Don't emit trailing zeros in exponential notation (#1376)

include/fmt/format-inl.h

@@ -1070,7 +1070,15 @@ bool grisu_format(Double value, buffer<char>& buf, int precision,
     fixed_handler handler{buf.data(), 0, precision, -cached_exp10, fixed};
     if (grisu_gen_digits(normalized, 1, exp, handler) == digits::error)
       return false;
-    buf.resize(to_unsigned(handler.size));
+    int num_digits = handler.size;
+    if (!fixed) {
+      // Remove trailing zeros.
+      while (num_digits > 0 && buf[num_digits - 1] == '0') {
+        --num_digits;
+        ++exp;
+      }
+    }
+    buf.resize(to_unsigned(num_digits));
   } else {
     fp fp_value;
     fp lower, upper;  // w^- and w^+ in the Grisu paper.

include/fmt/format.h

@@ -1073,10 +1073,6 @@ template <typename Char> class grisu_writer {
       *it++ = static_cast<Char>(*digits_);
       if (num_digits_ > 1) *it++ = decimal_point_;
       it = copy_str<Char>(digits_ + 1, digits_ + num_digits_, it);
-      if (num_digits_ < params_.num_digits) {
-        it = std::fill_n(it, params_.num_digits - num_digits_,
-                         static_cast<Char>('0'));
-      }
       *it++ = static_cast<Char>(params_.upper ? 'E' : 'e');
       return write_exponent<Char>(full_exp - 1, it);
     }