diff --git a/CMakeLists.txt b/CMakeLists.txt
index b08f9cbe..d99babdb 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2,6 +2,14 @@ message(STATUS "CMake version: ${CMAKE_VERSION}")
 
 cmake_minimum_required(VERSION 2.8.12)
 
+if (POLICY CMP0048) # Version variables
+  cmake_policy(SET CMP0048 OLD)
+endif ()
+
+if (POLICY CMP0063) # Visibility
+  cmake_policy(SET CMP0063 OLD)
+endif (POLICY CMP0063)
+
 # Determine if fmt is built as a subproject (using add_subdirectory)
 # or if it is the master project.
 set(MASTER_PROJECT OFF)
diff --git a/ChangeLog.rst b/ChangeLog.rst
index 4a16be95..ce0406a9 100644
--- a/ChangeLog.rst
+++ b/ChangeLog.rst
@@ -1,7 +1,32 @@
+4.1.0 - 2017-12-20
+------------------
+
+* Added ``fmt::to_wstring()`` in addition to ``fmt::to_string()`` (`#559 <https://github.com/fmtlib/fmt/pull/559>`_). Thanks `@alabuzhev (Alex Alabuzhev) <https://github.com/alabuzhev>`_.
+
+* Added support for C++17 ``std::string_view`` (`#571 <https://github.com/fmtlib/fmt/pull/571>`_ and `#578 <https://github.com/fmtlib/fmt/pull/578>`_). Thanks `@thelostt (Mário Feroldi) <https://github.com/thelostt>`_ and `@mwinterb <https://github.com/mwinterb>`_.
+
+* Enabled stream exceptions to catch errors (`#581 <https://github.com/fmtlib/fmt/issues/581>`_). Thanks `@crusader-mike <https://github.com/crusader-mike>`_.
+
+* Allowed formatting of class hierarchies with ``fmt::format_arg()`` (`#547 <https://github.com/fmtlib/fmt/pull/547>`_). Thanks `@rollbear (Björn Fahller) <https://github.com/rollbear>`_.
+
+* Removed limitations on character types
+  (`#563 <https://github.com/fmtlib/fmt/pull/563>`_).
+  Thanks `@Yelnats321 (Elnar Dakeshov) <https://github.com/Yelnats321>`_.
+
+* Conditionally enabled use of ``std::allocator_traits`` (`#583 <https://github.com/fmtlib/fmt/pull/583>`_). Thanks `@mwinterb <https://github.com/mwinterb>`_.
+
+* Added support for ``const`` variadic member function emulation with ``FMT_VARIADIC_CONST`` (`#591 <https://github.com/fmtlib/fmt/pull/591>`_). Thanks `@ludekvodicka (Ludek Vodicka) <https://github.com/ludekvodicka>`_.
+
+* Various bugfixes: bad overflow check, unsupported implicit type conversion when determining formatting function, test segfaults (`#551 <https://github.com/fmtlib/fmt/issues/551>`_), ill-formed macros (`#542 <https://github.com/fmtlib/fmt/pull/542>`_) and ambiguous overloads (`#580 <https://github.com/fmtlib/fmt/issues/580>`_). Thanks `@xylosper (Byoung-young Lee) <https://github.com/xylosper>`_.
+
+* Prevented warnings on MSVC (`#605 <https://github.com/fmtlib/fmt/pull/605>`_, `#602 <https://github.com/fmtlib/fmt/pull/602>`_, and `#545 <https://github.com/fmtlib/fmt/pull/545>`_), clang (`#582 <https://github.com/fmtlib/fmt/pull/582>`_), GCC (`#573 <https://github.com/fmtlib/fmt/issues/573>`_), various conversion warnings (`#609 <https://github.com/fmtlib/fmt/pull/609>`_, `#567 <https://github.com/fmtlib/fmt/pull/567>`_, `#553 <https://github.com/fmtlib/fmt/pull/553>`_ and `#553 <https://github.com/fmtlib/fmt/pull/553>`_), and added ``override`` and ``[[noreturn]]`` (`#549 <https://github.com/fmtlib/fmt/pull/549>`_ and `#555 <https://github.com/fmtlib/fmt/issues/555>`_). Thanks `@alabuzhev (Alex Alabuzhev) <https://github.com/alabuzhev>`_, `@virgiliofornazin (Virgilio Alexandre Fornazin) <https://gihtub.com/virgiliofornazin>`_, `@alexanderbock (Alexander Bock) <https://github.com/alexanderbock>`_, `@yumetodo <https://github.com/yumetodo>`_, `@VaderY (Császár Mátyás) <https://github.com/VaderY>`_, `@jpcima (JP Cimalando) <https://github.com/jpcima>`_, `@thelostt (Mário Feroldi) <https://github.com/thelostt>`_, and `@Manu343726 (Manu Sánchez) <https://github.com/Manu343726>`_.
+
+* Improved CMake: Used GNUInstallDirs to set installation location (`#610 <https://github.com/fmtlib/fmt/pull/610>`_) and fixed warnings (`#536 <https://github.com/fmtlib/fmt/pull/536>`_ and `#556 <https://github.com/fmtlib/fmt/pull/556>`_). Thanks `@mikecrowe (Mike Crowe) <https://github.com/mikecrowe>`_, `@evgen231 <https://github.com/evgen231>`_ and `@henryiii (Henry Schreiner) <https://github.com/henryiii>`_.
+
 4.0.0 - 2017-06-27
 ------------------
 
-* Removed old compatibility headers ``cppformat/*.h`` and CMake options (`#527 <https://github.com/pull/527>`_). Thanks `@maddinat0r (Alex Martin) <https://github.com/maddinat0r>`_.
+* Removed old compatibility headers ``cppformat/*.h`` and CMake options (`#527 <https://github.com/fmtlib/fmt/pull/527>`_). Thanks `@maddinat0r (Alex Martin) <https://github.com/maddinat0r>`_.
 
 * Added ``string.h`` containing ``fmt::to_string()`` as alternative to ``std::to_string()`` as well as other string writer functionality (`#326 <https://github.com/fmtlib/fmt/issues/326>`_ and `#441 <https://github.com/fmtlib/fmt/pull/441>`_):
 
diff --git a/README.rst b/README.rst
index ea2a6da4..32f50257 100644
--- a/README.rst
+++ b/README.rst
@@ -142,6 +142,8 @@ Projects using this library
 
 * `Envoy <https://lyft.github.io/envoy/>`_: C++ L7 proxy and communication bus (Lyft)
 
+* `FiveM <https://fivem.net/>`_: a modification framework for GTA V
+
 * `HarpyWar/pvpgn <https://github.com/pvpgn/pvpgn-server>`_:
   Player vs Player Gaming Network with tweaks
 
@@ -155,6 +157,8 @@ Projects using this library
 
 * `MongoDB Smasher <https://github.com/duckie/mongo_smasher>`_: A small tool to generate randomized datasets
 
+* `OpenSpace <http://openspaceproject.com/>`_: An open-source astrovisualization framework
+
 * `PenUltima Online (POL) <http://www.polserver.com/>`_:
   An MMO server, compatible with most Ultima Online clients
 
diff --git a/doc/api.rst b/doc/api.rst
index 8dbef39e..9647c90b 100644
--- a/doc/api.rst
+++ b/doc/api.rst
@@ -84,6 +84,36 @@ Note in the example above the ``format_arg`` function ignores the contents of
 ``format_arg`` in :file:`fmt/time.h` for an advanced example of how to use
 the ``format_str`` argument to customize the formatted output.
 
+This technique can also be used for formatting class hierarchies::
+
+  namespace local {
+  struct Parent {
+    Parent(int p) : p(p) {}
+    virtual void write(fmt::Writer &w) const {
+      w.write("Parent : p={}", p);
+    }
+    int p;
+  };
+
+  struct Child : Parent {
+    Child(int c, int p) : Parent(p), c(c) {}
+    virtual void write(fmt::Writer &w) const {
+      w.write("Child c={} : ", c);
+      Parent::write(w);
+    }
+    int c;
+  };
+
+  void format_arg(fmt::BasicFormatter<char> &f,
+                  const char *&format_str, const Parent &p) {
+    p.write(f.writer());
+  }
+  }
+  Local::Child c(1,2);
+  Local::Parent &p = c;
+  fmt::print("via ref to base: {}\n", p);
+  fmt::print("direct to child: {}\n", c);
+
 This section shows how to define a custom format function for a user-defined
 type. The next section describes how to get ``fmt`` to use a conventional stream
 output ``operator<<`` when one is defined for a user-defined type.
@@ -232,6 +262,8 @@ Utilities
 
 .. doxygenfunction:: fmt::to_string(const T&)
 
+.. doxygenfunction:: fmt::to_wstring(const T&)
+
 .. doxygenclass:: fmt::BasicStringRef
    :members:
 
diff --git a/doc/build.py b/doc/build.py
index 55992b9f..cb8d0c3c 100755
--- a/doc/build.py
+++ b/doc/build.py
@@ -6,6 +6,8 @@ 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']
+
 def pip_install(package, commit=None, **kwargs):
   "Install package using pip."
   min_version = kwargs.get('min_version')
@@ -93,11 +95,11 @@ def build_docs(version='dev', **kwargs):
   if p.returncode != 0:
     raise CalledProcessError(p.returncode, cmd)
   html_dir = os.path.join(work_dir, 'html')
-  versions = ['3.0.0', '2.0.0', '1.1.0']
+  main_versions = reversed(versions[-3:])
   check_call(['sphinx-build',
               '-Dbreathe_projects.format=' + os.path.abspath(doxyxml_dir),
               '-Dversion=' + version, '-Drelease=' + version,
-              '-Aversion=' + version, '-Aversions=' + ','.join(versions),
+              '-Aversion=' + version, '-Aversions=' + ','.join(main_versions),
               '-b', 'html', doc_dir, html_dir])
   try:
     check_call(['lessc', '--clean-css',
diff --git a/doc/index.rst b/doc/index.rst
index ce9b7bf9..a00828b0 100644
--- a/doc/index.rst
+++ b/doc/index.rst
@@ -143,6 +143,12 @@ 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.
 
+Note that fmt does not use the value of the ``errno`` global to communicate
+errors to the user, but it may call system functions which set ``errno``. Since
+fmt does not attempt to preserve the value of ``errno``, users should not make
+any assumptions about it and always set it to ``0`` before making any system
+calls that convey error information via ``errno``.
+
 .. _portability:
 
 Portability
diff --git a/doc/syntax.rst b/doc/syntax.rst
index 1051467a..e6d2efeb 100644
--- a/doc/syntax.rst
+++ b/doc/syntax.rst
@@ -335,6 +335,16 @@ Aligning the text and specifying a width::
    format("{:*^30}", "centered");  // use '*' as a fill char
    // Result: "***********centered***********"
 
+Dynamic width::
+
+   format("{:<{}}", "left aligned", 30);
+   // Result: "left aligned                  "
+
+Dynamic precision::
+
+   format("{:.{}f}", 3.14, 1);
+   // Result: "3.1"
+
 Replacing ``%+f``, ``%-f``, and ``% f`` and specifying a sign::
 
    format("{:+f}; {:+f}", 3.14, -3.14);  // show it always
@@ -350,7 +360,7 @@ Replacing ``%x`` and ``%o`` and converting the value to different bases::
    // Result: "int: 42;  hex: 2a;  oct: 52; bin: 101010"
    // with 0x or 0 or 0b as prefix:
    format("int: {0:d};  hex: {0:#x};  oct: {0:#o};  bin: {0:#b}", 42);
-   // Result: "int: 42;  hex: 0x2a;  oct: 052;  bin: 0b101010"
+   // Result: "int: 42;  hex: 0x2a;  oct: 052;  bin: 0b101010"   
 
 .. ifconfig:: False
 
@@ -359,13 +369,6 @@ Replacing ``%x`` and ``%o`` and converting the value to different bases::
       format("{:,}", 1234567890);
       '1,234,567,890'
 
-   Expressing a percentage::
-
-      >>> points = 19
-      >>> total = 22
-      Format("Correct answers: {:.2%}") << points/total)
-      'Correct answers: 86.36%'
-
    Using type-specific formatting::
 
       >>> import datetime
diff --git a/doc/usage.rst b/doc/usage.rst
index dff312df..4c65f8ab 100644
--- a/doc/usage.rst
+++ b/doc/usage.rst
@@ -41,6 +41,10 @@ current directory. Now you can build the library by running :command:`make`.
 Once the library has been built you can invoke :command:`make test` to run
 the tests.
 
+You can control generation of the make ``test`` target with the ``FMT_TEST``
+CMake option. This can be useful if you include fmt as a subdirectory in
+your project but don't want to add fmt's tests to your ``test`` target.
+
 If you use Windows and have Visual Studio installed, a :file:`FORMAT.sln`
 file and several :file:`.vcproj` files will be created. You can then build them
 using Visual Studio or msbuild.
diff --git a/fmt/CMakeLists.txt b/fmt/CMakeLists.txt
index 90eaf575..3259d788 100644
--- a/fmt/CMakeLists.txt
+++ b/fmt/CMakeLists.txt
@@ -49,8 +49,9 @@ endif ()
 
 # Install targets.
 if (FMT_INSTALL)
+  include(GNUInstallDirs)
   include(CMakePackageConfigHelpers)
-  set(FMT_CMAKE_DIR lib/cmake/fmt CACHE STRING
+  set(FMT_CMAKE_DIR ${CMAKE_INSTALL_LIBDIR}/cmake/fmt CACHE STRING
     "Installation directory for cmake files, relative to ${CMAKE_INSTALL_PREFIX}.")
   set(version_config ${PROJECT_BINARY_DIR}/fmt-config-version.cmake)
   set(project_config ${PROJECT_BINARY_DIR}/fmt-config.cmake)
@@ -61,9 +62,12 @@ if (FMT_INSTALL)
     set(INSTALL_TARGETS ${INSTALL_TARGETS} fmt-header-only)
   endif ()
 
-  set(FMT_LIB_DIR lib CACHE STRING
+  set(FMT_LIB_DIR ${CMAKE_INSTALL_LIBDIR} CACHE STRING
     "Installation directory for libraries, relative to ${CMAKE_INSTALL_PREFIX}.")
 
+  set(FMT_INC_DIR ${CMAKE_INSTALL_INCLUDEDIR}/fmt CACHE STRING
+    "Installation directory for include files, relative to ${CMAKE_INSTALL_PREFIX}.")
+
   # Generate the version, config and target files into the build directory.
   write_basic_package_version_file(
     ${version_config}
@@ -86,5 +90,5 @@ if (FMT_INSTALL)
   # Install the library and headers.
   install(TARGETS ${INSTALL_TARGETS} EXPORT ${targets_export_name}
           DESTINATION ${FMT_LIB_DIR})
-  install(FILES ${FMT_HEADERS} DESTINATION include/fmt)
+  install(FILES ${FMT_HEADERS} DESTINATION ${FMT_INC_DIR})
 endif ()
diff --git a/fmt/format.cc b/fmt/format.cc
index 09d2ea9f..2d236bc6 100644
--- a/fmt/format.cc
+++ b/fmt/format.cc
@@ -72,9 +72,11 @@
 
 // Dummy implementations of strerror_r and strerror_s called if corresponding
 // system functions are not available.
+FMT_MAYBE_UNUSED
 static inline fmt::internal::Null<> strerror_r(int, char *, ...) {
   return fmt::internal::Null<>();
 }
+FMT_MAYBE_UNUSED
 static inline fmt::internal::Null<> strerror_s(char *, std::size_t, ...) {
   return fmt::internal::Null<>();
 }
@@ -121,7 +123,7 @@ typedef void (*FormatFunc)(Writer &, int, StringRef);
 // Buffer should be at least of size 1.
 int safe_strerror(
     int error_code, char *&buffer, std::size_t buffer_size) FMT_NOEXCEPT {
-  FMT_ASSERT(buffer != 0 && buffer_size != 0, "invalid buffer");
+  FMT_ASSERT(buffer != FMT_NULL && buffer_size != 0, "invalid buffer");
 
   class StrError {
    private:
@@ -159,6 +161,11 @@ int safe_strerror(
             ERANGE : result;
     }
 
+#ifdef __c2__
+# pragma clang diagnostic push
+# pragma clang diagnostic ignored "-Wdeprecated-declarations"
+#endif
+
     // Fallback to strerror if strerror_r and strerror_s are not available.
     int fallback(internal::Null<>) {
       errno = 0;
@@ -166,13 +173,15 @@ int safe_strerror(
       return errno;
     }
 
+#ifdef __c2__
+# pragma clang diagnostic pop
+#endif
+
    public:
     StrError(int err_code, char *&buf, std::size_t buf_size)
       : error_code_(err_code), buffer_(buf), buffer_size_(buf_size) {}
 
     int run() {
-      // Suppress a warning about unused strerror_r.
-      strerror_r(0, FMT_NULL, "");
       return handle(strerror_r(error_code_, buffer_, buffer_size_));
     }
   };
@@ -396,51 +405,6 @@ FMT_FUNC void format_system_error(
   fmt::format_error_code(out, error_code, message);  // 'fmt::' is for bcc32.
 }
 
-template <typename Char>
-void internal::ArgMap<Char>::init(const ArgList &args) {
-  if (!map_.empty())
-    return;
-  typedef internal::NamedArg<Char> NamedArg;
-  const NamedArg *named_arg = FMT_NULL;
-  bool use_values =
-      args.type(ArgList::MAX_PACKED_ARGS - 1) == internal::Arg::NONE;
-  if (use_values) {
-    for (unsigned i = 0;/*nothing*/; ++i) {
-      internal::Arg::Type arg_type = args.type(i);
-      switch (arg_type) {
-      case internal::Arg::NONE:
-        return;
-      case internal::Arg::NAMED_ARG:
-        named_arg = static_cast<const NamedArg*>(args.values_[i].pointer);
-        map_.push_back(Pair(named_arg->name, *named_arg));
-        break;
-      default:
-        /*nothing*/;
-      }
-    }
-    return;
-  }
-  for (unsigned i = 0; i != ArgList::MAX_PACKED_ARGS; ++i) {
-    internal::Arg::Type arg_type = args.type(i);
-    if (arg_type == internal::Arg::NAMED_ARG) {
-      named_arg = static_cast<const NamedArg*>(args.args_[i].pointer);
-      map_.push_back(Pair(named_arg->name, *named_arg));
-    }
-  }
-  for (unsigned i = ArgList::MAX_PACKED_ARGS;/*nothing*/; ++i) {
-    switch (args.args_[i].type) {
-    case internal::Arg::NONE:
-      return;
-    case internal::Arg::NAMED_ARG:
-      named_arg = static_cast<const NamedArg*>(args.args_[i].pointer);
-      map_.push_back(Pair(named_arg->name, *named_arg));
-      break;
-    default:
-      /*nothing*/;
-    }
-  }
-}
-
 template <typename Char>
 void internal::FixedBuffer<Char>::grow(std::size_t) {
   FMT_THROW(std::runtime_error("buffer overflow"));
@@ -502,8 +466,6 @@ template struct internal::BasicData<void>;
 
 template void internal::FixedBuffer<char>::grow(std::size_t);
 
-template void internal::ArgMap<char>::init(const ArgList &args);
-
 template FMT_API int internal::CharTraits<char>::format_float(
     char *buffer, std::size_t size, const char *format,
     unsigned width, int precision, double value);
@@ -516,8 +478,6 @@ template FMT_API int internal::CharTraits<char>::format_float(
 
 template void internal::FixedBuffer<wchar_t>::grow(std::size_t);
 
-template void internal::ArgMap<wchar_t>::init(const ArgList &args);
-
 template FMT_API int internal::CharTraits<wchar_t>::format_float(
     wchar_t *buffer, std::size_t size, const wchar_t *format,
     unsigned width, int precision, double value);
diff --git a/fmt/format.h b/fmt/format.h
index 6ee9d2a2..561a9e07 100644
--- a/fmt/format.h
+++ b/fmt/format.h
@@ -28,6 +28,7 @@
 #ifndef FMT_FORMAT_H_
 #define FMT_FORMAT_H_
 
+#define FMT_INCLUDE
 #include <cassert>
 #include <clocale>
 #include <cmath>
@@ -39,11 +40,26 @@
 #include <string>
 #include <vector>
 #include <utility>  // for std::pair
+#undef FMT_INCLUDE
 
 // The fmt library version in the form major * 10000 + minor * 100 + patch.
-#define FMT_VERSION 40000
+#define FMT_VERSION 40100
 
-#ifdef _SECURE_SCL
+#if defined(__has_include)
+# define FMT_HAS_INCLUDE(x) __has_include(x)
+#else
+# define FMT_HAS_INCLUDE(x) 0
+#endif
+
+#if (FMT_HAS_INCLUDE(<string_view>) && __cplusplus > 201402L) || \
+    (defined(_MSVC_LANG) && _MSVC_LANG > 201402L && _MSC_VER >= 1910)
+# include <string_view>
+# define FMT_HAS_STRING_VIEW 1
+#else
+# define FMT_HAS_STRING_VIEW 0
+#endif
+
+#if defined _SECURE_SCL && _SECURE_SCL
 # define FMT_SECURE_SCL _SECURE_SCL
 #else
 # define FMT_SECURE_SCL 0
@@ -97,7 +113,9 @@ typedef __int64          intmax_t;
 #  define FMT_HAS_GXX_CXX11 1
 # endif
 #else
+# define FMT_GCC_VERSION 0
 # define FMT_GCC_EXTENSION
+# define FMT_HAS_GXX_CXX11 0
 #endif
 
 #if defined(__INTEL_COMPILER)
@@ -135,6 +153,32 @@ typedef __int64          intmax_t;
 # define FMT_HAS_CPP_ATTRIBUTE(x) 0
 #endif
 
+#if FMT_HAS_CPP_ATTRIBUTE(maybe_unused)
+# define FMT_HAS_CXX17_ATTRIBUTE_MAYBE_UNUSED
+// VC++ 1910 support /std: option and that will set _MSVC_LANG macro
+// Clang with Microsoft CodeGen doesn't define _MSVC_LANG macro
+#elif defined(_MSVC_LANG) && _MSVC_LANG > 201402 && _MSC_VER >= 1910
+# define FMT_HAS_CXX17_ATTRIBUTE_MAYBE_UNUSED
+#endif
+
+#ifdef FMT_HAS_CXX17_ATTRIBUTE_MAYBE_UNUSED
+# define FMT_MAYBE_UNUSED [[maybe_unused]]
+// g++/clang++ also support [[gnu::unused]]. However, we don't use it.
+#elif defined(__GNUC__)
+# define FMT_MAYBE_UNUSED __attribute__((unused))
+#else
+# define FMT_MAYBE_UNUSED
+#endif
+
+// Use the compiler's attribute noreturn
+#if defined(__MINGW32__) || defined(__MINGW64__)
+# define FMT_NORETURN __attribute__((noreturn))
+#elif FMT_HAS_CPP_ATTRIBUTE(noreturn) && __cplusplus >= 201103L
+# define FMT_NORETURN [[noreturn]]
+#else
+# define FMT_NORETURN
+#endif
+
 #ifndef FMT_USE_VARIADIC_TEMPLATES
 // Variadic templates are available in GCC since version 4.4
 // (http://gcc.gnu.org/projects/cxx0x.html) and in Visual C++
@@ -156,6 +200,12 @@ typedef __int64          intmax_t;
 # endif
 #endif
 
+#if __cplusplus >= 201103L || FMT_MSC_VER >= 1700
+# define FMT_USE_ALLOCATOR_TRAITS 1
+#else
+# define FMT_USE_ALLOCATOR_TRAITS 0
+#endif
+
 // Check if exceptions are disabled.
 #if defined(__GNUC__) && !defined(__EXCEPTIONS)
 # define FMT_EXCEPTIONS 0
@@ -262,11 +312,14 @@ typedef __int64          intmax_t;
 // makes the fmt::literals implementation easier. However, an explicit check
 // for variadic templates is added here just in case.
 // For Intel's compiler both it and the system gcc/msc must support UDLs.
-# define FMT_USE_USER_DEFINED_LITERALS \
-   FMT_USE_VARIADIC_TEMPLATES && FMT_USE_RVALUE_REFERENCES && \
+# if FMT_USE_VARIADIC_TEMPLATES && FMT_USE_RVALUE_REFERENCES && \
    (FMT_HAS_FEATURE(cxx_user_literals) || \
      (FMT_GCC_VERSION >= 407 && FMT_HAS_GXX_CXX11) || FMT_MSC_VER >= 1900) && \
    (!defined(FMT_ICC_VERSION) || FMT_ICC_VERSION >= 1500)
+#  define FMT_USE_USER_DEFINED_LITERALS 1
+# else
+#  define FMT_USE_USER_DEFINED_LITERALS 0
+# endif
 #endif
 
 #ifndef FMT_USE_EXTERN_TEMPLATES
@@ -305,7 +358,10 @@ typedef __int64          intmax_t;
 
 namespace fmt {
 namespace internal {
-# pragma intrinsic(_BitScanReverse)
+// avoid Clang with Microsoft CodeGen's -Wunknown-pragmas warning
+# ifndef __clang__
+#  pragma intrinsic(_BitScanReverse)
+# endif
 inline uint32_t clz(uint32_t x) {
   unsigned long r = 0;
   _BitScanReverse(&r, x);
@@ -319,7 +375,8 @@ inline uint32_t clz(uint32_t x) {
 }
 # define FMT_BUILTIN_CLZ(n) fmt::internal::clz(n)
 
-# ifdef _WIN64
+// avoid Clang with Microsoft CodeGen's -Wunknown-pragmas warning
+# if defined(_WIN64) && !defined(__clang__)
 #  pragma intrinsic(_BitScanReverse64)
 # endif
 
@@ -505,6 +562,26 @@ class BasicStringRef {
       const std::basic_string<Char, std::char_traits<Char>, Allocator> &s)
   : data_(s.c_str()), size_(s.size()) {}
 
+#if FMT_HAS_STRING_VIEW
+  /**
+    \rst
+    Constructs a string reference from a ``std::basic_string_view`` object.
+    \endrst
+   */
+  BasicStringRef(
+      const std::basic_string_view<Char, std::char_traits<Char>> &s)
+  : data_(s.data()), size_(s.size()) {}
+
+  /**
+   \rst
+   Converts a string reference to an ``std::string_view`` object.
+   \endrst
+  */
+  explicit operator std::basic_string_view<Char>() const FMT_NOEXCEPT {
+    return std::basic_string_view<Char>(data_, size_);
+  }
+#endif
+
   /**
     \rst
     Converts a string reference to an ``std::string`` object.
@@ -609,7 +686,7 @@ class FormatError : public std::runtime_error {
   explicit FormatError(CStringRef message)
   : std::runtime_error(message.c_str()) {}
   FormatError(const FormatError &ferr) : std::runtime_error(ferr) {}
-  FMT_API ~FormatError() FMT_DTOR_NOEXCEPT;
+  FMT_API ~FormatError() FMT_DTOR_NOEXCEPT FMT_OVERRIDE;
 };
 
 namespace internal {
@@ -726,7 +803,7 @@ template <typename T>
 template <typename U>
 void Buffer<T>::append(const U *begin, const U *end) {
   FMT_ASSERT(end >= begin, "negative value");
-  std::size_t new_size = size_ + (end - begin);
+  std::size_t new_size = size_ + static_cast<std::size_t>(end - begin);
   if (new_size > capacity_)
     grow(new_size);
   std::uninitialized_copy(begin, end,
@@ -754,7 +831,7 @@ class MemoryBuffer : private Allocator, public Buffer<T> {
  public:
   explicit MemoryBuffer(const Allocator &alloc = Allocator())
       : Allocator(alloc), Buffer<T>(data_, SIZE) {}
-  ~MemoryBuffer() { deallocate(); }
+  ~MemoryBuffer() FMT_OVERRIDE { deallocate(); }
 
 #if FMT_USE_RVALUE_REFERENCES
  private:
@@ -798,7 +875,12 @@ void MemoryBuffer<T, SIZE, Allocator>::grow(std::size_t size) {
   std::size_t new_capacity = this->capacity_ + this->capacity_ / 2;
   if (size > new_capacity)
       new_capacity = size;
+#if FMT_USE_ALLOCATOR_TRAITS
+  T *new_ptr =
+      std::allocator_traits<Allocator>::allocate(*this, new_capacity, FMT_NULL);
+#else
   T *new_ptr = this->allocate(new_capacity, FMT_NULL);
+#endif
   // The following code doesn't throw, so the raw pointer above doesn't leak.
   std::uninitialized_copy(this->ptr_, this->ptr_ + this->size_,
                           make_ptr(new_ptr, new_capacity));
@@ -916,7 +998,7 @@ struct IntTraits {
     TypeSelector<std::numeric_limits<T>::digits <= 32>::Type MainType;
 };
 
-FMT_API void report_unknown_type(char code, const char *type);
+FMT_API FMT_NORETURN void report_unknown_type(char code, const char *type);
 
 // Static data is placed in this class template to allow header-only
 // configuration.
@@ -1155,17 +1237,17 @@ T &get();
 Yes &convert(fmt::ULongLong);
 No &convert(...);
 
-template<typename T, bool ENABLE_CONVERSION>
+template <typename T, bool ENABLE_CONVERSION>
 struct ConvertToIntImpl {
   enum { value = ENABLE_CONVERSION };
 };
 
-template<typename T, bool ENABLE_CONVERSION>
+template <typename T, bool ENABLE_CONVERSION>
 struct ConvertToIntImpl2 {
   enum { value = false };
 };
 
-template<typename T>
+template <typename T>
 struct ConvertToIntImpl2<T, true> {
   enum {
     // Don't convert numeric types.
@@ -1173,7 +1255,7 @@ struct ConvertToIntImpl2<T, true> {
   };
 };
 
-template<typename T>
+template <typename T>
 struct ConvertToInt {
   enum {
     enable_conversion = sizeof(fmt::internal::convert(get<T>())) == sizeof(Yes)
@@ -1190,16 +1272,16 @@ FMT_DISABLE_CONVERSION_TO_INT(float);
 FMT_DISABLE_CONVERSION_TO_INT(double);
 FMT_DISABLE_CONVERSION_TO_INT(long double);
 
-template<bool B, class T = void>
+template <bool B, class T = void>
 struct EnableIf {};
 
-template<class T>
+template <class T>
 struct EnableIf<true, T> { typedef T type; };
 
-template<bool B, class T, class F>
+template <bool B, class T, class F>
 struct Conditional { typedef T type; };
 
-template<class T, class F>
+template <class T, class F>
 struct Conditional<false, T, F> { typedef F type; };
 
 // For bcc32 which doesn't understand ! in template arguments.
@@ -1248,9 +1330,9 @@ inline fmt::StringRef thousands_sep(...) { return ""; }
   typedef int FMT_CONCAT_(Assert, __LINE__)[(cond) ? 1 : -1] FMT_UNUSED
 #endif
 
-template <typename Formatter, typename Char, typename T>
-void format_arg(Formatter &, const Char *, const T &) {
-  FMT_STATIC_ASSERT(FalseType<T>::value,
+template <typename Formatter>
+void format_arg(Formatter&, ...) {
+  FMT_STATIC_ASSERT(FalseType<Formatter>::value,
                     "Cannot format argument. To enable the use of ostream "
                     "operator<< include fmt/ostream.h. Otherwise provide "
                     "an overload of format_arg.");
@@ -1283,6 +1365,9 @@ class MakeValue : public Arg {
   MakeValue(typename WCharHelper<wchar_t *, Char>::Unsupported);
   MakeValue(typename WCharHelper<const wchar_t *, Char>::Unsupported);
   MakeValue(typename WCharHelper<const std::wstring &, Char>::Unsupported);
+#if FMT_HAS_STRING_VIEW
+  MakeValue(typename WCharHelper<const std::wstring_view &, Char>::Unsupported);
+#endif
   MakeValue(typename WCharHelper<WStringRef, Char>::Unsupported);
 
   void set_string(StringRef str) {
@@ -1352,6 +1437,20 @@ class MakeValue : public Arg {
   FMT_MAKE_VALUE(unsigned char, uint_value, UINT)
   FMT_MAKE_VALUE(char, int_value, CHAR)
 
+#if __cplusplus >= 201103L
+  template <
+    typename T,
+    typename = typename std::enable_if<
+      std::is_enum<T>::value && ConvertToInt<T>::value>::type>
+   MakeValue(T value) { int_value = value; }
+
+  template <
+    typename T,
+    typename = typename std::enable_if<
+      std::is_enum<T>::value && ConvertToInt<T>::value>::type>
+  static uint64_t type(T) { return Arg::INT; }
+#endif
+
 #if !defined(_MSC_VER) || defined(_NATIVE_WCHAR_T_DEFINED)
   MakeValue(typename WCharHelper<wchar_t, Char>::Supported value) {
     int_value = value;
@@ -1370,6 +1469,9 @@ class MakeValue : public Arg {
   FMT_MAKE_VALUE(unsigned char *, ustring.value, CSTRING)
   FMT_MAKE_VALUE(const unsigned char *, ustring.value, CSTRING)
   FMT_MAKE_STR_VALUE(const std::string &, STRING)
+#if FMT_HAS_STRING_VIEW
+  FMT_MAKE_STR_VALUE(const std::string_view &, STRING)
+#endif
   FMT_MAKE_STR_VALUE(StringRef, STRING)
   FMT_MAKE_VALUE_(CStringRef, string.value, CSTRING, value.c_str())
 
@@ -1382,6 +1484,9 @@ class MakeValue : public Arg {
   FMT_MAKE_WSTR_VALUE(wchar_t *, WSTRING)
   FMT_MAKE_WSTR_VALUE(const wchar_t *, WSTRING)
   FMT_MAKE_WSTR_VALUE(const std::wstring &, WSTRING)
+#if FMT_HAS_STRING_VIEW
+  FMT_MAKE_WSTR_VALUE(const std::wstring_view &, WSTRING)
+#endif
   FMT_MAKE_WSTR_VALUE(WStringRef, WSTRING)
 
   FMT_MAKE_VALUE(void *, pointer, POINTER)
@@ -1447,7 +1552,7 @@ class RuntimeError : public std::runtime_error {
  protected:
   RuntimeError() : std::runtime_error("") {}
   RuntimeError(const RuntimeError &rerr) : std::runtime_error(rerr) {}
-  FMT_API ~RuntimeError() FMT_DTOR_NOEXCEPT;
+  FMT_API ~RuntimeError() FMT_DTOR_NOEXCEPT FMT_OVERRIDE;
 };
 
 template <typename Char>
@@ -1921,7 +2026,7 @@ class ArgMap {
   MapType map_;
 
  public:
-  FMT_API void init(const ArgList &args);
+  void init(const ArgList &args);
 
   const internal::Arg *find(const fmt::BasicStringRef<Char> &name) const {
     // The list is unsorted, so just return the first matching name.
@@ -1934,6 +2039,51 @@ class ArgMap {
   }
 };
 
+template <typename Char>
+void ArgMap<Char>::init(const ArgList &args) {
+  if (!map_.empty())
+    return;
+  typedef internal::NamedArg<Char> NamedArg;
+  const NamedArg *named_arg = FMT_NULL;
+  bool use_values =
+      args.type(ArgList::MAX_PACKED_ARGS - 1) == internal::Arg::NONE;
+  if (use_values) {
+    for (unsigned i = 0;/*nothing*/; ++i) {
+      internal::Arg::Type arg_type = args.type(i);
+      switch (arg_type) {
+      case internal::Arg::NONE:
+        return;
+      case internal::Arg::NAMED_ARG:
+        named_arg = static_cast<const NamedArg*>(args.values_[i].pointer);
+        map_.push_back(Pair(named_arg->name, *named_arg));
+        break;
+      default:
+        /*nothing*/;
+      }
+    }
+    return;
+  }
+  for (unsigned i = 0; i != ArgList::MAX_PACKED_ARGS; ++i) {
+    internal::Arg::Type arg_type = args.type(i);
+    if (arg_type == internal::Arg::NAMED_ARG) {
+      named_arg = static_cast<const NamedArg*>(args.args_[i].pointer);
+      map_.push_back(Pair(named_arg->name, *named_arg));
+    }
+  }
+  for (unsigned i = ArgList::MAX_PACKED_ARGS;/*nothing*/; ++i) {
+    switch (args.args_[i].type) {
+    case internal::Arg::NONE:
+      return;
+    case internal::Arg::NAMED_ARG:
+      named_arg = static_cast<const NamedArg*>(args.args_[i].pointer);
+      map_.push_back(Pair(named_arg->name, *named_arg));
+      break;
+    default:
+      /*nothing*/;
+    }
+  }
+}
+
 template <typename Impl, typename Char, typename Spec = fmt::FormatSpec>
 class ArgFormatterBase : public ArgVisitor<Impl, void> {
  private:
@@ -2220,7 +2370,8 @@ struct ArgArray;
 
 template <std::size_t N>
 struct ArgArray<N, true/*IsPacked*/> {
-  typedef Value Type[N > 0 ? N : 1];
+  // '+' is used to silence GCC -Wduplicated-branches warning.
+  typedef Value Type[N > 0 ? N : +1];
 
   template <typename Formatter, typename T>
   static Value make(const T &value) {
@@ -2410,7 +2561,7 @@ class SystemError : public internal::RuntimeError {
   FMT_DEFAULTED_COPY_CTOR(SystemError)
   FMT_VARIADIC_CTOR(SystemError, init, int, CStringRef)
 
-  FMT_API ~SystemError() FMT_DTOR_NOEXCEPT;
+  FMT_API ~SystemError() FMT_DTOR_NOEXCEPT FMT_OVERRIDE;
 
   int error_code() const { return error_code_; }
 };
@@ -3483,10 +3634,10 @@ void arg(WStringRef, const internal::NamedArg<Char>&) FMT_DELETED_OR_UNDEFINED;
 #define FMT_GET_ARG_NAME(type, index) arg##index
 
 #if FMT_USE_VARIADIC_TEMPLATES
-# define FMT_VARIADIC_(Char, ReturnType, func, call, ...) \
+# define FMT_VARIADIC_(Const, Char, ReturnType, func, call, ...) \
   template <typename... Args> \
   ReturnType func(FMT_FOR_EACH(FMT_ADD_ARG_NAME, __VA_ARGS__), \
-      const Args & ... args) { \
+      const Args & ... args) Const { \
     typedef fmt::internal::ArgArray<sizeof...(Args)> ArgArray; \
     typename ArgArray::Type array{ \
       ArgArray::template make<fmt::BasicFormatter<Char> >(args)...}; \
@@ -3496,35 +3647,35 @@ void arg(WStringRef, const internal::NamedArg<Char>&) FMT_DELETED_OR_UNDEFINED;
 #else
 // Defines a wrapper for a function taking __VA_ARGS__ arguments
 // and n additional arguments of arbitrary types.
-# define FMT_WRAP(Char, ReturnType, func, call, n, ...) \
+# define FMT_WRAP(Const, Char, ReturnType, func, call, n, ...) \
   template <FMT_GEN(n, FMT_MAKE_TEMPLATE_ARG)> \
   inline ReturnType func(FMT_FOR_EACH(FMT_ADD_ARG_NAME, __VA_ARGS__), \
-      FMT_GEN(n, FMT_MAKE_ARG)) { \
+      FMT_GEN(n, FMT_MAKE_ARG)) Const { \
     fmt::internal::ArgArray<n>::Type arr; \
     FMT_GEN(n, FMT_ASSIGN_##Char); \
     call(FMT_FOR_EACH(FMT_GET_ARG_NAME, __VA_ARGS__), fmt::ArgList( \
       fmt::internal::make_type(FMT_GEN(n, FMT_MAKE_REF2)), arr)); \
   }
 
-# define FMT_VARIADIC_(Char, ReturnType, func, call, ...) \
-  inline ReturnType func(FMT_FOR_EACH(FMT_ADD_ARG_NAME, __VA_ARGS__)) { \
+# define FMT_VARIADIC_(Const, Char, ReturnType, func, call, ...) \
+  inline ReturnType func(FMT_FOR_EACH(FMT_ADD_ARG_NAME, __VA_ARGS__)) Const { \
     call(FMT_FOR_EACH(FMT_GET_ARG_NAME, __VA_ARGS__), fmt::ArgList()); \
   } \
-  FMT_WRAP(Char, ReturnType, func, call, 1, __VA_ARGS__) \
-  FMT_WRAP(Char, ReturnType, func, call, 2, __VA_ARGS__) \
-  FMT_WRAP(Char, ReturnType, func, call, 3, __VA_ARGS__) \
-  FMT_WRAP(Char, ReturnType, func, call, 4, __VA_ARGS__) \
-  FMT_WRAP(Char, ReturnType, func, call, 5, __VA_ARGS__) \
-  FMT_WRAP(Char, ReturnType, func, call, 6, __VA_ARGS__) \
-  FMT_WRAP(Char, ReturnType, func, call, 7, __VA_ARGS__) \
-  FMT_WRAP(Char, ReturnType, func, call, 8, __VA_ARGS__) \
-  FMT_WRAP(Char, ReturnType, func, call, 9, __VA_ARGS__) \
-  FMT_WRAP(Char, ReturnType, func, call, 10, __VA_ARGS__) \
-  FMT_WRAP(Char, ReturnType, func, call, 11, __VA_ARGS__) \
-  FMT_WRAP(Char, ReturnType, func, call, 12, __VA_ARGS__) \
-  FMT_WRAP(Char, ReturnType, func, call, 13, __VA_ARGS__) \
-  FMT_WRAP(Char, ReturnType, func, call, 14, __VA_ARGS__) \
-  FMT_WRAP(Char, ReturnType, func, call, 15, __VA_ARGS__)
+  FMT_WRAP(Const, Char, ReturnType, func, call, 1, __VA_ARGS__) \
+  FMT_WRAP(Const, Char, ReturnType, func, call, 2, __VA_ARGS__) \
+  FMT_WRAP(Const, Char, ReturnType, func, call, 3, __VA_ARGS__) \
+  FMT_WRAP(Const, Char, ReturnType, func, call, 4, __VA_ARGS__) \
+  FMT_WRAP(Const, Char, ReturnType, func, call, 5, __VA_ARGS__) \
+  FMT_WRAP(Const, Char, ReturnType, func, call, 6, __VA_ARGS__) \
+  FMT_WRAP(Const, Char, ReturnType, func, call, 7, __VA_ARGS__) \
+  FMT_WRAP(Const, Char, ReturnType, func, call, 8, __VA_ARGS__) \
+  FMT_WRAP(Const, Char, ReturnType, func, call, 9, __VA_ARGS__) \
+  FMT_WRAP(Const, Char, ReturnType, func, call, 10, __VA_ARGS__) \
+  FMT_WRAP(Const, Char, ReturnType, func, call, 11, __VA_ARGS__) \
+  FMT_WRAP(Const, Char, ReturnType, func, call, 12, __VA_ARGS__) \
+  FMT_WRAP(Const, Char, ReturnType, func, call, 13, __VA_ARGS__) \
+  FMT_WRAP(Const, Char, ReturnType, func, call, 14, __VA_ARGS__) \
+  FMT_WRAP(Const, Char, ReturnType, func, call, 15, __VA_ARGS__)
 #endif  // FMT_USE_VARIADIC_TEMPLATES
 
 /**
@@ -3555,10 +3706,16 @@ void arg(WStringRef, const internal::NamedArg<Char>&) FMT_DELETED_OR_UNDEFINED;
   \endrst
  */
 #define FMT_VARIADIC(ReturnType, func, ...) \
-  FMT_VARIADIC_(char, ReturnType, func, return func, __VA_ARGS__)
+  FMT_VARIADIC_(, char, ReturnType, func, return func, __VA_ARGS__)
+
+#define FMT_VARIADIC_CONST(ReturnType, func, ...) \
+  FMT_VARIADIC_(const, char, ReturnType, func, return func, __VA_ARGS__)
 
 #define FMT_VARIADIC_W(ReturnType, func, ...) \
-  FMT_VARIADIC_(wchar_t, ReturnType, func, return func, __VA_ARGS__)
+  FMT_VARIADIC_(, wchar_t, ReturnType, func, return func, __VA_ARGS__)
+
+#define FMT_VARIADIC_CONST_W(ReturnType, func, ...) \
+  FMT_VARIADIC_(const, wchar_t, ReturnType, func, return func, __VA_ARGS__)
 
 #define FMT_CAPTURE_ARG_(id, index) ::fmt::arg(#id, id)
 
@@ -3601,17 +3758,19 @@ template <typename Char>
 unsigned parse_nonnegative_int(const Char *&s) {
   assert('0' <= *s && *s <= '9');
   unsigned value = 0;
-  do {
-    unsigned new_value = value * 10 + (*s++ - '0');
-    // Check if value wrapped around.
-    if (new_value < value) {
-      value = (std::numeric_limits<unsigned>::max)();
-      break;
-    }
-    value = new_value;
-  } while ('0' <= *s && *s <= '9');
   // Convert to unsigned to prevent a warning.
   unsigned max_int = (std::numeric_limits<int>::max)();
+  unsigned big = max_int / 10;
+  do {
+    // Check for overflow.
+    if (value > big) {
+      value = max_int + 1;
+      break;
+    }
+    value = value * 10 + (*s - '0');
+    ++s;
+  } while ('0' <= *s && *s <= '9');
+  // Convert to unsigned to prevent a warning.
   if (value > max_int)
     FMT_THROW(FormatError("number is too big"));
   return value;
@@ -3783,7 +3942,8 @@ const Char *BasicFormatter<Char, ArgFormatter>::format(
       default:
         FMT_THROW(FormatError("width is not integer"));
       }
-      if (value > (std::numeric_limits<int>::max)())
+      unsigned max_int = (std::numeric_limits<int>::max)();
+      if (value > max_int)
         FMT_THROW(FormatError("number is too big"));
       spec.width_ = static_cast<int>(value);
     }
@@ -3821,7 +3981,8 @@ const Char *BasicFormatter<Char, ArgFormatter>::format(
           default:
             FMT_THROW(FormatError("precision is not integer"));
         }
-        if (value > (std::numeric_limits<int>::max)())
+        unsigned max_int = (std::numeric_limits<int>::max)();
+        if (value > max_int)
           FMT_THROW(FormatError("number is too big"));
         spec.precision_ = static_cast<int>(value);
       } else {
diff --git a/fmt/ostream.h b/fmt/ostream.h
index 84a02d17..6848aac2 100644
--- a/fmt/ostream.h
+++ b/fmt/ostream.h
@@ -52,13 +52,15 @@ Yes &convert(std::ostream &);
 
 struct DummyStream : std::ostream {
   DummyStream();  // Suppress a bogus warning in MSVC.
+
   // Hide all operator<< overloads from std::ostream.
-  void operator<<(Null<>);
+  template <typename T>
+  typename EnableIf<sizeof(T) == 0>::type operator<<(const T &);
 };
 
 No &operator<<(std::ostream &, int);
 
-template<typename T>
+template <typename T>
 struct ConvertToIntImpl<T, true> {
   // Convert to int only if T doesn't have an overloaded operator<<.
   enum {
@@ -78,6 +80,7 @@ void format_arg(BasicFormatter<Char, ArgFormatter_> &f,
 
   internal::FormatBuf<Char> format_buf(buffer);
   std::basic_ostream<Char> output(&format_buf);
+  output.exceptions(std::ios_base::failbit | std::ios_base::badbit);
   output << value;
 
   BasicStringRef<Char> str(&buffer[0], buffer.size());
diff --git a/fmt/printf.h b/fmt/printf.h
index 30cbc49b..46205a78 100644
--- a/fmt/printf.h
+++ b/fmt/printf.h
@@ -110,7 +110,7 @@ class ArgConverter : public ArgVisitor<ArgConverter<T>, void> {
       visit_any_int(value);
   }
 
-  void visit_char(char value) {
+  void visit_char(int value) {
     if (type_ != 's')
       visit_any_int(value);
   }
@@ -125,7 +125,7 @@ class ArgConverter : public ArgVisitor<ArgConverter<T>, void> {
     using internal::Arg;
     typedef typename internal::Conditional<
         is_same<T, void>::value, U, T>::type TargetType;
-    if (sizeof(TargetType) <= sizeof(int)) {
+    if (const_check(sizeof(TargetType) <= sizeof(int))) {
       // Extra casts are used to silence warnings.
       if (is_signed) {
         arg_.type = Arg::INT;
diff --git a/fmt/string.h b/fmt/string.h
index ccf46ee1..05996eb5 100644
--- a/fmt/string.h
+++ b/fmt/string.h
@@ -7,6 +7,10 @@
  For the license information refer to format.h.
  */
 
+#ifdef FMT_INCLUDE
+# error "Add the fmt's parent directory and not fmt itself to includes."
+#endif
+
 #ifndef FMT_STRING_H_
 #define FMT_STRING_H_
 
@@ -121,6 +125,24 @@ std::string to_string(const T &value) {
   w << value;
   return w.str();
 }
+
+/**
+  \rst
+  Converts *value* to ``std::wstring`` using the default format for type *T*.
+
+  **Example**::
+
+    #include "fmt/string.h"
+
+    std::wstring answer = fmt::to_wstring(42);
+  \endrst
+ */
+template <typename T>
+std::wstring to_wstring(const T &value) {
+  fmt::WMemoryWriter w;
+  w << value;
+  return w.str();
+}
 }
 
 #endif  // FMT_STRING_H_
diff --git a/support/manage.py b/support/manage.py
index 1da371d4..baafe805 100755
--- a/support/manage.py
+++ b/support/manage.py
@@ -8,7 +8,7 @@ Usage:
 """
 
 from __future__ import print_function
-import datetime, docopt, fileinput, json, os
+import datetime, docopt, errno, fileinput, json, os
 import re, requests, shutil, sys, tempfile
 from contextlib import contextmanager
 from distutils.version import LooseVersion
@@ -80,6 +80,7 @@ def create_build_env():
     import build
 
     env.build_dir = 'build'
+    env.versions = build.versions
 
     # Virtualenv and repos are cached to speed up builds.
     build.create_build_env(os.path.join(env.build_dir, 'virtualenv'))
@@ -113,7 +114,7 @@ def update_site(env):
     doc_repo = Git(os.path.join(env.build_dir, 'fmtlib.github.io'))
     doc_repo.update('git@github.com:fmtlib/fmtlib.github.io')
 
-    for version in ['1.0.0', '1.1.0', '2.0.0', '3.0.0']:
+    for version in env.versions:
         clean_checkout(env.fmt_repo, version)
         target_doc_dir = os.path.join(env.fmt_repo.dir, 'doc')
         # Remove the old theme.
@@ -165,7 +166,11 @@ def update_site(env):
                 os.symlink(target, link)
         # Copy docs to the website.
         version_doc_dir = os.path.join(doc_repo.dir, version)
-        shutil.rmtree(version_doc_dir)
+        try:
+            shutil.rmtree(version_doc_dir)
+        except OSError as e:
+            if e.errno != errno.ENOENT:
+                raise
         shutil.move(html_dir, version_doc_dir)
 
 
@@ -204,27 +209,45 @@ def release(args):
             line = '-' * title_len + '\n'
             title_len = 0
         sys.stdout.write(line)
-    # TODO: add new version to manage.py
+
+    # Add the version to the build script.
+    script = os.path.join('doc', 'build.py')
+    script_path = os.path.join(fmt_repo.dir, script)
+    for line in fileinput.input(script_path, inplace=True):
+      m = re.match(r'( *versions = )\[(.+)\]', line)
+      if m:
+        line = '{}[{}, \'{}\']\n'.format(m.group(1), m.group(2), version)
+      sys.stdout.write(line)
+
     fmt_repo.checkout('-B', 'release')
-    fmt_repo.add(changelog, cmakelists)
+    fmt_repo.add(changelog, cmakelists, script)
     fmt_repo.commit('-m', 'Update version')
 
     # Build the docs and package.
     run = Runner(fmt_repo.dir)
     run('cmake', '.')
     run('make', 'doc', 'package_source')
-
     update_site(env)
 
     # Create a release on GitHub.
     fmt_repo.push('origin', 'release')
+    params = {'access_token': os.getenv('FMT_TOKEN')}
     r = requests.post('https://api.github.com/repos/fmtlib/fmt/releases',
-                      params={'access_token': os.getenv('FMT_TOKEN')},
+                      params=params,
                       data=json.dumps({'tag_name': version,
                                        'target_commitish': 'release',
                                        'body': changes, 'draft': True}))
     if r.status_code != 201:
         raise Exception('Failed to create a release ' + str(r))
+    id = r.json()['id']
+    uploads_url = 'https://uploads.github.com/repos/fmtlib/fmt/releases'
+    package = 'fmt-{}.zip'.format(version)
+    with open('build/fmt/' + package, 'rb') as f:
+        r = requests.post(
+            '{}/{}/assets?name={}'.format(uploads_url, id, package),
+            params=params, files={package: f})
+        if r.status_code != 201:
+            raise Exception('Failed to upload an asset ' + str(r))
 
 
 if __name__ == '__main__':
diff --git a/support/travis-build.py b/support/travis-build.py
index 91017792..c4b8daf1 100755
--- a/support/travis-build.py
+++ b/support/travis-build.py
@@ -30,7 +30,7 @@ def install_dependencies():
                '| sudo tee /etc/apt/sources.list.d/nodesource.list', shell=True)
     check_call(['sudo', 'apt-get', 'update'])
     check_call(['sudo', 'apt-get', 'install', 'python-virtualenv', 'nodejs'])
-    check_call(['npm', 'install', '-g', 'less', 'less-plugin-clean-css'])
+    check_call(['sudo', 'npm', 'install', '-g', 'less@2.6.1', 'less-plugin-clean-css'])
     deb_file = 'doxygen_1.8.6-2_amd64.deb'
     urllib.urlretrieve('http://mirrors.kernel.org/ubuntu/pool/main/d/doxygen/' +
                        deb_file, deb_file)
diff --git a/test/format-test.cc b/test/format-test.cc
index 6388d5a5..f512ef48 100644
--- a/test/format-test.cc
+++ b/test/format-test.cc
@@ -151,16 +151,31 @@ TEST(StringRefTest, Ctor) {
 
   EXPECT_STREQ("defg", StringRef(std::string("defg")).data());
   EXPECT_EQ(4u, StringRef(std::string("defg")).size());
+
+#if FMT_HAS_STRING_VIEW
+  EXPECT_STREQ("hijk", StringRef(std::string_view("hijk")).data());
+  EXPECT_EQ(4u, StringRef(std::string_view("hijk")).size());
+#endif
 }
 
 TEST(StringRefTest, ConvertToString) {
   std::string s = StringRef("abc").to_string();
   EXPECT_EQ("abc", s);
+
+#if FMT_HAS_STRING_VIEW
+  StringRef str_ref("defg");
+  std::string_view sv = static_cast<std::string_view>(str_ref);
+  EXPECT_EQ("defg", sv);
+#endif
 }
 
 TEST(CStringRefTest, Ctor) {
   EXPECT_STREQ("abc", CStringRef("abc").c_str());
   EXPECT_STREQ("defg", CStringRef(std::string("defg")).c_str());
+
+#if FMT_HAS_STRING_VIEW
+  EXPECT_STREQ("hijk", CStringRef(std::string_view("hijk")).c_str());
+#endif
 }
 
 #if FMT_USE_TYPE_TRAITS
@@ -1378,6 +1393,12 @@ TEST(FormatterTest, FormatCStringRef) {
   EXPECT_EQ("test", format("{0}", CStringRef("test")));
 }
 
+#if FMT_HAS_STRING_VIEW
+TEST(FormatterTest, FormatStringView) {
+  EXPECT_EQ("test", format("{0}", std::string_view("test")));
+}
+#endif
+
 void format_arg(fmt::BasicFormatter<char> &f, const char *, const Date &d) {
   f.writer() << d.year() << '-' << d.month() << '-' << d.day();
 }
@@ -1609,6 +1630,24 @@ TEST(FormatTest, FormatMessageExample) {
       format_message(42, "{} happened", "something"));
 }
 
+class test_class
+{
+public:
+  std::string format_message(int id, const char *format,const fmt::ArgList &args) const {
+    MemoryWriter w;
+    w.write("[{}] ", id);
+    w.write(format, args);
+    return w.str();
+  }
+  FMT_VARIADIC_CONST(std::string, format_message, int, const char *)
+};
+
+TEST(FormatTest, ConstFormatMessage) {
+  test_class c;
+  EXPECT_EQ("[42] something happened",
+    c.format_message(42, "{} happened", "something"));
+}
+
 #if FMT_USE_VARIADIC_TEMPLATES
 template<typename... Args>
 void print_error(const char *file, int line, const char *format,
@@ -1660,6 +1699,14 @@ TEST(FormatTest, Enum) {
   EXPECT_EQ("0", fmt::format("{}", A));
 }
 
+#if __cplusplus >= 201103L
+enum TestFixedEnum : short { B };
+
+TEST(FormatTest, FixedEnum) {
+  EXPECT_EQ("0", fmt::format("{}", B));
+}
+#endif
+
 class MockArgFormatter :
     public fmt::internal::ArgFormatterBase<MockArgFormatter, char> {
  public:
diff --git a/test/mock-allocator.h b/test/mock-allocator.h
index 34b9c11a..5f0f0bc4 100644
--- a/test/mock-allocator.h
+++ b/test/mock-allocator.h
@@ -36,7 +36,7 @@ class MockAllocator {
   MockAllocator() {}
   MockAllocator(const MockAllocator &) {}
   typedef T value_type;
-  MOCK_METHOD2_T(allocate, T *(std::size_t n, const T *h));
+  MOCK_METHOD2_T(allocate, T *(std::size_t n, const void *h));
   MOCK_METHOD2_T(deallocate, void (T *p, std::size_t n));
 };
 
@@ -78,8 +78,12 @@ class AllocatorRef {
 
   Allocator *get() const { return alloc_; }
 
-  value_type *allocate(std::size_t n,  const value_type *h) {
+  value_type *allocate(std::size_t n,  const void *h) {
+#if FMT_USE_ALLOCATOR_TRAITS
+    return std::allocator_traits<Allocator>::allocate(*alloc_, n, h);
+#else
     return alloc_->allocate(n, h);
+#endif
   }
   void deallocate(value_type *p, std::size_t n) { alloc_->deallocate(p, n); }
 };
diff --git a/test/ostream-test.cc b/test/ostream-test.cc
index 4081b43f..486981bc 100644
--- a/test/ostream-test.cc
+++ b/test/ostream-test.cc
@@ -172,3 +172,18 @@ TEST(OStreamTest, WriteToOStreamMaxSize) {
   } while (size != 0);
   fmt::internal::write(os, w);
 }
+
+struct ConvertibleToInt {
+  template <typename ValueType>
+  operator ValueType() const {
+    return 0;
+  }
+
+  friend std::ostream &operator<<(std::ostream &o, ConvertibleToInt) {
+    return o << "foo";
+  }
+};
+
+TEST(FormatTest, FormatConvertibleToInt) {
+  EXPECT_EQ("foo", fmt::format("{}", ConvertibleToInt()));
+}
diff --git a/test/string-test.cc b/test/string-test.cc
index 10e537b7..06f55f65 100644
--- a/test/string-test.cc
+++ b/test/string-test.cc
@@ -78,3 +78,7 @@ TEST(StringWriterTest, WString) {
 TEST(StringTest, ToString) {
   EXPECT_EQ("42", fmt::to_string(42));
 }
+
+TEST(StringTest, ToWString) {
+  EXPECT_EQ(L"42", fmt::to_wstring(42));
+}
diff --git a/test/util-test.cc b/test/util-test.cc
index a3882558..6617b857 100644
--- a/test/util-test.cc
+++ b/test/util-test.cc
@@ -837,8 +837,21 @@ TEST(UtilTest, FormatSystemError) {
   fmt::format_system_error(message, EDOM, "test");
   EXPECT_EQ(fmt::format("test: {}", get_system_error(EDOM)), message.str());
   message.clear();
-  fmt::format_system_error(
-        message, EDOM, fmt::StringRef(0, std::numeric_limits<size_t>::max()));
+
+  // Check if std::allocator throws on allocating max size_t / 2 chars.
+  size_t max_size = std::numeric_limits<size_t>::max() / 2;
+  bool throws_on_alloc = false;
+  try {
+    std::allocator<char> alloc;
+    alloc.deallocate(alloc.allocate(max_size), max_size);
+  } catch (std::bad_alloc) {
+    throws_on_alloc = true;
+  }
+  if (!throws_on_alloc) {
+    fmt::print("warning: std::allocator allocates {} chars", max_size);
+    return;
+  }
+  fmt::format_system_error(message, EDOM, fmt::StringRef(0, max_size));
   EXPECT_EQ(fmt::format("error {}", EDOM), message.str());
 }