merge 3.5 (#28119)

diff --cc Python/formatter_unicode.c
index c4a2d9dbfec982e996bc2811adddbac7b3f2fd4e,617d58b2072d1008ec82e7ebe690922cab378176..a2c2b3627c9ec74cebdf698962e73f170919c4d6
--- 1/Python/formatter_unicode.c
--- 2/Python/formatter_unicode.c
+++ b/Python/formatter_unicode.c
@@@ -114,12 -105,6 +114,14 @@@ is_sign_element(Py_UCS4 c
      }
  }
  
- #define LT_NO_LOCALE 0
- #define LT_DEFAULT_LOCALE 1
- #define LT_UNDERSCORE_LOCALE 2
- #define LT_UNDER_FOUR_LOCALE 3
- #define LT_CURRENT_LOCALE 4
 +/* Locale type codes. LT_NO_LOCALE must be zero. */
++enum LocaleType {
++    LT_NO_LOCALE = 0,
++    LT_DEFAULT_LOCALE,
++    LT_UNDERSCORE_LOCALE,
++    LT_UNDER_FOUR_LOCALE,
++    LT_CURRENT_LOCALE
++};
  
  typedef struct {
      Py_UCS4 fill_char;
@@@ -127,7 -112,7 +129,7 @@@
      int alternate;
      Py_UCS4 sign;
      Py_ssize_t width;
--    int thousands_separators;
++    enum LocaleType thousands_separators;
      Py_ssize_t precision;
      Py_UCS4 type;
  } InternalFormatSpec;
@@@ -180,7 -163,7 +182,7 @@@ parse_internal_render_format_spec(PyObj
      format->alternate = 0;
      format->sign = '\0';
      format->width = -1;
--    format->thousands_separators = 0;
++    format->thousands_separators = LT_NO_LOCALE;
      format->precision = -1;
      format->type = default_type;
  
@@@ -235,22 -218,9 +237,22 @@@
  
      /* Comma signifies add thousands separators */
      if (end-pos && READ_spec(pos) == ',') {
 -        format->thousands_separators = 1;
 +        format->thousands_separators = LT_DEFAULT_LOCALE;
 +        ++pos;
 +    }
 +    /* Underscore signifies add thousands separators */
 +    if (end-pos && READ_spec(pos) == '_') {
-         if (format->thousands_separators != 0) {
++        if (format->thousands_separators != LT_NO_LOCALE) {
 +            invalid_comma_and_underscore();
 +            return 0;
 +        }
 +        format->thousands_separators = LT_UNDERSCORE_LOCALE;
          ++pos;
      }
 +    if (end-pos && READ_spec(pos) == ',') {
 +        invalid_comma_and_underscore();
 +        return 0;
 +    }
  
      /* Parse field precision */
      if (end-pos && READ_spec(pos) == '.') {
@@@ -697,10 -662,10 +699,10 @@@ static const char no_grouping[1] = {CHA
  
  /* Find the decimal point character(s?), thousands_separator(s?), and
     grouping description, either for the current locale if type is
 -   LT_CURRENT_LOCALE, a hard-coded locale if LT_DEFAULT_LOCALE, or
 -   none if LT_NO_LOCALE. */
 +   LT_CURRENT_LOCALE, a hard-coded locale if LT_DEFAULT_LOCALE or
 +   LT_UNDERSCORE_LOCALE/LT_UNDER_FOUR_LOCALE, or none if LT_NO_LOCALE. */
  static int
- get_locale_info(int type, LocaleInfo *locale_info)
+ get_locale_info(enum LocaleType type, LocaleInfo *locale_info)
  {
      switch (type) {
      case LT_CURRENT_LOCALE: {
@@@ -721,22 -684,13 +721,19 @@@
          break;
      }
      case LT_DEFAULT_LOCALE:
 +    case LT_UNDERSCORE_LOCALE:
 +    case LT_UNDER_FOUR_LOCALE:
          locale_info->decimal_point = PyUnicode_FromOrdinal('.');
 -        locale_info->thousands_sep = PyUnicode_FromOrdinal(',');
 +        locale_info->thousands_sep = PyUnicode_FromOrdinal(
 +            type == LT_DEFAULT_LOCALE ? ',' : '_');
-         if (!locale_info->decimal_point || !locale_info->thousands_sep) {
-             Py_XDECREF(locale_info->decimal_point);
-             Py_XDECREF(locale_info->thousands_sep);
+         if (!locale_info->decimal_point || !locale_info->thousands_sep)
              return -1;
-         }
 -        locale_info->grouping = "\3"; /* Group every 3 characters.  The
 +        if (type != LT_UNDER_FOUR_LOCALE)
 +            locale_info->grouping = "\3"; /* Group every 3 characters.  The
                                           (implicit) trailing 0 means repeat
                                           infinitely. */
 +        else
 +            locale_info->grouping = "\4"; /* Bin/oct/hex group every four. */
          break;
      case LT_NO_LOCALE:
          locale_info->decimal_point = PyUnicode_FromOrdinal('.');