Merge remote-tracking branch 'upstream/master' into fuzz

doc/api.rst

@@ -200,6 +200,8 @@ The following user-defined literals are defined in ``fmt/format.h``.
 Utilities
 ---------
 
+.. doxygenclass:: fmt::is_char
+
 .. doxygentypedef:: fmt::char_t
 
 .. doxygenfunction:: fmt::formatted_size(string_view, const Args&...)
@@ -208,7 +210,7 @@ Utilities
 
 .. doxygenfunction:: fmt::to_wstring(const T&)
 
-.. doxygenfunction:: fmt::to_string_view(basic_string_view<Char>)
+.. doxygenfunction:: fmt::to_string_view(const Char *)
 
 .. doxygenfunction:: fmt::join(const Range&, string_view)
 

doc/build.py

@@ -94,7 +94,7 @@ def build_docs(version='dev', **kwargs):
                           "FMT_BEGIN_NAMESPACE=namespace fmt {{" \
                           "FMT_END_NAMESPACE=}}" \
                           "FMT_STRING_ALIAS=1" \
-                          "FMT_ENABLE_IF_T(B)="
+                          "FMT_ENABLE_IF(B)="
       EXCLUDE_SYMBOLS   = fmt::internal::* StringValue write_str
     '''.format(include_dir, doxyxml_dir).encode('UTF-8'))
   if p.returncode != 0:

include/fmt/chrono.h

@@ -496,9 +496,9 @@ struct chrono_formatter {
   OutputIt out;
   int precision;
   // rep is unsigned to avoid overflow.
-  using rep = typename std::conditional<
-      std::is_integral<Rep>::value && sizeof(Rep) < sizeof(int), unsigned,
-      typename make_unsigned_or_unchanged<Rep>::type>::type;
+  using rep =
+      conditional_t<std::is_integral<Rep>::value && sizeof(Rep) < sizeof(int),
+                    unsigned, typename make_unsigned_or_unchanged<Rep>::type>;
   rep val;
   typedef std::chrono::duration<rep> seconds;
   seconds s;

include/fmt/color.h

@@ -518,13 +518,6 @@ inline void reset_color(basic_memory_buffer<Char>& buffer) FMT_NOEXCEPT {
   buffer.append(begin, end);
 }
 
-// The following specialization disables using std::FILE as a character type,
-// which is needed because or else
-//   fmt::print(stderr, fmt::emphasis::bold, "");
-// would take stderr (a std::FILE *) as the format string.
-template <> struct is_string<std::FILE*> : std::false_type {};
-template <> struct is_string<const std::FILE*> : std::false_type {};
-
 template <typename Char>
 std::basic_string<Char> vformat(const text_style& ts,
                                 basic_string_view<Char> format_str,

include/fmt/core.h

@@ -200,13 +200,16 @@
 
 FMT_BEGIN_NAMESPACE
 
-// An implementation of enable_if_t for pre-C++14 systems.
+// Implementations of enable_if_t and other types for pre-C++14 systems.
 template <bool B, class T = void>
 using enable_if_t = typename std::enable_if<B, T>::type;
+template <bool B, class T, class F>
+using conditional_t = typename std::conditional<B, T, F>::type;
 
 // An enable_if helper to be used in template parameters which results in much
-// shorter symbols: https://godbolt.org/z/sWw4vP.
-#define FMT_ENABLE_IF(...) enable_if_t<__VA_ARGS__, int> = 0
+// shorter symbols: https://godbolt.org/z/sWw4vP. Extra parentheses are needed
+// to workaround a bug in MSVC 2019 (see #1140 and #1186).
+#define FMT_ENABLE_IF(...) enable_if_t<(__VA_ARGS__), int> = 0
 
 namespace internal {
 
@@ -441,30 +444,31 @@ template <typename Char> class basic_string_view {
 using string_view = basic_string_view<char>;
 using wstring_view = basic_string_view<wchar_t>;
 
+/** Specifies if ``T`` is a character type. Can be specialized by users. */
+template <typename T> struct is_char : std::false_type {};
+template <> struct is_char<char> : std::true_type {};
+template <> struct is_char<wchar_t> : std::true_type {};
+template <> struct is_char<char16_t> : std::true_type {};
+template <> struct is_char<char32_t> : std::true_type {};
+
 /**
   \rst
-  The function ``to_string_view`` adapts non-intrusively any kind of string or
-  string-like type if the user provides a (possibly templated) overload of
-  ``to_string_view`` which takes an instance of the string class
-  ``StringType<Char>`` and returns a ``fmt::basic_string_view<Char>``.
-  The conversion function must live in the very same namespace as
-  ``StringType<Char>`` to be picked up by ADL. Non-templated string types
-  like f.e. QString must return a ``basic_string_view`` with a fixed matching
-  char type.
+  Returns a string view of `s`. In order to add custom string type support to
+  {fmt} provide an overload of `to_string_view` for it in the same namespace as
+  the type for the argument-dependent lookup to work.
 
   **Example**::
 
     namespace my_ns {
-    inline string_view to_string_view(const my_string &s) {
+    inline string_view to_string_view(const my_string& s) {
       return {s.data(), s.length()};
     }
     }
-
     std::string message = fmt::format(my_string("The answer is {}"), 42);
   \endrst
  */
-template <typename Char>
-inline basic_string_view<Char> to_string_view(basic_string_view<Char> s) {
+template <typename Char, FMT_ENABLE_IF(is_char<Char>::value)>
+inline basic_string_view<Char> to_string_view(const Char* s) {
   return s;
 }
 
@@ -475,7 +479,7 @@ inline basic_string_view<Char> to_string_view(
 }
 
 template <typename Char>
-inline basic_string_view<Char> to_string_view(const Char* s) {
+inline basic_string_view<Char> to_string_view(basic_string_view<Char> s) {
   return s;
 }
 
@@ -589,17 +593,15 @@ dummy_string_view to_string_view(...);
 using fmt::v5::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
+// enable_if.
 template <typename S>
 struct is_string
     : std::integral_constant<
           bool,
           !std::is_same<dummy_string_view,
                         decltype(to_string_view(std::declval<S>()))>::value> {};
 
-// Forward declare FILE* specialization defined in color.h
-template <> struct is_string<std::FILE*>;
-template <> struct is_string<const std::FILE*>;
-
 template <typename S> struct char_t_impl {
   typedef decltype(to_string_view(std::declval<S>())) result;
   typedef typename result::char_type type;
@@ -646,10 +648,9 @@ template <typename Char> struct string_value {
 };
 
 template <typename Context> struct custom_value {
+  using parse_context = basic_parse_context<typename Context::char_type>;
   const void* value;
-  void (*format)(const void* arg,
-                 basic_parse_context<typename Context::char_type>& parse_ctx,
-                 Context& ctx);
+  void (*format)(const void* arg, parse_context& parse_ctx, Context& ctx);
 };
 
 template <typename T, typename Context>
@@ -704,10 +705,9 @@ template <typename Context> class value {
     // have different extension points, e.g. `formatter<T>` for `format` and
     // `printf_formatter<T>` for `printf`.
     custom.format = &format_custom_arg<
-        T, typename std::conditional<
-               is_formattable<T, Context>::value,
-               typename Context::template formatter_type<T>,
-               internal::fallback_formatter<T, char_type>>::type>;
+        T, conditional_t<is_formattable<T, Context>::value,
+                         typename Context::template formatter_type<T>,
+                         internal::fallback_formatter<T, char_type>>>;
   }
 
   const named_arg_base<char_type>& as_named_arg() {
@@ -758,12 +758,11 @@ FMT_MAKE_VALUE_SAME(uint_type, unsigned)
 
 // To minimize the number of types we need to deal with, long is translated
 // either to int or to long long depending on its size.
-using long_type =
-    std::conditional<sizeof(long) == sizeof(int), int, long long>::type;
+using long_type = conditional_t<sizeof(long) == sizeof(int), int, long long>;
 FMT_MAKE_VALUE((sizeof(long) == sizeof(int) ? int_type : long_long_type), long,
                long_type)
-using ulong_type = std::conditional<sizeof(unsigned long) == sizeof(unsigned),
-                                    unsigned, unsigned long long>::type;
+using ulong_type = conditional_t<sizeof(unsigned long) == sizeof(unsigned),
+                                 unsigned, unsigned long long>;
 FMT_MAKE_VALUE((sizeof(unsigned long) == sizeof(unsigned) ? uint_type
                                                           : ulong_long_type),
                unsigned long, ulong_type)
@@ -777,7 +776,7 @@ FMT_MAKE_VALUE(uint_type, unsigned char, unsigned)
 template <typename C, typename Char,
           FMT_ENABLE_IF(std::is_same<typename C::char_type, Char>::value)>
 FMT_CONSTEXPR init<C, int, char_type> make_value(Char val) {
-  return val;
+  return {val};
 }
 
 template <typename C,
@@ -1129,9 +1128,8 @@ template <typename Context, typename... Args> class format_arg_store {
   // Packed is a macro on MinGW so use IS_PACKED instead.
   static const bool IS_PACKED = NUM_ARGS < internal::max_packed_args;
 
-  using value_type =
-      typename std::conditional<IS_PACKED, internal::value<Context>,
-                                basic_format_arg<Context>>::type;
+  using value_type = conditional_t<IS_PACKED, internal::value<Context>,
+                                   basic_format_arg<Context>>;
 
   // If the arguments are not packed, add one more element to mark the end.
   static const size_t DATA_SIZE =
@@ -1274,7 +1272,7 @@ template <typename Context> class basic_format_args {
 };
 
 /** An alias to ``basic_format_args<context>``. */
-// It is a separate type rather than a typedef to make symbols readable.
+// It is a separate type rather than an alias to make symbols readable.
 struct format_args : basic_format_args<format_context> {
   template <typename... Args>
   format_args(Args&&... arg)
@@ -1385,6 +1383,8 @@ struct is_contiguous_back_insert_iterator<std::back_insert_iterator<Container>>
     : is_contiguous<Container> {};
 
 /** 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(is_contiguous_back_insert_iterator<OutputIt>::value)>
 OutputIt vformat_to(OutputIt out, const S& format_str,

include/fmt/format-inl.h

@@ -674,7 +674,8 @@ template <int GRISU_VERSION> struct grisu_shortest_handler {
   }
 };
 
-template <typename Double, enable_if_t<sizeof(Double) == sizeof(uint64_t), int>>
+template <typename Double,
+          enable_if_t<(sizeof(Double) == sizeof(uint64_t)), int>>
 FMT_API bool grisu_format(Double value, buffer<char>& buf, int precision,
                           unsigned options, int& exp) {
   FMT_ASSERT(value >= 0, "value is negative");

include/fmt/format.h

@@ -400,6 +400,7 @@ void buffer<T>::append(const U* begin, const U* end) {
 // A UTF-8 code unit type.
 enum char8_t : unsigned char {};
 #endif
+template <> struct is_char<char8_t> : std::true_type {};
 
 // A UTF-8 string view.
 class u8string_view : public basic_string_view<char8_t> {
@@ -702,8 +703,8 @@ FMT_CONSTEXPR bool is_negative(T) {
 template <typename T> struct int_traits {
   // Smallest of uint32_t and uint64_t that is large enough to represent
   // all values of T.
-  typedef typename std::conditional<std::numeric_limits<T>::digits <= 32,
-                                    uint32_t, uint64_t>::type main_type;
+  using main_type =
+      conditional_t<std::numeric_limits<T>::digits <= 32, uint32_t, uint64_t>;
 };
 
 // Static data is placed in this class template to allow header-only
@@ -2036,7 +2037,7 @@ template <typename Char, typename Handler>
 FMT_CONSTEXPR const Char* parse_precision(const Char* begin, const Char* end,
                                           Handler&& handler) {
   ++begin;
-  auto c = begin != end ? *begin : 0;
+  auto c = begin != end ? *begin : Char();
   if ('0' <= c && c <= '9') {
     handler.on_precision(parse_nonnegative_int(begin, end, handler));
   } else if (c == '{') {
@@ -2191,9 +2192,10 @@ FMT_CONSTEXPR const typename ParseContext::char_type* parse_format_specs(
     ParseContext& ctx) {
   // GCC 7.2 requires initializer.
   typedef typename ParseContext::char_type char_type;
-  typename std::conditional<is_formattable<T, format_context>::value,
-                            formatter<T, char_type>,
-                            internal::fallback_formatter<T, char_type>>::type f;
+  conditional_t<is_formattable<T, format_context>::value,
+                formatter<T, char_type>,
+                internal::fallback_formatter<T, char_type>>
+      f;
   return f.parse(ctx);
 }
 
@@ -2257,7 +2259,7 @@ FMT_CONSTEXPR bool do_check_format_string(basic_string_view<Char> s,
 }
 
 template <typename... Args, typename S,
-          enable_if_t<is_compile_string<S>::value, int>>
+          enable_if_t<(is_compile_string<S>::value), int>>
 void check_format_string(S format_str) {
   typedef typename S::char_type char_t;
   FMT_CONSTEXPR_DECL bool invalid_format =
@@ -2774,8 +2776,9 @@ template <typename Range> class basic_writer {
     auto&& it = reserve(1);
     *it++ = value;
   }
-  void write(wchar_t value) {
-    static_assert(std::is_same<char_type, wchar_t>::value, "");
+
+  template <typename Char, FMT_ENABLE_IF(std::is_same<Char, char_type>::value)>
+  void write(Char value) {
     auto&& it = reserve(1);
     *it++ = value;
   }

include/fmt/prepare.h

@@ -440,9 +440,8 @@ template <typename Format> class compiletime_prepared_parts_type_provider {
     typedef format_part<char_type> value_type;
   };
 
-  typedef typename std::conditional<static_cast<bool>(number_of_format_parts),
-                                    format_parts_array<number_of_format_parts>,
-                                    empty>::type type;
+  using type = conditional_t<static_cast<bool>(number_of_format_parts),
+                             format_parts_array<number_of_format_parts>, empty>;
 };
 
 template <typename Parts> class compiletime_prepared_parts_collector {
@@ -674,9 +673,8 @@ struct compiletime_format_tag {};
 struct runtime_format_tag {};
 
 template <typename Format> struct format_tag {
-  typedef typename std::conditional<is_compile_string<Format>::value,
-                                    compiletime_format_tag,
-                                    runtime_format_tag>::type type;
+  using type = conditional_t<is_compile_string<Format>::value,
+                             compiletime_format_tag, runtime_format_tag>;
 };
 
 #if FMT_USE_CONSTEXPR

include/fmt/printf.h

@@ -91,15 +91,14 @@ class arg_converter : public function<void> {
   template <typename U, FMT_ENABLE_IF(std::is_integral<U>::value)>
   void operator()(U value) {
     bool is_signed = type_ == 'd' || type_ == 'i';
-    typedef typename std::conditional<std::is_same<T, void>::value, U, T>::type
-        TargetType;
-    if (const_check(sizeof(TargetType) <= sizeof(int))) {
+    using target_type = conditional_t<std::is_same<T, void>::value, U, T>;
+    if (const_check(sizeof(target_type) <= sizeof(int))) {
       // Extra casts are used to silence warnings.
       if (is_signed) {
         arg_ = internal::make_arg<Context>(
-            static_cast<int>(static_cast<TargetType>(value)));
+            static_cast<int>(static_cast<target_type>(value)));
       } else {
-        typedef typename make_unsigned_or_bool<TargetType>::type Unsigned;
+        typedef typename make_unsigned_or_bool<target_type>::type Unsigned;
         arg_ = internal::make_arg<Context>(
             static_cast<unsigned>(static_cast<Unsigned>(value)));
       }

include/fmt/ranges.h

@@ -94,11 +94,11 @@ template <typename T, typename _ = void> struct is_range_ : std::false_type {};
 
 #if !FMT_MSC_VER || FMT_MSC_VER > 1800
 template <typename T>
-struct is_range_<T, typename std::conditional<
-                        false,
-                        conditional_helper<decltype(std::declval<T>().begin()),
-                                           decltype(std::declval<T>().end())>,
-                        void>::type> : std::true_type {};
+struct is_range_<
+    T, conditional_t<false,
+                     conditional_helper<decltype(std::declval<T>().begin()),
+                                        decltype(std::declval<T>().end())>,
+                     void>> : std::true_type {};
 #endif
 
 /// tuple_size and tuple_element check.

test/format-test.cc

@@ -2492,3 +2492,21 @@ TEST(FormatTest, CharTraitsIsNotAmbiguous) {
   (void)lval;
 #endif
 }
+
+struct mychar {
+  int value;
+  mychar() = default;
+  mychar(char val) : value(val) {}
+  operator int() const { return value; }
+};
+
+FMT_BEGIN_NAMESPACE
+template <> struct is_char<mychar> : std::true_type {};
+FMT_END_NAMESPACE
+
+TEST(FormatTest, FormatCustomChar) {
+  const mychar format[] = {'{', '}', 0};
+  auto result = fmt::format(format, mychar('x'));
+  EXPECT_EQ(result.size(), 1);
+  EXPECT_EQ(result[0], mychar('x'));
+}