+     int main() {
+       fmt::print("{:#.2g}", 0.5);
+     }
+
+  prints ``0.50``.
+
+* Changed the default floating point format to not include ``.0`` for
+  consistency with ``std::format`` and ``std::to_chars``
+  (`#1893 <https://github.com/fmtlib/fmt/issues/1893>`_,
+  `#1943 <https://github.com/fmtlib/fmt/issues/1943>`_). It is possible to get
+  the decimal point and trailing zero with the ``#`` specifier.
+
+* Fixed an issue with floating-point formatting that could result in addition of
+  a non-significant trailing zero in rare cases e.g. ``1.00e-34`` instead of
+  ``1.0e-34`` (`#1873 <https://github.com/fmtlib/fmt/issues/1873>`_,
+  `#1917 <https://github.com/fmtlib/fmt/issues/1917>`_).
+
+* Made ``fmt::to_string`` fallback on ``ostream`` insertion operator if
+  the ``formatter`` specialization is not provided
+  (`#1815 <https://github.com/fmtlib/fmt/issues/1815>`_,
+  `#1829 <https://github.com/fmtlib/fmt/pull/1829>`_).
+  Thanks `@alexezeder (Alexey Ochapov) <https://github.com/alexezeder>`_.
+
+* Added support for the append mode to the experimental file API and
+  improved ``fcntl.h`` detection.
+  (`#1847 <https://github.com/fmtlib/fmt/pull/1847>`_,
+  `#1848 <https://github.com/fmtlib/fmt/pull/1848>`_).
+  Thanks `@t-wiser <https://github.com/t-wiser>`_.
+
+* Fixed handling of types that have both an implicit conversion operator and
+  an overloaded ``ostream`` insertion operator
+  (`#1766 <https://github.com/fmtlib/fmt/issues/1766>`_).
+
+* Fixed a slicing issue in an internal iterator type
+  (`#1822 <https://github.com/fmtlib/fmt/pull/1822>`_).
+  Thanks `@BRevzin (Barry Revzin) <https://github.com/BRevzin>`_.
+
+* Fixed an issue in locale-specific integer formatting
+  (`#1927 <https://github.com/fmtlib/fmt/issues/1927>`_).
+
+* Fixed handling of exotic code unit types
+  (`#1870 <https://github.com/fmtlib/fmt/issues/1870>`_,
+  `#1932 <https://github.com/fmtlib/fmt/issues/1932>`_).
+
+* Improved ``FMT_ALWAYS_INLINE``
+  (`#1878 <https://github.com/fmtlib/fmt/pull/1878>`_).
+  Thanks `@jk-jeon (Junekey Jeon) <https://github.com/jk-jeon>`_.
+
+* Removed dependency on ``windows.h``
+  (`#1900 <https://github.com/fmtlib/fmt/pull/1900>`_).
+  Thanks `@bernd5 (Bernd Baumanns) <https://github.com/bernd5>`_.
+
+* Optimized counting of decimal digits on MSVC
+  (`#1890 <https://github.com/fmtlib/fmt/pull/1890>`_).
+  Thanks `@mwinterb <https://github.com/mwinterb>`_.
+
+* Improved documentation
+  (`#1772 <https://github.com/fmtlib/fmt/issues/1772>`_,
+  `#1775 <https://github.com/fmtlib/fmt/pull/1775>`_,
+  `#1792 <https://github.com/fmtlib/fmt/pull/1792>`_,
+  `#1838 <https://github.com/fmtlib/fmt/pull/1838>`_,
+  `#1888 <https://github.com/fmtlib/fmt/pull/1888>`_,
+  `#1918 <https://github.com/fmtlib/fmt/pull/1918>`_,
+  `#1939 <https://github.com/fmtlib/fmt/pull/1939>`_).
+  Thanks `@leolchat (Léonard Gérard) <https://github.com/leolchat>`_,
+  `@pepsiman (Malcolm Parsons) <https://github.com/pepsiman>`_,
+  `@Klaim (Joël Lamotte) <https://github.com/Klaim>`_,
+  `@ravijanjam (Ravi J) <https://github.com/ravijanjam>`_,
+  `@francesco-st <https://github.com/francesco-st>`_,
+  `@udnaan (Adnan) <https://github.com/udnaan>`_.
+
+* Added the ``FMT_REDUCE_INT_INSTANTIATIONS`` CMake option that reduces the
+  binary code size at the cost of some integer formatting performance. This can
+  be useful for extremely memory-constrained embedded systems
+  (`#1778 <https://github.com/fmtlib/fmt/issues/1778>`_,
+  `#1781 <https://github.com/fmtlib/fmt/pull/1781>`_).
+  Thanks `@kammce (Khalil Estell) <https://github.com/kammce>`_.
+
+* Added the ``FMT_USE_INLINE_NAMESPACES`` macro to control usage of inline
+  namespaces (`#1945 <https://github.com/fmtlib/fmt/pull/1945>`_).
+  Thanks `@darklukee <https://github.com/darklukee>`_.
+
+* Improved build configuration
+  (`#1760 <https://github.com/fmtlib/fmt/pull/1760>`_,
+  `#1770 <https://github.com/fmtlib/fmt/pull/1770>`_,
+  `#1779 <https://github.com/fmtlib/fmt/issues/1779>`_,
+  `#1783 <https://github.com/fmtlib/fmt/pull/1783>`_,
+  `#1823 <https://github.com/fmtlib/fmt/pull/1823>`_).
+  Thanks `@dvetutnev (Dmitriy Vetutnev) <https://github.com/dvetutnev>`_,
+  `@xvitaly (Vitaly Zaitsev) <https://github.com/xvitaly>`_,
+  `@tambry (Raul Tambre) <https://github.com/tambry>`_,
+  `@medithe <https://github.com/medithe>`_,
+  `@martinwuehrer (Martin Wührer) <https://github.com/martinwuehrer>`_.
+
+* Fixed various warnings and compilation issues
+  (`#1790 <https://github.com/fmtlib/fmt/pull/1790>`_,
+  `#1802 <https://github.com/fmtlib/fmt/pull/1802>`_,
+  `#1808 <https://github.com/fmtlib/fmt/pull/1808>`_,
+  `#1810 <https://github.com/fmtlib/fmt/issues/1810>`_,
+  `#1811 <https://github.com/fmtlib/fmt/issues/1811>`_,
+  `#1812 <https://github.com/fmtlib/fmt/pull/1812>`_,
+  `#1814 <https://github.com/fmtlib/fmt/pull/1814>`_,
+  `#1816 <https://github.com/fmtlib/fmt/pull/1816>`_,
+  `#1817 <https://github.com/fmtlib/fmt/pull/1817>`_,
+  `#1818 <https://github.com/fmtlib/fmt/pull/1818>`_,
+  `#1825 <https://github.com/fmtlib/fmt/issues/1825>`_,
+  `#1836 <https://github.com/fmtlib/fmt/pull/1836>`_,
+  `#1855 <https://github.com/fmtlib/fmt/pull/1855>`_,
+  `#1856 <https://github.com/fmtlib/fmt/pull/1856>`_,
+  `#1860 <https://github.com/fmtlib/fmt/pull/1860>`_,
+  `#1877 <https://github.com/fmtlib/fmt/pull/1877>`_,
+  `#1879 <https://github.com/fmtlib/fmt/pull/1879>`_,
+  `#1880 <https://github.com/fmtlib/fmt/pull/1880>`_,
+  `#1896 <https://github.com/fmtlib/fmt/issues/1896>`_,
+  `#1897 <https://github.com/fmtlib/fmt/pull/1897>`_,
+  `#1898 <https://github.com/fmtlib/fmt/pull/1898>`_,
+  `#1904 <https://github.com/fmtlib/fmt/issues/1904>`_,
+  `#1908 <https://github.com/fmtlib/fmt/pull/1908>`_,
+  `#1911 <https://github.com/fmtlib/fmt/issues/1911>`_,
+  `#1912 <https://github.com/fmtlib/fmt/issues/1912>`_,
+  `#1928 <https://github.com/fmtlib/fmt/issues/1928>`_,
+  `#1929 <https://github.com/fmtlib/fmt/pull/1929>`_,
+  `#1935 <https://github.com/fmtlib/fmt/issues/1935>`_
+  `#1937 <https://github.com/fmtlib/fmt/pull/1937>`_,
+  `#1942 <https://github.com/fmtlib/fmt/pull/1942>`_,
+  `#1949 <https://github.com/fmtlib/fmt/issues/1949>`_).
+  Thanks `@TheQwertiest <https://github.com/TheQwertiest>`_,
+  `@medithe <https://github.com/medithe>`_,
+  `@martinwuehrer (Martin Wührer) <https://github.com/martinwuehrer>`_,
+  `@n16h7hunt3r <https://github.com/n16h7hunt3r>`_,
+  `@Othereum (Seokjin Lee) <https://github.com/Othereum>`_,
+  `@gsjaardema (Greg Sjaardema) <https://github.com/gsjaardema>`_,
+  `@AlexanderLanin (Alexander Lanin) <https://github.com/AlexanderLanin>`_,
+  `@gcerretani (Giovanni Cerretani) <https://github.com/gcerretani>`_,
+  `@chronoxor (Ivan Shynkarenka) <https://github.com/chronoxor>`_,
+  `@noizefloor (Jan Schwers) <https://github.com/noizefloor>`_,
+  `@akohlmey (Axel Kohlmeyer) <https://github.com/akohlmey>`_,
+  `@jk-jeon (Junekey Jeon) <https://github.com/jk-jeon>`_,
+  `@rimathia <https://github.com/rimathia>`_,
+  `@rglarix (Riccardo Ghetta (larix)) <https://github.com/rglarix>`_,
+  `@moiwi <https://github.com/moiwi>`_,
+  `@heckad (Kazantcev Andrey) <https://github.com/heckad>`_,
+  `@MarcDirven <https://github.com/MarcDirven>`_.
+  `@BartSiwek (Bart Siwek) <https://github.com/BartSiwek>`_,
+  `@darklukee <https://github.com/darklukee>`_.
+
+7.0.3 - 2020-08-06
+------------------
+
+* Worked around broken ``numeric_limits`` for 128-bit integers
+  (`#1787 <https://github.com/fmtlib/fmt/issues/1787>`_).
+
+* Added error reporting on missing named arguments
+  (`#1796 <https://github.com/fmtlib/fmt/issues/1796>`_).
+
+* Stopped using 128-bit integers with clang-cl
+  (`#1800 <https://github.com/fmtlib/fmt/pull/1800>`_).
+  Thanks `@Kingcom <https://github.com/Kingcom>`_.
+
+* Fixed issues in locale-specific integer formatting
+  (`#1782 <https://github.com/fmtlib/fmt/issues/1782>`_,
+  `#1801 <https://github.com/fmtlib/fmt/issues/1801>`_).
+
+7.0.2 - 2020-07-29
+------------------
+
+* Worked around broken ``numeric_limits`` for 128-bit integers
+  (`#1725 <https://github.com/fmtlib/fmt/issues/1725>`_).
+
+* Fixed compatibility with CMake 3.4
+  (`#1779 <https://github.com/fmtlib/fmt/issues/1779>`_).
+
+* Fixed handling of digit separators in locale-specific formatting
+  (`#1782 <https://github.com/fmtlib/fmt/issues/1782>`_).
+
+7.0.1 - 2020-07-07
+------------------
+
+* Updated the inline version namespace name.
+
+* Worked around a gcc bug in mangling of alias templates
+  (`#1753 <https://github.com/fmtlib/fmt/issues/1753>`_).
+
+* Fixed a linkage error on Windows
+  (`#1757 <https://github.com/fmtlib/fmt/issues/1757>`_).
+  Thanks `@Kurkin (Dmitry Kurkin) <https://github.com/Kurkin>`_.
+
+* Fixed minor issues with the documentation.
+
 7.0.0 - 2020-07-05
 ------------------
 
@@ -6,7 +452,7 @@
   <http://www.zverovich.net/2020/05/21/reducing-library-size.html>`_.
 
 * Added a simpler and more efficient `format string compilation API
-  <https://fmt.dev/dev/api.html#compile-api>`_:
+  <https://fmt.dev/7.0.0/api.html#compile-api>`_:
 
   .. code:: c++
 
@@ -126,7 +572,7 @@
                             ^
 
 * Added sentinel support to ``fmt::join``
-  (`#1689 <https://github.com/fmtlib/fmt/pull/1689>`_))
+  (`#1689 <https://github.com/fmtlib/fmt/pull/1689>`_)
 
   .. code:: c++
 
@@ -145,7 +591,7 @@
 
   Thanks `@BRevzin (Barry Revzin) <https://github.com/BRevzin>`_.
 
-* Added support for named args, ``clear`` and ``reserve`` to
+* Added support for named arguments, ``clear`` and ``reserve`` to
   ``dynamic_format_arg_store``
   (`#1655 <https://github.com/fmtlib/fmt/issues/1655>`_,
   `#1663 <https://github.com/fmtlib/fmt/pull/1663>`_,
@@ -279,7 +725,7 @@
   Thanks `@gsjaardema (Greg Sjaardema) <https://github.com/gsjaardema>`_,
   `@gabime (Gabi Melman) <https://github.com/gabime>`_,
   `@johnor (Johan) <https://github.com/johnor>`_,
-  `@gabime (Dmitry Kurkin) <https://github.com/Kurkin>`_,
+  `@Kurkin (Dmitry Kurkin) <https://github.com/Kurkin>`_,
   `@invexed (James Beach) <https://github.com/invexed>`_,
   `@peterbell10 <https://github.com/peterbell10>`_,
   `@daixtrose (Markus Werle) <https://github.com/daixtrose>`_,
@@ -1662,7 +2108,7 @@
 
 * Implemented ``constexpr`` parsing of format strings and `compile-time format
   string checks
-  <https://fmt.dev/dev/api.html#compile-time-format-string-checks>`_. For
+  <https://fmt.dev/latest/api.html#compile-time-format-string-checks>`_. For
   example
 
   .. code:: c++
@@ -1723,7 +2169,7 @@
             throw format_error("invalid specifier");
 
 * Added `iterator support
-  <https://fmt.dev/dev/api.html#output-iterator-support>`_:
+  <https://fmt.dev/latest/api.html#output-iterator-support>`_:
 
   .. code:: c++
 
@@ -1734,7 +2180,7 @@
      fmt::format_to(std::back_inserter(out), "{}", 42);
 
 * Added the `format_to_n
-  <https://fmt.dev/dev/api.html#_CPPv2N3fmt11format_to_nE8OutputItNSt6size_tE11string_viewDpRK4Args>`_
+  <https://fmt.dev/latest/api.html#_CPPv2N3fmt11format_to_nE8OutputItNSt6size_tE11string_viewDpRK4Args>`_
   function that restricts the output to the specified number of characters
   (`#298 <https://github.com/fmtlib/fmt/issues/298>`_):
 
@@ -1745,7 +2191,7 @@
      // out == "1234" (without terminating '\0')
 
 * Added the `formatted_size
-  <https://fmt.dev/dev/api.html#_CPPv2N3fmt14formatted_sizeE11string_viewDpRK4Args>`_
+  <https://fmt.dev/latest/api.html#_CPPv2N3fmt14formatted_sizeE11string_viewDpRK4Args>`_
   function for computing the output size:
 
   .. code:: c++
@@ -1755,7 +2201,7 @@
      auto size = fmt::formatted_size("{}", 12345); // size == 5
 
 * Improved compile times by reducing dependencies on standard headers and
-  providing a lightweight `core API <https://fmt.dev/dev/api.html#core-api>`_:
+  providing a lightweight `core API <https://fmt.dev/latest/api.html#core-api>`_:
 
   .. code:: c++
 
@@ -1767,7 +2213,7 @@
   <https://github.com/fmtlib/fmt#compile-time-and-code-bloat>`_.
 
 * Added the `make_format_args
-  <https://fmt.dev/dev/api.html#_CPPv2N3fmt16make_format_argsEDpRK4Args>`_
+  <https://fmt.dev/latest/api.html#_CPPv2N3fmt16make_format_argsEDpRK4Args>`_
   function for capturing formatting arguments:
 
   .. code:: c++
@@ -1849,7 +2295,7 @@
      fmt::format("{} {two}", 1, fmt::arg("two", 2));
 
 * Removed the write API in favor of the `format API
-  <https://fmt.dev/dev/api.html#format-api>`_ with compile-time handling of
+  <https://fmt.dev/latest/api.html#format-api>`_ with compile-time handling of
   format strings.
 
 * Disallowed formatting of multibyte strings into a wide character target

README.rst

@@ -7,48 +7,57 @@
 .. image:: https://ci.appveyor.com/api/projects/status/ehjkiefde6gucy1v
    :target: https://ci.appveyor.com/project/vitaut/fmt
 
-.. image:: https://oss-fuzz-build-logs.storage.googleapis.com/badges/libfmt.svg
-   :alt: fmt is continuously fuzzed att oss-fuzz
+.. image:: https://oss-fuzz-build-logs.storage.googleapis.com/badges/fmt.svg
+   :alt: fmt is continuously fuzzed at oss-fuzz
    :target: https://bugs.chromium.org/p/oss-fuzz/issues/list?\
             colspec=ID%20Type%20Component%20Status%20Proj%20Reported%20Owner%20\
-            Summary&q=proj%3Dlibfmt&can=1
+            Summary&q=proj%3Dfmt&can=1
 
 .. image:: https://img.shields.io/badge/stackoverflow-fmt-blue.svg
    :alt: Ask questions at StackOverflow with the tag fmt
    :target: https://stackoverflow.com/questions/tagged/fmt
 
-**{fmt}** is an open-source formatting library for C++.
-It can be used as a safe and fast alternative to (s)printf and iostreams.
+**{fmt}** is an open-source formatting library providing a fast and safe
+alternative to C stdio and C++ iostreams.
 
-`Documentation <https://fmt.dev/latest/>`__
+If you like this project, please consider donating to BYSOL,
+an initiative to help victims of political repressions in Belarus:
+https://www.facebook.com/donate/759400044849707/108388587646909/.
+
+`Documentation <https://fmt.dev>`__
 
 Q&A: ask questions on `StackOverflow with the tag fmt
 <https://stackoverflow.com/questions/tagged/fmt>`_.
 
+Try {fmt} in `Compiler Explorer <https://godbolt.org/z/Eq5763>`_.
+
 Features
 --------
 
-* Simple `format API <https://fmt.dev/dev/api.html>`_ with positional arguments
+* 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>`__
-* `Format string syntax <https://fmt.dev/dev/syntax.html>`_ similar to the one
-  of Python's
+* `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
+  round-trip guarantees
 * Safe `printf implementation
-  <https://fmt.dev/latest/api.html#printf-formatting>`_ including
-  the POSIX extension for positional arguments
-* Extensibility: support for user-defined types
+  <https://fmt.dev/latest/api.html#printf-formatting>`_ including the POSIX
+  extension for positional arguments
+* Extensibility: `support for user-defined types
+  <https://fmt.dev/latest/api.html#formatting-user-defined-types>`_
 * High performance: faster than common standard library implementations of
-  `printf <https://en.cppreference.com/w/cpp/io/c/fprintf>`_,
-  iostreams, ``to_string`` and ``to_chars``, see `Speed tests`_ and
-  `Converting a hundred million integers to strings per second
+  ``(s)printf``, iostreams, ``to_string`` and ``to_chars``, see `Speed tests`_
+  and `Converting a hundred million integers to strings per second
   <http://www.zverovich.net/2020/06/13/fast-int-to-string-revisited.html>`_
-* Small code size both in terms of source code (the minimum configuration
-  consists of just three header files, ``core.h``, ``format.h`` and
-  ``format-inl.h``) and compiled code. See `Compile time and code bloat`_
-* Reliability: the library has an extensive set of `unit tests
-  <https://github.com/fmtlib/fmt/tree/master/test>`_ and is continuously fuzzed
+* Small code size both in terms of source code with the minimum configuration
+  consisting of just three files, ``core.h``, ``format.h`` and ``format-inl.h``,
+  and compiled code; see `Compile time and code bloat`_
+* Reliability: the library has an extensive set of `tests
+  <https://github.com/fmtlib/fmt/tree/master/test>`_ and is `continuously fuzzed
+  <https://bugs.chromium.org/p/oss-fuzz/issues/list?colspec=ID%20Type%20
+  Component%20Status%20Proj%20Reported%20Owner%20Summary&q=proj%3Dfmt&can=1>`_
 * Safety: the library is fully type safe, errors in format strings can be
   reported at compile time, automatic memory management prevents buffer overflow
   errors
@@ -57,18 +66,17 @@ Features
   <https://github.com/fmtlib/fmt/blob/master/LICENSE.rst>`_
 * `Portability <https://fmt.dev/latest/index.html#portability>`_ with
   consistent output across platforms and support for older compilers
-* Clean warning-free codebase even on high warning levels
-  (``-Wall -Wextra -pedantic``)
+* Clean warning-free codebase even on high warning levels such as
+  ``-Wall -Wextra -pedantic``
 * Locale-independence by default
-* Support for wide strings
 * Optional header-only configuration enabled with the ``FMT_HEADER_ONLY`` macro
 
-See the `documentation <https://fmt.dev/latest/>`_ for more details.
+See the `documentation <https://fmt.dev>`_ for more details.
 
 Examples
 --------
 
-Print ``Hello, world!`` to ``stdout``:
+**Print to stdout** (`run <https://godbolt.org/z/Tevcjh>`_)
 
 .. code:: c++
 
@@ -78,100 +86,95 @@ Print ``Hello, world!`` to ``stdout``:
       fmt::print("Hello, world!\n");
     }
 
-Format a string:
+**Format a string** (`run <https://godbolt.org/z/oK8h33>`_)
 
 .. code:: c++
 
     std::string s = fmt::format("The answer is {}.", 42);
     // s == "The answer is 42."
 
-Format a string using positional arguments:
+**Format a string using positional arguments** (`run <https://godbolt.org/z/Yn7Txe>`_)
 
 .. code:: c++
 
     std::string s = fmt::format("I'd rather be {1} than {0}.", "right", "happy");
     // s == "I'd rather be happy than right."
 
-Print a chrono duration:
+**Print chrono durations** (`run <https://godbolt.org/z/K8s4Mc>`_)
 
 .. code:: c++
 
     #include <fmt/chrono.h>
 
     int main() {
-      using namespace std::chrono_literals;
-      fmt::print("Elapsed time: {}", 42ms);
+      using namespace std::literals::chrono_literals;
+      fmt::print("Default format: {} {}\n", 42s, 100ms);
+      fmt::print("strftime-like format: {:%H:%M:%S}\n", 3h + 15min + 30s);
     }
 
-prints "Elapsed time: 42ms".
+Output::
 
-Check a format string at compile time:
+    Default format: 42s 100ms
+    strftime-like format: 03:15:30
+
+**Print a container** (`run <https://godbolt.org/z/MjsY7c>`_)
 
 .. code:: c++
 
-    // test.cc
-    #include <fmt/format.h>
-    std::string s = format(FMT_STRING("{:d}"), "hello");
+    #include <vector>
+    #include <fmt/ranges.h>
 
-gives a compile-time error because ``d`` is an invalid format specifier for a
-string.
-
-Use {fmt} as a safe portable replacement for ``itoa``
-(`godbolt <https://godbolt.org/g/NXmpU4>`_):
-
-.. code:: c++
-
-    fmt::memory_buffer buf;
-    format_to(buf, "{}", 42);    // replaces itoa(42, buffer, 10)
-    format_to(buf, "{:x}", 42);  // replaces itoa(42, buffer, 16)
-    // access the string with to_string(buf) or buf.data()
-
-Format objects of user-defined types via a simple `extension API
-<https://fmt.dev/latest/api.html#formatting-user-defined-types>`_:
-
-.. code:: c++
-
-    #include <fmt/format.h>
-
-    struct date {
-      int year, month, day;
-    };
-
-    template <>
-    struct fmt::formatter<date> {
-      constexpr auto parse(format_parse_context& ctx) { return ctx.begin(); }
-
-      template <typename FormatContext>
-      auto format(const date& d, FormatContext& ctx) {
-        return format_to(ctx.out(), "{}-{}-{}", d.year, d.month, d.day);
-      }
-    };
-
-    std::string s = fmt::format("The date is {}", date{2012, 12, 9});
-    // s == "The date is 2012-12-9"
-
-Create your own functions similar to `format
-<https://fmt.dev/latest/api.html#format>`_ and
-`print <https://fmt.dev/latest/api.html#print>`_
-which take arbitrary arguments (`godbolt <https://godbolt.org/g/MHjHVf>`_):
-
-.. code:: c++
-
-    // Prints formatted error message.
-    void vreport_error(const char* format, fmt::format_args args) {
-      fmt::print("Error: ");
-      fmt::vprint(format, args);
-    }
-    template <typename... Args>
-    void report_error(const char* format, const Args & ... args) {
-      vreport_error(format, fmt::make_format_args(args...));
+    int main() {
+      std::vector<int> v = {1, 2, 3};
+      fmt::print("{}\n", v);
     }
 
-    report_error("file not found: {}", path);
+Output::
 
-Note that ``vreport_error`` is not parameterized on argument types which can
-improve compile times and reduce code size compared to a fully parameterized
-version.
+    {1, 2, 3}
+
+**Check a format string at compile time**
+
+.. code:: c++
+
+    std::string s = fmt::format(FMT_STRING("{:d}"), "don't panic");
+
+This gives a compile-time error because ``d`` is an invalid format specifier for
+a string.
+
+**Write a file from a single thread**
+
+.. code:: c++
+
+    #include <fmt/os.h>
+
+    int main() {
+      auto out = fmt::output_file("guide.txt");
+      out.print("Don't {}", "Panic");
+    }
+
+This can be `5 to 9 times faster than fprintf
+<http://www.zverovich.net/2020/08/04/optimal-file-buffer-size.html>`_.
+
+**Print with colors and text styles**
+
+.. code:: c++
+
+    #include <fmt/color.h>
+
+    int main() {
+      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::print(fg(fmt::color::steel_blue) | fmt::emphasis::italic,
+                 "Hello, {}!\n", "世界");
+    }
+
+Output on a modern terminal:
+
+.. image:: https://user-images.githubusercontent.com/
+           576385/88485597-d312f600-cf2b-11ea-9cbe-61f535a86e28.png
 
 Benchmarks
 ----------
@@ -198,12 +201,14 @@ or equivalent is filled 2,000,000 times with output sent to ``/dev/null``; for
 further details refer to the `source
 <https://github.com/fmtlib/format-benchmark/blob/master/tinyformat_test.cpp>`_.
 
-{fmt} is up to 10x faster than ``std::ostringstream`` and ``sprintf`` on
+{fmt} is up to 20-30x faster than ``std::ostringstream`` and ``sprintf`` on
 floating-point formatting (`dtoa-benchmark <https://github.com/fmtlib/dtoa-benchmark>`_)
-and faster than `double-conversion <https://github.com/google/double-conversion>`_:
+and faster than `double-conversion <https://github.com/google/double-conversion>`_ and
+`ryu <https://github.com/ulfjack/ryu>`_:
 
-.. image:: https://user-images.githubusercontent.com/576385/69767160-cdaca400-112f-11ea-9fc5-347c9f83caad.png
-   :target: https://fmt.dev/unknown_mac64_clang10.0.html
+.. image:: https://user-images.githubusercontent.com/576385/
+           95684665-11719600-0ba8-11eb-8e5b-972ff4e49428.png
+   :target: https://fmt.dev/unknown_mac64_clang12.0.html
 
 Compile time and code bloat
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -282,30 +287,33 @@ or the bloat test::
 Projects using this library
 ---------------------------
 
-* `0 A.D. <https://play0ad.com/>`_: A free, open-source, cross-platform
+* `0 A.D. <https://play0ad.com/>`_: a free, open-source, cross-platform
   real-time strategy game
 
 * `AMPL/MP <https://github.com/ampl/mp>`_:
-  An open-source library for mathematical programming
+  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
+* `AvioBook <https://www.aviobook.aero/en>`_: a comprehensive aircraft
   operations suite
   
-* `Celestia <https://celestia.space/>`_: Real-time 3D visualization of space
+* `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
+* `Ceph <https://ceph.com/>`_: a scalable distributed storage system
 
-* `ccache <https://ccache.dev/>`_: A compiler cache
+* `ccache <https://ccache.dev/>`_: a compiler cache
 
-* `ClickHouse <https://github.com/ClickHouse/ClickHouse>`_: analytical database management system
+* `ClickHouse <https://github.com/ClickHouse/ClickHouse>`_: analytical database
+  management system
 
 * `CUAUV <http://cuauv.org/>`_: Cornell University's autonomous underwater
   vehicle
 
-* `Drake <https://drake.mit.edu/>`_: A planning, control, and analysis toolbox
+* `Drake <https://drake.mit.edu/>`_: a planning, control, and analysis toolbox
   for nonlinear dynamical systems (MIT)
 
 * `Envoy <https://lyft.github.io/envoy/>`_: C++ L7 proxy and communication bus
@@ -318,66 +326,70 @@ Projects using this library
 * `HarpyWar/pvpgn <https://github.com/pvpgn/pvpgn-server>`_:
   Player vs Player Gaming Network with tweaks
 
-* `KBEngine <https://kbengine.org/>`_: An open-source MMOG server engine
+* `KBEngine <https://github.com/kbengine/kbengine>`_: an open-source MMOG server
+  engine
 
-* `Keypirinha <https://keypirinha.com/>`_: A semantic launcher for Windows
+* `Keypirinha <https://keypirinha.com/>`_: a semantic launcher for Windows
 
-* `Kodi <https://kodi.tv/>`_ (formerly xbmc): Home theater software
+* `Kodi <https://kodi.tv/>`_ (formerly xbmc): home theater software
 
-* `Knuth <https://kth.cash/>`_: High-performance Bitcoin full-node
+* `Knuth <https://kth.cash/>`_: high-performance Bitcoin full-node
 
 * `Microsoft Verona <https://github.com/microsoft/verona>`_:
-  Research programming language for concurrent ownership
+  research programming language for concurrent ownership
 
-* `MongoDB <https://mongodb.com/>`_: Distributed document database
+* `MongoDB <https://mongodb.com/>`_: distributed document database
 
-* `MongoDB Smasher <https://github.com/duckie/mongo_smasher>`_: A small tool to
+* `MongoDB Smasher <https://github.com/duckie/mongo_smasher>`_: a small tool to
   generate randomized datasets
 
-* `OpenSpace <https://openspaceproject.com/>`_: An open-source
+* `OpenSpace <https://openspaceproject.com/>`_: an open-source
   astrovisualization framework
 
 * `PenUltima Online (POL) <https://www.polserver.com/>`_:
-  An MMO server, compatible with most Ultima Online clients
+  an MMO server, compatible with most Ultima Online clients
 
-* `PyTorch <https://github.com/pytorch/pytorch>`_: An open-source machine
+* `PyTorch <https://github.com/pytorch/pytorch>`_: an open-source machine
   learning library
 
-* `quasardb <https://www.quasardb.net/>`_: A distributed, high-performance,
+* `quasardb <https://www.quasardb.net/>`_: a distributed, high-performance,
   associative database
+  
+* `Quill <https://github.com/odygrd/quill>`_: asynchronous low-latency logging library
 
-* `readpe <https://bitbucket.org/sys_dev/readpe>`_: Read Portable Executable
+* `QKW <https://github.com/ravijanjam/qkw>`_: generalizing aliasing to simplify
+  navigation, and executing complex multi-line terminal command sequences
 
-* `redis-cerberus <https://github.com/HunanTV/redis-cerberus>`_: A Redis cluster
+* `redis-cerberus <https://github.com/HunanTV/redis-cerberus>`_: a Redis cluster
   proxy
 
-* `redpanda <https://vectorized.io/redpanda>`_: A 10x faster Kafka® replacement
+* `redpanda <https://vectorized.io/redpanda>`_: a 10x faster Kafka® replacement
   for mission critical systems written in C++
 
-* `rpclib <http://rpclib.net/>`_: A modern C++ msgpack-RPC server and client
+* `rpclib <http://rpclib.net/>`_: a modern C++ msgpack-RPC server and client
   library
 
 * `Salesforce Analytics Cloud
   <https://www.salesforce.com/analytics-cloud/overview/>`_:
-  Business intelligence software
+  business intelligence software
 
-* `Scylla <https://www.scylladb.com/>`_: A Cassandra-compatible NoSQL data store
+* `Scylla <https://www.scylladb.com/>`_: a Cassandra-compatible NoSQL data store
   that can handle 1 million transactions per second on a single server
 
-* `Seastar <http://www.seastar-project.org/>`_: An advanced, open-source C++
+* `Seastar <http://www.seastar-project.org/>`_: an advanced, open-source C++
   framework for high-performance server applications on modern hardware
 
-* `spdlog <https://github.com/gabime/spdlog>`_: Super fast C++ logging library
+* `spdlog <https://github.com/gabime/spdlog>`_: super fast C++ logging library
 
-* `Stellar <https://www.stellar.org/>`_: Financial platform
+* `Stellar <https://www.stellar.org/>`_: financial platform
 
-* `Touch Surgery <https://www.touchsurgery.com/>`_: Surgery simulator
+* `Touch Surgery <https://www.touchsurgery.com/>`_: surgery simulator
 
-* `TrinityCore <https://github.com/TrinityCore/TrinityCore>`_: Open-source
+* `TrinityCore <https://github.com/TrinityCore/TrinityCore>`_: open-source
   MMORPG framework
 
-* `Windows Terminal <https://github.com/microsoft/terminal>`_: The new Windows
-  Terminal
+* `Windows Terminal <https://github.com/microsoft/terminal>`_: the new Windows
+  terminal
 
 `More... <https://github.com/search?q=fmtlib&type=Code>`_
 
@@ -435,7 +447,7 @@ Boost Format
 
 This is a very powerful library which supports both ``printf``-like format
 strings and positional arguments. Its main drawback is performance. According to
-various benchmarks it is much slower than other methods considered here. Boost
+various, benchmarks it is much slower than other methods considered here. Boost
 Format also has excessive build times and severe code bloat issues (see
 `Benchmarks`_).
 

doc/CMakeLists.txt

@@ -4,10 +4,14 @@ if (NOT DOXYGEN)
   return ()
 endif ()
 
+find_package(PythonInterp QUIET REQUIRED)
+
 add_custom_target(doc
-  COMMAND ${CMAKE_CURRENT_SOURCE_DIR}/build.py ${FMT_VERSION}
+  COMMAND ${PYTHON_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/build.py
+                               ${FMT_VERSION}
   SOURCES api.rst syntax.rst usage.rst build.py conf.py _templates/layout.html)
 
+include(GNUInstallDirs)
 install(DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/html/
-        DESTINATION share/doc/fmt OPTIONAL
+        DESTINATION ${CMAKE_INSTALL_DATAROOTDIR}/doc/fmt OPTIONAL
         PATTERN ".doctrees" EXCLUDE)

doc/api.rst

@@ -15,6 +15,7 @@ The {fmt} library API consists of the following parts:
   and tuples
 * :ref:`fmt/chrono.h <chrono-api>`: date and time formatting
 * :ref:`fmt/compile.h <compile-api>`: format string compilation
+* :ref:`fmt/color.h <color-api>`: terminal color and text style
 * :ref:`fmt/ostream.h <ostream-api>`: ``std::ostream`` support
 * :ref:`fmt/printf.h <printf-api>`: ``printf`` formatting
 
@@ -47,6 +48,10 @@ participate in an overload resolution if the latter is not a string.
 .. doxygenfunction:: format(const S&, Args&&...)
 .. doxygenfunction:: vformat(const S&, basic_format_args<buffer_context<type_identity_t<Char>>>)
 
+.. doxygenfunction:: fmt::format_to(OutputIt, const S&, Args&&...)
+.. doxygenfunction:: fmt::format_to_n(OutputIt, size_t, const S&, const Args&...)
+.. doxygenfunction:: fmt::formatted_size(string_view, Args&&...)
+
 .. _print:
 
 .. doxygenfunction:: print(const S&, Args&&...)
@@ -65,6 +70,35 @@ Named arguments are not supported in compile-time checks at the moment.
 Argument Lists
 --------------
 
+You can create your own formatting function with compile-time checks and small
+binary footprint, for example (https://godbolt.org/z/oba4Mc):
+
+.. code:: c++
+
+    #include <fmt/format.h>
+
+    void vlog(const char* file, int line, fmt::string_view format,
+              fmt::format_args args) {
+      fmt::print("{}: {}: ", file, line);
+      fmt::vprint(format, args);
+    }
+
+    template <typename S, typename... Args>
+    void log(const char* file, int line, const S& format, Args&&... args) {
+      vlog(file, line, format,
+          fmt::make_args_checked<Args...>(format, args...));
+    }
+
+    #define MY_LOG(format, ...) \
+      log(__FILE__, __LINE__, FMT_STRING(format), __VA_ARGS__)
+
+    MY_LOG("invalid squishiness: {}", 42);
+
+Note that ``vlog`` is not parameterized on argument types which improves compile
+times and reduces binary code size compared to a fully parameterized version.
+
+.. doxygenfunction:: fmt::make_args_checked(const S&, const remove_reference_t<Args>&...)
+
 .. doxygenfunction:: fmt::make_format_args(const Args&...)
 
 .. doxygenclass:: fmt::format_arg_store
@@ -93,7 +127,7 @@ Compatibility
 Locale
 ------
 
-All formatting is locale-independent by default. Use the ``'n'`` format
+All formatting is locale-independent by default. Use the ``'L'`` format
 specifier to insert the appropriate number separator characters from the
 locale::
 
@@ -114,12 +148,14 @@ string checks, wide string, output iterator and user-defined type support.
 Compile-time Format String Checks
 ---------------------------------
 
-Compile-time checks are supported for built-in and string types as well as
-user-defined types with ``constexpr`` ``parse`` functions in their ``formatter``
-specializations.
+Compile-time checks are enabled when using ``FMT_STRING``. They support built-in
+and string types as well as user-defined types with ``constexpr`` ``parse``
+functions in their ``formatter`` specializations.
 
 .. doxygendefine:: FMT_STRING
 
+.. _udt:
+
 Formatting User-defined Types
 -----------------------------
 
@@ -237,6 +273,10 @@ You can also write a formatter for a hierarchy of classes::
     fmt::print("{}", a); // prints "B"
   }
 
+If a type provides both a ``formatter`` specialization and an implicit
+conversion to a formattable type, the specialization takes precedence over the
+conversion.
+
 .. doxygenclass:: fmt::basic_format_parse_context
    :members:
 
@@ -244,7 +284,7 @@ Output Iterator Support
 -----------------------
 
 .. doxygenfunction:: fmt::format_to(OutputIt, const S&, Args&&...)
-.. doxygenfunction:: fmt::format_to_n(OutputIt, std::size_t, string_view, Args&&...)
+.. doxygenfunction:: fmt::format_to_n(OutputIt, size_t, const S&, const Args&...)
 .. doxygenstruct:: fmt::format_to_n_result
    :members:
 
@@ -264,7 +304,9 @@ Utilities
 
 .. doxygentypedef:: fmt::char_t
 
-.. doxygenfunction:: fmt::formatted_size(string_view, const Args&...)
+.. doxygenfunction:: fmt::ptr(const T *)
+.. doxygenfunction:: fmt::ptr(const std::unique_ptr<T>&)
+.. doxygenfunction:: fmt::ptr(const std::shared_ptr<T>&)
 
 .. doxygenfunction:: fmt::to_string(const T&)
 
@@ -272,9 +314,9 @@ Utilities
 
 .. doxygenfunction:: fmt::to_string_view(const Char *)
 
-.. doxygenfunction:: fmt::join(const Range&, string_view)
+.. doxygenfunction:: fmt::join(Range&&, string_view)
 
-.. doxygenfunction:: fmt::join(It, It, string_view)
+.. doxygenfunction:: fmt::join(It, Sentinel, string_view)
 
 .. doxygenclass:: fmt::detail::buffer
    :members:
@@ -298,8 +340,6 @@ the value of ``errno`` being preserved by library functions.
 .. doxygenclass:: fmt::windows_error
    :members:
 
-.. _formatstrings:
-
 Custom Allocators
 -----------------
 
@@ -330,10 +370,10 @@ allocator::
       return vformat(alloc, format_str, fmt::make_format_args(args...));
     }
 
-The allocator will be used for the output container only. If you are using named
-arguments, the container that stores pointers to them will be allocated using
-the default allocator. Also floating-point formatting falls back on ``sprintf``
-which may do allocations.
+The allocator will be used for the output container only. Formatting functions
+normally don't do any allocations for built-in and string types except for
+non-default floating-point formatting that occasionally falls back on
+``sprintf``.
 
 .. _ranges-api:
 
@@ -383,9 +423,10 @@ The format string syntax is described in the documentation of
 Format string compilation
 =========================
 
-``fmt/compile.h`` provides format string compilation support. Format strings
-are parsed at compile time and converted into efficient formatting code. This
-supports arguments of built-in and string types as well as user-defined types
+``fmt/compile.h`` provides format string compilation support when using
+``FMT_COMPILE``. Format strings are parsed, checked and converted
+into efficient formatting code at compile-time.
+This supports arguments of built-in and string types as well as user-defined types
 with ``constexpr`` ``parse`` functions in their ``formatter`` specializations.
 Format string compilation can generate more binary code compared to the default
 API and is only recommended in places where formatting is a performance
@@ -393,6 +434,15 @@ bottleneck.
 
 .. doxygendefine:: FMT_COMPILE
 
+.. _color-api:
+
+Terminal color and text style
+=============================
+
+``fmt/color.h`` provides support for terminal color and text style output.
+
+.. doxygenfunction:: print(const text_style&, const S&, const Args&...)
+
 .. _ostream-api:
 
 ``std::ostream`` Support

doc/build.py

@@ -6,20 +6,10 @@ import errno, os, shutil, sys, tempfile
 from subprocess import check_call, check_output, CalledProcessError, Popen, PIPE
 from distutils.version import LooseVersion
 
-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']
+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']
 
 def pip_install(package, commit=None, **kwargs):
   "Install package using pip."
-  min_version = kwargs.get('min_version')
-  if min_version:
-    from pkg_resources import get_distribution, DistributionNotFound
-    try:
-      installed_version = get_distribution(os.path.basename(package)).version
-      if LooseVersion(installed_version) >= min_version:
-        print('{} {} already installed'.format(package, min_version))
-        return
-    except DistributionNotFound:
-      pass
   if commit:
     package = 'git+https://github.com/{0}.git@{1}'.format(package, commit)
   print('Installing {0}'.format(package))
@@ -52,12 +42,11 @@ def create_build_env(dirname='virtualenv'):
       check_call(['pip', 'install', '--upgrade', 'distribute'])
   except DistributionNotFound:
     pass
-  # Install Sphinx and Breathe.
-  pip_install('sphinx-doc/sphinx', '12b83372ac9316e8cbe86e7fed889296a4cc29ee',
-              min_version='1.4.1.dev20160531')
+  # Install Sphinx and Breathe. Require the exact version of Sphinx which is
+  # compatible with Breathe.
+  pip_install('sphinx-doc/sphinx', '12b83372ac9316e8cbe86e7fed889296a4cc29ee')
   pip_install('michaeljones/breathe',
-              '129222318f7c8f865d2631e7da7b033567e7f56a',
-              min_version='4.2.0')
+              '129222318f7c8f865d2631e7da7b033567e7f56a')
 
 def build_docs(version='dev', **kwargs):
   doc_dir = kwargs.get('doc_dir', os.path.dirname(os.path.realpath(__file__)))
@@ -74,8 +63,8 @@ def build_docs(version='dev', **kwargs):
       GENERATE_MAN      = NO
       GENERATE_RTF      = NO
       CASE_SENSE_NAMES  = NO
-      INPUT             = {0}/core.h {0}/compile.h {0}/format.h {0}/os.h \
-                          {0}/ostream.h {0}/printf.h {0}/time.h
+      INPUT             = {0}/chrono.h {0}/color.h {0}/core.h {0}/compile.h \
+                          {0}/format.h {0}/os.h {0}/ostream.h {0}/printf.h
       QUIET             = YES
       JAVADOC_AUTOBRIEF = YES
       AUTOLINK_SUPPORT  = NO
@@ -95,7 +84,8 @@ def build_docs(version='dev', **kwargs):
                           "FMT_END_NAMESPACE=}}" \
                           "FMT_STRING_ALIAS=1" \
                           "FMT_ENABLE_IF(B)="
-      EXCLUDE_SYMBOLS   = fmt::internal::* StringValue write_str
+      EXCLUDE_SYMBOLS   = fmt::formatter fmt::printf_formatter fmt::arg_join \
+                          fmt::basic_format_arg::handle
     '''.format(include_dir, doxyxml_dir).encode('UTF-8'))
   if p.returncode != 0:
     raise CalledProcessError(p.returncode, cmd)

doc/index.rst

@@ -23,7 +23,7 @@ Format API
 
 The format API is similar in spirit to the C ``printf`` family of function but
 is safer, simpler and several times `faster
-<http://zverovich.net/2013/09/07/integer-to-string-conversion-in-cplusplus.html>`_
+<https://www.zverovich.net/2020/06/13/fast-int-to-string-revisited.html>`_
 than common standard library implementations.
 The `format string syntax <syntax.html>`_ is similar to the one used by
 `str.format <http://docs.python.org/3/library/stdtypes.html#str.format>`_ in
@@ -48,21 +48,19 @@ The ``fmt::print`` function performs formatting and writes the result to a strea
 
   fmt::print(stderr, "System error code = {}\n", errno);
 
-The file argument can be omitted in which case the function prints to
-``stdout``:
+If you omit the file argument the function will print to ``stdout``:
 
 .. code:: c++
 
   fmt::print("Don't {}\n", "panic");
 
-The Format API also supports positional arguments useful for localization:
+The format API also supports positional arguments useful for localization:
 
 .. code:: c++
 
   fmt::print("I'd rather be {1} than {0}.", "right", "happy");
 
-Named arguments can be created with ``fmt::arg``. This makes it easier to track 
-what goes where when multiple arguments are being formatted:
+You can pass named arguments with ``fmt::arg``:
 
 .. code:: c++
 
@@ -91,16 +89,17 @@ time. For example, the code
 
   fmt::format("The answer is {:d}", "forty-two");
 
-throws a ``format_error`` exception with description "unknown format code 'd' for
-string", because the argument ``"forty-two"`` is a string while the format code
-``d`` only applies to integers, while
+throws the ``format_error`` exception because the argument ``"forty-two"`` is a
+string while the format code ``d`` only applies to integers.
+
+The code
 
 .. code:: c++
 
   format(FMT_STRING("The answer is {:d}"), "forty-two");
 
-reports a compile-time error for the same reason on compilers that support
-relaxed ``constexpr``. See `here <api.html#c.fmt>`_ for details.
+reports a compile-time error on compilers that support relaxed ``constexpr``.
+See `here <api.html#c.fmt>`_ for details.
 
 The following code
 
@@ -117,13 +116,13 @@ formatted into a narrow string. You can use a wide format string instead:
 
 For comparison, writing a wide character to ``std::ostream`` results in
 its numeric value being written to the stream (i.e. 1070 instead of letter 'ю'
-which is represented by ``L'\x42e'`` if we use Unicode) which is rarely what is
-needed.
+which is represented by ``L'\x42e'`` if we use Unicode) which is rarely
+desirable.
 
 Compact Binary Code
 -------------------
 
-The library is designed to produce compact per-call compiled code. For example
+The library produces compact per-call compiled code. For example
 (`godbolt <https://godbolt.org/g/TZU4KF>`_),
 
 .. code:: c++
@@ -144,8 +143,8 @@ compiles to just
      mov rcx, rsp
      mov edi, offset .L.str
      mov esi, 17
-     mov edx, 2
-     call fmt::v5::vprint(fmt::v5::basic_string_view<char>, fmt::v5::format_args)
+     mov edx, 1
+     call fmt::v7::vprint(fmt::v7::basic_string_view<char>, fmt::v7::format_args)
      xor eax, eax
      add rsp, 24
      ret
@@ -167,20 +166,19 @@ The library is highly portable and relies only on a small set of C++11 features:
 * deleted functions
 * alias templates
 
-These are available since GCC 4.8, Clang 3.0 and MSVC 19.0 (2015). For older
-compilers use {fmt} `version 4.x
-<https://github.com/fmtlib/fmt/releases/tag/4.1.0>`_ which continues to be
-maintained and only requires C++98.
+These are available in GCC 4.8, Clang 3.0, MSVC 19.0 (2015) and more recent
+compiler version. For older compilers use {fmt} `version 4.x
+<https://github.com/fmtlib/fmt/releases/tag/4.1.0>`_ which is maintained and
+only requires C++98.
 
-The output of all formatting functions is consistent across platforms. In
-particular, formatting a floating-point infinity always gives ``inf`` while the
-output of ``printf`` is platform-dependent. For example,
+The output of all formatting functions is consistent across platforms.
+For example,
 
 .. code::
 
   fmt::print("{}", std::numeric_limits<double>::infinity());
 
-always prints ``inf``.
+always prints ``inf`` while the output of ``printf`` is platform-dependent.
 
 .. _ease-of-use:
 

doc/usage.rst

@@ -52,6 +52,14 @@ To build a `shared library`__ set the ``BUILD_SHARED_LIBS`` CMake variable to
 
 __ http://en.wikipedia.org/wiki/Library_%28computing%29#Shared_libraries
 
+
+To build a `static library` with position independent code (required if the main
+consumer of the fmt library is a shared library i.e. a Python extension) set the
+``CMAKE_POSITION_INDEPENDENT_CODE`` CMake variable to ``TRUE``::
+
+  cmake -DCMAKE_POSITION_INDEPENDENT_CODE=TRUE ...
+
+
 Installing the Library
 ======================
 
@@ -83,6 +91,49 @@ Setting up your target to use a header-only version of ``fmt`` is equally easy::
 
    target_link_libraries(<your-target> PRIVATE fmt::fmt-header-only)
 
+Usage with build2
+=================
+
+You can use `build2 <https://build2.org>`_, a dependency manager and a
+build-system combined, to use ``fmt``.
+
+Currently this package is available in these package repositories:
+
+- **https://cppget.org/fmt/** for released and published versions.
+- `The git repository with the sources of the build2 package of fmt <https://github.com/build2-packaging/fmt.git>`_
+  for unreleased or custom revisions of ``fmt``.
+
+**Usage:**
+
+- ``build2`` package name: ``fmt``
+- Library target name : ``lib{fmt}``
+
+For example, to make your ``build2`` project depend on ``fmt``:
+
+- Add one of the repositories to your configurations, or in your
+  ``repositories.manifest``, if not already there::
+
+    :
+    role: prerequisite
+    location: https://pkg.cppget.org/1/stable
+
+- Add this package as a dependency to your ``./manifest`` file
+  (example for ``v7.0.x``)::
+
+    depends: fmt ~7.0.0
+
+- Import the target and use it as a prerequisite to your own target
+  using `fmt` in the appropriate ``buildfile``::
+
+    import fmt = fmt%lib{fmt}
+    lib{mylib} : cxx{**} ... $fmt
+
+Then build your project as usual with `b` or `bdep update`.
+
+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>`_.
+
 Building the Documentation
 ==========================
 
@@ -130,6 +181,18 @@ The fmt port in vcpkg is kept up to date by Microsoft team members and community
 contributors. If the version is out of date, please `create an issue or pull
 request <https://github.com/Microsoft/vcpkg>`__ on the vcpkg repository.
 
+LHelper
+=======
+
+You can download and install fmt using
+`lhelper <https://github.com/franko/lhelper>`__ dependency manager::
+
+  lhelper activate <some-environment>
+  lhelper install fmt
+
+All the recipes for lhelper are kept in the
+`lhelper's recipe <https://github.com/franko/lhelper-recipes>`__ repository.
+
 Android NDK
 ===========
 

include/fmt/chrono.h

@@ -72,43 +72,27 @@ FMT_CONSTEXPR To lossless_integral_conversion(const From from, int& ec) {
   static_assert(F::is_integer, "From must be integral");
   static_assert(T::is_integer, "To must be integral");
 
-  if (F::is_signed && !T::is_signed) {
+  if (detail::const_check(F::is_signed && !T::is_signed)) {
     // From may be negative, not allowed!
     if (fmt::detail::is_negative(from)) {
       ec = 1;
       return {};
     }
-
     // From is positive. Can it always fit in To?
-    if (F::digits <= T::digits) {
-      // yes, From always fits in To.
-    } else {
-      // from may not fit in To, we have to do a dynamic check
-      if (from > static_cast<From>((T::max)())) {
-        ec = 1;
-        return {};
-      }
+    if (F::digits > T::digits &&
+        from > static_cast<From>(detail::max_value<To>())) {
+      ec = 1;
+      return {};
     }
   }
 
-  if (!F::is_signed && T::is_signed) {
-    // can from be held in To?
-    if (F::digits < T::digits) {
-      // yes, From always fits in To.
-    } else {
-      // from may not fit in To, we have to do a dynamic check
-      if (from > static_cast<From>((T::max)())) {
-        // outside range.
-        ec = 1;
-        return {};
-      }
-    }
+  if (!F::is_signed && T::is_signed && F::digits >= T::digits &&
+      from > static_cast<From>(detail::max_value<To>())) {
+    ec = 1;
+    return {};
   }
-
-  // reaching here means all is ok for lossless conversion.
-  return static_cast<To>(from);
-
-}  // function
+  return static_cast<To>(from);  // Lossless conversion.
+}
 
 template <typename To, typename From,
           FMT_ENABLE_IF(std::is_same<From, To>::value)>
@@ -190,11 +174,9 @@ To safe_duration_cast(std::chrono::duration<FromRep, FromPeriod> from,
   // safe conversion to IntermediateRep
   IntermediateRep count =
       lossless_integral_conversion<IntermediateRep>(from.count(), ec);
-  if (ec) {
-    return {};
-  }
+  if (ec) return {};
   // multiply with Factor::num without overflow or underflow
-  if (Factor::num != 1) {
+  if (detail::const_check(Factor::num != 1)) {
     const auto max1 = detail::max_value<IntermediateRep>() / Factor::num;
     if (count > max1) {
       ec = 1;
@@ -209,17 +191,9 @@ To safe_duration_cast(std::chrono::duration<FromRep, FromPeriod> from,
     count *= Factor::num;
   }
 
-  // this can't go wrong, right? den>0 is checked earlier.
-  if (Factor::den != 1) {
-    count /= Factor::den;
-  }
-  // convert to the to type, safely
-  using ToRep = typename To::rep;
-  const ToRep tocount = lossless_integral_conversion<ToRep>(count, ec);
-  if (ec) {
-    return {};
-  }
-  return To{tocount};
+  if (detail::const_check(Factor::den != 1)) count /= Factor::den;
+  auto tocount = lossless_integral_conversion<typename To::rep>(count, ec);
+  return ec ? To() : To(tocount);
 }
 
 /**
@@ -351,6 +325,11 @@ inline std::tm localtime(std::time_t time) {
   return lt.tm_;
 }
 
+inline std::tm localtime(
+    std::chrono::time_point<std::chrono::system_clock> time_point) {
+  return localtime(std::chrono::system_clock::to_time_t(time_point));
+}
+
 // Thread-safe replacement for std::gmtime
 inline std::tm gmtime(std::time_t time) {
   struct dispatcher {
@@ -387,6 +366,11 @@ inline std::tm gmtime(std::time_t time) {
   return gt.tm_;
 }
 
+inline std::tm gmtime(
+    std::chrono::time_point<std::chrono::system_clock> time_point) {
+  return gmtime(std::chrono::system_clock::to_time_t(time_point));
+}
+
 namespace detail {
 inline size_t strftime(char* str, size_t count, const char* format,
                        const std::tm* time) {
@@ -399,6 +383,17 @@ inline size_t strftime(wchar_t* str, size_t count, const wchar_t* format,
 }
 }  // namespace detail
 
+template <typename Char>
+struct formatter<std::chrono::time_point<std::chrono::system_clock>, Char>
+    : formatter<std::tm, Char> {
+  template <typename FormatContext>
+  auto format(std::chrono::time_point<std::chrono::system_clock> val,
+              FormatContext& ctx) -> decltype(ctx.out()) {
+    std::tm time = localtime(val);
+    return formatter<std::tm, Char>::format(time, ctx);
+  }
+};
+
 template <typename Char> struct formatter<std::tm, Char> {
   template <typename ParseContext>
   auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {

include/fmt/color.h

@@ -463,16 +463,16 @@ template <> inline void reset_color<wchar_t>(FILE* stream) FMT_NOEXCEPT {
 }
 
 template <typename Char>
-inline void reset_color(basic_memory_buffer<Char>& buffer) FMT_NOEXCEPT {
+inline void reset_color(buffer<Char>& buffer) FMT_NOEXCEPT {
   const char* begin = data::reset_color;
   const char* end = begin + sizeof(data::reset_color) - 1;
   buffer.append(begin, end);
 }
 
 template <typename Char>
-void vformat_to(basic_memory_buffer<Char>& buf, const text_style& ts,
+void vformat_to(buffer<Char>& buf, const text_style& ts,
                 basic_string_view<Char> format_str,
-                basic_format_args<buffer_context<Char>> args) {
+                basic_format_args<buffer_context<type_identity_t<Char>>> args) {
   bool has_style = false;
   if (ts.has_emphasis()) {
     has_style = true;
@@ -496,7 +496,7 @@ void vformat_to(basic_memory_buffer<Char>& buf, const text_style& ts,
 
 template <typename S, typename Char = char_t<S>>
 void vprint(std::FILE* f, const text_style& ts, const S& format,
-            basic_format_args<buffer_context<Char>> args) {
+            basic_format_args<buffer_context<type_identity_t<Char>>> args) {
   basic_memory_buffer<Char> buf;
   detail::vformat_to(buf, ts, to_string_view(format), args);
   buf.push_back(Char(0));
@@ -504,20 +504,22 @@ void vprint(std::FILE* f, const text_style& ts, const S& format,
 }
 
 /**
+  \rst
   Formats a string and prints it to the specified file stream using ANSI
   escape sequences to specify text formatting.
-  Example:
+
+  **Example**::
+
     fmt::print(fmt::emphasis::bold | fg(fmt::color::red),
                "Elapsed time: {0:.2f} seconds", 1.23);
+  \endrst
  */
 template <typename S, typename... Args,
           FMT_ENABLE_IF(detail::is_string<S>::value)>
 void print(std::FILE* f, const text_style& ts, const S& format_str,
            const Args&... args) {
-  detail::check_format_string<Args...>(format_str);
-  using context = buffer_context<char_t<S>>;
-  format_arg_store<context, Args...> as{args...};
-  vprint(f, ts, format_str, basic_format_args<context>(as));
+  vprint(f, ts, format_str,
+         fmt::make_args_checked<Args...>(format_str, args...));
 }
 
 /**
@@ -558,7 +560,42 @@ template <typename S, typename... Args, typename Char = char_t<S>>
 inline std::basic_string<Char> format(const text_style& ts, const S& format_str,
                                       const Args&... args) {
   return vformat(ts, to_string_view(format_str),
-                 detail::make_args_checked<Args...>(format_str, args...));
+                 fmt::make_args_checked<Args...>(format_str, args...));
+}
+
+/**
+  Formats a string with the given text_style and writes the output to ``out``.
+ */
+template <typename OutputIt, typename Char,
+          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value)>
+OutputIt vformat_to(
+    OutputIt out, const text_style& ts, basic_string_view<Char> format_str,
+    basic_format_args<buffer_context<type_identity_t<Char>>> args) {
+  decltype(detail::get_buffer<Char>(out)) buf(detail::get_buffer_init(out));
+  detail::vformat_to(buf, ts, format_str, args);
+  return detail::get_iterator(buf);
+}
+
+/**
+  \rst
+  Formats arguments with the given text_style, writes the result to the output
+  iterator ``out`` and returns the iterator past the end of the output range.
+
+  **Example**::
+
+    std::vector<char> out;
+    fmt::format_to(std::back_inserter(out),
+                   fmt::emphasis::bold | fg(fmt::color::red), "{}", 42);
+  \endrst
+*/
+template <typename OutputIt, typename S, typename... Args,
+          bool enable = detail::is_output_iterator<OutputIt, char_t<S>>::value&&
+              detail::is_string<S>::value>
+inline auto format_to(OutputIt out, const text_style& ts, const S& format_str,
+                      Args&&... args) ->
+    typename std::enable_if<enable, OutputIt>::type {
+  return vformat_to(out, ts, to_string_view(format_str),
+                    fmt::make_args_checked<Args...>(format_str, args...));
 }
 
 FMT_END_NAMESPACE

include/fmt/compile.h

@@ -368,7 +368,8 @@ template <typename... Args> struct type_list {};
 
 // Returns a reference to the argument at index N from [first, rest...].
 template <int N, typename T, typename... Args>
-constexpr const auto& get(const T& first, const Args&... rest) {
+constexpr const auto& get([[maybe_unused]] const T& first,
+                          [[maybe_unused]] const Args&... rest) {
   static_assert(N < 1 + sizeof...(Args), "index is out of bounds");
   if constexpr (N == 0)
     return first;
@@ -406,6 +407,19 @@ constexpr text<Char> make_text(basic_string_view<Char> s, size_t pos,
   return {{&s[pos], size}};
 }
 
+template <typename Char> struct code_unit {
+  Char value;
+  using char_type = Char;
+
+  template <typename OutputIt, typename... Args>
+  OutputIt format(OutputIt out, const Args&...) const {
+    return write<Char>(out, value);
+  }
+};
+
+template <typename Char>
+struct is_compiled_format<code_unit<Char>> : std::true_type {};
+
 // A replacement field that refers to argument N.
 template <typename Char, typename T, int N> struct field {
   using char_type = Char;
@@ -430,7 +444,9 @@ template <typename Char, typename T, int N> struct spec_field {
   OutputIt format(OutputIt out, const Args&... args) const {
     // This ensures that the argument type is convertile to `const T&`.
     const T& arg = get<N>(args...);
-    basic_format_context<OutputIt, Char> ctx(out, {});
+    const auto& vargs =
+        make_format_args<basic_format_context<OutputIt, Char>>(args...);
+    basic_format_context<OutputIt, Char> ctx(out, vargs);
     return fmt.format(arg, ctx);
   }
 };
@@ -489,16 +505,17 @@ constexpr auto parse_tail(T head, S format_str) {
 template <typename T, typename Char> struct parse_specs_result {
   formatter<T, Char> fmt;
   size_t end;
+  int next_arg_id;
 };
 
 template <typename T, typename Char>
 constexpr parse_specs_result<T, Char> parse_specs(basic_string_view<Char> str,
-                                                  size_t pos) {
+                                                  size_t pos, int arg_id) {
   str.remove_prefix(pos);
-  auto ctx = basic_format_parse_context<Char>(str);
+  auto ctx = basic_format_parse_context<Char>(str, {}, arg_id + 1);
   auto f = formatter<T, Char>();
   auto end = f.parse(ctx);
-  return {f, pos + (end - str.data()) + 1};
+  return {f, pos + (end - str.data()) + 1, ctx.next_arg_id()};
 }
 
 // Compiles a non-empty format string and returns the compiled representation
@@ -518,8 +535,8 @@ constexpr auto compile_format_string(S format_str) {
                                                format_str);
     } else if constexpr (str[POS + 1] == ':') {
       using type = get_type<ID, Args>;
-      constexpr auto result = parse_specs<type>(str, POS + 2);
-      return parse_tail<Args, result.end, ID + 1>(
+      constexpr auto result = parse_specs<type>(str, POS + 2, ID);
+      return parse_tail<Args, result.end, result.next_arg_id>(
           spec_field<char_type, type, ID>{result.fmt}, format_str);
     } else {
       return unknown_format();
@@ -530,8 +547,13 @@ constexpr auto compile_format_string(S format_str) {
     return parse_tail<Args, POS + 2, ID>(make_text(str, POS, 1), format_str);
   } else {
     constexpr auto end = parse_text(str, POS + 1);
-    return parse_tail<Args, end, ID>(make_text(str, POS, end - POS),
-                                     format_str);
+    if constexpr (end - POS > 1) {
+      return parse_tail<Args, end, ID>(make_text(str, POS, end - POS),
+                                       format_str);
+    } else {
+      return parse_tail<Args, end, ID>(code_unit<char_type>{str[POS]},
+                                       format_str);
+    }
   }
 }
 
@@ -587,8 +609,7 @@ template <typename CompiledFormat, typename... Args,
 FMT_INLINE std::basic_string<Char> format(const CompiledFormat& cf,
                                           const Args&... args) {
   basic_memory_buffer<Char> buffer;
-  detail::buffer<Char>& base = buffer;
-  cf.format(std::back_inserter(base), args...);
+  cf.format(detail::buffer_appender<Char>(buffer), args...);
   return to_string(buffer);
 }
 
@@ -608,8 +629,7 @@ template <typename CompiledFormat, typename... Args,
 std::basic_string<Char> format(const CompiledFormat& cf, const Args&... args) {
   basic_memory_buffer<Char> buffer;
   using context = buffer_context<Char>;
-  detail::buffer<Char>& base = buffer;
-  detail::cf::vformat_to<context>(std::back_inserter(base), cf,
+  detail::cf::vformat_to<context>(detail::buffer_appender<Char>(buffer), cf,
                                   make_format_args<context>(args...));
   return to_string(buffer);
 }
@@ -618,9 +638,13 @@ template <typename S, typename... Args,
           FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
 FMT_INLINE std::basic_string<typename S::char_type> format(const S&,
                                                            Args&&... args) {
-  constexpr basic_string_view<typename S::char_type> str = S();
-  if (str.size() == 2 && str[0] == '{' && str[1] == '}')
-    return fmt::to_string(detail::first(args...));
+#ifdef __cpp_if_constexpr
+  if constexpr (std::is_same<typename S::char_type, char>::value) {
+    constexpr basic_string_view<typename S::char_type> str = S();
+    if (str.size() == 2 && str[0] == '{' && str[1] == '}')
+      return fmt::to_string(detail::first(args...));
+  }
+#endif
   constexpr auto compiled = detail::compile<Args...>(S());
   return format(compiled, std::forward<Args>(args)...);
 }
@@ -643,18 +667,30 @@ OutputIt format_to(OutputIt out, const S&, const Args&... args) {
   return format_to(out, compiled, args...);
 }
 
-template <
-    typename OutputIt, typename CompiledFormat, typename... Args,
-    FMT_ENABLE_IF(detail::is_output_iterator<OutputIt>::value&& std::is_base_of<
-                  detail::basic_compiled_format, CompiledFormat>::value)>
-format_to_n_result<OutputIt> format_to_n(OutputIt out, size_t n,
-                                         const CompiledFormat& cf,
-                                         const Args&... args) {
+template <typename OutputIt, typename CompiledFormat, typename... Args>
+auto format_to_n(OutputIt out, size_t n, const CompiledFormat& cf,
+                 const Args&... args) ->
+    typename std::enable_if<
+        detail::is_output_iterator<OutputIt,
+                                   typename CompiledFormat::char_type>::value &&
+            std::is_base_of<detail::basic_compiled_format,
+                            CompiledFormat>::value,
+        format_to_n_result<OutputIt>>::type {
   auto it =
       format_to(detail::truncating_iterator<OutputIt>(out, n), cf, args...);
   return {it.base(), it.count()};
 }
 
+template <typename OutputIt, typename S, typename... Args,
+          FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
+format_to_n_result<OutputIt> format_to_n(OutputIt out, size_t n, const S&,
+                                         const Args&... args) {
+  constexpr auto compiled = detail::compile<Args...>(S());
+  auto it = format_to(detail::truncating_iterator<OutputIt>(out, n), compiled,
+                      args...);
+  return {it.base(), it.count()};
+}
+
 template <typename CompiledFormat, typename... Args>
 size_t formatted_size(const CompiledFormat& cf, const Args&... args) {
   return format_to(detail::counting_iterator(), cf, args...).count();

include/fmt/core.h

@@ -18,7 +18,7 @@
 #include <vector>
 
 // The fmt library version in the form major * 10000 + minor * 100 + patch.
-#define FMT_VERSION 70000
+#define FMT_VERSION 70101
 
 #ifdef __clang__
 #  define FMT_CLANG_VERSION (__clang_major__ * 100 + __clang_minor__)
@@ -57,6 +57,7 @@
 #  define FMT_MSC_VER 0
 #  define FMT_SUPPRESS_MSC_WARNING(n)
 #endif
+
 #ifdef __has_feature
 #  define FMT_HAS_FEATURE(x) __has_feature(x)
 #else
@@ -64,7 +65,7 @@
 #endif
 
 #if defined(__has_include) && !defined(__INTELLISENSE__) && \
-    !(FMT_ICC_VERSION && FMT_ICC_VERSION < 1600)
+    (!FMT_ICC_VERSION || FMT_ICC_VERSION >= 1600)
 #  define FMT_HAS_INCLUDE(x) __has_include(x)
 #else
 #  define FMT_HAS_INCLUDE(x) 0
@@ -99,7 +100,7 @@
 #endif
 
 #ifndef FMT_OVERRIDE
-#  if FMT_HAS_FEATURE(cxx_override) || \
+#  if FMT_HAS_FEATURE(cxx_override_control) || \
       (FMT_GCC_VERSION >= 408 && FMT_HAS_GXX_CXX11) || FMT_MSC_VER >= 1900
 #    define FMT_OVERRIDE override
 #  else
@@ -152,7 +153,7 @@
 #  if FMT_HAS_CPP14_ATTRIBUTE(deprecated) || FMT_MSC_VER >= 1900
 #    define FMT_DEPRECATED [[deprecated]]
 #  else
-#    if defined(__GNUC__) || defined(__clang__)
+#    if (defined(__GNUC__) && !defined(__LCC__)) || defined(__clang__)
 #      define FMT_DEPRECATED __attribute__((deprecated))
 #    elif FMT_MSC_VER
 #      define FMT_DEPRECATED __declspec(deprecated)
@@ -177,9 +178,17 @@
 #  endif
 #endif
 
-#ifndef FMT_BEGIN_NAMESPACE
+#ifndef FMT_USE_INLINE_NAMESPACES
 #  if FMT_HAS_FEATURE(cxx_inline_namespaces) || FMT_GCC_VERSION >= 404 || \
-      FMT_MSC_VER >= 1900
+      (FMT_MSC_VER >= 1900 && !_MANAGED)
+#    define FMT_USE_INLINE_NAMESPACES 1
+#  else
+#    define FMT_USE_INLINE_NAMESPACES 0
+#  endif
+#endif
+
+#ifndef FMT_BEGIN_NAMESPACE
+#  if FMT_USE_INLINE_NAMESPACES
 #    define FMT_INLINE_NAMESPACE inline namespace
 #    define FMT_END_NAMESPACE \
       }                       \
@@ -188,12 +197,12 @@
 #    define FMT_INLINE_NAMESPACE namespace
 #    define FMT_END_NAMESPACE \
       }                       \
-      using namespace v6;     \
+      using namespace v7;     \
       }
 #  endif
 #  define FMT_BEGIN_NAMESPACE \
     namespace fmt {           \
-    FMT_INLINE_NAMESPACE v6 {
+    FMT_INLINE_NAMESPACE v7 {
 #endif
 
 #if !defined(FMT_HEADER_ONLY) && defined(_WIN32)
@@ -269,8 +278,7 @@ struct monostate {};
 
 namespace detail {
 
-// A helper function to suppress bogus "conditional expression is constant"
-// warnings.
+// A helper function to suppress "conditional expression is constant" warnings.
 template <typename T> constexpr T const_check(T value) { return value; }
 
 FMT_NORETURN FMT_API void assert_fail(const char* file, int line,
@@ -299,7 +307,8 @@ template <typename T> struct std_string_view {};
 
 #ifdef FMT_USE_INT128
 // Do nothing.
-#elif defined(__SIZEOF_INT128__) && !FMT_NVCC
+#elif defined(__SIZEOF_INT128__) && !FMT_NVCC && \
+    !(FMT_CLANG_VERSION && FMT_MSC_VER)
 #  define FMT_USE_INT128 1
 using int128_t = __int128_t;
 using uint128_t = __uint128_t;
@@ -491,7 +500,7 @@ constexpr basic_string_view<typename S::char_type> to_string_view(const S& s) {
 
 namespace detail {
 void to_string_view(...);
-using fmt::v6::to_string_view;
+using fmt::v7::to_string_view;
 
 // Specifies whether S is a string type convertible to fmt::basic_string_view.
 // It should be a constexpr function but MSVC 2017 fails to compile it in
@@ -506,6 +515,18 @@ template <typename S> struct char_t_impl<S, enable_if_t<is_string<S>::value>> {
   using type = typename result::value_type;
 };
 
+// Reports a compile-time error if S is not a valid format string.
+template <typename..., typename S, FMT_ENABLE_IF(!is_compile_string<S>::value)>
+FMT_INLINE void check_format_string(const S&) {
+#ifdef FMT_ENFORCE_COMPILE_STRING
+  static_assert(is_compile_string<S>::value,
+                "FMT_ENFORCE_COMPILE_STRING requires all format strings to use "
+                "FMT_STRING.");
+#endif
+}
+template <typename..., typename S, FMT_ENABLE_IF(is_compile_string<S>::value)>
+void check_format_string(S);
+
 struct error_handler {
   constexpr error_handler() = default;
   constexpr error_handler(const error_handler&) = default;
@@ -545,8 +566,9 @@ class basic_format_parse_context : private ErrorHandler {
   using iterator = typename basic_string_view<Char>::iterator;
 
   explicit constexpr basic_format_parse_context(
-      basic_string_view<Char> format_str, ErrorHandler eh = {})
-      : ErrorHandler(eh), format_str_(format_str), next_arg_id_(0) {}
+      basic_string_view<Char> format_str, ErrorHandler eh = {},
+      int next_arg_id = 0)
+      : ErrorHandler(eh), format_str_(format_str), next_arg_id_(next_arg_id) {}
 
   /**
     Returns an iterator to the beginning of the format string range being
@@ -616,8 +638,24 @@ template <typename T, typename Context>
 using has_formatter =
     std::is_constructible<typename Context::template formatter_type<T>>;
 
+// Checks whether T is a container with contiguous storage.
+template <typename T> struct is_contiguous : std::false_type {};
+template <typename Char>
+struct is_contiguous<std::basic_string<Char>> : std::true_type {};
+
 namespace detail {
 
+// Extracts a reference to the container from back_insert_iterator.
+template <typename Container>
+inline Container& get_container(std::back_insert_iterator<Container> it) {
+  using bi_iterator = std::back_insert_iterator<Container>;
+  struct accessor : bi_iterator {
+    accessor(bi_iterator iter) : bi_iterator(iter) {}
+    using bi_iterator::container;
+  };
+  return *accessor(it).container;
+}
+
 /**
   \rst
   A contiguous memory buffer with an optional growing ability. It is an internal
@@ -640,6 +678,8 @@ template <typename T> class buffer {
         size_(sz),
         capacity_(cap) {}
 
+  ~buffer() = default;
+
   /** Sets the buffer data and capacity. */
   void set(T* buf_data, size_t buf_capacity) FMT_NOEXCEPT {
     ptr_ = buf_data;
@@ -655,7 +695,6 @@ template <typename T> class buffer {
 
   buffer(const buffer&) = delete;
   void operator=(const buffer&) = delete;
-  virtual ~buffer() = default;
 
   T* begin() FMT_NOEXCEPT { return ptr_; }
   T* end() FMT_NOEXCEPT { return ptr_ + size_; }
@@ -675,24 +714,26 @@ template <typename T> class buffer {
   /** Returns a pointer to the buffer data. */
   const T* data() const FMT_NOEXCEPT { return ptr_; }
 
-  /**
-    Resizes the buffer. If T is a POD type new elements may not be initialized.
-   */
-  void resize(size_t new_size) {
-    reserve(new_size);
-    size_ = new_size;
-  }
-
   /** Clears this buffer. */
   void clear() { size_ = 0; }
 
-  /** Reserves space to store at least *capacity* elements. */
-  void reserve(size_t new_capacity) {
+  // Tries resizing the buffer to contain *count* elements. If T is a POD type
+  // the new elements may not be initialized.
+  void try_resize(size_t count) {
+    try_reserve(count);
+    size_ = count <= capacity_ ? count : capacity_;
+  }
+
+  // Tries increasing the buffer capacity to *new_capacity*. It can increase the
+  // capacity by a smaller amount than requested but guarantees there is space
+  // for at least one additional element either by increasing the capacity or by
+  // flushing the buffer if it is full.
+  void try_reserve(size_t new_capacity) {
     if (new_capacity > capacity_) grow(new_capacity);
   }
 
   void push_back(const T& value) {
-    reserve(size_ + 1);
+    try_reserve(size_ + 1);
     ptr_[size_++] = value;
   }
 
@@ -705,32 +746,150 @@ template <typename T> class buffer {
   }
 };
 
-// A container-backed buffer.
+struct buffer_traits {
+  explicit buffer_traits(size_t) {}
+  size_t count() const { return 0; }
+  size_t limit(size_t size) { return size; }
+};
+
+class fixed_buffer_traits {
+ private:
+  size_t count_ = 0;
+  size_t limit_;
+
+ public:
+  explicit fixed_buffer_traits(size_t limit) : limit_(limit) {}
+  size_t count() const { return count_; }
+  size_t limit(size_t size) {
+    size_t n = limit_ - count_;
+    count_ += size;
+    return size < n ? size : n;
+  }
+};
+
+// A buffer that writes to an output iterator when flushed.
+template <typename OutputIt, typename T, typename Traits = buffer_traits>
+class iterator_buffer final : public Traits, public buffer<T> {
+ private:
+  OutputIt out_;
+  enum { buffer_size = 256 };
+  T data_[buffer_size];
+
+ protected:
+  void grow(size_t) final FMT_OVERRIDE {
+    if (this->size() == buffer_size) flush();
+  }
+  void flush();
+
+ public:
+  explicit iterator_buffer(OutputIt out, size_t n = buffer_size)
+      : Traits(n),
+        buffer<T>(data_, 0, n < size_t(buffer_size) ? n : size_t(buffer_size)),
+        out_(out) {}
+  ~iterator_buffer() { flush(); }
+
+  OutputIt out() {
+    flush();
+    return out_;
+  }
+  size_t count() const { return Traits::count() + this->size(); }
+};
+
+template <typename T> class iterator_buffer<T*, T> final : public buffer<T> {
+ protected:
+  void grow(size_t) final FMT_OVERRIDE {}
+
+ public:
+  explicit iterator_buffer(T* out, size_t = 0) : buffer<T>(out, 0, ~size_t()) {}
+
+  T* out() { return &*this->end(); }
+};
+
+// A buffer that writes to a container with the contiguous storage.
 template <typename Container>
-class container_buffer : public buffer<typename Container::value_type> {
+class iterator_buffer<std::back_insert_iterator<Container>,
+                      enable_if_t<is_contiguous<Container>::value,
+                                  typename Container::value_type>>
+    final : public buffer<typename Container::value_type> {
  private:
   Container& container_;
 
  protected:
-  void grow(size_t capacity) FMT_OVERRIDE {
+  void grow(size_t capacity) final FMT_OVERRIDE {
     container_.resize(capacity);
     this->set(&container_[0], capacity);
   }
 
  public:
-  explicit container_buffer(Container& c)
+  explicit iterator_buffer(Container& c)
       : buffer<typename Container::value_type>(c.size()), container_(c) {}
+  explicit iterator_buffer(std::back_insert_iterator<Container> out, size_t = 0)
+      : iterator_buffer(get_container(out)) {}
+  std::back_insert_iterator<Container> out() {
+    return std::back_inserter(container_);
+  }
 };
 
-// Extracts a reference to the container from back_insert_iterator.
-template <typename Container>
-inline Container& get_container(std::back_insert_iterator<Container> it) {
-  using bi_iterator = std::back_insert_iterator<Container>;
-  struct accessor : bi_iterator {
-    accessor(bi_iterator iter) : bi_iterator(iter) {}
-    using bi_iterator::container;
-  };
-  return *accessor(it).container;
+// A buffer that counts the number of code units written discarding the output.
+template <typename T = char> class counting_buffer final : public buffer<T> {
+ private:
+  enum { buffer_size = 256 };
+  T data_[buffer_size];
+  size_t count_ = 0;
+
+ protected:
+  void grow(size_t) final FMT_OVERRIDE {
+    if (this->size() != buffer_size) return;
+    count_ += this->size();
+    this->clear();
+  }
+
+ public:
+  counting_buffer() : buffer<T>(data_, 0, buffer_size) {}
+
+  size_t count() { return count_ + this->size(); }
+};
+
+// An output iterator that appends to the buffer.
+// It is used to reduce symbol sizes for the common case.
+template <typename T>
+class buffer_appender : public std::back_insert_iterator<buffer<T>> {
+  using base = std::back_insert_iterator<buffer<T>>;
+
+ public:
+  explicit buffer_appender(buffer<T>& buf) : base(buf) {}
+  buffer_appender(base it) : base(it) {}
+
+  buffer_appender& operator++() {
+    base::operator++();
+    return *this;
+  }
+
+  buffer_appender operator++(int) {
+    buffer_appender tmp = *this;
+    ++*this;
+    return tmp;
+  }
+};
+
+// Maps an output iterator into a buffer.
+template <typename T, typename OutputIt>
+iterator_buffer<OutputIt, T> get_buffer(OutputIt);
+template <typename T> buffer<T>& get_buffer(buffer_appender<T>);
+
+template <typename OutputIt> OutputIt get_buffer_init(OutputIt out) {
+  return out;
+}
+template <typename T> buffer<T>& get_buffer_init(buffer_appender<T> out) {
+  return get_container(out);
+}
+
+template <typename Buffer>
+auto get_iterator(Buffer& buf) -> decltype(buf.out()) {
+  return buf.out();
+}
+template <typename T> buffer_appender<T> get_iterator(buffer<T>& buf) {
+  return buffer_appender<T>(buf);
 }
 
 template <typename T, typename Char = char, typename Enable = void>
@@ -759,7 +918,8 @@ template <typename Char> struct named_arg_info {
 template <typename T, typename Char, size_t NUM_ARGS, size_t NUM_NAMED_ARGS>
 struct arg_data {
   // args_[0].named_args points to named_args_ to avoid bloating format_args.
-  T args_[1 + (NUM_ARGS != 0 ? NUM_ARGS : 1)];
+  // +1 to workaround a bug in gcc 7.5 that causes duplicated-branches warning.
+  T args_[1 + (NUM_ARGS != 0 ? NUM_ARGS : +1)];
   named_arg_info<Char> named_args_[NUM_NAMED_ARGS];
 
   template <typename... U>
@@ -771,7 +931,8 @@ struct arg_data {
 
 template <typename T, typename Char, size_t NUM_ARGS>
 struct arg_data<T, Char, NUM_ARGS, 0> {
-  T args_[NUM_ARGS != 0 ? NUM_ARGS : 1];
+  // +1 to workaround a bug in gcc 7.5 that causes duplicated-branches warning.
+  T args_[NUM_ARGS != 0 ? NUM_ARGS : +1];
 
   template <typename... U>
   FMT_INLINE arg_data(const U&... init) : args_{init...} {}
@@ -959,6 +1120,8 @@ enum { long_short = sizeof(long) == sizeof(int) };
 using long_type = conditional_t<long_short, int, long long>;
 using ulong_type = conditional_t<long_short, unsigned, unsigned long long>;
 
+struct unformattable {};
+
 // Maps formatting arguments to core types.
 template <typename Context> struct arg_mapper {
   using char_type = typename Context::char_type;
@@ -1067,15 +1230,7 @@ template <typename Context> struct arg_mapper {
     return map(val.value);
   }
 
-  int map(...) {
-    constexpr bool formattable = sizeof(Context) == 0;
-    static_assert(
-        formattable,
-        "Cannot format argument. To make type T formattable provide a "
-        "formatter<T> specialization: "
-        "https://fmt.dev/latest/api.html#formatting-user-defined-types");
-    return 0;
-  }
+  unformattable map(...) { return {}; }
 };
 
 // A type constant after applying arg_mapper<Context>.
@@ -1199,15 +1354,25 @@ FMT_CONSTEXPR_DECL FMT_INLINE auto visit_format_arg(
   return vis(monostate());
 }
 
-// Checks whether T is a container with contiguous storage.
-template <typename T> struct is_contiguous : std::false_type {};
-template <typename Char>
-struct is_contiguous<std::basic_string<Char>> : std::true_type {};
-template <typename Char>
-struct is_contiguous<detail::buffer<Char>> : std::true_type {};
+template <typename T> struct formattable : std::false_type {};
 
 namespace detail {
 
+// A workaround for gcc 4.8 to make void_t work in a SFINAE context.
+template <typename... Ts> struct void_t_impl { using type = void; };
+template <typename... Ts>
+using void_t = typename detail::void_t_impl<Ts...>::type;
+
+template <typename It, typename T, typename Enable = void>
+struct is_output_iterator : std::false_type {};
+
+template <typename It, typename T>
+struct is_output_iterator<
+    It, T,
+    void_t<typename std::iterator_traits<It>::iterator_category,
+           decltype(*std::declval<It>() = std::declval<T>())>>
+    : std::true_type {};
+
 template <typename OutputIt>
 struct is_back_insert_iterator : std::false_type {};
 template <typename Container>
@@ -1219,6 +1384,9 @@ struct is_contiguous_back_insert_iterator : std::false_type {};
 template <typename Container>
 struct is_contiguous_back_insert_iterator<std::back_insert_iterator<Container>>
     : is_contiguous<Container> {};
+template <typename Char>
+struct is_contiguous_back_insert_iterator<buffer_appender<Char>>
+    : std::true_type {};
 
 // A type-erased reference to an std::locale to avoid heavy <locale> include.
 class locale_ref {
@@ -1250,13 +1418,24 @@ FMT_CONSTEXPR basic_format_arg<Context> make_arg(const T& value) {
   return arg;
 }
 
+template <typename T> int check(unformattable) {
+  static_assert(
+      formattable<T>(),
+      "Cannot format an argument. To make type T formattable provide a "
+      "formatter<T> specialization: https://fmt.dev/latest/api.html#udt");
+  return 0;
+}
+template <typename T, typename U> inline const U& check(const U& val) {
+  return val;
+}
+
 // The type template parameter is there to avoid an ODR violation when using
 // a fallback formatter in one translation unit and an implicit conversion in
 // another (not recommended).
 template <bool IS_PACKED, typename Context, type, typename T,
           FMT_ENABLE_IF(IS_PACKED)>
 inline value<Context> make_arg(const T& val) {
-  return arg_mapper<Context>().map(val);
+  return check<T>(arg_mapper<Context>().map(val));
 }
 
 template <bool IS_PACKED, typename Context, type, typename T,
@@ -1356,10 +1535,14 @@ template <typename OutputIt, typename Char> class basic_format_context {
 
 template <typename Char>
 using buffer_context =
-    basic_format_context<std::back_insert_iterator<detail::buffer<Char>>, Char>;
+    basic_format_context<detail::buffer_appender<Char>, Char>;
 using format_context = buffer_context<char>;
 using wformat_context = buffer_context<wchar_t>;
 
+// Workaround an alias issue: https://stackoverflow.com/q/62767544/471164.
+#define FMT_BUFFER_CONTEXT(Char) \
+  basic_format_context<detail::buffer_appender<Char>, Char>
+
 /**
   \rst
   An array of references to arguments. It can be implicitly converted into
@@ -1410,7 +1593,7 @@ class format_arg_store
 
 /**
   \rst
-  Constructs an `~fmt::format_arg_store` object that contains references to
+  Constructs a `~fmt::format_arg_store` object that contains references to
   arguments and can be implicitly converted to `~fmt::format_args`. `Context`
   can be omitted in which case it defaults to `~fmt::context`.
   See `~fmt::arg` for lifetime considerations.
@@ -1422,6 +1605,27 @@ inline format_arg_store<Context, Args...> make_format_args(
   return {args...};
 }
 
+/**
+  \rst
+  Constructs a `~fmt::format_arg_store` object that contains references
+  to arguments and can be implicitly converted to `~fmt::format_args`.
+  If ``format_str`` is a compile-time string then `make_args_checked` checks
+  its validity at compile time.
+  \endrst
+ */
+template <typename... Args, typename S, typename Char = char_t<S>>
+inline auto make_args_checked(const S& format_str,
+                              const remove_reference_t<Args>&... args)
+    -> format_arg_store<buffer_context<Char>, remove_reference_t<Args>...> {
+  static_assert(
+      detail::count<(
+              std::is_base_of<detail::view, remove_reference_t<Args>>::value &&
+              std::is_reference<Args>::value)...>() == 0,
+      "passing views as lvalues is disallowed");
+  detail::check_format_string<Args...>(format_str);
+  return {args...};
+}
+
 /**
   \rst
   Returns a named argument to be used in a formatting function. It should only
@@ -1709,7 +1913,7 @@ template <typename Context> class basic_format_args {
   }
 
   template <typename Char> int get_id(basic_string_view<Char> name) const {
-    if (!has_named_args()) return {};
+    if (!has_named_args()) return -1;
     const auto& named_args =
         (is_packed() ? values_[-1] : args_[-1].value_).named_args;
     for (size_t i = 0; i < named_args.size; ++i) {
@@ -1725,7 +1929,14 @@ template <typename Context> class basic_format_args {
   }
 };
 
-/** An alias to ``basic_format_args<context>``. */
+#ifdef FMT_ARM_ABI_COMPATIBILITY
+/** An alias to ``basic_format_args<format_context>``. */
+// Separate types would result in shorter symbols but break ABI compatibility
+// between clang and gcc on ARM (#1919).
+using format_args = basic_format_args<format_context>;
+using wformat_args = basic_format_args<wformat_context>;
+#else
+// DEPRECATED! These are kept for ABI compatibility.
 // It is a separate type rather than an alias to make symbols readable.
 struct format_args : basic_format_args<format_context> {
   template <typename... Args>
@@ -1734,43 +1945,22 @@ struct format_args : basic_format_args<format_context> {
 struct wformat_args : basic_format_args<wformat_context> {
   using basic_format_args::basic_format_args;
 };
+#endif
 
 namespace detail {
 
-// Reports a compile-time error if S is not a valid format string.
-template <typename..., typename S, FMT_ENABLE_IF(!is_compile_string<S>::value)>
-FMT_INLINE void check_format_string(const S&) {
-#ifdef FMT_ENFORCE_COMPILE_STRING
-  static_assert(is_compile_string<S>::value,
-                "FMT_ENFORCE_COMPILE_STRING requires all format strings to use "
-                "FMT_STRING.");
-#endif
-}
-template <typename..., typename S, FMT_ENABLE_IF(is_compile_string<S>::value)>
-void check_format_string(S);
-
-template <typename... Args, typename S, typename Char = char_t<S>>
-inline format_arg_store<buffer_context<Char>, remove_reference_t<Args>...>
-make_args_checked(const S& format_str,
-                  const remove_reference_t<Args>&... args) {
-  static_assert(count<(std::is_base_of<view, remove_reference_t<Args>>::value &&
-                       std::is_reference<Args>::value)...>() == 0,
-                "passing views as lvalues is disallowed");
-  check_format_string<Args...>(format_str);
-  return {args...};
-}
-
 template <typename Char, FMT_ENABLE_IF(!std::is_same<Char, char>::value)>
 std::basic_string<Char> vformat(
     basic_string_view<Char> format_str,
     basic_format_args<buffer_context<type_identity_t<Char>>> args);
 
-std::string vformat(string_view format_str, format_args args);
+FMT_API std::string vformat(string_view format_str, format_args args);
 
 template <typename Char>
-typename buffer_context<Char>::iterator vformat_to(
+void vformat_to(
     buffer<Char>& buf, basic_string_view<Char> format_str,
-    basic_format_args<buffer_context<type_identity_t<Char>>> args);
+    basic_format_args<FMT_BUFFER_CONTEXT(type_identity_t<Char>)> args,
+    detail::locale_ref loc = {});
 
 template <typename Char, typename Args,
           FMT_ENABLE_IF(!std::is_same<Char, char>::value)>
@@ -1785,26 +1975,80 @@ inline void vprint_mojibake(std::FILE*, string_view, format_args) {}
 /** Formats a string and writes the output to ``out``. */
 // GCC 8 and earlier cannot handle std::back_insert_iterator<Container> with
 // vformat_to<ArgFormatter>(...) overload, so SFINAE on iterator type instead.
-template <
-    typename OutputIt, typename S, typename Char = char_t<S>,
-    FMT_ENABLE_IF(detail::is_contiguous_back_insert_iterator<OutputIt>::value)>
-OutputIt vformat_to(
-    OutputIt out, const S& format_str,
-    basic_format_args<buffer_context<type_identity_t<Char>>> args) {
-  auto& c = detail::get_container(out);
-  detail::container_buffer<remove_reference_t<decltype(c)>> buf(c);
+template <typename OutputIt, typename S, typename Char = char_t<S>,
+          bool enable = detail::is_output_iterator<OutputIt, Char>::value>
+auto vformat_to(OutputIt out, const S& format_str,
+                basic_format_args<buffer_context<type_identity_t<Char>>> args)
+    -> typename std::enable_if<enable, OutputIt>::type {
+  decltype(detail::get_buffer<Char>(out)) buf(detail::get_buffer_init(out));
   detail::vformat_to(buf, to_string_view(format_str), args);
-  return out;
+  return detail::get_iterator(buf);
 }
 
-template <typename Container, typename S, typename... Args,
-          FMT_ENABLE_IF(
-              is_contiguous<Container>::value&& detail::is_string<S>::value)>
-inline std::back_insert_iterator<Container> format_to(
-    std::back_insert_iterator<Container> out, const S& format_str,
-    Args&&... args) {
-  return vformat_to(out, to_string_view(format_str),
-                    detail::make_args_checked<Args...>(format_str, args...));
+/**
+ \rst
+ Formats arguments, writes the result to the output iterator ``out`` and returns
+ the iterator past the end of the output range.
+
+ **Example**::
+
+   std::vector<char> out;
+   fmt::format_to(std::back_inserter(out), "{}", 42);
+ \endrst
+ */
+// We cannot use FMT_ENABLE_IF because of a bug in gcc 8.3.
+template <typename OutputIt, typename S, typename... Args,
+          bool enable = detail::is_output_iterator<OutputIt, char_t<S>>::value>
+inline auto format_to(OutputIt out, const S& format_str, Args&&... args) ->
+    typename std::enable_if<enable, OutputIt>::type {
+  const auto& vargs = fmt::make_args_checked<Args...>(format_str, args...);
+  return vformat_to(out, to_string_view(format_str), vargs);
+}
+
+template <typename OutputIt> struct format_to_n_result {
+  /** Iterator past the end of the output range. */
+  OutputIt out;
+  /** Total (not truncated) output size. */
+  size_t size;
+};
+
+template <typename OutputIt, typename Char, typename... Args,
+          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value)>
+inline format_to_n_result<OutputIt> vformat_to_n(
+    OutputIt out, size_t n, basic_string_view<Char> format_str,
+    basic_format_args<buffer_context<type_identity_t<Char>>> args) {
+  detail::iterator_buffer<OutputIt, Char, detail::fixed_buffer_traits> buf(out,
+                                                                           n);
+  detail::vformat_to(buf, format_str, args);
+  return {buf.out(), buf.count()};
+}
+
+/**
+ \rst
+ Formats arguments, writes up to ``n`` characters of the result to the output
+ iterator ``out`` and returns the total output size and the iterator past the
+ end of the output range.
+ \endrst
+ */
+template <typename OutputIt, typename S, typename... Args,
+          bool enable = detail::is_output_iterator<OutputIt, char_t<S>>::value>
+inline auto format_to_n(OutputIt out, size_t n, const S& format_str,
+                        const Args&... args) ->
+    typename std::enable_if<enable, format_to_n_result<OutputIt>>::type {
+  const auto& vargs = fmt::make_args_checked<Args...>(format_str, args...);
+  return vformat_to_n(out, n, to_string_view(format_str), vargs);
+}
+
+/**
+  Returns the number of characters in the output of
+  ``format(format_str, args...)``.
+ */
+template <typename... Args>
+inline size_t formatted_size(string_view format_str, Args&&... args) {
+  const auto& vargs = fmt::make_args_checked<Args...>(format_str, args...);
+  detail::counting_buffer<> buf;
+  detail::vformat_to(buf, format_str, vargs);
+  return buf.count();
 }
 
 template <typename S, typename Char = char_t<S>>
@@ -1828,7 +2072,7 @@ FMT_INLINE std::basic_string<Char> vformat(
 // std::basic_string<char_t<S>> to reduce the symbol size.
 template <typename S, typename... Args, typename Char = char_t<S>>
 FMT_INLINE std::basic_string<Char> format(const S& format_str, Args&&... args) {
-  const auto& vargs = detail::make_args_checked<Args...>(format_str, args...);
+  const auto& vargs = fmt::make_args_checked<Args...>(format_str, args...);
   return detail::vformat(to_string_view(format_str), vargs);
 }
 
@@ -1848,7 +2092,7 @@ FMT_API void vprint(std::FILE*, string_view, format_args);
  */
 template <typename S, typename... Args, typename Char = char_t<S>>
 inline void print(std::FILE* f, const S& format_str, Args&&... args) {
-  const auto& vargs = detail::make_args_checked<Args...>(format_str, args...);
+  const auto& vargs = fmt::make_args_checked<Args...>(format_str, args...);
   return detail::is_unicode<Char>()
              ? vprint(f, to_string_view(format_str), vargs)
              : detail::vprint_mojibake(f, to_string_view(format_str), vargs);
@@ -1867,7 +2111,7 @@ inline void print(std::FILE* f, const S& format_str, Args&&... args) {
  */
 template <typename S, typename... Args, typename Char = char_t<S>>
 inline void print(const S& format_str, Args&&... args) {
-  const auto& vargs = detail::make_args_checked<Args...>(format_str, args...);
+  const auto& vargs = fmt::make_args_checked<Args...>(format_str, args...);
   return detail::is_unicode<Char>()
              ? vprint(to_string_view(format_str), vargs)
              : detail::vprint_mojibake(stdout, to_string_view(format_str),

include/fmt/locale.h

@@ -15,22 +15,12 @@
 FMT_BEGIN_NAMESPACE
 
 namespace detail {
-template <typename Char>
-typename buffer_context<Char>::iterator vformat_to(
-    const std::locale& loc, buffer<Char>& buf,
-    basic_string_view<Char> format_str,
-    basic_format_args<buffer_context<type_identity_t<Char>>> args) {
-  using af = arg_formatter<typename buffer_context<Char>::iterator, Char>;
-  return vformat_to<af>(std::back_inserter(buf), to_string_view(format_str),
-                        args, detail::locale_ref(loc));
-}
-
 template <typename Char>
 std::basic_string<Char> vformat(
     const std::locale& loc, basic_string_view<Char> format_str,
     basic_format_args<buffer_context<type_identity_t<Char>>> args) {
   basic_memory_buffer<Char> buffer;
-  detail::vformat_to(loc, buffer, format_str, args);
+  detail::vformat_to(buffer, format_str, args, detail::locale_ref(loc));
   return fmt::to_string(buffer);
 }
 }  // namespace detail
@@ -45,32 +35,28 @@ inline std::basic_string<Char> vformat(
 template <typename S, typename... Args, typename Char = char_t<S>>
 inline std::basic_string<Char> format(const std::locale& loc,
                                       const S& format_str, Args&&... args) {
-  return detail::vformat(
-      loc, to_string_view(format_str),
-      detail::make_args_checked<Args...>(format_str, args...));
+  return detail::vformat(loc, to_string_view(format_str),
+                         fmt::make_args_checked<Args...>(format_str, args...));
 }
 
 template <typename S, typename OutputIt, typename... Args,
-          typename Char = enable_if_t<
-              detail::is_output_iterator<OutputIt>::value, char_t<S>>>
+          typename Char = char_t<S>,
+          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value)>
 inline OutputIt vformat_to(
     OutputIt out, const std::locale& loc, const S& format_str,
-    format_args_t<type_identity_t<OutputIt>, Char> args) {
-  using af = detail::arg_formatter<OutputIt, Char>;
-  return vformat_to<af>(out, to_string_view(format_str), args,
-                        detail::locale_ref(loc));
+    basic_format_args<buffer_context<type_identity_t<Char>>> args) {
+  decltype(detail::get_buffer<Char>(out)) buf(detail::get_buffer_init(out));
+  vformat_to(buf, to_string_view(format_str), args, detail::locale_ref(loc));
+  return detail::get_iterator(buf);
 }
 
 template <typename OutputIt, typename S, typename... Args,
-          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt>::value&&
-                            detail::is_string<S>::value)>
-inline OutputIt format_to(OutputIt out, const std::locale& loc,
-                          const S& format_str, Args&&... args) {
-  detail::check_format_string<Args...>(format_str);
-  using context = format_context_t<OutputIt, char_t<S>>;
-  format_arg_store<context, Args...> as{args...};
-  return vformat_to(out, loc, to_string_view(format_str),
-                    basic_format_args<context>(as));
+          bool enable = detail::is_output_iterator<OutputIt, char_t<S>>::value>
+inline auto format_to(OutputIt out, const std::locale& loc,
+                      const S& format_str, Args&&... args) ->
+    typename std::enable_if<enable, OutputIt>::type {
+  const auto& vargs = fmt::make_args_checked<Args...>(format_str, args...);
+  return vformat_to(out, loc, to_string_view(format_str), vargs);
 }
 
 FMT_END_NAMESPACE

include/fmt/os.h

@@ -29,7 +29,8 @@
 #if FMT_HAS_INCLUDE("winapifamily.h")
 #  include <winapifamily.h>
 #endif
-#if FMT_HAS_INCLUDE("fcntl.h") && \
+#if (FMT_HAS_INCLUDE(<fcntl.h>) || defined(__APPLE__) || \
+     defined(__linux__)) &&                              \
     (!defined(WINAPI_FAMILY) || (WINAPI_FAMILY == WINAPI_FAMILY_DESKTOP_APP))
 #  include <fcntl.h>  // for O_RDONLY
 #  define FMT_USE_FCNTL 1
@@ -278,7 +279,8 @@ class file {
     RDONLY = FMT_POSIX(O_RDONLY),  // Open for reading only.
     WRONLY = FMT_POSIX(O_WRONLY),  // Open for writing only.
     RDWR = FMT_POSIX(O_RDWR),      // Open for reading and writing.
-    CREATE = FMT_POSIX(O_CREAT)    // Create if the file doesn't exist.
+    CREATE = FMT_POSIX(O_CREAT),   // Create if the file doesn't exist.
+    APPEND = FMT_POSIX(O_APPEND)   // Open in append mode.
   };
 
   // Constructs a file object which doesn't represent any file.
@@ -343,36 +345,69 @@ class file {
 // Returns the memory page size.
 long getpagesize();
 
-class direct_buffered_file;
+namespace detail {
 
-template <typename S, typename... Args>
-void print(direct_buffered_file& f, const S& format_str,
-           const Args&... args);
+struct buffer_size {
+  size_t value = 0;
+  buffer_size operator=(size_t val) const {
+    auto bs = buffer_size();
+    bs.value = val;
+    return bs;
+  }
+};
 
-// A buffered file with a direct buffer access and no synchronization.
-class direct_buffered_file {
+struct ostream_params {
+  int oflag = file::WRONLY | file::CREATE;
+  size_t buffer_size = BUFSIZ > 32768 ? BUFSIZ : 32768;
+
+  ostream_params() {}
+
+  template <typename... T>
+  ostream_params(T... params, int oflag) : ostream_params(params...) {
+    this->oflag = oflag;
+  }
+
+  template <typename... T>
+  ostream_params(T... params, detail::buffer_size bs)
+      : ostream_params(params...) {
+    this->buffer_size = bs.value;
+  }
+};
+}  // namespace detail
+
+static constexpr detail::buffer_size buffer_size;
+
+// A fast output stream which is not thread-safe.
+class ostream final : private detail::buffer<char> {
  private:
   file file_;
 
-  enum { buffer_size = 4096 };
-  char buffer_[buffer_size];
-  int pos_;
-
   void flush() {
-    if (pos_ == 0) return;
-    file_.write(buffer_, pos_);
-    pos_ = 0;
+    if (size() == 0) return;
+    file_.write(data(), size());
+    clear();
   }
 
-  int free_capacity() const { return buffer_size - pos_; }
+  void grow(size_t) final;
+
+  ostream(cstring_view path, const detail::ostream_params& params)
+      : file_(path, params.oflag) {
+    set(new char[params.buffer_size], params.buffer_size);
+  }
 
  public:
-  direct_buffered_file(cstring_view path, int oflag)
-    : file_(path, oflag), pos_(0) {}
-
-  ~direct_buffered_file() {
-    flush();
+  ostream(ostream&& other)
+      : detail::buffer<char>(other.data(), other.size(), other.capacity()),
+        file_(std::move(other.file_)) {
+    other.set(nullptr, 0);
   }
+  ~ostream() {
+    flush();
+    delete[] data();
+  }
+
+  template <typename... T>
+  friend ostream output_file(cstring_view path, T... params);
 
   void close() {
     flush();
@@ -380,25 +415,20 @@ class direct_buffered_file {
   }
 
   template <typename S, typename... Args>
-  friend void print(direct_buffered_file& f, const S& format_str,
-                    const Args&... args) {
-    // We could avoid double buffering.
-    auto buf = fmt::memory_buffer();
-    fmt::format_to(std::back_inserter(buf), format_str, args...);
-    auto remaining_pos = 0;
-    auto remaining_size = buf.size();
-    while (remaining_size > detail::to_unsigned(f.free_capacity())) {
-      auto size = f.free_capacity();
-      memcpy(f.buffer_ + f.pos_, buf.data() + remaining_pos, size);
-      f.pos_ += size;
-      f.flush();
-      remaining_pos += size;
-      remaining_size -= size;
-    }
-    memcpy(f.buffer_ + f.pos_, buf.data() + remaining_pos, remaining_size);
-    f.pos_ += static_cast<int>(remaining_size);
+  void print(const S& format_str, const Args&... args) {
+    format_to(detail::buffer_appender<char>(*this), format_str, args...);
   }
 };
+
+/**
+  Opens a file for writing. Supported parameters passed in `params`:
+  * ``<integer>``: Output flags (``file::WRONLY | file::CREATE`` by default)
+  * ``buffer_size=<integer>``: Output buffer size
+ */
+template <typename... T>
+inline ostream output_file(cstring_view path, T... params) {
+  return {path, detail::ostream_params(params...)};
+}
 #endif  // FMT_USE_FCNTL
 
 #ifdef FMT_LOCALE

include/fmt/ostream.h

@@ -49,17 +49,27 @@ template <class Char> class formatbuf : public std::basic_streambuf<Char> {
   }
 };
 
+struct converter {
+  template <typename T, FMT_ENABLE_IF(is_integral<T>::value)> converter(T);
+};
+
 template <typename Char> struct test_stream : std::basic_ostream<Char> {
  private:
-  // Hide all operator<< from std::basic_ostream<Char>.
-  void_t<> operator<<(null<>);
-  void_t<> operator<<(const Char*);
-
-  template <typename T, FMT_ENABLE_IF(std::is_convertible<T, int>::value &&
-                                      !std::is_enum<T>::value)>
-  void_t<> operator<<(T);
+  void_t<> operator<<(converter);
 };
 
+// Hide insertion operators for built-in types.
+template <typename Char, typename Traits>
+void_t<> operator<<(std::basic_ostream<Char, Traits>&, Char);
+template <typename Char, typename Traits>
+void_t<> operator<<(std::basic_ostream<Char, Traits>&, char);
+template <typename Traits>
+void_t<> operator<<(std::basic_ostream<char, Traits>&, char);
+template <typename Traits>
+void_t<> operator<<(std::basic_ostream<char, Traits>&, signed char);
+template <typename Traits>
+void_t<> operator<<(std::basic_ostream<char, Traits>&, unsigned char);
+
 // Checks if T has a user-defined operator<< (e.g. not a member of
 // std::ostream).
 template <typename T, typename Char> class is_streamable {
@@ -103,7 +113,7 @@ void format_value(buffer<Char>& buf, const T& value,
 #endif
   output << value;
   output.exceptions(std::ios_base::failbit | std::ios_base::badbit);
-  buf.resize(buf.size());
+  buf.try_resize(buf.size());
 }
 
 // Formats an object of type T that has an overloaded ostream operator<<.
@@ -160,7 +170,7 @@ template <typename S, typename... Args,
           typename Char = enable_if_t<detail::is_string<S>::value, char_t<S>>>
 void print(std::basic_ostream<Char>& os, const S& format_str, Args&&... args) {
   vprint(os, to_string_view(format_str),
-         detail::make_args_checked<Args...>(format_str, args...));
+         fmt::make_args_checked<Args...>(format_str, args...));
 }
 FMT_END_NAMESPACE
 

include/fmt/printf.h

@@ -181,7 +181,7 @@ template <typename Char> class printf_width_handler {
 template <typename Char, typename Context>
 void vprintf(buffer<Char>& buf, basic_string_view<Char> format,
              basic_format_args<Context> args) {
-  Context(std::back_inserter(buf), format, args).format();
+  Context(buffer_appender<Char>(buf), format, args).format();
 }
 }  // namespace detail
 
@@ -598,7 +598,7 @@ OutputIt basic_printf_context<OutputIt, Char>::format() {
 
 template <typename Char>
 using basic_printf_context_t =
-    basic_printf_context<std::back_insert_iterator<detail::buffer<Char>>, Char>;
+    basic_printf_context<detail::buffer_appender<Char>, Char>;
 
 using printf_context = basic_printf_context_t<char>;
 using wprintf_context = basic_printf_context_t<wchar_t>;

include/fmt/ranges.h

@@ -157,6 +157,9 @@ template <class Tuple, class F> void for_each(Tuple&& tup, F&& f) {
   for_each(indexes, std::forward<Tuple>(tup), std::forward<F>(f));
 }
 
+template <typename Range>
+using value_type = remove_cvref_t<decltype(*std::declval<Range>().begin())>;
+
 template <typename Arg, FMT_ENABLE_IF(!is_like_std_string<
                                       typename std::decay<Arg>::type>::value)>
 FMT_CONSTEXPR const char* format_str_quoted(bool add_space, const Arg&) {
@@ -182,7 +185,6 @@ FMT_CONSTEXPR const char* format_str_quoted(bool add_space, const char) {
 FMT_CONSTEXPR const wchar_t* format_str_quoted(bool add_space, const wchar_t) {
   return add_space ? L" '{}'" : L"'{}'";
 }
-
 }  // namespace detail
 
 template <typename T> struct is_tuple_like {
@@ -246,9 +248,15 @@ template <typename T, typename Char> struct is_range {
       !std::is_constructible<detail::std_string_view<Char>, T>::value;
 };
 
-template <typename RangeT, typename Char>
-struct formatter<RangeT, Char,
-                 enable_if_t<fmt::is_range<RangeT, Char>::value>> {
+template <typename T, typename Char>
+struct formatter<
+    T, Char,
+    enable_if_t<fmt::is_range<T, Char>::value
+// Workaround a bug in MSVC 2017 and earlier.
+#if !FMT_MSC_VER || FMT_MSC_VER >= 1927
+                && has_formatter<detail::value_type<T>, format_context>::value
+#endif
+                >> {
   formatting_range<Char> formatting;
 
   template <typename ParseContext>
@@ -257,8 +265,7 @@ struct formatter<RangeT, Char,
   }
 
   template <typename FormatContext>
-  typename FormatContext::iterator format(const RangeT& values,
-                                          FormatContext& ctx) {
+  typename FormatContext::iterator format(const T& values, FormatContext& ctx) {
     auto out = detail::copy(formatting.prefix, ctx.out());
     size_t i = 0;
     auto it = values.begin();

src/format.cc

@@ -23,6 +23,36 @@ int format_float(char* buf, std::size_t size, const char* format, int precision,
   return precision < 0 ? snprintf_ptr(buf, size, format, value)
                        : snprintf_ptr(buf, size, format, precision, value);
 }
+
+template dragonbox::decimal_fp<float> dragonbox::to_decimal(float x)
+    FMT_NOEXCEPT;
+template dragonbox::decimal_fp<double> dragonbox::to_decimal(double x)
+    FMT_NOEXCEPT;
+
+// DEPRECATED! This function exists for ABI compatibility.
+template <typename Char>
+typename basic_format_context<std::back_insert_iterator<buffer<Char>>,
+                              Char>::iterator
+vformat_to(buffer<Char>& buf, basic_string_view<Char> format_str,
+           basic_format_args<basic_format_context<
+               std::back_insert_iterator<buffer<type_identity_t<Char>>>,
+               type_identity_t<Char>>>
+               args) {
+  using iterator = std::back_insert_iterator<buffer<char>>;
+  using context = basic_format_context<
+      std::back_insert_iterator<buffer<type_identity_t<Char>>>,
+      type_identity_t<Char>>;
+  auto out = iterator(buf);
+  format_handler<iterator, Char, context> h(out, format_str, args, {});
+  parse_format_string<false>(format_str, h);
+  return out;
+}
+template basic_format_context<std::back_insert_iterator<buffer<char>>,
+                              char>::iterator
+vformat_to(buffer<char>&, string_view,
+           basic_format_args<basic_format_context<
+               std::back_insert_iterator<buffer<type_identity_t<char>>>,
+               type_identity_t<char>>>);
 }  // namespace detail
 
 template struct FMT_INSTANTIATION_DEF_API detail::basic_data<void>;
@@ -44,8 +74,9 @@ template FMT_API char detail::decimal_point_impl(locale_ref);
 
 template FMT_API void detail::buffer<char>::append(const char*, const char*);
 
-template FMT_API format_context::iterator detail::vformat_to(
-    detail::buffer<char>&, string_view, basic_format_args<format_context>);
+template FMT_API void detail::vformat_to(
+    detail::buffer<char>&, string_view,
+    basic_format_args<FMT_BUFFER_CONTEXT(char)>, detail::locale_ref);
 
 template FMT_API int detail::snprintf_float(double, int, detail::float_specs,
                                             detail::buffer<char>&);

src/os.cc

@@ -62,7 +62,7 @@ using RWResult = int;
 inline unsigned convert_rwcount(std::size_t count) {
   return count <= UINT_MAX ? static_cast<unsigned>(count) : UINT_MAX;
 }
-#else
+#elif FMT_USE_FCNTL
 // Return type of read and write functions.
 using RWResult = ssize_t;
 
@@ -124,7 +124,8 @@ void detail::format_windows_error(detail::buffer<char>& out, int error_code,
       if (result != 0) {
         utf16_to_utf8 utf8_message;
         if (utf8_message.convert(system_message) == ERROR_SUCCESS) {
-          format_to(std::back_inserter(out), "{}: {}", message, utf8_message);
+          format_to(buffer_appender<char>(out), "{}: {}", message,
+                    utf8_message);
           return;
         }
         break;
@@ -288,12 +289,12 @@ void file::pipe(file& read_end, file& write_end) {
 }
 
 buffered_file file::fdopen(const char* mode) {
-  // Don't retry as fdopen doesn't return EINTR.
-  #if defined(__MINGW32__) && defined(_POSIX_)
+// Don't retry as fdopen doesn't return EINTR.
+#  if defined(__MINGW32__) && defined(_POSIX_)
   FILE* f = ::fdopen(fd_, mode);
-  #else
+#  else
   FILE* f = FMT_POSIX_CALL(fdopen(fd_, mode));
-  #endif
+#  endif
   if (!f)
     FMT_THROW(
         system_error(errno, "cannot associate stream with file descriptor"));
@@ -313,5 +314,9 @@ long getpagesize() {
   return size;
 #  endif
 }
+
+void ostream::grow(size_t) {
+  if (this->size() == this->capacity()) flush();
+}
 #endif  // FMT_USE_FCNTL
 FMT_END_NAMESPACE

support/README

@@ -2,5 +2,3 @@ This directory contains build support files such as
 
 * CMake modules
 * Build scripts
-* qmake (static build with dynamic libc only)
-

support/fmt.pro

@@ -1,27 +0,0 @@
-# Staticlib configuration for qmake builds
-# For some reason qmake 3.1 fails to identify source dependencies and excludes format.cc and printf.cc
-# from compilation so it _MUST_ be called as qmake -nodepend
-# A workaround is implemented below: a custom compiler is defined which does not track dependencies
-
-TEMPLATE = lib
-
-TARGET = fmt
-
-QMAKE_EXT_CPP = .cc
-
-CONFIG = staticlib warn_on c++11
-
-FMT_SOURCES = \
-    ../src/format.cc \
-    ../src/posix.cc
-
-fmt.name = libfmt
-fmt.input = FMT_SOURCES
-fmt.output = ${QMAKE_FILE_BASE}$$QMAKE_EXT_OBJ
-fmt.clean = ${QMAKE_FILE_BASE}$$QMAKE_EXT_OBJ
-fmt.depends = ${QMAKE_FILE_IN}
-# QMAKE_RUN_CXX will not be expanded
-fmt.commands = $$QMAKE_CXX -c $$QMAKE_CXXFLAGS $$QMAKE_CXXFLAGS_WARN_ON $$QMAKE_CXXFLAGS_RELEASE_WITH_DEBUGINFO $$QMAKE_CXXFLAGS_CXX11 ${QMAKE_FILE_IN}
-fmt.variable_out = OBJECTS
-fmt.CONFIG = no_dependencies no_link
-QMAKE_EXTRA_COMPILERS += fmt

support/manage.py

@@ -145,7 +145,24 @@ def update_site(env):
                 b.data = b.data.replace('std::FILE*', 'std::FILE *')
                 b.data = b.data.replace('unsigned int', 'unsigned')
                 #b.data = b.data.replace('operator""_', 'operator"" _')
-                b.data = b.data.replace(', size_t', ', std::size_t')
+                b.data = b.data.replace(
+                    'format_to_n(OutputIt, size_t, string_view, Args&&',
+                    'format_to_n(OutputIt, size_t, const S&, const Args&')
+                b.data = b.data.replace(
+                    'format_to_n(OutputIt, std::size_t, string_view, Args&&',
+                    'format_to_n(OutputIt, std::size_t, const S&, const Args&')
+                if version == ('3.0.2'):
+                    b.data = b.data.replace(
+                        'fprintf(std::ostream&', 'fprintf(std::ostream &')
+                if version == ('5.3.0'):
+                    b.data = b.data.replace(
+                        'format_to(OutputIt, const S&, const Args&...)',
+                        'format_to(OutputIt, const S &, const Args &...)')
+                if version.startswith('5.') or version.startswith('6.'):
+                    b.data = b.data.replace(', size_t', ', std::size_t')
+                if version.startswith('7.'):
+                    b.data = b.data.replace(', std::size_t', ', size_t')
+                    b.data = b.data.replace('join(It, It', 'join(It, Sentinel')
                 b.data = b.data.replace('aa long', 'a long')
                 b.data = b.data.replace('serveral', 'several')
                 if version.startswith('6.2.'):

support/update-coverity-branch.py

@@ -1,30 +0,0 @@
-#!/usr/bin/env python
-# Update the coverity branch from the master branch.
-# It is not done automatically because Coverity Scan limits
-# the number of submissions per day.
-
-from __future__ import print_function
-import shutil, tempfile
-from subprocess import check_output, STDOUT
-
-class Git:
-    def __init__(self, dir):
-        self.dir = dir
-
-    def __call__(self, *args):
-        output = check_output(['git'] + list(args), cwd=self.dir, stderr=STDOUT)
-        print(output)
-        return output
-
-dir = tempfile.mkdtemp()
-try:
-    git = Git(dir)
-    git('clone', '-b', 'coverity', 'git@github.com:fmtlib/fmt.git', dir)
-    output = git('merge', '-X', 'theirs', '--no-commit', 'origin/master')
-    if 'Fast-forward' not in output:
-        git('reset', 'HEAD', '.travis.yml')
-        git('checkout', '--', '.travis.yml')
-        git('commit', '-m', 'Update coverity branch')
-    git('push')
-finally:
-    shutil.rmtree(dir)

test/CMakeLists.txt

@@ -91,8 +91,6 @@ add_fmt_test(assert-test)
 add_fmt_test(chrono-test)
 add_fmt_test(color-test)
 add_fmt_test(core-test)
-add_fmt_test(grisu-test)
-target_compile_definitions(grisu-test PRIVATE FMT_USE_GRISU=1)
 add_fmt_test(gtest-extra-test)
 add_fmt_test(format-test mock-allocator.h)
 if (MSVC)
@@ -105,11 +103,21 @@ add_fmt_test(locale-test)
 add_fmt_test(ostream-test)
 add_fmt_test(compile-test)
 add_fmt_test(printf-test)
-add_fmt_test(custom-formatter-test)
 add_fmt_test(ranges-test)
 add_fmt_test(scan-test)
 
-if (NOT MSVC_BUILD_STATIC)
+if (NOT DEFINED MSVC_STATIC_RUNTIME AND MSVC)
+  foreach (flag_var
+			 CMAKE_CXX_FLAGS CMAKE_CXX_FLAGS_DEBUG CMAKE_CXX_FLAGS_RELEASE
+			 CMAKE_CXX_FLAGS_MINSIZEREL CMAKE_CXX_FLAGS_RELWITHDEBINFO)
+	if (${flag_var} MATCHES "^(/|-)(MT|MTd)")
+	  set(MSVC_STATIC_RUNTIME ON)
+	  break()
+	endif()
+  endforeach()
+endif()
+
+if (NOT MSVC_STATIC_RUNTIME)
   add_fmt_executable(posix-mock-test
     posix-mock-test.cc ../src/format.cc ${TEST_MAIN_SRC})
   target_include_directories(

test/add-subdirectory-test/CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.1.0)
+cmake_minimum_required(VERSION 3.1...3.18)
 
 project(fmt-test)
 

test/assert-test.cc

@@ -1,4 +1,8 @@
-// Formatting library for C++ - assertion tests
+// Formatting library for C++ - FMT_ASSERT test
+//
+// It is a separate test to minimize the number of EXPECT_DEBUG_DEATH checks
+// which are slow on some platforms. In other tests FMT_ASSERT is made to throw
+// an exception which is much faster and easier to check.
 //
 // Copyright (c) 2012 - present, Victor Zverovich
 // All rights reserved.

test/chrono-test.cc

@@ -95,6 +95,17 @@ TEST(TimeTest, GMTime) {
   EXPECT_TRUE(EqualTime(tm, fmt::gmtime(t)));
 }
 
+TEST(TimeTest, TimePoint) {
+  std::chrono::system_clock::time_point point = std::chrono::system_clock::now();
+
+  std::time_t t = std::chrono::system_clock::to_time_t(point);
+  std::tm tm = *std::localtime(&t);
+  char strftime_output[256];
+  std::strftime(strftime_output, sizeof(strftime_output), "It is %Y-%m-%d %H:%M:%S", &tm);
+
+  EXPECT_EQ(strftime_output, fmt::format("It is {:%Y-%m-%d %H:%M:%S}", point));
+}
+
 #define EXPECT_TIME(spec, time, duration)                 \
   {                                                       \
     std::locale loc("ja_JP.utf8");                        \

test/color-test.cc

@@ -7,6 +7,10 @@
 
 #include "fmt/color.h"
 
+#include <iterator>
+#include <string>
+#include <utility>
+
 #include "gtest-extra.h"
 
 TEST(ColorsTest, ColorsPrint) {
@@ -84,3 +88,12 @@ TEST(ColorsTest, Format) {
   EXPECT_EQ(fmt::format(fg(fmt::terminal_color::red), "{}", "foo"),
             "\x1b[31mfoo\x1b[0m");
 }
+
+TEST(ColorsTest, FormatToOutAcceptsTextStyle) {
+  fmt::text_style ts = fg(fmt::rgb(255, 20, 30));
+  std::string out;
+  fmt::format_to(std::back_inserter(out), ts, "rgb(255,20,30){}{}{}", 1, 2, 3);
+
+  EXPECT_EQ(fmt::to_string(out),
+            "\x1b[38;2;255;020;030mrgb(255,20,30)123\x1b[0m");
+}

test/compile-error-test/CMakeLists.txt

@@ -1,6 +1,6 @@
 # Test if compile errors are produced where necessary.
 
-cmake_minimum_required(VERSION 3.1.0)
+cmake_minimum_required(VERSION 3.1...3.18)
 
 include(CheckCXXSourceCompiles)
 include(CheckCXXCompilerFlag)

test/compile-test.cc

@@ -5,19 +5,10 @@
 //
 // For the license information refer to format.h.
 
-#include <stdint.h>
-
-#include <cctype>
-#include <cfloat>
-#include <climits>
-#include <cmath>
-#include <cstring>
-#include <deque>
-#include <list>
-#include <memory>
 #include <string>
+#include <type_traits>
 
-// Check if fmt/compile.h compiles with windows.h included before it.
+// Check that fmt/compile.h compiles with windows.h included before it.
 #ifdef _WIN32
 #  include <windows.h>
 #endif
@@ -25,16 +16,8 @@
 #include "fmt/compile.h"
 #include "gmock.h"
 #include "gtest-extra.h"
-#include "mock-allocator.h"
 #include "util.h"
 
-#undef ERROR
-#undef min
-#undef max
-
-using testing::Return;
-using testing::StrictMock;
-
 // compiletime_prepared_parts_type_provider is useful only with relaxed
 // constexpr.
 #if FMT_USE_CONSTEXPR
@@ -114,20 +97,20 @@ TEST(CompileTest, MultipleTypes) {
   EXPECT_EQ(fmt::format(f, 42, 42), "42 42");
 }
 
-struct formattable {};
+struct test_formattable {};
 
 FMT_BEGIN_NAMESPACE
-template <> struct formatter<formattable> : formatter<const char*> {
+template <> struct formatter<test_formattable> : formatter<const char*> {
   template <typename FormatContext>
-  auto format(formattable, FormatContext& ctx) -> decltype(ctx.out()) {
+  auto format(test_formattable, FormatContext& ctx) -> decltype(ctx.out()) {
     return formatter<const char*>::format("foo", ctx);
   }
 };
 FMT_END_NAMESPACE
 
 TEST(CompileTest, FormatUserDefinedType) {
-  auto f = fmt::detail::compile<formattable>("{}");
-  EXPECT_EQ(fmt::format(f, formattable()), "foo");
+  auto f = fmt::detail::compile<test_formattable>("{}");
+  EXPECT_EQ(fmt::format(f, test_formattable()), "foo");
 }
 
 TEST(CompileTest, EmptyFormatString) {
@@ -146,21 +129,45 @@ TEST(CompileTest, FormatDefault) {
   EXPECT_EQ("4.2", fmt::format(FMT_COMPILE("{}"), 4.2));
   EXPECT_EQ("foo", fmt::format(FMT_COMPILE("{}"), "foo"));
   EXPECT_EQ("foo", fmt::format(FMT_COMPILE("{}"), std::string("foo")));
-  EXPECT_EQ("foo", fmt::format(FMT_COMPILE("{}"), formattable()));
+  EXPECT_EQ("foo", fmt::format(FMT_COMPILE("{}"), test_formattable()));
+}
+
+TEST(CompileTest, FormatWideString) {
+  EXPECT_EQ(L"42", fmt::format(FMT_COMPILE(L"{}"), 42));
 }
 
 TEST(CompileTest, FormatSpecs) {
   EXPECT_EQ("42", fmt::format(FMT_COMPILE("{:x}"), 0x42));
 }
 
+TEST(CompileTest, DynamicWidth) {
+  EXPECT_EQ("  42foo  ",
+            fmt::format(FMT_COMPILE("{:{}}{:{}}"), 42, 4, "foo", 5));
+}
+
 TEST(CompileTest, FormatTo) {
   char buf[8];
   auto end = fmt::format_to(buf, FMT_COMPILE("{}"), 42);
   *end = '\0';
   EXPECT_STREQ("42", buf);
+  end = fmt::format_to(buf, FMT_COMPILE("{:x}"), 42);
+  *end = '\0';
+  EXPECT_STREQ("2a", buf);
+}
+
+TEST(CompileTest, FormatToNWithCompileMacro) {
+  constexpr auto buffer_size = 8;
+  char buffer[buffer_size];
+  auto res = fmt::format_to_n(buffer, buffer_size, FMT_COMPILE("{}"), 42);
+  *res.out = '\0';
+  EXPECT_STREQ("42", buffer);
+  res = fmt::format_to_n(buffer, buffer_size, FMT_COMPILE("{:x}"), 42);
+  *res.out = '\0';
+  EXPECT_STREQ("2a", buffer);
 }
 
 TEST(CompileTest, TextAndArg) {
   EXPECT_EQ(">>>42<<<", fmt::format(FMT_COMPILE(">>>{}<<<"), 42));
+  EXPECT_EQ("42!", fmt::format(FMT_COMPILE("{}!"), 42));
 }
 #endif

test/core-test.cc

@@ -31,21 +31,16 @@
 using fmt::basic_format_arg;
 using fmt::string_view;
 using fmt::detail::buffer;
+using fmt::detail::make_arg;
 using fmt::detail::value;
 
 using testing::_;
+using testing::Invoke;
+using testing::Return;
 using testing::StrictMock;
 
-namespace {
-
 struct test_struct {};
 
-template <typename Context, typename T>
-basic_format_arg<Context> make_arg(const T& value) {
-  return fmt::detail::make_arg<Context>(value);
-}
-}  // namespace
-
 FMT_BEGIN_NAMESPACE
 template <typename Char> struct formatter<test_struct, Char> {
   template <typename ParseContext>
@@ -53,10 +48,7 @@ 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());
   }
@@ -81,22 +73,22 @@ TEST(BufferTest, Nonmoveable) {
 }
 #endif
 
-// A test buffer with a dummy grow method.
-template <typename T> struct test_buffer : buffer<T> {
-  void grow(size_t capacity) { this->set(nullptr, capacity); }
-};
+TEST(BufferTest, Indestructible) {
+  static_assert(!std::is_destructible<fmt::detail::buffer<int>>(),
+                "buffer's destructor is protected");
+}
 
-template <typename T> struct mock_buffer : buffer<T> {
-  MOCK_METHOD1(do_grow, void(size_t capacity));
+template <typename T> struct mock_buffer final : buffer<T> {
+  MOCK_METHOD1(do_grow, size_t(size_t capacity));
 
-  void grow(size_t capacity) {
-    this->set(this->data(), capacity);
-    do_grow(capacity);
+  void grow(size_t capacity) { this->set(this->data(), do_grow(capacity)); }
+
+  mock_buffer(T* data = nullptr, size_t capacity = 0) {
+    this->set(data, capacity);
+    ON_CALL(*this, do_grow(_)).WillByDefault(Invoke([](size_t capacity) {
+      return capacity;
+    }));
   }
-
-  mock_buffer() {}
-  mock_buffer(T* data) { this->set(data, 0); }
-  mock_buffer(T* data, size_t capacity) { this->set(data, capacity); }
 };
 
 TEST(BufferTest, Ctor) {
@@ -123,24 +115,6 @@ TEST(BufferTest, Ctor) {
   }
 }
 
-struct dying_buffer : test_buffer<int> {
-  MOCK_METHOD0(die, void());
-  ~dying_buffer() { die(); }
-
- private:
-  virtual void avoid_weak_vtable();
-};
-
-void dying_buffer::avoid_weak_vtable() {}
-
-TEST(BufferTest, VirtualDtor) {
-  typedef StrictMock<dying_buffer> stict_mock_buffer;
-  stict_mock_buffer* mock_buffer = new stict_mock_buffer();
-  EXPECT_CALL(*mock_buffer, die());
-  buffer<int>* buffer = mock_buffer;
-  delete buffer;
-}
-
 TEST(BufferTest, Access) {
   char data[10];
   mock_buffer<char> buffer(data, sizeof(data));
@@ -152,30 +126,40 @@ TEST(BufferTest, Access) {
   EXPECT_EQ(42, const_buffer[3]);
 }
 
-TEST(BufferTest, Resize) {
+TEST(BufferTest, TryResize) {
   char data[123];
   mock_buffer<char> buffer(data, sizeof(data));
   buffer[10] = 42;
   EXPECT_EQ(42, buffer[10]);
-  buffer.resize(20);
+  buffer.try_resize(20);
   EXPECT_EQ(20u, buffer.size());
   EXPECT_EQ(123u, buffer.capacity());
   EXPECT_EQ(42, buffer[10]);
-  buffer.resize(5);
+  buffer.try_resize(5);
   EXPECT_EQ(5u, buffer.size());
   EXPECT_EQ(123u, buffer.capacity());
   EXPECT_EQ(42, buffer[10]);
-  // Check if resize calls grow.
+  // Check if try_resize calls grow.
   EXPECT_CALL(buffer, do_grow(124));
-  buffer.resize(124);
+  buffer.try_resize(124);
   EXPECT_CALL(buffer, do_grow(200));
-  buffer.resize(200);
+  buffer.try_resize(200);
+}
+
+TEST(BufferTest, TryResizePartial) {
+  char data[10];
+  mock_buffer<char> buffer(data, sizeof(data));
+  EXPECT_CALL(buffer, do_grow(20)).WillOnce(Return(15));
+  buffer.try_resize(20);
+  EXPECT_EQ(buffer.capacity(), 15);
+  EXPECT_EQ(buffer.size(), 15);
 }
 
 TEST(BufferTest, Clear) {
-  test_buffer<char> buffer;
-  buffer.resize(20);
-  buffer.resize(0);
+  mock_buffer<char> buffer;
+  EXPECT_CALL(buffer, do_grow(20));
+  buffer.try_resize(20);
+  buffer.try_resize(0);
   EXPECT_EQ(static_cast<size_t>(0), buffer.size());
   EXPECT_EQ(20u, buffer.capacity());
 }
@@ -183,11 +167,11 @@ TEST(BufferTest, Clear) {
 TEST(BufferTest, Append) {
   char data[15];
   mock_buffer<char> buffer(data, 10);
-  const char* test = "test";
+  auto test = "test";
   buffer.append(test, test + 5);
   EXPECT_STREQ(test, &buffer[0]);
   EXPECT_EQ(5u, buffer.size());
-  buffer.resize(10);
+  buffer.try_resize(10);
   EXPECT_CALL(buffer, do_grow(12));
   buffer.append(test, test + 2);
   EXPECT_EQ('t', buffer[10]);
@@ -195,17 +179,31 @@ TEST(BufferTest, Append) {
   EXPECT_EQ(12u, buffer.size());
 }
 
+TEST(BufferTest, AppendPartial) {
+  char data[10];
+  mock_buffer<char> buffer(data, sizeof(data));
+  testing::InSequence seq;
+  EXPECT_CALL(buffer, do_grow(15)).WillOnce(Return(10));
+  EXPECT_CALL(buffer, do_grow(15)).WillOnce(Invoke([&buffer](size_t) {
+    EXPECT_EQ(fmt::string_view(buffer.data(), buffer.size()), "0123456789");
+    buffer.clear();
+    return 10;
+  }));
+  auto test = "0123456789abcde";
+  buffer.append(test, test + 15);
+}
+
 TEST(BufferTest, AppendAllocatesEnoughStorage) {
   char data[19];
   mock_buffer<char> buffer(data, 10);
-  const char* test = "abcdefgh";
-  buffer.resize(10);
+  auto test = "abcdefgh";
+  buffer.try_resize(10);
   EXPECT_CALL(buffer, do_grow(19));
   buffer.append(test, test + 9);
 }
 
 TEST(ArgTest, FormatArgs) {
-  fmt::format_args args;
+  auto args = fmt::format_args();
   EXPECT_FALSE(args.get(1));
 }
 
@@ -233,7 +231,7 @@ struct custom_context {
 };
 
 TEST(ArgTest, MakeValueWithCustomContext) {
-  test_struct t;
+  auto t = test_struct();
   fmt::detail::value<custom_context> arg(
       fmt::detail::arg_mapper<custom_context>().map(t));
   custom_context ctx = {false, fmt::format_parse_context("")};
@@ -255,10 +253,10 @@ FMT_END_NAMESPACE
 struct test_result {};
 
 template <typename T> struct mock_visitor {
-  template <typename U> struct result { typedef test_result type; };
+  template <typename U> struct result { using type = test_result; };
 
   mock_visitor() {
-    ON_CALL(*this, visit(_)).WillByDefault(testing::Return(test_result()));
+    ON_CALL(*this, visit(_)).WillByDefault(Return(test_result()));
   }
 
   MOCK_METHOD1_T(visit, test_result(T value));
@@ -272,10 +270,10 @@ template <typename T> struct mock_visitor {
   }
 };
 
-template <typename T> struct visit_type { typedef T Type; };
+template <typename T> struct visit_type { using type = T; };
 
-#define VISIT_TYPE(Type_, visit_type_) \
-  template <> struct visit_type<Type_> { typedef visit_type_ Type; }
+#define VISIT_TYPE(type_, visit_type_) \
+  template <> struct visit_type<type_> { using type = visit_type_; }
 
 VISIT_TYPE(signed char, int);
 VISIT_TYPE(unsigned char, unsigned);
@@ -294,36 +292,34 @@ VISIT_TYPE(unsigned long, unsigned long long);
   {                                                                           \
     testing::StrictMock<mock_visitor<decltype(expected)>> visitor;            \
     EXPECT_CALL(visitor, visit(expected));                                    \
-    typedef std::back_insert_iterator<buffer<Char>> iterator;                 \
+    using iterator = std::back_insert_iterator<buffer<Char>>;                 \
     fmt::visit_format_arg(                                                    \
         visitor, make_arg<fmt::basic_format_context<iterator, Char>>(value)); \
   }
 
 #define CHECK_ARG(value, typename_)                          \
   {                                                          \
-    typedef decltype(value) value_type;                      \
-    typename_ visit_type<value_type>::Type expected = value; \
+    using value_type = decltype(value);                      \
+    typename_ visit_type<value_type>::type expected = value; \
     CHECK_ARG_(char, expected, value)                        \
     CHECK_ARG_(wchar_t, expected, value)                     \
   }
 
 template <typename T> class NumericArgTest : public testing::Test {};
 
-typedef ::testing::Types<bool, signed char, unsigned char, signed,
-                         unsigned short, int, unsigned, long, unsigned long,
-                         long long, unsigned long long, float, double,
-                         long double>
-    Types;
-TYPED_TEST_CASE(NumericArgTest, Types);
+using types =
+    ::testing::Types<bool, signed char, unsigned char, signed, unsigned short,
+                     int, unsigned, long, unsigned long, long long,
+                     unsigned long long, float, double, long double>;
+TYPED_TEST_CASE(NumericArgTest, types);
 
 template <typename T>
-typename std::enable_if<std::is_integral<T>::value, T>::type test_value() {
+fmt::enable_if_t<std::is_integral<T>::value, T> test_value() {
   return static_cast<T>(42);
 }
 
 template <typename T>
-typename std::enable_if<std::is_floating_point<T>::value, T>::type
-test_value() {
+fmt::enable_if_t<std::is_floating_point<T>::value, T> test_value() {
   return static_cast<T>(4.2);
 }
 
@@ -345,7 +341,7 @@ TEST(ArgTest, StringArg) {
   const char* cstr = str;
   CHECK_ARG_(char, cstr, str);
 
-  string_view sref(str);
+  auto sref = string_view(str);
   CHECK_ARG_(char, sref, std::string(str));
 }
 
@@ -372,14 +368,14 @@ TEST(ArgTest, PointerArg) {
 struct check_custom {
   test_result operator()(
       fmt::basic_format_arg<fmt::format_context>::handle h) const {
-    struct test_buffer : fmt::detail::buffer<char> {
+    struct test_buffer final : fmt::detail::buffer<char> {
       char data[10];
       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();
@@ -388,10 +384,10 @@ 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()));
+  EXPECT_CALL(v, visit(_)).WillOnce(Invoke(check_custom()));
   fmt::visit_format_arg(v, make_arg<fmt::format_context>(test));
 }
 
@@ -407,9 +403,7 @@ TEST(FormatDynArgsTest, Basic) {
   store.push_back(42);
   store.push_back("abc1");
   store.push_back(1.5f);
-
-  std::string result = fmt::vformat("{} and {} and {}", store);
-  EXPECT_EQ("42 and abc1 and 1.5", result);
+  EXPECT_EQ("42 and abc1 and 1.5", fmt::vformat("{} and {} and {}", store));
 }
 
 TEST(FormatDynArgsTest, StringsAndRefs) {
@@ -451,7 +445,6 @@ TEST(FormatDynArgsTest, CustomFormat) {
   ++c.i;
   store.push_back(std::cref(c));
   ++c.i;
-
   std::string result = fmt::vformat("{} and {} and {}", store);
   EXPECT_EQ("cust=0 and cust=1 and cust=3", result);
 }
@@ -459,8 +452,7 @@ TEST(FormatDynArgsTest, CustomFormat) {
 TEST(FormatDynArgsTest, NamedInt) {
   fmt::dynamic_format_arg_store<fmt::format_context> store;
   store.push_back(fmt::arg("a1", 42));
-  std::string result = fmt::vformat("{a1}", store);
-  EXPECT_EQ("42", result);
+  EXPECT_EQ("42", fmt::vformat("{a1}", store));
 }
 
 TEST(FormatDynArgsTest, NamedStrings) {
@@ -469,10 +461,7 @@ TEST(FormatDynArgsTest, NamedStrings) {
   store.push_back(fmt::arg("a1", str));
   store.push_back(fmt::arg("a2", std::cref(str)));
   str[0] = 'X';
-
-  std::string result = fmt::vformat("{a1} and {a2}", store);
-
-  EXPECT_EQ("1234567890 and X234567890", result);
+  EXPECT_EQ("1234567890 and X234567890", fmt::vformat("{a1} and {a2}", store));
 }
 
 TEST(FormatDynArgsTest, NamedArgByRef) {
@@ -494,7 +483,6 @@ TEST(FormatDynArgsTest, NamedArgByRef) {
   store.push_back(std::cref(a1));
 
   std::string result = fmt::vformat("{a1_} and {} and {} and {}", store);
-
   EXPECT_EQ("42 and abc and 1.5 and 42", result);
 }
 
@@ -507,7 +495,6 @@ TEST(FormatDynArgsTest, NamedCustomFormat) {
   ++c.i;
   store.push_back(fmt::arg("c_ref", std::cref(c)));
   ++c.i;
-
   std::string result = fmt::vformat("{c1} and {c2} and {c_ref}", store);
   EXPECT_EQ("cust=0 and cust=1 and cust=3", result);
 }
@@ -663,14 +650,14 @@ TEST(CoreTest, FormatterOverridesImplicitConversion) {
 
 namespace my_ns {
 template <typename Char> class my_string {
+ private:
+  std::basic_string<Char> s_;
+
  public:
   my_string(const Char* s) : s_(s) {}
   const Char* data() const FMT_NOEXCEPT { return s_.data(); }
   size_t length() const FMT_NOEXCEPT { return s_.size(); }
   operator const Char*() const { return s_.c_str(); }
-
- private:
-  std::basic_string<Char> s_;
 };
 
 template <typename Char>
@@ -748,7 +735,7 @@ struct implicitly_convertible_to_string_view {
   operator fmt::string_view() const { return "foo"; }
 };
 
-TEST(FormatterTest, FormatImplicitlyConvertibleToStringView) {
+TEST(CoreTest, FormatImplicitlyConvertibleToStringView) {
   EXPECT_EQ("foo", fmt::format("{}", implicitly_convertible_to_string_view()));
 }
 
@@ -758,7 +745,7 @@ struct explicitly_convertible_to_string_view {
   explicit operator fmt::string_view() const { return "foo"; }
 };
 
-TEST(FormatterTest, FormatExplicitlyConvertibleToStringView) {
+TEST(CoreTest, FormatExplicitlyConvertibleToStringView) {
   EXPECT_EQ("foo", fmt::format("{}", explicitly_convertible_to_string_view()));
 }
 
@@ -767,7 +754,7 @@ struct explicitly_convertible_to_std_string_view {
   explicit operator std::string_view() const { return "foo"; }
 };
 
-TEST(FormatterTest, FormatExplicitlyConvertibleToStdStringView) {
+TEST(CoreTest, FormatExplicitlyConvertibleToStdStringView) {
   EXPECT_EQ("foo",
             fmt::format("{}", explicitly_convertible_to_std_string_view()));
 }
@@ -781,6 +768,6 @@ struct disabled_rvalue_conversion {
   operator const char*() && = delete;
 };
 
-TEST(FormatterTest, DisabledRValueConversion) {
+TEST(CoreTest, DisabledRValueConversion) {
   EXPECT_EQ("foo", fmt::format("{}", disabled_rvalue_conversion()));
 }

test/custom-formatter-test.cc

@@ -1,58 +0,0 @@
-// Formatting library for C++ - custom argument formatter tests
-//
-// Copyright (c) 2012 - present, Victor Zverovich
-// All rights reserved.
-//
-// For the license information refer to format.h.
-
-#ifndef _CRT_SECURE_NO_WARNINGS
-#define _CRT_SECURE_NO_WARNINGS
-#endif
-
-#include "fmt/format.h"
-#include "gtest-extra.h"
-
-// MSVC 2013 is known to be broken.
-#if !FMT_MSC_VER || FMT_MSC_VER > 1800
-
-// A custom argument formatter that doesn't print `-` for floating-point values
-// rounded to 0.
-class custom_arg_formatter
-    : public fmt::detail::arg_formatter<fmt::format_context::iterator, char> {
- public:
-  using base = fmt::detail::arg_formatter<fmt::format_context::iterator, char>;
-
-  custom_arg_formatter(fmt::format_context& ctx,
-                       fmt::format_parse_context* parse_ctx,
-                       fmt::format_specs* s = nullptr,
-                       const char* = nullptr)
-      : base(ctx, parse_ctx, s) {}
-
-  using base::operator();
-
-  iterator operator()(double value) {
-    // Comparing a float to 0.0 is safe.
-    if (round(value * pow(10, specs()->precision)) == 0.0) value = 0;
-    return base::operator()(value);
-  }
-};
-
-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);
-  return std::string(buffer.data(), buffer.size());
-}
-
-template <typename... Args>
-std::string custom_format(const char* format_str, const Args&... args) {
-  auto va = fmt::make_format_args(args...);
-  return custom_vformat(format_str, va);
-}
-
-TEST(CustomFormatterTest, Format) {
-  EXPECT_EQ("0.00", custom_format("{:.2f}", -.00001));
-}
-#endif

test/find-package-test/CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.1.0)
+cmake_minimum_required(VERSION 3.1...3.18)
 
 project(fmt-test)
 

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-dyn-args-test.cc

@@ -1,6 +0,0 @@
-// Copyright (c) 2020 Vladimir Solontsov
-// SPDX-License-Identifier: MIT Licence
-
-#include <fmt/core.h>
-
-#include "gtest-extra.h"

test/format-impl-test.cc

@@ -19,7 +19,10 @@
 #include "gtest-extra.h"
 #include "util.h"
 
-#undef max
+#ifdef _WIN32
+#  include <windows.h>
+#  undef max
+#endif
 
 using fmt::detail::bigint;
 using fmt::detail::fp;
@@ -186,29 +189,6 @@ template <bool is_iec559> void run_double_tests() {
 template <> void run_double_tests<true>() {
   // Construct from double.
   EXPECT_EQ(fp(1.23), fp(0x13ae147ae147aeu, -52));
-
-  // Compute boundaries:
-  fp value;
-  // Normalized & not power of 2 - equidistant boundaries:
-  auto b = value.assign_with_boundaries(1.23);
-  EXPECT_EQ(value, fp(0x0013ae147ae147ae, -52));
-  EXPECT_EQ(b.lower, 0x9d70a3d70a3d6c00);
-  EXPECT_EQ(b.upper, 0x9d70a3d70a3d7400);
-  // Normalized power of 2 - lower boundary is closer:
-  b = value.assign_with_boundaries(1.9807040628566084e+28);  // 2**94
-  EXPECT_EQ(value, fp(0x0010000000000000, 42));
-  EXPECT_EQ(b.lower, 0x7ffffffffffffe00);
-  EXPECT_EQ(b.upper, 0x8000000000000400);
-  // Smallest normalized double - equidistant boundaries:
-  b = value.assign_with_boundaries(2.2250738585072014e-308);
-  EXPECT_EQ(value, fp(0x0010000000000000, -1074));
-  EXPECT_EQ(b.lower, 0x7ffffffffffffc00);
-  EXPECT_EQ(b.upper, 0x8000000000000400);
-  // Subnormal - equidistant boundaries:
-  b = value.assign_with_boundaries(4.9406564584124654e-324);
-  EXPECT_EQ(value, fp(0x0000000000000001, -1074));
-  EXPECT_EQ(b.lower, 0x4000000000000000);
-  EXPECT_EQ(b.upper, 0xc000000000000000);
 }
 
 TEST(FPTest, DoubleTests) {
@@ -222,33 +202,6 @@ TEST(FPTest, Normalize) {
   EXPECT_EQ(-6, normalized.e);
 }
 
-TEST(FPTest, ComputeFloatBoundaries) {
-  struct {
-    double x, lower, upper;
-  } tests[] = {
-      // regular
-      {1.5f, 1.4999999403953552, 1.5000000596046448},
-      // boundary
-      {1.0f, 0.9999999701976776, 1.0000000596046448},
-      // min normal
-      {1.1754944e-38f, 1.1754942807573643e-38, 1.1754944208872107e-38},
-      // max subnormal
-      {1.1754942e-38f, 1.1754941406275179e-38, 1.1754942807573643e-38},
-      // min subnormal
-      {1e-45f, 7.006492321624085e-46, 2.1019476964872256e-45},
-  };
-  for (auto test : tests) {
-    fp vlower = normalize(fp(test.lower));
-    fp vupper = normalize(fp(test.upper));
-    vlower.f >>= vupper.e - vlower.e;
-    vlower.e = vupper.e;
-    fp value;
-    auto b = value.assign_float_with_boundaries(test.x);
-    EXPECT_EQ(vlower.f, b.lower);
-    EXPECT_EQ(vupper.f, b.upper);
-  }
-}
-
 TEST(FPTest, Multiply) {
   auto v = fp(123ULL << 32, 4) * fp(56ULL << 32, 7);
   EXPECT_EQ(v.f, 123u * 56u);
@@ -259,17 +212,55 @@ TEST(FPTest, Multiply) {
 }
 
 TEST(FPTest, GetCachedPower) {
-  typedef std::numeric_limits<double> limits;
+  using limits = std::numeric_limits<double>;
   for (auto exp = limits::min_exponent; exp <= limits::max_exponent; ++exp) {
     int dec_exp = 0;
     auto fp = fmt::detail::get_cached_power(exp, dec_exp);
-    EXPECT_LE(exp, fp.e);
-    int dec_exp_step = 8;
-    EXPECT_LE(fp.e, exp + dec_exp_step * log2(10));
-    EXPECT_DOUBLE_EQ(pow(10, dec_exp), ldexp(static_cast<double>(fp.f), fp.e));
+    bigint exact, cache(fp.f);
+    if (dec_exp >= 0) {
+      exact.assign_pow10(dec_exp);
+      if (fp.e <= 0)
+        exact <<= -fp.e;
+      else
+        cache <<= fp.e;
+      exact.align(cache);
+      cache.align(exact);
+      auto exact_str = fmt::format("{}", exact);
+      auto cache_str = fmt::format("{}", cache);
+      EXPECT_EQ(exact_str.size(), cache_str.size());
+      EXPECT_EQ(exact_str.substr(0, 15), cache_str.substr(0, 15));
+      int diff = cache_str[15] - exact_str[15];
+      if (diff == 1)
+        EXPECT_GT(exact_str[16], '8');
+      else
+        EXPECT_EQ(diff, 0);
+    } else {
+      cache.assign_pow10(-dec_exp);
+      cache *= fp.f + 1;  // Inexact check.
+      exact.assign(1);
+      exact <<= -fp.e;
+      exact.align(cache);
+      auto exact_str = fmt::format("{}", exact);
+      auto cache_str = fmt::format("{}", cache);
+      EXPECT_EQ(exact_str.size(), cache_str.size());
+      EXPECT_EQ(exact_str.substr(0, 16), cache_str.substr(0, 16));
+    }
   }
 }
 
+TEST(FPTest, DragonboxMaxK) {
+  using fmt::detail::dragonbox::floor_log10_pow2;
+  using float_info = fmt::detail::dragonbox::float_info<float>;
+  EXPECT_EQ(fmt::detail::const_check(float_info::max_k),
+            float_info::kappa - floor_log10_pow2(float_info::min_exponent -
+                                                 float_info::significand_bits));
+  using double_info = fmt::detail::dragonbox::float_info<double>;
+  EXPECT_EQ(
+      fmt::detail::const_check(double_info::max_k),
+      double_info::kappa - floor_log10_pow2(double_info::min_exponent -
+                                            double_info::significand_bits));
+}
+
 TEST(FPTest, GetRoundDirection) {
   using fmt::detail::get_round_direction;
   using fmt::detail::round_direction;
@@ -307,7 +298,7 @@ TEST(FPTest, FixedHandler) {
   EXPECT_THROW(handler().on_digit('0', 100, 100, 0, exp, false),
                assertion_failure);
   namespace digits = fmt::detail::digits;
-  EXPECT_EQ(handler(1).on_digit('0', 100, 10, 10, exp, false), digits::done);
+  EXPECT_EQ(handler(1).on_digit('0', 100, 10, 10, exp, false), digits::error);
   // Check that divisor - error doesn't overflow.
   EXPECT_EQ(handler(1).on_digit('0', 100, 10, 101, exp, false), digits::error);
   // Check that 2 * error doesn't overflow.
@@ -349,14 +340,6 @@ TEST(FormatTest, ArgConverter) {
   EXPECT_EQ(value, fmt::visit_format_arg(value_extractor<long long>(), arg));
 }
 
-TEST(FormatTest, FormatNegativeNaN) {
-  double nan = std::numeric_limits<double>::quiet_NaN();
-  if (std::signbit(-nan))
-    EXPECT_EQ("-nan", fmt::format("{}", -nan));
-  else
-    fmt::print("Warning: compiler doesn't handle negative NaN correctly");
-}
-
 TEST(FormatTest, StrError) {
   char* message = nullptr;
   char buffer[BUFFER_SIZE];
@@ -454,3 +437,10 @@ TEST(UtilTest, WriteFallbackUIntPtr) {
       fmt::detail::fallback_uintptr(reinterpret_cast<void*>(0xface)), nullptr);
   EXPECT_EQ(s, "0xface");
 }
+
+#ifdef _WIN32
+TEST(UtilTest, WriteConsoleSignature) {
+  decltype(WriteConsoleW)* p = fmt::detail::WriteConsoleW;
+  (void)p;
+}
+#endif

test/format-test.cc

@@ -24,7 +24,6 @@
 // Check if fmt/format.h compiles with the X11 index macro defined.
 #define index(x, y) no nice things
 
-#include "fmt/color.h"
 #include "fmt/format.h"
 
 #undef index
@@ -147,6 +146,7 @@ TEST(IteratorTest, CountingIterator) {
   auto prev = it++;
   EXPECT_EQ(prev.count(), 0);
   EXPECT_EQ(it.count(), 1);
+  EXPECT_EQ((it + 41).count(), 42);
 }
 
 TEST(IteratorTest, TruncatingIterator) {
@@ -169,20 +169,22 @@ TEST(IteratorTest, TruncatingBackInserter) {
 }
 
 TEST(IteratorTest, IsOutputIterator) {
-  EXPECT_TRUE(fmt::detail::is_output_iterator<char*>::value);
-  EXPECT_FALSE(fmt::detail::is_output_iterator<const char*>::value);
-  EXPECT_FALSE(fmt::detail::is_output_iterator<std::string>::value);
-  EXPECT_TRUE(fmt::detail::is_output_iterator<
-              std::back_insert_iterator<std::string>>::value);
-  EXPECT_TRUE(fmt::detail::is_output_iterator<std::string::iterator>::value);
-  EXPECT_FALSE(
-      fmt::detail::is_output_iterator<std::string::const_iterator>::value);
-  EXPECT_FALSE(fmt::detail::is_output_iterator<std::list<char>>::value);
+  EXPECT_TRUE((fmt::detail::is_output_iterator<char*, char>::value));
+  EXPECT_FALSE((fmt::detail::is_output_iterator<const char*, char>::value));
+  EXPECT_FALSE((fmt::detail::is_output_iterator<std::string, char>::value));
   EXPECT_TRUE(
-      fmt::detail::is_output_iterator<std::list<char>::iterator>::value);
-  EXPECT_FALSE(
-      fmt::detail::is_output_iterator<std::list<char>::const_iterator>::value);
-  EXPECT_FALSE(fmt::detail::is_output_iterator<uint32_pair>::value);
+      (fmt::detail::is_output_iterator<std::back_insert_iterator<std::string>,
+                                       char>::value));
+  EXPECT_TRUE(
+      (fmt::detail::is_output_iterator<std::string::iterator, char>::value));
+  EXPECT_FALSE((fmt::detail::is_output_iterator<std::string::const_iterator,
+                                                char>::value));
+  EXPECT_FALSE((fmt::detail::is_output_iterator<std::list<char>, char>::value));
+  EXPECT_TRUE((
+      fmt::detail::is_output_iterator<std::list<char>::iterator, char>::value));
+  EXPECT_FALSE((fmt::detail::is_output_iterator<std::list<char>::const_iterator,
+                                                char>::value));
+  EXPECT_FALSE((fmt::detail::is_output_iterator<uint32_pair, char>::value));
 }
 
 TEST(MemoryBufferTest, Ctor) {
@@ -236,7 +238,7 @@ TEST(MemoryBufferTest, MoveCtorInlineBuffer) {
   std::allocator<char> alloc;
   basic_memory_buffer<char, 5, TestAllocator> buffer((TestAllocator(&alloc)));
   const char test[] = "test";
-  buffer.append(test, test + 4);
+  buffer.append(string_view(test, 4));
   check_move_buffer("test", buffer);
   // Adding one more character fills the inline buffer, but doesn't cause
   // dynamic allocation.
@@ -293,12 +295,8 @@ TEST(MemoryBufferTest, MoveAssignment) {
 
 TEST(MemoryBufferTest, Grow) {
   typedef allocator_ref<mock_allocator<int>> Allocator;
-  typedef basic_memory_buffer<int, 10, Allocator> Base;
   mock_allocator<int> alloc;
-  struct TestMemoryBuffer : Base {
-    TestMemoryBuffer(Allocator alloc) : Base(alloc) {}
-    void grow(size_t size) { Base::grow(size); }
-  } buffer((Allocator(&alloc)));
+  basic_memory_buffer<int, 10, Allocator> buffer((Allocator(&alloc)));
   buffer.resize(7);
   using fmt::detail::to_unsigned;
   for (int i = 0; i < 7; ++i) buffer[to_unsigned(i)] = i * i;
@@ -306,7 +304,7 @@ TEST(MemoryBufferTest, Grow) {
   int mem[20];
   mem[7] = 0xdead;
   EXPECT_CALL(alloc, allocate(20)).WillOnce(Return(mem));
-  buffer.grow(20);
+  buffer.try_reserve(20);
   EXPECT_EQ(20u, buffer.capacity());
   // Check if size elements have been copied
   for (int i = 0; i < 7; ++i) EXPECT_EQ(i * i, buffer[to_unsigned(i)]);
@@ -543,7 +541,6 @@ TEST(FormatterTest, ManyArgs) {
 TEST(FormatterTest, NamedArg) {
   EXPECT_EQ("1/a/A", format("{_1}/{a_}/{A_}", fmt::arg("a_", 'a'),
                             fmt::arg("A_", "A"), fmt::arg("_1", 1)));
-  EXPECT_THROW_MSG(format("{a}"), format_error, "argument not found");
   EXPECT_EQ(" -42", format("{0:{width}}", -42, fmt::arg("width", 4)));
   EXPECT_EQ("st", format("{0:.{precision}}", "str", fmt::arg("precision", 2)));
   EXPECT_EQ("1 2", format("{} {two}", 1, fmt::arg("two", 2)));
@@ -553,6 +550,8 @@ TEST(FormatterTest, NamedArg) {
                          fmt::arg("i", 0), fmt::arg("j", 0), fmt::arg("k", 0),
                          fmt::arg("l", 0), fmt::arg("m", 0), fmt::arg("n", 0),
                          fmt::arg("o", 0), fmt::arg("p", 0)));
+  EXPECT_THROW_MSG(format("{a}"), format_error, "argument not found");
+  EXPECT_THROW_MSG(format("{a}", 42), format_error, "argument not found");
 }
 
 TEST(FormatterTest, AutoArgIndex) {
@@ -581,8 +580,8 @@ TEST(FormatterTest, LeftAlign) {
   EXPECT_EQ("42   ", format("{0:<5}", 42ul));
   EXPECT_EQ("-42  ", format("{0:<5}", -42ll));
   EXPECT_EQ("42   ", format("{0:<5}", 42ull));
-  EXPECT_EQ("-42.0  ", format("{0:<7}", -42.0));
-  EXPECT_EQ("-42.0  ", format("{0:<7}", -42.0l));
+  EXPECT_EQ("-42  ", format("{0:<5}", -42.0));
+  EXPECT_EQ("-42  ", format("{0:<5}", -42.0l));
   EXPECT_EQ("c    ", format("{0:<5}", 'c'));
   EXPECT_EQ("abc  ", format("{0:<5}", "abc"));
   EXPECT_EQ("0xface  ", format("{0:<8}", reinterpret_cast<void*>(0xface)));
@@ -598,8 +597,8 @@ TEST(FormatterTest, RightAlign) {
   EXPECT_EQ("   42", format("{0:>5}", 42ul));
   EXPECT_EQ("  -42", format("{0:>5}", -42ll));
   EXPECT_EQ("   42", format("{0:>5}", 42ull));
-  EXPECT_EQ("  -42.0", format("{0:>7}", -42.0));
-  EXPECT_EQ("  -42.0", format("{0:>7}", -42.0l));
+  EXPECT_EQ("  -42", format("{0:>5}", -42.0));
+  EXPECT_EQ("  -42", format("{0:>5}", -42.0l));
   EXPECT_EQ("    c", format("{0:>5}", 'c'));
   EXPECT_EQ("  abc", format("{0:>5}", "abc"));
   EXPECT_EQ("  0xface", format("{0:>8}", reinterpret_cast<void*>(0xface)));
@@ -619,8 +618,8 @@ TEST(FormatterTest, CenterAlign) {
   EXPECT_EQ(" 42  ", format("{0:^5}", 42ul));
   EXPECT_EQ(" -42 ", format("{0:^5}", -42ll));
   EXPECT_EQ(" 42  ", format("{0:^5}", 42ull));
-  EXPECT_EQ(" -42.0 ", format("{0:^7}", -42.0));
-  EXPECT_EQ(" -42.0 ", format("{0:^7}", -42.0l));
+  EXPECT_EQ(" -42 ", format("{0:^5}", -42.0));
+  EXPECT_EQ(" -42 ", format("{0:^5}", -42.0l));
   EXPECT_EQ("  c  ", format("{0:^5}", 'c'));
   EXPECT_EQ(" abc  ", format("{0:^6}", "abc"));
   EXPECT_EQ(" 0xface ", format("{0:^8}", reinterpret_cast<void*>(0xface)));
@@ -638,8 +637,8 @@ TEST(FormatterTest, Fill) {
   EXPECT_EQ("***42", format("{0:*>5}", 42ul));
   EXPECT_EQ("**-42", format("{0:*>5}", -42ll));
   EXPECT_EQ("***42", format("{0:*>5}", 42ull));
-  EXPECT_EQ("**-42.0", format("{0:*>7}", -42.0));
-  EXPECT_EQ("**-42.0", format("{0:*>7}", -42.0l));
+  EXPECT_EQ("**-42", format("{0:*>5}", -42.0));
+  EXPECT_EQ("**-42", format("{0:*>5}", -42.0l));
   EXPECT_EQ("c****", format("{0:*<5}", 'c'));
   EXPECT_EQ("abc**", format("{0:*<5}", "abc"));
   EXPECT_EQ("**0xface", format("{0:*>8}", reinterpret_cast<void*>(0xface)));
@@ -647,7 +646,7 @@ TEST(FormatterTest, Fill) {
   EXPECT_EQ(std::string("\0\0\0*", 4), format(string_view("{:\0>4}", 6), '*'));
   EXPECT_EQ("жж42", format("{0:ж>4}", 42));
   EXPECT_THROW_MSG(format("{:\x80\x80\x80\x80\x80>}", 0), format_error,
-                   "invalid fill");
+                   "missing '}' in format string");
 }
 
 TEST(FormatterTest, PlusSign) {
@@ -662,8 +661,8 @@ TEST(FormatterTest, PlusSign) {
   EXPECT_EQ("+42", format("{0:+}", 42ll));
   EXPECT_THROW_MSG(format("{0:+}", 42ull), format_error,
                    "format specifier requires signed argument");
-  EXPECT_EQ("+42.0", format("{0:+}", 42.0));
-  EXPECT_EQ("+42.0", format("{0:+}", 42.0l));
+  EXPECT_EQ("+42", format("{0:+}", 42.0));
+  EXPECT_EQ("+42", format("{0:+}", 42.0l));
   EXPECT_THROW_MSG(format("{0:+", 'c'), format_error,
                    "missing '}' in format string");
   EXPECT_THROW_MSG(format("{0:+}", 'c'), format_error,
@@ -686,8 +685,8 @@ TEST(FormatterTest, MinusSign) {
   EXPECT_EQ("42", format("{0:-}", 42ll));
   EXPECT_THROW_MSG(format("{0:-}", 42ull), format_error,
                    "format specifier requires signed argument");
-  EXPECT_EQ("42.0", format("{0:-}", 42.0));
-  EXPECT_EQ("42.0", format("{0:-}", 42.0l));
+  EXPECT_EQ("42", format("{0:-}", 42.0));
+  EXPECT_EQ("42", format("{0:-}", 42.0l));
   EXPECT_THROW_MSG(format("{0:-", 'c'), format_error,
                    "missing '}' in format string");
   EXPECT_THROW_MSG(format("{0:-}", 'c'), format_error,
@@ -710,8 +709,8 @@ TEST(FormatterTest, SpaceSign) {
   EXPECT_EQ(" 42", format("{0: }", 42ll));
   EXPECT_THROW_MSG(format("{0: }", 42ull), format_error,
                    "format specifier requires signed argument");
-  EXPECT_EQ(" 42.0", format("{0: }", 42.0));
-  EXPECT_EQ(" 42.0", format("{0: }", 42.0l));
+  EXPECT_EQ(" 42", format("{0: }", 42.0));
+  EXPECT_EQ(" 42", format("{0: }", 42.0l));
   EXPECT_THROW_MSG(format("{0: ", 'c'), format_error,
                    "missing '}' in format string");
   EXPECT_THROW_MSG(format("{0: }", 'c'), format_error,
@@ -722,6 +721,12 @@ TEST(FormatterTest, SpaceSign) {
                    "format specifier requires numeric argument");
 }
 
+TEST(FormatterTest, SignNotTruncated) {
+  wchar_t format_str[] = {L'{', L':',
+                          '+' | (1 << fmt::detail::num_bits<char>()), L'}', 0};
+  EXPECT_THROW(format(format_str, 42), format_error);
+}
+
 TEST(FormatterTest, HashFlag) {
   EXPECT_EQ("42", format("{0:#}", 42));
   EXPECT_EQ("-42", format("{0:#}", -42));
@@ -760,8 +765,8 @@ TEST(FormatterTest, HashFlag) {
   EXPECT_EQ("-42.0", format("{0:#}", -42.0l));
   EXPECT_EQ("4.e+01", format("{:#.0e}", 42.0));
   EXPECT_EQ("0.", format("{:#.0f}", 0.01));
-  auto s = format("{:#.0f}", 0.5);  // MSVC's printf uses wrong rounding mode.
-  EXPECT_TRUE(s == "0." || s == "1.");
+  EXPECT_EQ("0.50", format("{:#.2g}", 0.5));
+  EXPECT_EQ("0.", format("{:#.0f}", 0.5));
   EXPECT_THROW_MSG(format("{0:#", 'c'), format_error,
                    "missing '}' in format string");
   EXPECT_THROW_MSG(format("{0:#}", 'c'), format_error,
@@ -780,8 +785,8 @@ TEST(FormatterTest, ZeroFlag) {
   EXPECT_EQ("00042", format("{0:05}", 42ul));
   EXPECT_EQ("-0042", format("{0:05}", -42ll));
   EXPECT_EQ("00042", format("{0:05}", 42ull));
-  EXPECT_EQ("-0042.0", format("{0:07}", -42.0));
-  EXPECT_EQ("-0042.0", format("{0:07}", -42.0l));
+  EXPECT_EQ("-000042", format("{0:07}", -42.0));
+  EXPECT_EQ("-000042", format("{0:07}", -42.0l));
   EXPECT_THROW_MSG(format("{0:0", 'c'), format_error,
                    "missing '}' in format string");
   EXPECT_THROW_MSG(format("{0:05}", 'c'), format_error,
@@ -954,6 +959,9 @@ TEST(FormatterTest, Precision) {
   EXPECT_EQ("123.", format("{:#.0f}", 123.0));
   EXPECT_EQ("1.23", format("{:.02f}", 1.234));
   EXPECT_EQ("0.001", format("{:.1g}", 0.001));
+  EXPECT_EQ("1019666400", format("{}", 1019666432.0f));
+  EXPECT_EQ("1e+01", format("{:.0e}", 9.5));
+  EXPECT_EQ("1.0e-34", fmt::format("{:.1e}", 1e-34));
 
   EXPECT_THROW_MSG(format("{0:.2}", reinterpret_cast<void*>(0xcafe)),
                    format_error,
@@ -1235,17 +1243,20 @@ TEST(FormatterTest, FormatConvertibleToLongLong) {
 }
 
 TEST(FormatterTest, FormatFloat) {
+  EXPECT_EQ("0", format("{}", 0.0f));
   EXPECT_EQ("392.500000", format("{0:f}", 392.5f));
 }
 
 TEST(FormatterTest, FormatDouble) {
+  EXPECT_EQ("0", format("{}", 0.0));
   check_unknown_types(1.2, "eEfFgGaAnL%", "double");
-  EXPECT_EQ("0.0", format("{:}", 0.0));
+  EXPECT_EQ("0", format("{:}", 0.0));
   EXPECT_EQ("0.000000", format("{:f}", 0.0));
   EXPECT_EQ("0", format("{:g}", 0.0));
   EXPECT_EQ("392.65", format("{:}", 392.65));
   EXPECT_EQ("392.65", format("{:g}", 392.65));
   EXPECT_EQ("392.65", format("{:G}", 392.65));
+  EXPECT_EQ("4.9014e+06", format("{:g}", 4.9014e6));
   EXPECT_EQ("392.650000", format("{:f}", 392.65));
   EXPECT_EQ("392.650000", format("{:F}", 392.65));
   EXPECT_EQ("42", format("{:L}", 42.0));
@@ -1272,17 +1283,42 @@ TEST(FormatterTest, PrecisionRounding) {
   EXPECT_EQ("1.000", format("{:.3f}", 0.9999));
   EXPECT_EQ("0.00123", format("{:.3}", 0.00123));
   EXPECT_EQ("0.1", format("{:.16g}", 0.1));
-  // Trigger rounding error in Grisu by a carefully chosen number.
-  auto n = 3788512123356.985352;
-  char buffer[64];
-  safe_sprintf(buffer, "%f", n);
-  EXPECT_EQ(buffer, format("{:f}", n));
+  EXPECT_EQ("1", fmt::format("{:.0}", 1.0));
+  EXPECT_EQ("225.51575035152063720",
+            fmt::format("{:.17f}", 225.51575035152064));
+  EXPECT_EQ("-761519619559038.2", fmt::format("{:.1f}", -761519619559038.2));
+  EXPECT_EQ("1.9156918820264798e-56",
+            fmt::format("{}", 1.9156918820264798e-56));
+  EXPECT_EQ("0.0000", fmt::format("{:.4f}", 7.2809479766055470e-15));
+
+  // Trigger a rounding error in Grisu by a specially chosen number.
+  EXPECT_EQ("3788512123356.985352", format("{:f}", 3788512123356.985352));
+}
+
+TEST(FormatterTest, PrettifyFloat) {
+  EXPECT_EQ("0.0001", fmt::format("{}", 1e-4));
+  EXPECT_EQ("1e-05", fmt::format("{}", 1e-5));
+  EXPECT_EQ("1000000000000000", fmt::format("{}", 1e15));
+  EXPECT_EQ("1e+16", fmt::format("{}", 1e16));
+  EXPECT_EQ("9.999e-05", fmt::format("{}", 9.999e-5));
+  EXPECT_EQ("10000000000", fmt::format("{}", 1e10));
+  EXPECT_EQ("100000000000", fmt::format("{}", 1e11));
+  EXPECT_EQ("12340000000", fmt::format("{}", 1234e7));
+  EXPECT_EQ("12.34", fmt::format("{}", 1234e-2));
+  EXPECT_EQ("0.001234", fmt::format("{}", 1234e-6));
+  EXPECT_EQ("0.1", fmt::format("{}", 0.1f));
+  EXPECT_EQ("0.10000000149011612", fmt::format("{}", double(0.1f)));
+  EXPECT_EQ("1.3563156e-19", fmt::format("{}", 1.35631564e-19f));
 }
 
 TEST(FormatterTest, FormatNaN) {
   double nan = std::numeric_limits<double>::quiet_NaN();
   EXPECT_EQ("nan", format("{}", nan));
   EXPECT_EQ("+nan", format("{:+}", nan));
+  if (std::signbit(-nan))
+    EXPECT_EQ("-nan", format("{}", -nan));
+  else
+    fmt::print("Warning: compiler doesn't handle negative NaN correctly");
   EXPECT_EQ(" nan", format("{: }", nan));
   EXPECT_EQ("NAN", format("{:F}", nan));
   EXPECT_EQ("nan    ", format("{:<7}", nan));
@@ -1303,7 +1339,7 @@ TEST(FormatterTest, FormatInfinity) {
 }
 
 TEST(FormatterTest, FormatLongDouble) {
-  EXPECT_EQ("0.0", format("{0:}", 0.0l));
+  EXPECT_EQ("0", format("{0:}", 0.0l));
   EXPECT_EQ("0.000000", format("{0:f}", 0.0l));
   EXPECT_EQ("392.65", format("{0:}", 392.65l));
   EXPECT_EQ("392.65", format("{0:g}", 392.65l));
@@ -1520,6 +1556,7 @@ TEST(FormatterTest, WideFormatString) {
   EXPECT_EQ(L"4.2", format(L"{}", 4.2));
   EXPECT_EQ(L"abc", format(L"{}", L"abc"));
   EXPECT_EQ(L"z", format(L"{}", L'z'));
+  EXPECT_THROW(fmt::format(L"{:*\x343E}", 42), fmt::format_error);
 }
 
 TEST(FormatterTest, FormatStringFromSpeedTest) {
@@ -1805,59 +1842,6 @@ TEST(FormatTest, StrongEnum) {
 }
 #endif
 
-using buffer_iterator = fmt::format_context::iterator;
-
-class mock_arg_formatter
-    : public fmt::detail::arg_formatter_base<buffer_iterator, char> {
- private:
-#if FMT_USE_INT128
-  MOCK_METHOD1(call, void(__int128_t value));
-#else
-  MOCK_METHOD1(call, void(long long value));
-#endif
-
- public:
-  using base = fmt::detail::arg_formatter_base<buffer_iterator, char>;
-
-  mock_arg_formatter(fmt::format_context& ctx, fmt::format_parse_context*,
-                     fmt::format_specs* s = nullptr, const char* = nullptr)
-      : base(ctx.out(), s, ctx.locale()) {
-    EXPECT_CALL(*this, call(42));
-  }
-
-  template <typename T>
-  typename std::enable_if<fmt::detail::is_integral<T>::value, iterator>::type
-  operator()(T value) {
-    call(value);
-    return base::operator()(value);
-  }
-
-  template <typename T>
-  typename std::enable_if<!fmt::detail::is_integral<T>::value, iterator>::type
-  operator()(T value) {
-    return base::operator()(value);
-  }
-
-  iterator operator()(fmt::basic_format_arg<fmt::format_context>::handle) {
-    return base::operator()(fmt::monostate());
-  }
-};
-
-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);
-}
-
-template <typename... Args>
-void custom_format(const char* format_str, const Args&... args) {
-  auto va = fmt::make_format_args(args...);
-  return custom_vformat(format_str, va);
-}
-
-TEST(FormatTest, CustomArgFormatter) { custom_format("{}", 42); }
-
 TEST(FormatTest, NonNullTerminatedFormatString) {
   EXPECT_EQ("42", format(string_view("{}foo", 2), 42));
 }
@@ -1946,6 +1930,12 @@ TEST(FormatTest, FormattedSize) {
   EXPECT_EQ(2u, fmt::formatted_size("{}", 42));
 }
 
+TEST(FormatTest, FormatTo) {
+  std::vector<char> v;
+  fmt::format_to(std::back_inserter(v), "{}", "foo");
+  EXPECT_EQ(string_view(v.data(), v.size()), "foo");
+}
+
 TEST(FormatTest, FormatToN) {
   char buffer[4];
   buffer[3] = 'x';
@@ -2412,12 +2402,6 @@ TEST(FormatTest, FmtStringInTemplate) {
 
 #endif  // FMT_USE_CONSTEXPR
 
-TEST(FormatTest, EmphasisNonHeaderOnly) {
-  // Ensure this compiles even if FMT_HEADER_ONLY is not defined.
-  EXPECT_EQ(fmt::format(fmt::emphasis::bold, "bold error"),
-            "\x1b[1mbold error\x1b[0m");
-}
-
 TEST(FormatTest, CharTraitsIsNotAmbiguous) {
   // Test that we don't inject detail names into the std namespace.
   using namespace std;
@@ -2430,24 +2414,26 @@ TEST(FormatTest, CharTraitsIsNotAmbiguous) {
 #endif
 }
 
-struct mychar {
+struct custom_char {
   int value;
-  mychar() = default;
+  custom_char() = default;
 
-  template <typename T> mychar(T val) : value(static_cast<int>(val)) {}
+  template <typename T> custom_char(T val) : value(static_cast<int>(val)) {}
 
   operator int() const { return value; }
 };
 
+int to_ascii(custom_char c) { return c; }
+
 FMT_BEGIN_NAMESPACE
-template <> struct is_char<mychar> : std::true_type {};
+template <> struct is_char<custom_char> : std::true_type {};
 FMT_END_NAMESPACE
 
 TEST(FormatTest, FormatCustomChar) {
-  const mychar format[] = {'{', '}', 0};
-  auto result = fmt::format(format, mychar('x'));
+  const custom_char format[] = {'{', '}', 0};
+  auto result = fmt::format(format, custom_char('x'));
   EXPECT_EQ(result.size(), 1);
-  EXPECT_EQ(result[0], mychar('x'));
+  EXPECT_EQ(result[0], custom_char('x'));
 }
 
 // Convert a char8_t string to std::string. Otherwise GTest will insist on
@@ -2466,3 +2452,27 @@ TEST(FormatTest, FormatUTF8Precision) {
   EXPECT_EQ(result.size(), 5);
   EXPECT_EQ(from_u8str(result), from_u8str(str.substr(0, 5)));
 }
+
+struct check_back_appender {};
+
+FMT_BEGIN_NAMESPACE
+template <> struct formatter<check_back_appender> {
+  template <typename ParseContext>
+  auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
+    return ctx.begin();
+  }
+
+  template <typename Context>
+  auto format(check_back_appender, Context& ctx) -> decltype(ctx.out()) {
+    auto out = ctx.out();
+    static_assert(std::is_same<decltype(++out), decltype(out)&>::value,
+                  "needs to satisfy weakly_incrementable");
+    *out = 'y';
+    return ++out;
+  }
+};
+FMT_END_NAMESPACE
+
+TEST(FormatTest, BackInsertSlicing) {
+  EXPECT_EQ(fmt::format("{}", check_back_appender{}), "y");
+}

test/fuzzing/CMakeLists.txt

@@ -1,38 +1,30 @@
 # Copyright (c) 2019, Paul Dreik
 # License: see LICENSE.rst in the fmt root directory
 
-# settings this links in a main. useful for reproducing,
-# kcov, gdb, afl, valgrind.
-# (note that libFuzzer can also reproduce, just pass it the files)
-option(FMT_FUZZ_LINKMAIN "enables the reproduce mode, instead of libFuzzer" On)
+# Link in the main function. Useful for reproducing, kcov, gdb, afl, valgrind.
+# (Note that libFuzzer can also reproduce, just pass it the files.)
+option(FMT_FUZZ_LINKMAIN "Enables the reproduce mode, instead of libFuzzer" On)
 
 # For oss-fuzz - insert $LIB_FUZZING_ENGINE into the link flags, but only for
-# the fuzz targets, otherwise the cmake configuration step fails.
+# the fuzz targets, otherwise the CMake configuration step fails.
 set(FMT_FUZZ_LDFLAGS "" CACHE STRING "LDFLAGS for the fuzz targets")
 
-# Find all fuzzers.
-set(SOURCES
-  chrono_duration.cpp
-  named_arg.cpp
-  one_arg.cpp
-  sprintf.cpp
-  two_args.cpp
-)
-
-macro(implement_fuzzer sourcefile)
-  get_filename_component(basename ${sourcefile} NAME_WE)
-  set(name fuzzer_${basename})
-  add_executable(${name} ${sourcefile} fuzzer_common.h)
+# Adds a binary for reproducing, i.e. no fuzzing, just enables replaying data
+# through the fuzzers.
+function(add_fuzzer source)
+  get_filename_component(basename ${source} NAME_WE)
+  set(name ${basename}-fuzzer)
+  add_executable(${name} ${source} fuzzer-common.h)
   if (FMT_FUZZ_LINKMAIN)
-      target_sources(${name} PRIVATE main.cpp)
+    target_sources(${name} PRIVATE main.cc)
   endif ()
   target_link_libraries(${name} PRIVATE fmt)
-if (FMT_FUZZ_LDFLAGS)
-  target_link_libraries(${name} PRIVATE ${FMT_FUZZ_LDFLAGS})
-endif ()
+  if (FMT_FUZZ_LDFLAGS)
+    target_link_libraries(${name} PRIVATE ${FMT_FUZZ_LDFLAGS})
+  endif ()
   target_compile_features(${name} PRIVATE cxx_generic_lambdas)
-endmacro ()
+endfunction()
 
-foreach (X IN ITEMS ${SOURCES})
-  implement_fuzzer(${X})
+foreach (source chrono-duration.cc float.cc named-arg.cc one-arg.cc two-args.cc)
+  add_fuzzer(${source})
 endforeach ()

test/fuzzing/README.md

@@ -1,27 +1,4 @@
-# FMT Fuzzer
-
-Fuzzing has revealed [several bugs](https://github.com/fmtlib/fmt/issues?&q=is%3Aissue+fuzz)
-in fmt. It is a part of the continous fuzzing at
-[oss-fuzz](https://github.com/google/oss-fuzz).
-
-The source code is modified to make the fuzzing possible without locking up on
-resource exhaustion:
-```cpp
-#ifdef FMT_FUZZ
-if(spec.precision>100000) {
-  throw std::runtime_error("fuzz mode - avoiding large precision");
-}
-#endif
-``` 
-This macro `FMT_FUZZ` is enabled on OSS-Fuzz builds and makes fuzzing
-practically possible. It is used in fmt code to prevent resource exhaustion in
-fuzzing mode.  
-The macro `FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION` is the
-defacto standard for making fuzzing practically possible to disable certain
-fuzzing-unfriendly features (for example, randomness), see [the libFuzzer
-documentation](https://llvm.org/docs/LibFuzzer.html#fuzzer-friendly-build-mode).
-
-## Running the fuzzers locally
+# Running the fuzzers locally
 
 There is a [helper script](build.sh) to build the fuzzers, which has only been
 tested on Debian and Ubuntu linux so far. There should be no problems fuzzing on
@@ -34,7 +11,7 @@ mkdir build
 cd build
 export CXX=clang++
 export CXXFLAGS="-fsanitize=fuzzer-no-link -DFUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION= -g"
-cmake ..  -DFMT_SAFE_DURATION_CAST=On -DFMT_FUZZ=On -DFMT_FUZZ_LINKMAIN=Off -DFMT_FUZZ_LDFLAGS="-fsanitize=fuzzer"
+cmake .. -DFMT_SAFE_DURATION_CAST=On -DFMT_FUZZ=On -DFMT_FUZZ_LINKMAIN=Off -DFMT_FUZZ_LDFLAGS="-fsanitize=fuzzer"
 cmake --build .
 ```
 should work to build the fuzzers for all platforms which clang supports.
@@ -44,5 +21,5 @@ Execute a fuzzer with for instance
 cd build
 export UBSAN_OPTIONS=halt_on_error=1
 mkdir out_chrono
-bin/fuzzer_chrono_duration  out_chrono
+bin/fuzzer_chrono_duration out_chrono
 ```

test/fuzzing/build.sh

@@ -1,7 +1,6 @@
 #!/bin/sh
 #
 # Creates fuzzer builds of various kinds
-# - reproduce mode (no fuzzing, just enables replaying data through the fuzzers)
 # - oss-fuzz emulated mode (makes sure a simulated invocation by oss-fuzz works)
 # - libFuzzer build (you will need clang)
 # - afl build (you will need afl)
@@ -9,7 +8,7 @@
 #
 # Copyright (c) 2019 Paul Dreik
 #
-# License: see LICENSE.rst in the fmt root directory
+# For the license information refer to format.h.
 
 set -e
 me=$(basename $0)
@@ -23,16 +22,7 @@ here=$(pwd)
 CXXFLAGSALL="-DFUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION= -g"
 CMAKEFLAGSALL="$root -GNinja -DCMAKE_BUILD_TYPE=Debug -DFMT_DOC=Off -DFMT_TEST=Off -DFMT_FUZZ=On -DCMAKE_CXX_STANDARD=17"
 
-#builds the fuzzers as one would do if using afl or just making
-#binaries for reproducing.
-builddir=$here/build-fuzzers-reproduce
-mkdir -p $builddir
-cd $builddir
-CXX="ccache g++" CXXFLAGS="$CXXFLAGSALL" cmake \
-$CMAKEFLAGSALL
-cmake --build $builddir
-
-#for performance analysis of the fuzzers
+# For performance analysis of the fuzzers.
 builddir=$here/build-fuzzers-perfanalysis
 mkdir -p $builddir
 cd $builddir
@@ -43,7 +33,7 @@ $CMAKEFLAGSALL \
 
 cmake --build $builddir
 
-#builds the fuzzers as oss-fuzz does
+# Builds the fuzzers as oss-fuzz does.
 builddir=$here/build-fuzzers-ossfuzz
 mkdir -p $builddir
 cd $builddir
@@ -56,7 +46,7 @@ cmake $CMAKEFLAGSALL \
 cmake --build $builddir
 
 
-#builds fuzzers for local fuzzing with libfuzzer with asan+usan
+# Builds fuzzers for local fuzzing with libfuzzer with asan+usan.
 builddir=$here/build-fuzzers-libfuzzer
 mkdir -p $builddir
 cd $builddir
@@ -68,19 +58,7 @@ cmake $CMAKEFLAGSALL \
 
 cmake --build $builddir
 
-#builds fuzzers for local fuzzing with libfuzzer with asan only
-builddir=$here/build-fuzzers-libfuzzer-addr
-mkdir -p $builddir
-cd $builddir
-CXX="clang++" \
-CXXFLAGS="$CXXFLAGSALL -fsanitize=fuzzer-no-link,undefined" cmake \
-cmake $CMAKEFLAGSALL \
--DFMT_FUZZ_LINKMAIN=Off \
--DFMT_FUZZ_LDFLAGS="-fsanitize=fuzzer"
-
-cmake --build $builddir
-
-#builds a fast fuzzer for making coverage fast
+# Builds a fast fuzzer for making coverage fast.
 builddir=$here/build-fuzzers-fast
 mkdir -p $builddir
 cd $builddir
@@ -94,7 +72,7 @@ cmake $CMAKEFLAGSALL \
 cmake --build $builddir
 
 
-#builds fuzzers for local fuzzing with afl
+# Builds fuzzers for local fuzzing with afl.
 builddir=$here/build-fuzzers-afl
 mkdir -p $builddir
 cd $builddir

test/fuzzing/chrono-duration.cc

@@ -0,0 +1,135 @@
+// Copyright (c) 2019, Paul Dreik
+// For the license information refer to format.h.
+
+#include <cstdint>
+#include <fmt/chrono.h>
+
+#include "fuzzer-common.h"
+
+template <typename Period, typename Rep>
+void invoke_inner(fmt::string_view format_str, Rep rep) {
+  auto value = std::chrono::duration<Rep, Period>(rep);
+  try {
+#if FMT_FUZZ_FORMAT_TO_STRING
+    std::string message = fmt::format(format_str, value);
+#else
+    fmt::memory_buffer buf;
+    fmt::format_to(buf, format_str, value);
+#endif
+  } catch (std::exception&) {
+  }
+}
+
+// Rep is a duration's representation type.
+template <typename Rep>
+void invoke_outer(const uint8_t* data, size_t size, int period) {
+  // Always use a fixed location of the data.
+  static_assert(sizeof(Rep) <= fixed_size, "fixed size is too small");
+  if (size <= fixed_size + 1) return;
+
+  const Rep rep = assign_from_buf<Rep>(data);
+  data += fixed_size;
+  size -= fixed_size;
+
+  // data is already allocated separately in libFuzzer so reading past the end 
+  // will most likely be detected anyway.
+  const auto format_str = fmt::string_view(as_chars(data), size);
+
+  // yocto, zepto, zetta and yotta are not handled.
+  switch (period) {
+  case 1:
+    invoke_inner<std::atto>(format_str, rep);
+    break;
+  case 2:
+    invoke_inner<std::femto>(format_str, rep);
+    break;
+  case 3:
+    invoke_inner<std::pico>(format_str, rep);
+    break;
+  case 4:
+    invoke_inner<std::nano>(format_str, rep);
+    break;
+  case 5:
+    invoke_inner<std::micro>(format_str, rep);
+    break;
+  case 6:
+    invoke_inner<std::milli>(format_str, rep);
+    break;
+  case 7:
+    invoke_inner<std::centi>(format_str, rep);
+    break;
+  case 8:
+    invoke_inner<std::deci>(format_str, rep);
+    break;
+  case 9:
+    invoke_inner<std::deca>(format_str, rep);
+    break;
+  case 10:
+    invoke_inner<std::kilo>(format_str, rep);
+    break;
+  case 11:
+    invoke_inner<std::mega>(format_str, rep);
+    break;
+  case 12:
+    invoke_inner<std::giga>(format_str, rep);
+    break;
+  case 13:
+    invoke_inner<std::tera>(format_str, rep);
+    break;
+  case 14:
+    invoke_inner<std::peta>(format_str, rep);
+    break;
+  case 15:
+    invoke_inner<std::exa>(format_str, rep);
+    break;
+  }
+}
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+  if (size <= 4)  return 0;
+
+  const auto representation = data[0];
+  const auto period = data[1];
+  data += 2;
+  size -= 2;
+
+  switch (representation) {
+  case 1:
+    invoke_outer<char>(data, size, period);
+    break;
+  case 2:
+    invoke_outer<signed char>(data, size, period);
+    break;
+  case 3:
+    invoke_outer<unsigned char>(data, size, period);
+    break;
+  case 4:
+    invoke_outer<short>(data, size, period);
+    break;
+  case 5:
+    invoke_outer<unsigned short>(data, size, period);
+    break;
+  case 6:
+    invoke_outer<int>(data, size, period);
+    break;
+  case 7:
+    invoke_outer<unsigned int>(data, size, period);
+    break;
+  case 8:
+    invoke_outer<long>(data, size, period);
+    break;
+  case 9:
+    invoke_outer<unsigned long>(data, size, period);
+    break;
+  case 10:
+    invoke_outer<float>(data, size, period);
+    break;
+  case 11:
+    invoke_outer<double>(data, size, period);
+    break;
+  case 12:
+    invoke_outer<long double>(data, size, period);
+    break;
+  }
+  return 0;
+}

test/fuzzing/chrono_duration.cpp

@@ -1,152 +0,0 @@
-// Copyright (c) 2019, Paul Dreik
-// License: see LICENSE.rst in the fmt root directory
-
-#include <fmt/chrono.h>
-#include <cstdint>
-#include <limits>
-#include <stdexcept>
-#include <type_traits>
-#include <vector>
-#include "fuzzer_common.h"
-
-template <typename Item, typename Ratio>
-void invoke_inner(fmt::string_view formatstring, const Item item) {
-  const std::chrono::duration<Item, Ratio> value(item);
-  try {
-#if FMT_FUZZ_FORMAT_TO_STRING
-    std::string message = fmt::format(formatstring, value);
-#else
-    fmt::memory_buffer buf;
-    fmt::format_to(buf, formatstring, value);
-#endif
-  } catch (std::exception& /*e*/) {
-  }
-}
-
-// Item is the underlying type for duration (int, long etc)
-template <typename Item>
-void invoke_outer(const uint8_t* Data, size_t Size, const int scaling) {
-  // always use a fixed location of the data
-  using fmt_fuzzer::Nfixed;
-
-  constexpr auto N = sizeof(Item);
-  static_assert(N <= Nfixed, "fixed size is too small");
-  if (Size <= Nfixed + 1) {
-    return;
-  }
-
-  const Item item = fmt_fuzzer::assignFromBuf<Item>(Data);
-
-  // fast forward
-  Data += Nfixed;
-  Size -= Nfixed;
-
-  // Data is already allocated separately in libFuzzer so reading past
-  // the end will most likely be detected anyway
-  const auto formatstring = fmt::string_view(fmt_fuzzer::as_chars(Data), Size);
-
-  // doit_impl<Item,std::yocto>(buf.data(),item);
-  // doit_impl<Item,std::zepto>(buf.data(),item);
-  switch (scaling) {
-  case 1:
-    invoke_inner<Item, std::atto>(formatstring, item);
-    break;
-  case 2:
-    invoke_inner<Item, std::femto>(formatstring, item);
-    break;
-  case 3:
-    invoke_inner<Item, std::pico>(formatstring, item);
-    break;
-  case 4:
-    invoke_inner<Item, std::nano>(formatstring, item);
-    break;
-  case 5:
-    invoke_inner<Item, std::micro>(formatstring, item);
-    break;
-  case 6:
-    invoke_inner<Item, std::milli>(formatstring, item);
-    break;
-  case 7:
-    invoke_inner<Item, std::centi>(formatstring, item);
-    break;
-  case 8:
-    invoke_inner<Item, std::deci>(formatstring, item);
-    break;
-  case 9:
-    invoke_inner<Item, std::deca>(formatstring, item);
-    break;
-  case 10:
-    invoke_inner<Item, std::kilo>(formatstring, item);
-    break;
-  case 11:
-    invoke_inner<Item, std::mega>(formatstring, item);
-    break;
-  case 12:
-    invoke_inner<Item, std::giga>(formatstring, item);
-    break;
-  case 13:
-    invoke_inner<Item, std::tera>(formatstring, item);
-    break;
-  case 14:
-    invoke_inner<Item, std::peta>(formatstring, item);
-    break;
-  case 15:
-    invoke_inner<Item, std::exa>(formatstring, item);
-  }
-  // doit_impl<Item,std::zeta>(buf.data(),item);
-  // doit_impl<Item,std::yotta>(buf.data(),item);
-}
-
-extern "C" int LLVMFuzzerTestOneInput(const uint8_t* Data, size_t Size) {
-  if (Size <= 4) {
-    return 0;
-  }
-
-  const auto representation = Data[0];
-  const auto scaling = Data[1];
-  Data += 2;
-  Size -= 2;
-
-  switch (representation) {
-  case 1:
-    invoke_outer<char>(Data, Size, scaling);
-    break;
-  case 2:
-    invoke_outer<unsigned char>(Data, Size, scaling);
-    break;
-  case 3:
-    invoke_outer<signed char>(Data, Size, scaling);
-    break;
-  case 4:
-    invoke_outer<short>(Data, Size, scaling);
-    break;
-  case 5:
-    invoke_outer<unsigned short>(Data, Size, scaling);
-    break;
-  case 6:
-    invoke_outer<int>(Data, Size, scaling);
-    break;
-  case 7:
-    invoke_outer<unsigned int>(Data, Size, scaling);
-    break;
-  case 8:
-    invoke_outer<long>(Data, Size, scaling);
-    break;
-  case 9:
-    invoke_outer<unsigned long>(Data, Size, scaling);
-    break;
-  case 10:
-    invoke_outer<float>(Data, Size, scaling);
-    break;
-  case 11:
-    invoke_outer<double>(Data, Size, scaling);
-    break;
-  case 12:
-    invoke_outer<long double>(Data, Size, scaling);
-    break;
-  default:
-    break;
-  }
-
-  return 0;
-}

test/fuzzing/float.cc

@@ -0,0 +1,34 @@
+// A fuzzer for floating-point formatter.
+// For the license information refer to format.h.
+
+#include <cstdint>
+#include <cstdlib>
+#include <stdexcept>
+#include <limits>
+#include <fmt/format.h>
+
+#include "fuzzer-common.h"
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+  if (size <= sizeof(double) || !std::numeric_limits<double>::is_iec559)
+    return 0;
+
+  auto value = assign_from_buf<double>(data);
+  auto buffer = fmt::memory_buffer();
+  fmt::format_to(buffer, "{}", value);
+
+  // Check a round trip.
+  if (std::isnan(value)) {
+    auto nan = std::signbit(value) ? "-nan" : "nan";
+    if (fmt::string_view(buffer.data(), buffer.size()) != nan)
+      throw std::runtime_error("round trip failure");
+    return 0;
+  }
+  buffer.push_back('\0');
+  char* ptr = nullptr;
+  if (std::strtod(buffer.data(), &ptr) != value)
+    throw std::runtime_error("round trip failure");
+  if (ptr + 1 != buffer.end())
+    throw std::runtime_error("unparsed output");
+  return 0;
+}

test/fuzzing/fuzzer-common.h

@@ -0,0 +1,75 @@
+// Copyright (c) 2019, Paul Dreik
+// For the license information refer to format.h.
+
+#ifndef FUZZER_COMMON_H
+#define FUZZER_COMMON_H
+
+#include <cstdint>      // std::uint8_t
+#include <cstring>      // memcpy
+#include <vector>
+
+#include <fmt/core.h>
+
+// One can format to either a string, or a buffer. The latter is faster, but
+// one may be interested in formatting to a string instead to verify it works
+// as intended. To avoid a combinatoric explosion, select this at compile time
+// instead of dynamically from the fuzz data.
+#define FMT_FUZZ_FORMAT_TO_STRING 0
+
+// If {fmt} is given a buffer that is separately allocated, chances that address
+// sanitizer detects out of bound reads is much higher. However, it slows down
+// the fuzzing.
+#define FMT_FUZZ_SEPARATE_ALLOCATION 1
+
+// The size of the largest possible type in use.
+// To let the the fuzzer mutation be efficient at cross pollinating between
+// different types, use a fixed size format. The same bit pattern, interpreted
+// as another type, is likely interesting.
+constexpr auto fixed_size = 16;
+
+// Casts data to a char pointer.
+template <typename T> inline const char* as_chars(const T* data) {
+  return reinterpret_cast<const char*>(data);
+}
+
+// Casts data to a byte pointer.
+template <typename T> inline const std::uint8_t* as_bytes(const T* data) {
+  return reinterpret_cast<const std::uint8_t*>(data);
+}
+
+// Blits bytes from data to form an (assumed trivially constructible) object
+// of type Item.
+template <class Item> inline Item assign_from_buf(const std::uint8_t* data) {
+  auto item = Item();
+  std::memcpy(&item, data, sizeof(Item));
+  return item;
+}
+
+// Reads a boolean value by looking at the first byte from data.
+template <> inline bool assign_from_buf<bool>(const std::uint8_t* data) {
+  return *data != 0;
+}
+
+struct data_to_string {
+#if FMT_FUZZ_SEPARATE_ALLOCATION
+  std::vector<char> buffer;
+
+  data_to_string(const uint8_t* data, size_t size, bool add_terminator = false)
+      : buffer(size + (add_terminator ? 1 : 0)) {
+    std::memcpy(buffer.data(), data, size);
+  }
+
+  fmt::string_view get() const { return {buffer.data(), buffer.size()}; }
+#else
+  fmt::string_view sv;
+
+  data_to_string(const uint8_t* data, size_t size, bool = false)
+      : str(as_chars(data), size) {}
+
+  fmt::string_view get() const { return sv; }
+#endif
+
+  const char* data() const { return get().data(); }
+};
+
+#endif  // FUZZER_COMMON_H

test/fuzzing/fuzzer_common.h

@@ -1,67 +0,0 @@
-#ifndef FUZZER_COMMON_H
-#define FUZZER_COMMON_H
-
-// Copyright (c) 2019, Paul Dreik
-// License: see LICENSE.rst in the fmt root directory
-
-#include <cstdint>      // std::uint8_t
-#include <cstring>      // memcpy
-#include <type_traits>  // trivially copyable
-
-// one can format to either a string, or a buf. buf is faster,
-// but one may be interested in formatting to a string instead to
-// verify it works as intended. to avoid a combinatoric explosion,
-// select this at compile time instead of dynamically from the fuzz data
-#define FMT_FUZZ_FORMAT_TO_STRING 0
-
-// if fmt is given a buffer that is separately allocated,
-// chances that address sanitizer detects out of bound reads is
-// much higher. However, it slows down the fuzzing.
-#define FMT_FUZZ_SEPARATE_ALLOCATION 1
-
-// To let the the fuzzer mutation be efficient at cross pollinating
-// between different types, use a fixed size format.
-// The same bit pattern, interpreted as another type,
-// is likely interesting.
-// For this, we must know the size of the largest possible type in use.
-
-// There are some problems on travis, claiming Nfixed is not a constant
-// expression which seems to be an issue with older versions of libstdc++
-#if _GLIBCXX_RELEASE >= 7
-#  include <algorithm>
-namespace fmt_fuzzer {
-constexpr auto Nfixed = std::max(sizeof(long double), sizeof(std::intmax_t));
-}
-#else
-namespace fmt_fuzzer {
-constexpr auto Nfixed = 16;
-}
-#endif
-
-namespace fmt_fuzzer {
-// view data as a c char pointer.
-template <typename T> inline const char* as_chars(const T* data) {
-  return static_cast<const char*>(static_cast<const void*>(data));
-}
-
-// view data as a byte pointer
-template <typename T> inline const std::uint8_t* as_bytes(const T* data) {
-  return static_cast<const std::uint8_t*>(static_cast<const void*>(data));
-}
-
-// blits bytes from Data to form an (assumed trivially constructible) object
-// of type Item
-template <class Item> inline Item assignFromBuf(const std::uint8_t* Data) {
-  Item item{};
-  std::memcpy(&item, Data, sizeof(Item));
-  return item;
-}
-
-// reads a boolean value by looking at the first byte from Data
-template <> inline bool assignFromBuf<bool>(const std::uint8_t* Data) {
-  return !!Data[0];
-}
-
-}  // namespace fmt_fuzzer
-
-#endif  // FUZZER_COMMON_H

test/fuzzing/main.cc

@@ -0,0 +1,22 @@
+#include <cassert>
+#include <fstream>
+#include <vector>
+
+#include "fuzzer-common.h"
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size);
+
+int main(int argc, char** argv) {
+  for (int i = 1; i < argc; ++i) {
+    std::ifstream in(argv[i]);
+    assert(in);
+    in.seekg(0, std::ios_base::end);
+    const auto size = in.tellg();
+    assert(size >= 0);
+    in.seekg(0, std::ios_base::beg);
+    std::vector<char> buf(static_cast<size_t>(size));
+    in.read(buf.data(), size);
+    assert(in.gcount() == size);
+    LLVMFuzzerTestOneInput(as_bytes(buf.data()), buf.size());
+  }
+}

test/fuzzing/main.cpp

@@ -1,21 +0,0 @@
-#include <cassert>
-#include <fstream>
-#include <sstream>
-#include <vector>
-#include "fuzzer_common.h"
-
-extern "C" int LLVMFuzzerTestOneInput(const uint8_t* Data, size_t Size);
-int main(int argc, char* argv[]) {
-  for (int i = 1; i < argc; ++i) {
-    std::ifstream in(argv[i]);
-    assert(in);
-    in.seekg(0, std::ios_base::end);
-    const auto pos = in.tellg();
-    assert(pos >= 0);
-    in.seekg(0, std::ios_base::beg);
-    std::vector<char> buf(static_cast<size_t>(pos));
-    in.read(buf.data(), static_cast<long>(buf.size()));
-    assert(in.gcount() == pos);
-    LLVMFuzzerTestOneInput(fmt_fuzzer::as_bytes(buf.data()), buf.size());
-  }
-}

test/fuzzing/named-arg.cc

@@ -0,0 +1,100 @@
+// Copyright (c) 2019, Paul Dreik
+// For the license information refer to format.h.
+
+#include <cstdint>
+#include <type_traits>
+#include <vector>
+#include <fmt/chrono.h>
+
+#include "fuzzer-common.h"
+
+template <typename T>
+void invoke_fmt(const uint8_t* data, size_t size, unsigned arg_name_size) {
+  static_assert(sizeof(T) <= fixed_size, "fixed_size too small");
+  if (size <= fixed_size) return;
+  const T value = assign_from_buf<T>(data);
+  data += fixed_size;
+  size -= fixed_size;
+
+  if (arg_name_size <= 0 || arg_name_size >= size) return;
+  data_to_string arg_name(data, arg_name_size, true);
+  data += arg_name_size;
+  size -= arg_name_size;
+
+  data_to_string format_str(data, size);
+  try {
+#if FMT_FUZZ_FORMAT_TO_STRING
+    std::string message =
+      fmt::format(format_str.get(), fmt::arg(arg_name.data(), value));
+#else
+    fmt::memory_buffer out;
+    fmt::format_to(out, format_str.get(), fmt::arg(arg_name.data(), value));
+#endif
+  } catch (std::exception&) {
+  }
+}
+
+// For dynamic dispatching to an explicit instantiation.
+template <typename Callback> void invoke(int type, Callback callback) {
+  switch (type) {
+  case 0:
+    callback(bool());
+    break;
+  case 1:
+    callback(char());
+    break;
+  case 2:
+    using sc = signed char;
+    callback(sc());
+    break;
+  case 3:
+    using uc = unsigned char;
+    callback(uc());
+    break;
+  case 4:
+    callback(short());
+    break;
+  case 5:
+    using us = unsigned short;
+    callback(us());
+    break;
+  case 6:
+    callback(int());
+    break;
+  case 7:
+    callback(unsigned());
+    break;
+  case 8:
+    callback(long());
+    break;
+  case 9:
+    using ul = unsigned long;
+    callback(ul());
+    break;
+  case 10:
+    callback(float());
+    break;
+  case 11:
+    callback(double());
+    break;
+  case 12:
+    using LD = long double;
+    callback(LD());
+    break;
+  }
+}
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+  if (size <= 3) return 0;
+
+  // Switch types depending on the first byte of the input.
+  const auto type = data[0] & 0x0F;
+  const unsigned arg_name_size = (data[0] & 0xF0) >> 4;
+  data++;
+  size--;
+
+  invoke(type, [=](auto arg) {
+    invoke_fmt<decltype(arg)>(data, size, arg_name_size);
+  });
+  return 0;
+}

test/fuzzing/named_arg.cpp

@@ -1,128 +0,0 @@
-// Copyright (c) 2019, Paul Dreik
-// License: see LICENSE.rst in the fmt root directory
-
-#include <fmt/chrono.h>
-#include <fmt/core.h>
-#include <cstdint>
-#include <stdexcept>
-#include <type_traits>
-#include <vector>
-#include "fuzzer_common.h"
-
-template <typename Item1>
-void invoke_fmt(const uint8_t* Data, size_t Size, unsigned int argsize) {
-  constexpr auto N1 = sizeof(Item1);
-  static_assert(N1 <= fmt_fuzzer::Nfixed, "Nfixed too small");
-  if (Size <= fmt_fuzzer::Nfixed) {
-    return;
-  }
-  const Item1 item1 = fmt_fuzzer::assignFromBuf<Item1>(Data);
-
-  Data += fmt_fuzzer::Nfixed;
-  Size -= fmt_fuzzer::Nfixed;
-
-  // how many chars should be used for the argument name?
-  if (argsize <= 0 || argsize >= Size) {
-    return;
-  }
-
-  // allocating buffers separately is slower, but increases chances
-  // of detecting memory errors
-#if FMT_FUZZ_SEPARATE_ALLOCATION
-  std::vector<char> argnamebuffer(argsize + 1);
-  std::memcpy(argnamebuffer.data(), Data, argsize);
-  auto argname = argnamebuffer.data();
-#else
-  auto argname = fmt_fuzzer::as_chars(Data);
-#endif
-  Data += argsize;
-  Size -= argsize;
-
-#if FMT_FUZZ_SEPARATE_ALLOCATION
-  // allocates as tight as possible, making it easier to catch buffer overruns.
-  std::vector<char> fmtstringbuffer(Size);
-  std::memcpy(fmtstringbuffer.data(), Data, Size);
-  auto fmtstring = fmt::string_view(fmtstringbuffer.data(), Size);
-#else
-  auto fmtstring = fmt::string_view(fmt_fuzzer::as_chars(Data), Size);
-#endif
-
-#if FMT_FUZZ_FORMAT_TO_STRING
-  std::string message = fmt::format(fmtstring, fmt::arg(argname, item1));
-#else
-  fmt::memory_buffer outbuf;
-  fmt::format_to(outbuf, fmtstring, fmt::arg(argname, item1));
-#endif
-}
-
-// for dynamic dispatching to an explicit instantiation
-template <typename Callback> void invoke(int index, Callback callback) {
-  switch (index) {
-  case 0:
-    callback(bool{});
-    break;
-  case 1:
-    callback(char{});
-    break;
-  case 2:
-    using sc = signed char;
-    callback(sc{});
-    break;
-  case 3:
-    using uc = unsigned char;
-    callback(uc{});
-    break;
-  case 4:
-    callback(short{});
-    break;
-  case 5:
-    using us = unsigned short;
-    callback(us{});
-    break;
-  case 6:
-    callback(int{});
-    break;
-  case 7:
-    callback(unsigned{});
-    break;
-  case 8:
-    callback(long{});
-    break;
-  case 9:
-    using ul = unsigned long;
-    callback(ul{});
-    break;
-  case 10:
-    callback(float{});
-    break;
-  case 11:
-    callback(double{});
-    break;
-  case 12:
-    using LD = long double;
-    callback(LD{});
-    break;
-  }
-}
-
-extern "C" int LLVMFuzzerTestOneInput(const uint8_t* Data, size_t Size) {
-  if (Size <= 3) {
-    return 0;
-  }
-
-  // switch types depending on the first byte of the input
-  const auto first = Data[0] & 0x0F;
-  const unsigned int second = (Data[0] & 0xF0) >> 4;
-  Data++;
-  Size--;
-
-  auto outerfcn = [=](auto param1) {
-    invoke_fmt<decltype(param1)>(Data, Size, second);
-  };
-
-  try {
-    invoke(first, outerfcn);
-  } catch (std::exception& /*e*/) {
-  }
-  return 0;
-}

test/fuzzing/one-arg.cc

@@ -0,0 +1,91 @@
+// Copyright (c) 2019, Paul Dreik
+// For the license information refer to format.h.
+
+#include <cstdint>
+#include <exception>
+#include <fmt/chrono.h>
+
+#include "fuzzer-common.h"
+
+template <typename T, typename Repr>
+const T* from_repr(const Repr& r) { return &r; }
+
+template <>
+const std::tm* from_repr<std::tm>(const std::time_t& t) {
+  return std::localtime(&t);
+}
+
+template <typename T, typename Repr = T>
+void invoke_fmt(const uint8_t* data, size_t size) {
+  static_assert(sizeof(Repr) <= fixed_size, "Nfixed is too small");
+  if (size <= fixed_size) return;
+  auto repr = assign_from_buf<Repr>(data);
+  const T* value = from_repr<T>(repr);
+  if (!value) return;
+  data += fixed_size;
+  size -= fixed_size;
+  data_to_string format_str(data, size);
+  try {
+#if FMT_FUZZ_FORMAT_TO_STRING
+    std::string message = fmt::format(format_str.get(), *value);
+#else
+    fmt::memory_buffer message;
+    fmt::format_to(message, format_str.get(), *value);
+#endif
+  } catch (std::exception&) {
+  }
+}
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+  if (size <= 3) return 0;
+
+  const auto first = data[0];
+  data++;
+  size--;
+
+  switch (first) {
+  case 0:
+    invoke_fmt<bool>(data, size);
+    break;
+  case 1:
+    invoke_fmt<char>(data, size);
+    break;
+  case 2:
+    invoke_fmt<unsigned char>(data, size);
+    break;
+  case 3:
+    invoke_fmt<signed char>(data, size);
+    break;
+  case 4:
+    invoke_fmt<short>(data, size);
+    break;
+  case 5:
+    invoke_fmt<unsigned short>(data, size);
+    break;
+  case 6:
+    invoke_fmt<int>(data, size);
+    break;
+  case 7:
+    invoke_fmt<unsigned int>(data, size);
+    break;
+  case 8:
+    invoke_fmt<long>(data, size);
+    break;
+  case 9:
+    invoke_fmt<unsigned long>(data, size);
+    break;
+  case 10:
+    invoke_fmt<float>(data, size);
+    break;
+  case 11:
+    invoke_fmt<double>(data, size);
+    break;
+  case 12:
+    invoke_fmt<long double>(data, size);
+    break;
+  case 13:
+    invoke_fmt<std::tm, std::time_t>(data, size);
+    break;
+  }
+  return 0;
+}

test/fuzzing/one_arg.cpp

@@ -1,131 +0,0 @@
-// Copyright (c) 2019, Paul Dreik
-// License: see LICENSE.rst in the fmt root directory
-
-#include <fmt/core.h>
-#include <cstdint>
-#include <stdexcept>
-#include <type_traits>
-#include <vector>
-
-#include <fmt/chrono.h>
-#include "fuzzer_common.h"
-
-using fmt_fuzzer::Nfixed;
-
-template <typename Item>
-void invoke_fmt(const uint8_t* Data, size_t Size) {
-  constexpr auto N = sizeof(Item);
-  static_assert(N <= Nfixed, "Nfixed is too small");
-  if (Size <= Nfixed) {
-    return;
-  }
-  const Item item = fmt_fuzzer::assignFromBuf<Item>(Data);
-  Data += Nfixed;
-  Size -= Nfixed;
-
-#if FMT_FUZZ_SEPARATE_ALLOCATION
-  // allocates as tight as possible, making it easier to catch buffer overruns.
-  std::vector<char> fmtstringbuffer(Size);
-  std::memcpy(fmtstringbuffer.data(), Data, Size);
-  auto fmtstring = fmt::string_view(fmtstringbuffer.data(), Size);
-#else
-  auto fmtstring = fmt::string_view(fmt_fuzzer::as_chars(Data), Size);
-#endif
-
-#if FMT_FUZZ_FORMAT_TO_STRING
-  std::string message = fmt::format(fmtstring, item);
-#else
-  fmt::memory_buffer message;
-  fmt::format_to(message, fmtstring, item);
-#endif
-}
-
-void invoke_fmt_time(const uint8_t* Data, size_t Size) {
-  using Item = std::time_t;
-  constexpr auto N = sizeof(Item);
-  static_assert(N <= Nfixed, "Nfixed too small");
-  if (Size <= Nfixed) {
-    return;
-  }
-  const Item item = fmt_fuzzer::assignFromBuf<Item>(Data);
-  Data += Nfixed;
-  Size -= Nfixed;
-#if FMT_FUZZ_SEPARATE_ALLOCATION
-  // allocates as tight as possible, making it easier to catch buffer overruns.
-  std::vector<char> fmtstringbuffer(Size);
-  std::memcpy(fmtstringbuffer.data(), Data, Size);
-  auto fmtstring = fmt::string_view(fmtstringbuffer.data(), Size);
-#else
-  auto fmtstring = fmt::string_view(fmt_fuzzer::as_chars(Data), Size);
-#endif
-  auto* b = std::localtime(&item);
-  if (b) {
-#if FMT_FUZZ_FORMAT_TO_STRING
-    std::string message = fmt::format(fmtstring, *b);
-#else
-    fmt::memory_buffer message;
-    fmt::format_to(message, fmtstring, *b);
-#endif
-  }
-}
-
-extern "C" int LLVMFuzzerTestOneInput(const uint8_t* Data, size_t Size) {
-  if (Size <= 3) {
-    return 0;
-  }
-
-  const auto first = Data[0];
-  Data++;
-  Size--;
-
-  try {
-    switch (first) {
-    case 0:
-      invoke_fmt<bool>(Data, Size);
-      break;
-    case 1:
-      invoke_fmt<char>(Data, Size);
-      break;
-    case 2:
-      invoke_fmt<unsigned char>(Data, Size);
-      break;
-    case 3:
-      invoke_fmt<signed char>(Data, Size);
-      break;
-    case 4:
-      invoke_fmt<short>(Data, Size);
-      break;
-    case 5:
-      invoke_fmt<unsigned short>(Data, Size);
-      break;
-    case 6:
-      invoke_fmt<int>(Data, Size);
-      break;
-    case 7:
-      invoke_fmt<unsigned int>(Data, Size);
-      break;
-    case 8:
-      invoke_fmt<long>(Data, Size);
-      break;
-    case 9:
-      invoke_fmt<unsigned long>(Data, Size);
-      break;
-    case 10:
-      invoke_fmt<float>(Data, Size);
-      break;
-    case 11:
-      invoke_fmt<double>(Data, Size);
-      break;
-    case 12:
-      invoke_fmt<long double>(Data, Size);
-      break;
-    case 13:
-      invoke_fmt_time(Data, Size);
-      break;
-    default:
-      break;
-    }
-  } catch (std::exception& /*e*/) {
-  }
-  return 0;
-}

test/fuzzing/sprintf.cpp

@@ -1,116 +0,0 @@
-// Copyright (c) 2019, Paul Dreik
-// License: see LICENSE.rst in the fmt root directory
-#include <fmt/format.h>
-#include <fmt/printf.h>
-#include <cstdint>
-#include <stdexcept>
-
-#include "fuzzer_common.h"
-
-using fmt_fuzzer::Nfixed;
-
-template <typename Item1, typename Item2>
-void invoke_fmt(const uint8_t* Data, size_t Size) {
-  constexpr auto N1 = sizeof(Item1);
-  constexpr auto N2 = sizeof(Item2);
-  static_assert(N1 <= Nfixed, "size1 exceeded");
-  static_assert(N2 <= Nfixed, "size2 exceeded");
-  if (Size <= Nfixed + Nfixed) {
-    return;
-  }
-  Item1 item1 = fmt_fuzzer::assignFromBuf<Item1>(Data);
-  Data += Nfixed;
-  Size -= Nfixed;
-
-  Item2 item2 = fmt_fuzzer::assignFromBuf<Item2>(Data);
-  Data += Nfixed;
-  Size -= Nfixed;
-
-  auto fmtstring = fmt::string_view(fmt_fuzzer::as_chars(Data), Size);
-
-#if FMT_FUZZ_FORMAT_TO_STRING
-  std::string message = fmt::format(fmtstring, item1, item2);
-#else
-  fmt::memory_buffer message;
-  fmt::format_to(message, fmtstring, item1, item2);
-#endif
-}
-
-// for dynamic dispatching to an explicit instantiation
-template <typename Callback> void invoke(int index, Callback callback) {
-  switch (index) {
-  case 0:
-    callback(bool{});
-    break;
-  case 1:
-    callback(char{});
-    break;
-  case 2:
-    using sc = signed char;
-    callback(sc{});
-    break;
-  case 3:
-    using uc = unsigned char;
-    callback(uc{});
-    break;
-  case 4:
-    callback(short{});
-    break;
-  case 5:
-    using us = unsigned short;
-    callback(us{});
-    break;
-  case 6:
-    callback(int{});
-    break;
-  case 7:
-    callback(unsigned{});
-    break;
-  case 8:
-    callback(long{});
-    break;
-  case 9:
-    using ul = unsigned long;
-    callback(ul{});
-    break;
-  case 10:
-    callback(float{});
-    break;
-  case 11:
-    callback(double{});
-    break;
-  case 12:
-    using LD = long double;
-    callback(LD{});
-    break;
-  case 13:
-    using ptr = void*;
-    callback(ptr{});
-    break;
-  }
-}
-
-extern "C" int LLVMFuzzerTestOneInput(const uint8_t* Data, size_t Size) {
-  if (Size <= 3) {
-    return 0;
-  }
-
-  // switch types depending on the first byte of the input
-  const auto first = Data[0] & 0x0F;
-  const auto second = (Data[0] & 0xF0) >> 4;
-  Data++;
-  Size--;
-
-  auto outer = [=](auto param1) {
-    auto inner = [=](auto param2) {
-      invoke_fmt<decltype(param1), decltype(param2)>(Data, Size);
-    };
-    invoke(second, inner);
-  };
-
-  try {
-    invoke(first, outer);
-  } catch (std::exception& /*e*/) {
-  }
-  return 0;
-}

test/fuzzing/two-args.cc

@@ -0,0 +1,105 @@
+// Copyright (c) 2019, Paul Dreik
+// For the license information refer to format.h.
+
+#include <cstdint>
+#include <exception>
+#include <string>
+#include <fmt/format.h>
+
+#include "fuzzer-common.h"
+
+template <typename Item1, typename Item2>
+void invoke_fmt(const uint8_t* data, size_t size) {
+  static_assert(sizeof(Item1) <= fixed_size, "size1 exceeded");
+  static_assert(sizeof(Item2) <= fixed_size, "size2 exceeded");
+  if (size <= fixed_size + fixed_size) return;
+
+  const Item1 item1 = assign_from_buf<Item1>(data);
+  data += fixed_size;
+  size -= fixed_size;
+
+  const Item2 item2 = assign_from_buf<Item2>(data);
+  data += fixed_size;
+  size -= fixed_size;
+
+  auto format_str = fmt::string_view(as_chars(data), size);
+#if FMT_FUZZ_FORMAT_TO_STRING
+  std::string message = fmt::format(format_str, item1, item2);
+#else
+  fmt::memory_buffer message;
+  fmt::format_to(message, format_str, item1, item2);
+#endif
+}
+
+// For dynamic dispatching to an explicit instantiation.
+template <typename Callback> void invoke(int index, Callback callback) {
+  switch (index) {
+  case 0:
+    callback(bool());
+    break;
+  case 1:
+    callback(char());
+    break;
+  case 2:
+    using sc = signed char;
+    callback(sc());
+    break;
+  case 3:
+    using uc = unsigned char;
+    callback(uc());
+    break;
+  case 4:
+    callback(short());
+    break;
+  case 5:
+    using us = unsigned short;
+    callback(us());
+    break;
+  case 6:
+    callback(int());
+    break;
+  case 7:
+    callback(unsigned());
+    break;
+  case 8:
+    callback(long());
+    break;
+  case 9:
+    using ul = unsigned long;
+    callback(ul());
+    break;
+  case 10:
+    callback(float());
+    break;
+  case 11:
+    callback(double());
+    break;
+  case 12:
+    using LD = long double;
+    callback(LD());
+    break;
+  case 13:
+    using ptr = void*;
+    callback(ptr());
+    break;
+  }
+}
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+  if (size <= 3) return 0;
+
+  // Switch types depending on the first byte of the input.
+  const auto type1 = data[0] & 0x0F;
+  const auto type2 = (data[0] & 0xF0) >> 4;
+  data++;
+  size--;
+  try {
+    invoke(type1, [=](auto param1) {
+      invoke(type2, [=](auto param2) {
+        invoke_fmt<decltype(param1), decltype(param2)>(data, size);
+      });
+    });
+  } catch (std::exception&) {
+  }
+  return 0;
+}

test/fuzzing/two_args.cpp

@@ -1,112 +0,0 @@
-// Copyright (c) 2019, Paul Dreik
-// License: see LICENSE.rst in the fmt root directory
-#include <fmt/format.h>
-#include <cstdint>
-#include <stdexcept>
-#include <type_traits>
-
-#include "fuzzer_common.h"
-
-constexpr auto Nfixed = fmt_fuzzer::Nfixed;
-
-template <typename Item1, typename Item2>
-void invoke_fmt(const uint8_t* Data, size_t Size) {
-  constexpr auto N1 = sizeof(Item1);
-  constexpr auto N2 = sizeof(Item2);
-  static_assert(N1 <= Nfixed, "size1 exceeded");
-  static_assert(N2 <= Nfixed, "size2 exceeded");
-  if (Size <= Nfixed + Nfixed) {
-    return;
-  }
-  const Item1 item1 = fmt_fuzzer::assignFromBuf<Item1>(Data);
-  Data += Nfixed;
-  Size -= Nfixed;
-
-  const Item2 item2 = fmt_fuzzer::assignFromBuf<Item2>(Data);
-  Data += Nfixed;
-  Size -= Nfixed;
-
-  auto fmtstring = fmt::string_view(fmt_fuzzer::as_chars(Data), Size);
-
-#if FMT_FUZZ_FORMAT_TO_STRING
-  std::string message = fmt::format(fmtstring, item1, item2);
-#else
-  fmt::memory_buffer message;
-  fmt::format_to(message, fmtstring, item1, item2);
-#endif
-}
-
-// for dynamic dispatching to an explicit instantiation
-template <typename Callback> void invoke(int index, Callback callback) {
-  switch (index) {
-  case 0:
-    callback(bool{});
-    break;
-  case 1:
-    callback(char{});
-    break;
-  case 2:
-    using sc = signed char;
-    callback(sc{});
-    break;
-  case 3:
-    using uc = unsigned char;
-    callback(uc{});
-    break;
-  case 4:
-    callback(short{});
-    break;
-  case 5:
-    using us = unsigned short;
-    callback(us{});
-    break;
-  case 6:
-    callback(int{});
-    break;
-  case 7:
-    callback(unsigned{});
-    break;
-  case 8:
-    callback(long{});
-    break;
-  case 9:
-    using ul = unsigned long;
-    callback(ul{});
-    break;
-  case 10:
-    callback(float{});
-    break;
-  case 11:
-    callback(double{});
-    break;
-  case 12:
-    using LD = long double;
-    callback(LD{});
-    break;
-  }
-}
-
-extern "C" int LLVMFuzzerTestOneInput(const uint8_t* Data, size_t Size) {
-  if (Size <= 3) {
-    return 0;
-  }
-
-  // switch types depending on the first byte of the input
-  const auto first = Data[0] & 0x0F;
-  const auto second = (Data[0] & 0xF0) >> 4;
-  Data++;
-  Size--;
-
-  auto outer = [=](auto param1) {
-    auto inner = [=](auto param2) {
-      invoke_fmt<decltype(param1), decltype(param2)>(Data, Size);
-    };
-    invoke(second, inner);
-  };
-
-  try {
-    invoke(first, outer);
-  } catch (std::exception& /*e*/) {
-  }
-  return 0;
-}

test/grisu-test.cc

@@ -1,75 +0,0 @@
-// Formatting library for C++ - Grisu tests
-//
-// Copyright (c) 2012 - present, Victor Zverovich
-// All rights reserved.
-//
-// For the license information refer to format.h.
-
-#include "fmt/format.h"
-#include "gtest.h"
-
-static bool reported_skipped;
-
-#undef TEST
-#define TEST(test_fixture, test_name)        \
-  void test_fixture##test_name();            \
-  GTEST_TEST(test_fixture, test_name) {      \
-    if (FMT_USE_GRISU) {                     \
-      test_fixture##test_name();             \
-    } else if (!reported_skipped) {          \
-      reported_skipped = true;               \
-      fmt::print("Skipping Grisu tests.\n"); \
-    }                                        \
-  }                                          \
-  void test_fixture##test_name()
-
-TEST(GrisuTest, NaN) {
-  auto nan = std::numeric_limits<double>::quiet_NaN();
-  EXPECT_EQ("nan", fmt::format("{}", nan));
-  EXPECT_EQ("-nan", fmt::format("{}", -nan));
-}
-
-TEST(GrisuTest, Inf) {
-  auto inf = std::numeric_limits<double>::infinity();
-  EXPECT_EQ("inf", fmt::format("{}", inf));
-  EXPECT_EQ("-inf", fmt::format("{}", -inf));
-}
-
-TEST(GrisuTest, Zero) { EXPECT_EQ("0.0", fmt::format("{}", 0.0)); }
-
-TEST(GrisuTest, Round) {
-  EXPECT_EQ("1.9156918820264798e-56",
-            fmt::format("{}", 1.9156918820264798e-56));
-  EXPECT_EQ("0.0000", fmt::format("{:.4f}", 7.2809479766055470e-15));
-}
-
-TEST(GrisuTest, Prettify) {
-  EXPECT_EQ("0.0001", fmt::format("{}", 1e-4));
-  EXPECT_EQ("1e-05", fmt::format("{}", 1e-5));
-  EXPECT_EQ("9.999e-05", fmt::format("{}", 9.999e-5));
-  EXPECT_EQ("10000000000.0", fmt::format("{}", 1e10));
-  EXPECT_EQ("100000000000.0", fmt::format("{}", 1e11));
-  EXPECT_EQ("12340000000.0", fmt::format("{}", 1234e7));
-  EXPECT_EQ("12.34", fmt::format("{}", 1234e-2));
-  EXPECT_EQ("0.001234", fmt::format("{}", 1234e-6));
-  EXPECT_EQ("0.1", fmt::format("{}", 0.1f));
-  EXPECT_EQ("0.10000000149011612", fmt::format("{}", double(0.1f)));
-}
-
-TEST(GrisuTest, ZeroPrecision) { EXPECT_EQ("1", fmt::format("{:.0}", 1.0)); }
-
-TEST(GrisuTest, Fallback) {
-  EXPECT_EQ("1e+23", fmt::format("{}", 1e23));
-  EXPECT_EQ("9e-265", fmt::format("{}", 9e-265));
-  EXPECT_EQ("5.423717798060526e+125",
-            fmt::format("{}", 5.423717798060526e+125));
-  EXPECT_EQ("1.372371880954233e-288",
-            fmt::format("{}", 1.372371880954233e-288));
-  EXPECT_EQ("55388492.622190244", fmt::format("{}", 55388492.622190244));
-  EXPECT_EQ("2.2506787569811123e-253",
-            fmt::format("{}", 2.2506787569811123e-253));
-  EXPECT_EQ("1103618912042992.8", fmt::format("{}", 1103618912042992.8));
-  // pow(2, -25) - assymetric boundaries:
-  EXPECT_EQ("2.9802322387695312e-08",
-            fmt::format("{}", 2.9802322387695312e-08));
-}

test/gtest-extra.h

@@ -145,7 +145,13 @@ std::string read(fmt::file& f, size_t count);
               read(file, fmt::string_view(expected_content).size()))
 
 #else
-#  define EXPECT_WRITE(file, statement, expected_output) SUCCEED()
+#  define EXPECT_WRITE(file, statement, expected_output) \
+    do {                                                 \
+      (void)(file);                                      \
+      (void)(statement);                                 \
+      (void)(expected_output);                           \
+      SUCCEED();                                         \
+    } while (false)
 #endif  // FMT_USE_FCNTL
 
 template <typename Mock> struct ScopedMock : testing::StrictMock<Mock> {

test/locale-test.cc

@@ -7,6 +7,8 @@
 
 #include "fmt/locale.h"
 
+#include <complex>
+
 #include "gmock.h"
 
 using fmt::detail::max_value;
@@ -50,6 +52,7 @@ TEST(LocaleTest, Format) {
   EXPECT_EQ("1234567", fmt::format(std::locale(), "{:L}", 1234567));
   EXPECT_EQ("1~234~567", fmt::format(loc, "{:L}", 1234567));
   EXPECT_EQ("-1~234~567", fmt::format(loc, "{:L}", -1234567));
+  EXPECT_EQ("-256", fmt::format(loc, "{:L}", -256));
   fmt::format_arg_store<fmt::format_context, int> as{1234567};
   EXPECT_EQ("1~234~567", fmt::vformat(loc, "{:L}", fmt::format_args(as)));
   std::string s;
@@ -61,12 +64,18 @@ TEST(LocaleTest, Format) {
 
   std::locale special_grouping_loc(std::locale(), new special_grouping<char>());
   EXPECT_EQ("1,23,45,678", fmt::format(special_grouping_loc, "{:L}", 12345678));
+  EXPECT_EQ("12,345", fmt::format(special_grouping_loc, "{:L}", 12345));
 
   std::locale small_grouping_loc(std::locale(), new small_grouping<char>());
   EXPECT_EQ("4,2,9,4,9,6,7,2,9,5",
             fmt::format(small_grouping_loc, "{:L}", max_value<uint32_t>()));
 }
 
+TEST(LocaleTest, FormatDetaultAlign) {
+  std::locale special_grouping_loc(std::locale(), new special_grouping<char>());
+  EXPECT_EQ("  12,345", fmt::format(special_grouping_loc, "{:8L}", 12345));
+}
+
 TEST(LocaleTest, WFormat) {
   std::locale loc(std::locale(), new numpunct<wchar_t>());
   EXPECT_EQ(L"1234567", fmt::format(std::locale(), L"{:L}", 1234567));
@@ -88,4 +97,64 @@ TEST(LocaleTest, WFormat) {
             fmt::format(small_grouping_loc, L"{:L}", max_value<uint32_t>()));
 }
 
+TEST(LocaleTest, DoubleFormatter) {
+  auto loc = std::locale(std::locale(), new special_grouping<char>());
+  auto f = fmt::formatter<int>();
+  auto parse_ctx = fmt::format_parse_context("L");
+  f.parse(parse_ctx);
+  char buf[10] = {};
+  fmt::basic_format_context<char*, char> format_ctx(
+      buf, {}, fmt::detail::locale_ref(loc));
+  *f.format(12345, format_ctx) = 0;
+  EXPECT_STREQ("12,345", buf);
+}
+
+FMT_BEGIN_NAMESPACE
+template <class charT> struct formatter<std::complex<double>, charT> {
+ private:
+  detail::dynamic_format_specs<char> specs_;
+
+ public:
+  typename basic_format_parse_context<charT>::iterator parse(
+      basic_format_parse_context<charT>& ctx) {
+    using handler_type =
+        detail::dynamic_specs_handler<basic_format_parse_context<charT>>;
+    detail::specs_checker<handler_type> handler(handler_type(specs_, ctx),
+                                                detail::type::string_type);
+    auto it = parse_format_specs(ctx.begin(), ctx.end(), handler);
+    detail::parse_float_type_spec(specs_, ctx.error_handler());
+    return it;
+  }
+
+  template <class FormatContext>
+  typename FormatContext::iterator format(const std::complex<double>& c,
+                                          FormatContext& ctx) {
+    detail::handle_dynamic_spec<detail::precision_checker>(
+        specs_.precision, specs_.precision_ref, ctx);
+    auto format_specs = std::string();
+    if (specs_.precision > 0)
+      format_specs = fmt::format(".{}", specs_.precision);
+    if (specs_.type)
+      format_specs += specs_.type;
+    auto real = fmt::format(ctx.locale().template get<std::locale>(),
+                            "{:" + format_specs + "}", c.real());
+    auto imag = fmt::format(ctx.locale().template get<std::locale>(),
+                            "{:" + format_specs + "}", c.imag());
+    auto fill_align_width = std::string();
+    if (specs_.width > 0)
+      fill_align_width = fmt::format(">{}", specs_.width);
+    return format_to(
+        ctx.out(), "{:" + fill_align_width + "}",
+        fmt::format(c.real() != 0 ? "({0}+{1}i)" : "{1}i", real, imag));
+  }
+};
+FMT_END_NAMESPACE
+
+TEST(FormatTest, Complex) {
+  std::string s = fmt::format("{}", std::complex<double>(1, 2));
+  EXPECT_EQ(s, "(1+2i)");
+  EXPECT_EQ(fmt::format("{:.2f}", std::complex<double>(1, 2)), "(1.00+2.00i)");
+  EXPECT_EQ(fmt::format("{:8}", std::complex<double>(1, 2)), "  (1+2i)");
+}
+
 #endif  // FMT_STATIC_THOUSANDS_SEPARATOR

test/os-test.cc

@@ -81,9 +81,9 @@ TEST(UtilTest, FormatWindowsError) {
   EXPECT_EQ(fmt::format("test: {}", utf8_message.str()),
             fmt::to_string(actual_message));
   actual_message.resize(0);
-  auto max_size = fmt::detail::max_value<size_t>();
+  auto max_size = fmt::detail::max_value<size_t>() / 2;
   fmt::detail::format_windows_error(actual_message, ERROR_FILE_EXISTS,
-                                    fmt::string_view(0, max_size));
+                                    fmt::string_view(nullptr, max_size));
   EXPECT_EQ(fmt::format("error {}", ERROR_FILE_EXISTS),
             fmt::to_string(actual_message));
 }
@@ -287,26 +287,38 @@ TEST(BufferedFileTest, Fileno) {
   EXPECT_READ(copy, FILE_CONTENT);
 }
 
-TEST(DirectBufferedFileTest, Print) {
-  fmt::direct_buffered_file out(
-    "test-file", fmt::file::WRONLY | fmt::file::CREATE);
-  fmt::print(out, "The answer is {}.\n", 42);
+TEST(OStreamTest, Move) {
+  fmt::ostream out = fmt::output_file("test-file");
+  fmt::ostream moved(std::move(out));
+  moved.print("hello");
+}
+
+TEST(OStreamTest, Print) {
+  fmt::ostream out = fmt::output_file("test-file");
+  out.print("The answer is {}.\n", 42);
   out.close();
   file in("test-file", file::RDONLY);
   EXPECT_READ(in, "The answer is 42.\n");
 }
 
-TEST(DirectBufferedFileTest, BufferBoundary) {
+TEST(OStreamTest, BufferBoundary) {
   auto str = std::string(4096, 'x');
-  fmt::direct_buffered_file out(
-    "test-file", fmt::file::WRONLY | fmt::file::CREATE);
-  fmt::print(out, "{}", str);
-  fmt::print(out, "{}", str);
+  fmt::ostream out = fmt::output_file("test-file");
+  out.print("{}", str);
+  out.print("{}", str);
   out.close();
   file in("test-file", file::RDONLY);
   EXPECT_READ(in, str + str);
 }
 
+TEST(OStreamTest, BufferSize) {
+  fmt::ostream out = fmt::output_file("test-file", fmt::buffer_size=1);
+  out.print("{}", "foo");
+  out.close();
+  file in("test-file", file::RDONLY);
+  EXPECT_READ(in, "foo");
+}
+
 TEST(FileTest, DefaultCtor) {
   file f;
   EXPECT_EQ(-1, f.descriptor());

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(
@@ -150,8 +150,9 @@ TEST(OStreamTest, WriteToOStreamMaxSize) {
   std::streamsize max_streamsize = fmt::detail::max_value<std::streamsize>();
   if (max_size <= fmt::detail::to_unsigned(max_streamsize)) return;
 
-  struct test_buffer : fmt::detail::buffer<char> {
-    explicit test_buffer(size_t size) { resize(size); }
+  struct test_buffer final : fmt::detail::buffer<char> {
+    explicit test_buffer(size_t size)
+      : fmt::detail::buffer<char>(nullptr, size, size) {}
     void grow(size_t) {}
   } buffer(max_size);
 
@@ -289,9 +290,20 @@ std::ostream& operator<<(std::ostream& os,
 TEST(OStreamTest, FormatExplicitlyConvertibleToStdStringView) {
   EXPECT_EQ("bar", fmt::format("{}", explicitly_convertible_to_string_like()));
 }
-
 #endif  // FMT_USE_STRING_VIEW
 
+struct streamable_and_convertible_to_bool {
+  operator bool() const { return true; }
+};
+
+std::ostream& operator<<(std::ostream& os, streamable_and_convertible_to_bool) {
+  return os << "foo";
+}
+
+TEST(OStreamTest, FormatConvertibleToBool) {
+  EXPECT_EQ("foo", fmt::format("{}", streamable_and_convertible_to_bool()));
+}
+
 struct copyfmt_test {};
 
 std::ostream& operator<<(std::ostream& os, copyfmt_test) {
@@ -307,3 +319,7 @@ TEST(OStreamTest, CopyFmt) {
 TEST(OStreamTest, CompileTimeString) {
   EXPECT_EQ("42", fmt::format(FMT_STRING("{}"), 42));
 }
+
+TEST(OStreamTest, ToString) {
+  EXPECT_EQ("ABC", fmt::to_string(fmt_test::ABC()));
+}

test/ranges-test.cc

@@ -54,7 +54,7 @@ TEST(RangesTest, FormatTuple) {
 TEST(RangesTest, JoinTuple) {
   // Value tuple args
   std::tuple<char, int, float> t1 = std::make_tuple('a', 1, 2.0f);
-  EXPECT_EQ("(a, 1, 2.0)", fmt::format("({})", fmt::join(t1, ", ")));
+  EXPECT_EQ("(a, 1, 2)", fmt::format("({})", fmt::join(t1, ", ")));
 
   // Testing lvalue tuple args
   int x = 4;
@@ -67,7 +67,7 @@ TEST(RangesTest, JoinTuple) {
 
   // Single element tuple
   std::tuple<float> t4{4.0f};
-  EXPECT_EQ("4.0", fmt::format("{}", fmt::join(t4, "/")));
+  EXPECT_EQ("4", fmt::format("{}", fmt::join(t4, "/")));
 }
 
 TEST(RangesTest, JoinInitializerList) {
@@ -141,15 +141,63 @@ TEST(RangesTest, FormatStringLike) {
 #endif  // FMT_USE_STRING_VIEW
 
 struct zstring_sentinel {};
+
 bool operator==(const char* p, zstring_sentinel) { return *p == '\0'; }
 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 {}; }
 };
+
 TEST(RangesTest, JoinSentinel) {
   zstring hello{"hello"};
   EXPECT_EQ("{'h', 'e', 'l', 'l', 'o'}", fmt::format("{}", hello));
   EXPECT_EQ("h_e_l_l_o", fmt::format("{}", fmt::join(hello, "_")));
 }
+
+// A range that provides non-const only begin()/end() to test fmt::join handles
+// that
+//
+// Some ranges (eg those produced by range-v3's views::filter()) can cache
+// information during iteration so they only provide non-const begin()/end().
+template <typename T> class non_const_only_range {
+ private:
+  std::vector<T> vec;
+
+ public:
+  using const_iterator = typename ::std::vector<T>::const_iterator;
+
+  template <typename... Args>
+  explicit non_const_only_range(Args&&... args)
+      : vec(::std::forward<Args>(args)...) {}
+
+  const_iterator begin() { return vec.begin(); }
+  const_iterator end() { return vec.end(); }
+};
+
+TEST(RangesTest, JoinRange) {
+  non_const_only_range<int> x(3u, 0);
+  EXPECT_EQ("0,0,0", fmt::format("{}", fmt::join(x, ",")));
+  EXPECT_EQ(
+      "0,0,0",
+      fmt::format("{}", fmt::join(non_const_only_range<int>(3u, 0), ",")));
+
+  std::vector<int> y(3u, 0);
+  EXPECT_EQ("0,0,0", fmt::format("{}", fmt::join(y, ",")));
+  EXPECT_EQ("0,0,0",
+            fmt::format("{}", fmt::join(std::vector<int>(3u, 0), ",")));
+
+  const std::vector<int> z(3u, 0);
+  EXPECT_EQ("0,0,0", fmt::format("{}", fmt::join(z, ",")));
+}
+
+#if !FMT_MSC_VER || FMT_MSC_VER >= 1927
+struct unformattable {};
+
+TEST(RangesTest, UnformattableRange) {
+  EXPECT_FALSE((fmt::has_formatter<std::vector<unformattable>,
+                                   fmt::format_context>::value));
+}
+#endif