Fix formatting of extreme durations (#1154)

include/fmt/chrono.h

@@ -414,9 +414,8 @@ template <
     typename std::enable_if<std::is_floating_point<Rep>::value, int>::type = 0>
 inline std::chrono::duration<Rep, std::milli> get_milliseconds(
     std::chrono::duration<Rep, Period> d) {
-  auto ms =
-      std::chrono::duration_cast<std::chrono::duration<Rep, std::milli>>(d);
-  return std::chrono::duration<Rep, std::milli>(mod(ms.count(), 1000));
+  return std::chrono::duration<Rep, std::milli>(
+      mod(d.count() * Period::num / Period::den * 1000, 1000));
 }
 
 template <typename Rep, typename OutputIt>
@@ -431,12 +430,9 @@ OutputIt static format_chrono_duration_value(OutputIt out, Rep val,
 
 template <typename Period, typename OutputIt>
 static OutputIt format_chrono_duration_unit(OutputIt out) {
-  if (const char* unit = get_units<Period>())
-    return format_to(out, "{}", unit);
-  else if (Period::den == 1)
-    return format_to(out, "[{}]s", Period::num);
-  else
-    return format_to(out, "[{}/{}]s", Period::num, Period::den);
+  if (const char* unit = get_units<Period>()) return format_to(out, "{}", unit);
+  if (Period::den == 1) return format_to(out, "[{}]s", Period::num);
+  return format_to(out, "[{}/{}]s", Period::num, Period::den);
 }
 
 template <typename FormatContext, typename OutputIt, typename Rep,
@@ -449,7 +445,6 @@ struct chrono_formatter {
   typedef std::chrono::duration<Rep> seconds;
   seconds s;
   typedef std::chrono::duration<Rep, std::milli> milliseconds;
-  milliseconds ms;
 
   typedef typename FormatContext::char_type char_type;
 
@@ -461,7 +456,6 @@ struct chrono_formatter {
       *out++ = '-';
     }
     s = std::chrono::duration_cast<seconds>(d);
-    ms = get_milliseconds(d);
   }
 
   Rep hour() const { return mod((s.count() / 3600), 24); }
@@ -547,6 +541,7 @@ struct chrono_formatter {
   void on_second(numeric_system ns) {
     if (ns == numeric_system::standard) {
       write(second(), 2);
+      auto ms = get_milliseconds(std::chrono::duration<Rep, Period>(val));
       if (ms != std::chrono::milliseconds(0)) {
         *out++ = '.';
         write(ms.count(), 3);

include/fmt/format.h

@@ -251,7 +251,7 @@ namespace uintptr {
 struct uintptr_t {
   unsigned char value[sizeof(void*)];
 };
-}
+}  // namespace uintptr
 using uintptr::uintptr_t;
 typedef std::numeric_limits<uintptr_t> numutil;
 
@@ -1113,10 +1113,7 @@ FMT_CONSTEXPR unsigned basic_parse_context<Char, ErrorHandler>::next_arg_id() {
 namespace internal {
 
 namespace grisu_options {
-enum {
-  fixed = 1,
-  grisu3 = 2
-};
+enum { fixed = 1, grisu3 = 2 };
 }
 
 // Formats value using the Grisu algorithm:
@@ -1190,8 +1187,7 @@ It grisu_prettify(const char* digits, int size, int exp, It it,
     if (!params.trailing_zeros) {
       // Remove trailing zeros.
       while (size > full_exp && digits[size - 1] == '0') --size;
-      if (size != full_exp)
-        *it++ = static_cast<Char>('.');
+      if (size != full_exp) *it++ = static_cast<Char>('.');
       return copy_str<Char>(digits + full_exp, digits + size, it);
     }
     *it++ = static_cast<Char>('.');
@@ -2877,7 +2873,7 @@ void basic_writer<Range>::write_double(T value, const format_specs& spec) {
                    (spec.type != 'a' && spec.type != 'A' && spec.type != 'e' &&
                     spec.type != 'E') &&
                    internal::grisu_format(static_cast<double>(value), buffer,
-                                           precision, options, exp);
+                                          precision, options, exp);
   if (!use_grisu) internal::sprintf_format(value, buffer, spec);
 
   if (handler.as_percentage) {

include/fmt/time.h

@@ -11,9 +11,9 @@
 #include "chrono.h"
 
 #ifdef _MSC_VER
-#pragma message("fmt/time.h is deprecated, use fmt/chrono.h instead")
+#  pragma message("fmt/time.h is deprecated, use fmt/chrono.h instead")
 #else
-#warning fmt/time.h is deprecated, use fmt/chrono.h instead
+#  warning fmt/time.h is deprecated, use fmt/chrono.h instead
 #endif
 
 #endif  // FMT_TIME_H_

test/chrono-test.cc

@@ -318,6 +318,10 @@ TEST(ChronoTest, SpecialDurations) {
       fmt::format("{:%I %H %M %S %R %r}", std::chrono::duration<double>(nan)));
   fmt::format("{:%S}",
               std::chrono::duration<float, std::atto>(1.79400457e+31f));
+  EXPECT_EQ(fmt::format("{}", std::chrono::duration<float, std::exa>(1)),
+            "1Es");
+  EXPECT_EQ(fmt::format("{}", std::chrono::duration<float, std::atto>(1)),
+            "1as");
 }
 
 #endif  // FMT_STATIC_THOUSANDS_SEPARATOR