bpo-28604: Fix localeconv() for different LC_MONETARY (GH-10606)

locale.localeconv() now sets temporarily the LC_CTYPE locale to the
LC_MONETARY locale if the two locales are different and monetary
strings are non-ASCII. This temporary change affects other threads.

Changes:

* locale.localeconv() can now set LC_CTYPE to LC_MONETARY to decode
  monetary fields.
* Add LocaleInfo.grouping_buffer: copy localeconv() grouping string
  since it can be replaced anytime if a different thread calls
  localeconv().
* _Py_GetLocaleconvNumeric() now requires a "struct lconv *"
  structure, so locale.localeconv() now longer calls localeconv()
  twice. Moreover, the function now requires all arguments to be
  non-NULL.
* Rename STATIC_LOCALE_INFO_INIT to LocaleInfo_STATIC_INIT.
* Move _Py_GetLocaleconvNumeric() definition from fileutils.h
  to pycore_fileutils.h. pycore_fileutils.h now includes locale.h.
* The _locale module is now built with Py_BUILD_CORE defined.

1 files changed, 2 insertions, 4 deletions

diff --git a/Doc/library/locale.rst b/Doc/library/locale.rst
index 2fd44fe..bf57a08 100644
--- a/Doc/library/locale.rst
+++ b/Doc/library/locale.rst
@@ -148,10 +148,8 @@ The :mod:`locale` module defines the following exception and functions:
    +--------------+-----------------------------------------+
 
    The function sets temporarily the ``LC_CTYPE`` locale to the ``LC_NUMERIC``
-   locale to decode ``decimal_point`` and ``thousands_sep`` byte strings if
-   they are non-ASCII or longer than 1 byte, and the ``LC_NUMERIC`` locale is
-   different than the ``LC_CTYPE`` locale. This temporary change affects other
-   threads.
+   locale or the ``LC_MONETARY`` locale if locales are different and numeric or
+   monetary strings are non-ASCII. This temporary change affects other threads.
 
    .. versionchanged:: 3.7
       The function now sets temporarily the ``LC_CTYPE`` locale to the