Windows default locale vs initdb

diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index 403adb0..23bf991 100644
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -2040,6 +2040,28 @@ check_locale_name(int category, const char *locale, char **canonname)
 
 	/* set the locale with setlocale, to see if it accepts it. */
 	res = setlocale(category, locale);
+#if defined(WIN32) && _WIN32_WINNT >= 0x0600
+	{
+		wchar_t		localename[LOCALE_NAME_MAX_LENGTH];
+		char		localebuf[LOCALE_NAME_MAX_LENGTH];
+		LCID		lcid;
+		char	   *hyphen;
+
+		if (MultiByteToWideChar(CP_ACP, 0, res, -1, localename,
+								LOCALE_NAME_MAX_LENGTH) &&
+			GetLocaleInfoEx(localename, LOCALE_RETURN_NUMBER | LOCALE_ILANGUAGE,
+							(LPWSTR)&lcid, sizeof(lcid)) &&
+			LCIDToLocaleName(lcid, localename, LOCALE_NAME_MAX_LENGTH, 0) &&
+			WideCharToMultiByte(CP_ACP, 0, localename, -1, localebuf,
+								LOCALE_NAME_MAX_LENGTH, NULL, NULL))
+		{
+			hyphen = strchr(localebuf, '-');
+			if (hyphen)
+				*hyphen = '_';
+			res = pg_strdup(localebuf);
+		}
+	}
+#endif
 
 	/* save canonical name if requested. */
 	if (res && canonname)

From d6d677fd185242590f0f716cf69d09e735122ff7 Mon Sep 17 00:00:00 2001
From: Thomas Munro <thomas.munro@gmail.com>
Date: Tue, 19 Jul 2022 06:31:17 +1200
Subject: [PATCH 1/2] Default to BCP 47 locale in initdb on Windows.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Avoid selecting traditional Windows locale names written with English
words, because they are unstable and not recommended for use in
databases.  Since setlocale() returns such names, instead use
GetUserDefaultLocaleName() if the user didn't provide an explicit
locale.

Also update the documentation to recommend BCP 47 over the traditional
names when providing explicit values to initdb.

Reviewed-by: Juan José Santamaría Flecha <juanjo.santamaria@gmail.com>
Discussion: https://postgr.es/m/CA%2BhUKGJ%3DXThErgAQRoqfCy1bKPxXVuF0%3D2zDbB%2BSxDs59pv7Fw%40mail.gmail.com
---
 doc/src/sgml/charset.sgml | 10 ++++++++--
 src/bin/initdb/initdb.c   | 28 +++++++++++++++++++++++++++-
 2 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/doc/src/sgml/charset.sgml b/doc/src/sgml/charset.sgml
index 445fd175d8..22e33f0f57 100644
--- a/doc/src/sgml/charset.sgml
+++ b/doc/src/sgml/charset.sgml
@@ -83,8 +83,14 @@ initdb --locale=sv_SE
     system under what names depends on what was provided by the operating
     system vendor and what was installed.  On most Unix systems, the command
     <literal>locale -a</literal> will provide a list of available locales.
-    Windows uses more verbose locale names, such as <literal>German_Germany</literal>
-    or <literal>Swedish_Sweden.1252</literal>, but the principles are the same.
+   </para>
+
+   <para>
+    Windows uses BCP 47 language tags.
+    For example, <literal>sv-SE</literal> represents Swedish as spoken in Sweden.
+    Windows also supports more verbose locale names based on English words,
+    such as <literal>German_Germany</literal> or <literal>Swedish_Sweden.1252</literal>,
+    but these are not recommended.
    </para>
 
    <para>
diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index 89b888eaa5..57c5ecf3cf 100644
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -59,6 +59,10 @@
 #include "sys/mman.h"
 #endif
 
+#ifdef WIN32
+#include <winnls.h>
+#endif
+
 #include "access/xlog_internal.h"
 #include "catalog/pg_authid_d.h"
 #include "catalog/pg_class_d.h" /* pgrminclude ignore */
@@ -2022,7 +2026,27 @@ check_locale_name(int category, const char *locale, char **canonname)
 
 	/* for setlocale() call */
 	if (!locale)
-		locale = "";
+	{
+#ifdef WIN32
+		wchar_t		wide_name[LOCALE_NAME_MAX_LENGTH];
+		char		name[LOCALE_NAME_MAX_LENGTH];
+
+		/* use Windows API to find the default in BCP47 format */
+		if (GetUserDefaultLocaleName(wide_name, LOCALE_NAME_MAX_LENGTH) == 0)
+			pg_fatal("failed to get default locale name, error %d",
+					 GetLastError());
+		if (WideCharToMultiByte(CP_ACP, 0, wide_name, -1, name,
+								LOCALE_NAME_MAX_LENGTH, NULL, NULL) == 0)
+			pg_fatal("failed to convert locale name, error %d",
+					 GetLastError());
+		locale = pg_strdup(name);
+#else
+		/* use environment to find the default */
+		locale = pg_strdup("");
+#endif
+	}
+	else
+		locale = pg_strdup(locale);
 
 	/* set the locale with setlocale, to see if it accepts it. */
 	res = setlocale(category, locale);
@@ -2054,6 +2078,8 @@ check_locale_name(int category, const char *locale, char **canonname)
 			pg_fatal("invalid locale settings; check LANG and LC_* environment variables");
 		}
 	}
+
+	free(locale);
 }
 
 /*
-- 
2.30.2

From a440c6675d92682782f8a10667eec30d35e6fd9c Mon Sep 17 00:00:00 2001
From: Thomas Munro <thomas.munro@gmail.com>
Date: Tue, 19 Jul 2022 08:53:08 +1200
Subject: [PATCH 2/2] Remove support for old Windows locale names.

We now use BCP 47 locale names by default and also advise those for
explicit use.  Remove support for munging the old unstable and
unsystematic English word-style locale names.

XXX When could we do this?
XXX How are you supposed to pg_upgrade a system with datcollate =
"English_Canada" to "en-CA"?
---
 configure                         |   6 -
 configure.ac                      |   1 -
 doc/src/sgml/charset.sgml         |   2 +-
 src/backend/utils/adt/pg_locale.c | 235 ++----------------------------
 src/include/port/win32_port.h     |   9 --
 src/port/win32setlocale.c         | 193 ------------------------
 src/tools/msvc/Mkvcbuild.pm       |   2 +-
 7 files changed, 18 insertions(+), 430 deletions(-)
 delete mode 100644 src/port/win32setlocale.c

diff --git a/configure b/configure
index a4f4d321fb..5b7704352d 100755
--- a/configure
+++ b/configure
@@ -17174,12 +17174,6 @@ esac
  ;;
 esac
 
-  case " $LIBOBJS " in
-  *" win32setlocale.$ac_objext "* ) ;;
-  *) LIBOBJS="$LIBOBJS win32setlocale.$ac_objext"
- ;;
-esac
-
   case " $LIBOBJS " in
   *" win32stat.$ac_objext "* ) ;;
   *) LIBOBJS="$LIBOBJS win32stat.$ac_objext"
diff --git a/configure.ac b/configure.ac
index 5bd29a4d2f..358580e6d6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1995,7 +1995,6 @@ if test "$PORTNAME" = "win32"; then
   AC_LIBOBJ(win32error)
   AC_LIBOBJ(win32ntdll)
   AC_LIBOBJ(win32security)
-  AC_LIBOBJ(win32setlocale)
   AC_LIBOBJ(win32stat)
   AC_DEFINE([HAVE_SYMLINK], 1,
             [Define to 1 if you have the `symlink' function.])
diff --git a/doc/src/sgml/charset.sgml b/doc/src/sgml/charset.sgml
index 22e33f0f57..e02d7e0020 100644
--- a/doc/src/sgml/charset.sgml
+++ b/doc/src/sgml/charset.sgml
@@ -90,7 +90,7 @@ initdb --locale=sv_SE
     For example, <literal>sv-SE</literal> represents Swedish as spoken in Sweden.
     Windows also supports more verbose locale names based on English words,
     such as <literal>German_Germany</literal> or <literal>Swedish_Sweden.1252</literal>,
-    but these are not recommended.
+    but these should not be used in PostgreSQL.
    </para>
 
    <para>
diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 607a4b7340..044f62de2b 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -118,7 +118,7 @@ static HTAB *collation_cache = NULL;
 
 
 #if defined(WIN32) && defined(LC_MESSAGES)
-static char *IsoLocaleName(const char *);	/* MSVC specific */
+static char *PosixLocaleName(const char *);
 #endif
 
 #ifdef USE_ICU
@@ -204,10 +204,7 @@ pg_perm_setlocale(int category, const char *locale)
 		case LC_MESSAGES:
 			envvar = "LC_MESSAGES";
 #ifdef WIN32
-			result = IsoLocaleName(locale);
-			if (result == NULL)
-				result = (char *) locale;
-			elog(DEBUG3, "IsoLocaleName() executed; locale: \"%s\"", result);
+			locale = PosixLocaleName(locale);
 #endif							/* WIN32 */
 			break;
 #endif							/* LC_MESSAGES */
@@ -905,218 +902,35 @@ cache_locale_time(void)
 
 #if defined(WIN32) && defined(LC_MESSAGES)
 /*
- * Convert a Windows setlocale() argument to a Unix-style one.
+ * Convert a Windows BCP 47 locale name to a POSIX one.
  *
  * Regardless of platform, we install message catalogs under a Unix-style
  * LL[_CC][.ENCODING][@VARIANT] naming convention.  Only LC_MESSAGES settings
  * following that style will elicit localized interface strings.
  *
- * Before Visual Studio 2012 (msvcr110.dll), Windows setlocale() accepted "C"
- * (but not "c") and strings of the form <Language>[_<Country>][.<CodePage>],
- * case-insensitive.  setlocale() returns the fully-qualified form; for
- * example, setlocale("thaI") returns "Thai_Thailand.874".  Internally,
- * setlocale() and _create_locale() select a "locale identifier"[1] and store
- * it in an undocumented _locale_t field.  From that LCID, we can retrieve the
- * ISO 639 language and the ISO 3166 country.  Character encoding does not
- * matter, because the server and client encodings govern that.
- *
- * Windows Vista introduced the "locale name" concept[2], closely following
- * RFC 4646.  Locale identifiers are now deprecated.  Starting with Visual
- * Studio 2012, setlocale() accepts locale names in addition to the strings it
- * accepted historically.  It does not standardize them; setlocale("Th-tH")
- * returns "Th-tH".  setlocale(category, "") still returns a traditional
- * string.  Furthermore, msvcr110.dll changed the undocumented _locale_t
- * content to carry locale names instead of locale identifiers.
- *
- * Visual Studio 2015 should still be able to do the same as Visual Studio
- * 2012, but the declaration of locale_name is missing in _locale_t, causing
- * this code compilation to fail, hence this falls back instead on to
- * enumerating all system locales by using EnumSystemLocalesEx to find the
- * required locale name.  If the input argument is in Unix-style then we can
- * get ISO Locale name directly by using GetLocaleInfoEx() with LCType as
- * LOCALE_SNAME.
- *
- * MinGW headers declare _create_locale(), but msvcrt.dll lacks that symbol in
- * releases before Windows 8. IsoLocaleName() always fails in a MinGW-built
- * postgres.exe, so only Unix-style values of the lc_messages GUC can elicit
- * localized messages. In particular, every lc_messages setting that initdb
- * can select automatically will yield only C-locale messages. XXX This could
- * be fixed by running the fully-qualified locale name through a lookup table.
- *
- * This function returns a pointer to a static buffer bearing the converted
- * name or NULL if conversion fails.
- *
- * [1] https://docs.microsoft.com/en-us/windows/win32/intl/locale-identifiers
- * [2] https://docs.microsoft.com/en-us/windows/win32/intl/locale-names
- */
-
-/*
- * Callback function for EnumSystemLocalesEx() in get_iso_localename().
- *
- * This function enumerates all system locales, searching for one that matches
- * an input with the format: <Language>[_<Country>], e.g.
- * English[_United States]
- *
- * The input is a three wchar_t array as an LPARAM. The first element is the
- * locale_name we want to match, the second element is an allocated buffer
- * where the Unix-style locale is copied if a match is found, and the third
- * element is the search status, 1 if a match was found, 0 otherwise.
+ * Historically, verbose, but unsystematic and unstable names like
+ * "Thai_Thailand.874" were supported, but now only BCP 47 input is expected.
+ * That means we just need to be able to convert "en-US" to "en_US".
  */
-static BOOL CALLBACK
-search_locale_enum(LPWSTR pStr, DWORD dwFlags, LPARAM lparam)
-{
-	wchar_t		test_locale[LOCALE_NAME_MAX_LENGTH];
-	wchar_t   **argv;
-
-	(void) (dwFlags);
-
-	argv = (wchar_t **) lparam;
-	*argv[2] = (wchar_t) 0;
-
-	memset(test_locale, 0, sizeof(test_locale));
-
-	/* Get the name of the <Language> in English */
-	if (GetLocaleInfoEx(pStr, LOCALE_SENGLISHLANGUAGENAME,
-						test_locale, LOCALE_NAME_MAX_LENGTH))
-	{
-		/*
-		 * If the enumerated locale does not have a hyphen ("en") OR the
-		 * lc_message input does not have an underscore ("English"), we only
-		 * need to compare the <Language> tags.
-		 */
-		if (wcsrchr(pStr, '-') == NULL || wcsrchr(argv[0], '_') == NULL)
-		{
-			if (_wcsicmp(argv[0], test_locale) == 0)
-			{
-				wcscpy(argv[1], pStr);
-				*argv[2] = (wchar_t) 1;
-				return FALSE;
-			}
-		}
-
-		/*
-		 * We have to compare a full <Language>_<Country> tag, so we append
-		 * the underscore and name of the country/region in English, e.g.
-		 * "English_United States".
-		 */
-		else
-		{
-			size_t		len;
-
-			wcscat(test_locale, L"_");
-			len = wcslen(test_locale);
-			if (GetLocaleInfoEx(pStr, LOCALE_SENGLISHCOUNTRYNAME,
-								test_locale + len,
-								LOCALE_NAME_MAX_LENGTH - len))
-			{
-				if (_wcsicmp(argv[0], test_locale) == 0)
-				{
-					wcscpy(argv[1], pStr);
-					*argv[2] = (wchar_t) 1;
-					return FALSE;
-				}
-			}
-		}
-	}
-
-	return TRUE;
-}
-
-/*
- * This function converts a Windows locale name to an ISO formatted version
- * for Visual Studio 2015 or greater.
- *
- * Returns NULL, if no valid conversion was found.
- */
-static char *
-get_iso_localename(const char *winlocname)
-{
-	wchar_t		wc_locale_name[LOCALE_NAME_MAX_LENGTH];
-	wchar_t		buffer[LOCALE_NAME_MAX_LENGTH];
-	static char iso_lc_messages[LOCALE_NAME_MAX_LENGTH];
-	char	   *period;
-	int			len;
-	int			ret_val;
-
-	/*
-	 * Valid locales have the following syntax:
-	 * <Language>[_<Country>[.<CodePage>]]
-	 *
-	 * GetLocaleInfoEx can only take locale name without code-page and for the
-	 * purpose of this API the code-page doesn't matter.
-	 */
-	period = strchr(winlocname, '.');
-	if (period != NULL)
-		len = period - winlocname;
-	else
-		len = pg_mbstrlen(winlocname);
-
-	memset(wc_locale_name, 0, sizeof(wc_locale_name));
-	memset(buffer, 0, sizeof(buffer));
-	MultiByteToWideChar(CP_ACP, 0, winlocname, len, wc_locale_name,
-						LOCALE_NAME_MAX_LENGTH);
-
-	/*
-	 * If the lc_messages is already a Unix-style string, we have a direct
-	 * match with LOCALE_SNAME, e.g. en-US, en_US.
-	 */
-	ret_val = GetLocaleInfoEx(wc_locale_name, LOCALE_SNAME, (LPWSTR) &buffer,
-							  LOCALE_NAME_MAX_LENGTH);
-	if (!ret_val)
-	{
-		/*
-		 * Search for a locale in the system that matches language and country
-		 * name.
-		 */
-		wchar_t    *argv[3];
-
-		argv[0] = wc_locale_name;
-		argv[1] = buffer;
-		argv[2] = (wchar_t *) &ret_val;
-		EnumSystemLocalesEx(search_locale_enum, LOCALE_WINDOWS, (LPARAM) argv,
-							NULL);
-	}
-
-	if (ret_val)
-	{
-		size_t		rc;
-		char	   *hyphen;
-
-		/* Locale names use only ASCII, any conversion locale suffices. */
-		rc = wchar2char(iso_lc_messages, buffer, sizeof(iso_lc_messages), NULL);
-		if (rc == -1 || rc == sizeof(iso_lc_messages))
-			return NULL;
-
-		/*
-		 * Simply replace the hyphen with an underscore.  See comments in
-		 * IsoLocaleName.
-		 */
-		hyphen = strchr(iso_lc_messages, '-');
-		if (hyphen)
-			*hyphen = '_';
-		return iso_lc_messages;
-	}
-
-	return NULL;
-}
-
 static char *
-IsoLocaleName(const char *winlocname)
+PosixLocaleName(const char *winlocname)
 {
-#if defined(_MSC_VER)
-	static char iso_lc_messages[LOCALE_NAME_MAX_LENGTH];
+	char iso_lc_messages[LOCALE_NAME_MAX_LENGTH];
+	char *hyphen;
 
 	if (pg_strcasecmp("c", winlocname) == 0 ||
 		pg_strcasecmp("posix", winlocname) == 0)
 	{
 		strcpy(iso_lc_messages, "C");
-		return iso_lc_messages;
 	}
 	else
-		return get_iso_localename(winlocname);
-
-#endif							/* defined(_MSC_VER) */
-	return NULL;				/* Not supported on this version of msvc/mingw */
+	{
+		strlcpy(iso_lc_messages, winlocname, sizeof(iso_lc_messages));
+		hypen = strchr(iso_lc_messages, '-');
+		if (hyphen)
+			*hyphen = '_';
+	}
+	return pg_strcpy(iso_lc_messages);
 }
 #endif							/* WIN32 && LC_MESSAGES */
 
@@ -1680,33 +1494,16 @@ get_collation_actual_version(char collprovider, const char *collcollate)
 			ereport(ERROR,
 					(errmsg("could not load locale \"%s\"", collcollate)));
 #elif defined(WIN32)
-		/*
-		 * If we are targeting Windows Vista and above, we can ask for a name
-		 * given a collation name (earlier versions required a location code
-		 * that we don't have).
-		 */
 		NLSVERSIONINFOEX version = {sizeof(NLSVERSIONINFOEX)};
 		WCHAR		wide_collcollate[LOCALE_NAME_MAX_LENGTH];
 
 		MultiByteToWideChar(CP_ACP, 0, collcollate, -1, wide_collcollate,
 							LOCALE_NAME_MAX_LENGTH);
 		if (!GetNLSVersionEx(COMPARE_STRING, wide_collcollate, &version))
-		{
-			/*
-			 * GetNLSVersionEx() wants a language tag such as "en-US", not a
-			 * locale name like "English_United States.1252".  Until those
-			 * values can be prevented from entering the system, or 100%
-			 * reliably converted to the more useful tag format, tolerate the
-			 * resulting error and report that we have no version data.
-			 */
-			if (GetLastError() == ERROR_INVALID_PARAMETER)
-				return NULL;
-
 			ereport(ERROR,
 					(errmsg("could not get collation version for locale \"%s\": error code %lu",
 							collcollate,
 							GetLastError())));
-		}
 		collversion = psprintf("%ld.%ld,%ld.%ld",
 							   (version.dwNLSVersion >> 8) & 0xFFFF,
 							   version.dwNLSVersion & 0xFF,
diff --git a/src/include/port/win32_port.h b/src/include/port/win32_port.h
index 5121c0c626..13ed144a8f 100644
--- a/src/include/port/win32_port.h
+++ b/src/include/port/win32_port.h
@@ -437,15 +437,6 @@ extern int	_pgstat64(const char *name, struct stat *buf);
 #undef setlocale
 #endif
 
-/*
- * Define our own wrapper macro around setlocale() to work around bugs in
- * Windows' native setlocale() function.
- */
-extern char *pgwin32_setlocale(int category, const char *locale);
-
-#define setlocale(a,b) pgwin32_setlocale(a,b)
-
-
 /* In backend/port/win32/signal.c */
 extern PGDLLIMPORT volatile int pg_signal_queue;
 extern PGDLLIMPORT int pg_signal_mask;
diff --git a/src/port/win32setlocale.c b/src/port/win32setlocale.c
deleted file mode 100644
index aadd09a4e9..0000000000
--- a/src/port/win32setlocale.c
+++ /dev/null
@@ -1,193 +0,0 @@
-/*-------------------------------------------------------------------------
- *
- * win32setlocale.c
- *		Wrapper to work around bugs in Windows setlocale() implementation
- *
- * Copyright (c) 2011-2022, PostgreSQL Global Development Group
- *
- * IDENTIFICATION
- *	  src/port/win32setlocale.c
- *
- *
- * The setlocale() function in Windows is broken in two ways. First, it
- * has a problem with locale names that have a dot in the country name. For
- * example:
- *
- * "Chinese (Traditional)_Hong Kong S.A.R..950"
- *
- * For some reason, setlocale() doesn't accept that as argument, even though
- * setlocale(LC_ALL, NULL) returns exactly that. Fortunately, it accepts
- * various alternative names for such countries, so to work around the broken
- * setlocale() function, we map the troublemaking locale names to accepted
- * aliases, before calling setlocale().
- *
- * The second problem is that the locale name for "Norwegian (Bokm&aring;l)"
- * contains a non-ASCII character. That's problematic, because it's not clear
- * what encoding the locale name itself is supposed to be in, when you
- * haven't yet set a locale. Also, it causes problems when the cluster
- * contains databases with different encodings, as the locale name is stored
- * in the pg_database system catalog. To work around that, when setlocale()
- * returns that locale name, map it to a pure-ASCII alias for the same
- * locale.
- *-------------------------------------------------------------------------
- */
-
-#include "c.h"
-
-#undef setlocale
-
-struct locale_map
-{
-	/*
-	 * String in locale name to replace. Can be a single string (end is NULL),
-	 * or separate start and end strings. If two strings are given, the locale
-	 * name must contain both of them, and everything between them is
-	 * replaced. This is used for a poor-man's regexp search, allowing
-	 * replacement of "start.*end".
-	 */
-	const char *locale_name_start;
-	const char *locale_name_end;
-
-	const char *replacement;	/* string to replace the match with */
-};
-
-/*
- * Mappings applied before calling setlocale(), to the argument.
- */
-static const struct locale_map locale_map_argument[] = {
-	/*
-	 * "HKG" is listed here:
-	 * http://msdn.microsoft.com/en-us/library/cdax410z%28v=vs.71%29.aspx
-	 * (Country/Region Strings).
-	 *
-	 * "ARE" is the ISO-3166 three-letter code for U.A.E. It is not on the
-	 * above list, but seems to work anyway.
-	 */
-	{"Hong Kong S.A.R.", NULL, "HKG"},
-	{"U.A.E.", NULL, "ARE"},
-
-	/*
-	 * The ISO-3166 country code for Macau S.A.R. is MAC, but Windows doesn't
-	 * seem to recognize that. And Macau isn't listed in the table of accepted
-	 * abbreviations linked above. Fortunately, "ZHM" seems to be accepted as
-	 * an alias for "Chinese (Traditional)_Macau S.A.R..950". I'm not sure
-	 * where "ZHM" comes from, must be some legacy naming scheme. But hey, it
-	 * works.
-	 *
-	 * Note that unlike HKG and ARE, ZHM is an alias for the *whole* locale
-	 * name, not just the country part.
-	 *
-	 * Some versions of Windows spell it "Macau", others "Macao".
-	 */
-	{"Chinese (Traditional)_Macau S.A.R..950", NULL, "ZHM"},
-	{"Chinese_Macau S.A.R..950", NULL, "ZHM"},
-	{"Chinese (Traditional)_Macao S.A.R..950", NULL, "ZHM"},
-	{"Chinese_Macao S.A.R..950", NULL, "ZHM"},
-	{NULL, NULL, NULL}
-};
-
-/*
- * Mappings applied after calling setlocale(), to its return value.
- */
-static const struct locale_map locale_map_result[] = {
-	/*
-	 * "Norwegian (Bokm&aring;l)" locale name contains the a-ring character.
-	 * Map it to a pure-ASCII alias.
-	 *
-	 * It's not clear what encoding setlocale() uses when it returns the
-	 * locale name, so to play it safe, we search for "Norwegian (Bok*l)".
-	 *
-	 * Just to make life even more complicated, some versions of Windows spell
-	 * the locale name without parentheses.  Translate that too.
-	 */
-	{"Norwegian (Bokm", "l)_Norway", "Norwegian_Norway"},
-	{"Norwegian Bokm", "l_Norway", "Norwegian_Norway"},
-	{NULL, NULL, NULL}
-};
-
-#define MAX_LOCALE_NAME_LEN		100
-
-static const char *
-map_locale(const struct locale_map *map, const char *locale)
-{
-	static char aliasbuf[MAX_LOCALE_NAME_LEN];
-	int			i;
-
-	/* Check if the locale name matches any of the problematic ones. */
-	for (i = 0; map[i].locale_name_start != NULL; i++)
-	{
-		const char *needle_start = map[i].locale_name_start;
-		const char *needle_end = map[i].locale_name_end;
-		const char *replacement = map[i].replacement;
-		char	   *match;
-		char	   *match_start = NULL;
-		char	   *match_end = NULL;
-
-		match = strstr(locale, needle_start);
-		if (match)
-		{
-			/*
-			 * Found a match for the first part. If this was a two-part
-			 * replacement, find the second part.
-			 */
-			match_start = match;
-			if (needle_end)
-			{
-				match = strstr(match_start + strlen(needle_start), needle_end);
-				if (match)
-					match_end = match + strlen(needle_end);
-				else
-					match_start = NULL;
-			}
-			else
-				match_end = match_start + strlen(needle_start);
-		}
-
-		if (match_start)
-		{
-			/* Found a match. Replace the matched string. */
-			int			matchpos = match_start - locale;
-			int			replacementlen = strlen(replacement);
-			char	   *rest = match_end;
-			int			restlen = strlen(rest);
-
-			/* check that the result fits in the static buffer */
-			if (matchpos + replacementlen + restlen + 1 > MAX_LOCALE_NAME_LEN)
-				return NULL;
-
-			memcpy(&aliasbuf[0], &locale[0], matchpos);
-			memcpy(&aliasbuf[matchpos], replacement, replacementlen);
-			/* includes null terminator */
-			memcpy(&aliasbuf[matchpos + replacementlen], rest, restlen + 1);
-
-			return aliasbuf;
-		}
-	}
-
-	/* no match, just return the original string */
-	return locale;
-}
-
-char *
-pgwin32_setlocale(int category, const char *locale)
-{
-	const char *argument;
-	char	   *result;
-
-	if (locale == NULL)
-		argument = NULL;
-	else
-		argument = map_locale(locale_map_argument, locale);
-
-	/* Call the real setlocale() function */
-	result = setlocale(category, argument);
-
-	/*
-	 * setlocale() is specified to return a "char *" that the caller is
-	 * forbidden to modify, so casting away the "const" is innocuous.
-	 */
-	if (result)
-		result = unconstify(char *, map_locale(locale_map_result, result));
-
-	return result;
-}
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index e4feda10fd..1bc35ef926 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -108,7 +108,7 @@ sub mkvcbuild
 	  pqsignal.c mkdtemp.c qsort.c qsort_arg.c bsearch_arg.c quotes.c system.c
 	  strerror.c tar.c
 	  win32env.c win32error.c win32ntdll.c
-	  win32security.c win32setlocale.c win32stat.c);
+	  win32security.c win32stat.c);
 
 	push(@pgportfiles, 'strtof.c') if ($vsVersion < '14.00');
 
-- 
2.30.2

From 95f2684150e2938f2e555d16bbed4295a6dad279 Mon Sep 17 00:00:00 2001
From: Thomas Munro <thomas.munro@gmail.com>
Date: Tue, 19 Jul 2022 06:31:17 +1200
Subject: [PATCH v2 1/2] Default to BCP 47 locale in initdb on Windows.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Avoid selecting traditional Windows locale names written with English
words, because they are unstable and not recommended for use in
databases.  Since setlocale() returns such names, on Windows use
GetUserDefaultLocaleName() if the user didn't provide an explicit
locale.

Also update the documentation to recommend BCP 47 over the traditional
names when providing explicit values to initdb.

Reviewed-by: Juan José Santamaría Flecha <juanjo.santamaria@gmail.com>
Discussion: https://postgr.es/m/CA%2BhUKGJ%3DXThErgAQRoqfCy1bKPxXVuF0%3D2zDbB%2BSxDs59pv7Fw%40mail.gmail.com
---
 doc/src/sgml/charset.sgml | 10 ++++++++--
 src/bin/initdb/initdb.c   | 31 +++++++++++++++++++++++++++++--
 2 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/doc/src/sgml/charset.sgml b/doc/src/sgml/charset.sgml
index 445fd175d8..b656ca489f 100644
--- a/doc/src/sgml/charset.sgml
+++ b/doc/src/sgml/charset.sgml
@@ -83,8 +83,14 @@ initdb --locale=sv_SE
     system under what names depends on what was provided by the operating
     system vendor and what was installed.  On most Unix systems, the command
     <literal>locale -a</literal> will provide a list of available locales.
-    Windows uses more verbose locale names, such as <literal>German_Germany</literal>
-    or <literal>Swedish_Sweden.1252</literal>, but the principles are the same.
+   </para>
+
+   <para>
+    Windows uses BCP 47 language tags, like ICU.
+    For example, <literal>sv-SE</literal> represents Swedish as spoken in Sweden.
+    Windows also supports more verbose locale names based on English words,
+    such as <literal>German_Germany</literal> or <literal>Swedish_Sweden.1252</literal>,
+    but these are not recommended.
    </para>
 
    <para>
diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index 89b888eaa5..3af08b7b99 100644
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -59,6 +59,10 @@
 #include "sys/mman.h"
 #endif
 
+#ifdef WIN32
+#include <winnls.h>
+#endif
+
 #include "access/xlog_internal.h"
 #include "catalog/pg_authid_d.h"
 #include "catalog/pg_class_d.h" /* pgrminclude ignore */
@@ -2007,6 +2011,7 @@ locale_date_order(const char *locale)
 static void
 check_locale_name(int category, const char *locale, char **canonname)
 {
+	char	   *locale_copy;
 	char	   *save;
 	char	   *res;
 
@@ -2022,10 +2027,30 @@ check_locale_name(int category, const char *locale, char **canonname)
 
 	/* for setlocale() call */
 	if (!locale)
-		locale = "";
+	{
+#ifdef WIN32
+		wchar_t		wide_name[LOCALE_NAME_MAX_LENGTH];
+		char		name[LOCALE_NAME_MAX_LENGTH];
+
+		/* use Windows API to find the default in BCP47 format */
+		if (GetUserDefaultLocaleName(wide_name, LOCALE_NAME_MAX_LENGTH) == 0)
+			pg_fatal("failed to get default locale name: error code %lu",
+					 GetLastError());
+		if (WideCharToMultiByte(CP_ACP, 0, wide_name, -1, name,
+								LOCALE_NAME_MAX_LENGTH, NULL, NULL) == 0)
+			pg_fatal("failed to convert locale name: error code %lu",
+					 GetLastError());
+		locale_copy = pg_strdup(name);
+#else
+		/* use environment to find the default */
+		locale_copy = pg_strdup("");
+#endif
+	}
+	else
+		locale_copy = pg_strdup(locale);
 
 	/* set the locale with setlocale, to see if it accepts it. */
-	res = setlocale(category, locale);
+	res = setlocale(category, locale_copy);
 
 	/* save canonical name if requested. */
 	if (res && canonname)
@@ -2054,6 +2079,8 @@ check_locale_name(int category, const char *locale, char **canonname)
 			pg_fatal("invalid locale settings; check LANG and LC_* environment variables");
 		}
 	}
+
+	free(locale_copy);
 }
 
 /*
-- 
2.35.1

From 1e0b75b4c8958397a8e660fa0b8759f1da78a753 Mon Sep 17 00:00:00 2001
From: Thomas Munro <thomas.munro@gmail.com>
Date: Tue, 19 Jul 2022 08:53:08 +1200
Subject: [PATCH v2 2/2] Remove support for old Windows locale names.

We now use BCP 47 locale names by default and also advise those for
explicit use.  Remove support for munging the old unstable and
unsystematic English word-style locale names.

XXX When could we do this?
XXX How are you supposed to pg_upgrade a system with datcollate =
"English_Canada" to "en-CA"?
XXX There are more traces to remove in win32_langinfo()
---
 configure                         |   6 -
 configure.ac                      |   1 -
 doc/src/sgml/charset.sgml         |   2 +-
 src/backend/utils/adt/pg_locale.c | 235 ++----------------------------
 src/include/port/win32_port.h     |   9 --
 src/port/win32setlocale.c         | 193 ------------------------
 src/tools/msvc/Mkvcbuild.pm       |   2 +-
 7 files changed, 18 insertions(+), 430 deletions(-)
 delete mode 100644 src/port/win32setlocale.c

diff --git a/configure b/configure
index a4f4d321fb..5b7704352d 100755
--- a/configure
+++ b/configure
@@ -17174,12 +17174,6 @@ esac
  ;;
 esac
 
-  case " $LIBOBJS " in
-  *" win32setlocale.$ac_objext "* ) ;;
-  *) LIBOBJS="$LIBOBJS win32setlocale.$ac_objext"
- ;;
-esac
-
   case " $LIBOBJS " in
   *" win32stat.$ac_objext "* ) ;;
   *) LIBOBJS="$LIBOBJS win32stat.$ac_objext"
diff --git a/configure.ac b/configure.ac
index 5bd29a4d2f..358580e6d6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1995,7 +1995,6 @@ if test "$PORTNAME" = "win32"; then
   AC_LIBOBJ(win32error)
   AC_LIBOBJ(win32ntdll)
   AC_LIBOBJ(win32security)
-  AC_LIBOBJ(win32setlocale)
   AC_LIBOBJ(win32stat)
   AC_DEFINE([HAVE_SYMLINK], 1,
             [Define to 1 if you have the `symlink' function.])
diff --git a/doc/src/sgml/charset.sgml b/doc/src/sgml/charset.sgml
index b656ca489f..3c12f3f344 100644
--- a/doc/src/sgml/charset.sgml
+++ b/doc/src/sgml/charset.sgml
@@ -90,7 +90,7 @@ initdb --locale=sv_SE
     For example, <literal>sv-SE</literal> represents Swedish as spoken in Sweden.
     Windows also supports more verbose locale names based on English words,
     such as <literal>German_Germany</literal> or <literal>Swedish_Sweden.1252</literal>,
-    but these are not recommended.
+    but these should not be used in PostgreSQL.
    </para>
 
    <para>
diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 607a4b7340..044f62de2b 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -118,7 +118,7 @@ static HTAB *collation_cache = NULL;
 
 
 #if defined(WIN32) && defined(LC_MESSAGES)
-static char *IsoLocaleName(const char *);	/* MSVC specific */
+static char *PosixLocaleName(const char *);
 #endif
 
 #ifdef USE_ICU
@@ -204,10 +204,7 @@ pg_perm_setlocale(int category, const char *locale)
 		case LC_MESSAGES:
 			envvar = "LC_MESSAGES";
 #ifdef WIN32
-			result = IsoLocaleName(locale);
-			if (result == NULL)
-				result = (char *) locale;
-			elog(DEBUG3, "IsoLocaleName() executed; locale: \"%s\"", result);
+			locale = PosixLocaleName(locale);
 #endif							/* WIN32 */
 			break;
 #endif							/* LC_MESSAGES */
@@ -905,218 +902,35 @@ cache_locale_time(void)
 
 #if defined(WIN32) && defined(LC_MESSAGES)
 /*
- * Convert a Windows setlocale() argument to a Unix-style one.
+ * Convert a Windows BCP 47 locale name to a POSIX one.
  *
  * Regardless of platform, we install message catalogs under a Unix-style
  * LL[_CC][.ENCODING][@VARIANT] naming convention.  Only LC_MESSAGES settings
  * following that style will elicit localized interface strings.
  *
- * Before Visual Studio 2012 (msvcr110.dll), Windows setlocale() accepted "C"
- * (but not "c") and strings of the form <Language>[_<Country>][.<CodePage>],
- * case-insensitive.  setlocale() returns the fully-qualified form; for
- * example, setlocale("thaI") returns "Thai_Thailand.874".  Internally,
- * setlocale() and _create_locale() select a "locale identifier"[1] and store
- * it in an undocumented _locale_t field.  From that LCID, we can retrieve the
- * ISO 639 language and the ISO 3166 country.  Character encoding does not
- * matter, because the server and client encodings govern that.
- *
- * Windows Vista introduced the "locale name" concept[2], closely following
- * RFC 4646.  Locale identifiers are now deprecated.  Starting with Visual
- * Studio 2012, setlocale() accepts locale names in addition to the strings it
- * accepted historically.  It does not standardize them; setlocale("Th-tH")
- * returns "Th-tH".  setlocale(category, "") still returns a traditional
- * string.  Furthermore, msvcr110.dll changed the undocumented _locale_t
- * content to carry locale names instead of locale identifiers.
- *
- * Visual Studio 2015 should still be able to do the same as Visual Studio
- * 2012, but the declaration of locale_name is missing in _locale_t, causing
- * this code compilation to fail, hence this falls back instead on to
- * enumerating all system locales by using EnumSystemLocalesEx to find the
- * required locale name.  If the input argument is in Unix-style then we can
- * get ISO Locale name directly by using GetLocaleInfoEx() with LCType as
- * LOCALE_SNAME.
- *
- * MinGW headers declare _create_locale(), but msvcrt.dll lacks that symbol in
- * releases before Windows 8. IsoLocaleName() always fails in a MinGW-built
- * postgres.exe, so only Unix-style values of the lc_messages GUC can elicit
- * localized messages. In particular, every lc_messages setting that initdb
- * can select automatically will yield only C-locale messages. XXX This could
- * be fixed by running the fully-qualified locale name through a lookup table.
- *
- * This function returns a pointer to a static buffer bearing the converted
- * name or NULL if conversion fails.
- *
- * [1] https://docs.microsoft.com/en-us/windows/win32/intl/locale-identifiers
- * [2] https://docs.microsoft.com/en-us/windows/win32/intl/locale-names
- */
-
-/*
- * Callback function for EnumSystemLocalesEx() in get_iso_localename().
- *
- * This function enumerates all system locales, searching for one that matches
- * an input with the format: <Language>[_<Country>], e.g.
- * English[_United States]
- *
- * The input is a three wchar_t array as an LPARAM. The first element is the
- * locale_name we want to match, the second element is an allocated buffer
- * where the Unix-style locale is copied if a match is found, and the third
- * element is the search status, 1 if a match was found, 0 otherwise.
+ * Historically, verbose, but unsystematic and unstable names like
+ * "Thai_Thailand.874" were supported, but now only BCP 47 input is expected.
+ * That means we just need to be able to convert "en-US" to "en_US".
  */
-static BOOL CALLBACK
-search_locale_enum(LPWSTR pStr, DWORD dwFlags, LPARAM lparam)
-{
-	wchar_t		test_locale[LOCALE_NAME_MAX_LENGTH];
-	wchar_t   **argv;
-
-	(void) (dwFlags);
-
-	argv = (wchar_t **) lparam;
-	*argv[2] = (wchar_t) 0;
-
-	memset(test_locale, 0, sizeof(test_locale));
-
-	/* Get the name of the <Language> in English */
-	if (GetLocaleInfoEx(pStr, LOCALE_SENGLISHLANGUAGENAME,
-						test_locale, LOCALE_NAME_MAX_LENGTH))
-	{
-		/*
-		 * If the enumerated locale does not have a hyphen ("en") OR the
-		 * lc_message input does not have an underscore ("English"), we only
-		 * need to compare the <Language> tags.
-		 */
-		if (wcsrchr(pStr, '-') == NULL || wcsrchr(argv[0], '_') == NULL)
-		{
-			if (_wcsicmp(argv[0], test_locale) == 0)
-			{
-				wcscpy(argv[1], pStr);
-				*argv[2] = (wchar_t) 1;
-				return FALSE;
-			}
-		}
-
-		/*
-		 * We have to compare a full <Language>_<Country> tag, so we append
-		 * the underscore and name of the country/region in English, e.g.
-		 * "English_United States".
-		 */
-		else
-		{
-			size_t		len;
-
-			wcscat(test_locale, L"_");
-			len = wcslen(test_locale);
-			if (GetLocaleInfoEx(pStr, LOCALE_SENGLISHCOUNTRYNAME,
-								test_locale + len,
-								LOCALE_NAME_MAX_LENGTH - len))
-			{
-				if (_wcsicmp(argv[0], test_locale) == 0)
-				{
-					wcscpy(argv[1], pStr);
-					*argv[2] = (wchar_t) 1;
-					return FALSE;
-				}
-			}
-		}
-	}
-
-	return TRUE;
-}
-
-/*
- * This function converts a Windows locale name to an ISO formatted version
- * for Visual Studio 2015 or greater.
- *
- * Returns NULL, if no valid conversion was found.
- */
-static char *
-get_iso_localename(const char *winlocname)
-{
-	wchar_t		wc_locale_name[LOCALE_NAME_MAX_LENGTH];
-	wchar_t		buffer[LOCALE_NAME_MAX_LENGTH];
-	static char iso_lc_messages[LOCALE_NAME_MAX_LENGTH];
-	char	   *period;
-	int			len;
-	int			ret_val;
-
-	/*
-	 * Valid locales have the following syntax:
-	 * <Language>[_<Country>[.<CodePage>]]
-	 *
-	 * GetLocaleInfoEx can only take locale name without code-page and for the
-	 * purpose of this API the code-page doesn't matter.
-	 */
-	period = strchr(winlocname, '.');
-	if (period != NULL)
-		len = period - winlocname;
-	else
-		len = pg_mbstrlen(winlocname);
-
-	memset(wc_locale_name, 0, sizeof(wc_locale_name));
-	memset(buffer, 0, sizeof(buffer));
-	MultiByteToWideChar(CP_ACP, 0, winlocname, len, wc_locale_name,
-						LOCALE_NAME_MAX_LENGTH);
-
-	/*
-	 * If the lc_messages is already a Unix-style string, we have a direct
-	 * match with LOCALE_SNAME, e.g. en-US, en_US.
-	 */
-	ret_val = GetLocaleInfoEx(wc_locale_name, LOCALE_SNAME, (LPWSTR) &buffer,
-							  LOCALE_NAME_MAX_LENGTH);
-	if (!ret_val)
-	{
-		/*
-		 * Search for a locale in the system that matches language and country
-		 * name.
-		 */
-		wchar_t    *argv[3];
-
-		argv[0] = wc_locale_name;
-		argv[1] = buffer;
-		argv[2] = (wchar_t *) &ret_val;
-		EnumSystemLocalesEx(search_locale_enum, LOCALE_WINDOWS, (LPARAM) argv,
-							NULL);
-	}
-
-	if (ret_val)
-	{
-		size_t		rc;
-		char	   *hyphen;
-
-		/* Locale names use only ASCII, any conversion locale suffices. */
-		rc = wchar2char(iso_lc_messages, buffer, sizeof(iso_lc_messages), NULL);
-		if (rc == -1 || rc == sizeof(iso_lc_messages))
-			return NULL;
-
-		/*
-		 * Simply replace the hyphen with an underscore.  See comments in
-		 * IsoLocaleName.
-		 */
-		hyphen = strchr(iso_lc_messages, '-');
-		if (hyphen)
-			*hyphen = '_';
-		return iso_lc_messages;
-	}
-
-	return NULL;
-}
-
 static char *
-IsoLocaleName(const char *winlocname)
+PosixLocaleName(const char *winlocname)
 {
-#if defined(_MSC_VER)
-	static char iso_lc_messages[LOCALE_NAME_MAX_LENGTH];
+	char iso_lc_messages[LOCALE_NAME_MAX_LENGTH];
+	char *hyphen;
 
 	if (pg_strcasecmp("c", winlocname) == 0 ||
 		pg_strcasecmp("posix", winlocname) == 0)
 	{
 		strcpy(iso_lc_messages, "C");
-		return iso_lc_messages;
 	}
 	else
-		return get_iso_localename(winlocname);
-
-#endif							/* defined(_MSC_VER) */
-	return NULL;				/* Not supported on this version of msvc/mingw */
+	{
+		strlcpy(iso_lc_messages, winlocname, sizeof(iso_lc_messages));
+		hypen = strchr(iso_lc_messages, '-');
+		if (hyphen)
+			*hyphen = '_';
+	}
+	return pg_strcpy(iso_lc_messages);
 }
 #endif							/* WIN32 && LC_MESSAGES */
 
@@ -1680,33 +1494,16 @@ get_collation_actual_version(char collprovider, const char *collcollate)
 			ereport(ERROR,
 					(errmsg("could not load locale \"%s\"", collcollate)));
 #elif defined(WIN32)
-		/*
-		 * If we are targeting Windows Vista and above, we can ask for a name
-		 * given a collation name (earlier versions required a location code
-		 * that we don't have).
-		 */
 		NLSVERSIONINFOEX version = {sizeof(NLSVERSIONINFOEX)};
 		WCHAR		wide_collcollate[LOCALE_NAME_MAX_LENGTH];
 
 		MultiByteToWideChar(CP_ACP, 0, collcollate, -1, wide_collcollate,
 							LOCALE_NAME_MAX_LENGTH);
 		if (!GetNLSVersionEx(COMPARE_STRING, wide_collcollate, &version))
-		{
-			/*
-			 * GetNLSVersionEx() wants a language tag such as "en-US", not a
-			 * locale name like "English_United States.1252".  Until those
-			 * values can be prevented from entering the system, or 100%
-			 * reliably converted to the more useful tag format, tolerate the
-			 * resulting error and report that we have no version data.
-			 */
-			if (GetLastError() == ERROR_INVALID_PARAMETER)
-				return NULL;
-
 			ereport(ERROR,
 					(errmsg("could not get collation version for locale \"%s\": error code %lu",
 							collcollate,
 							GetLastError())));
-		}
 		collversion = psprintf("%ld.%ld,%ld.%ld",
 							   (version.dwNLSVersion >> 8) & 0xFFFF,
 							   version.dwNLSVersion & 0xFF,
diff --git a/src/include/port/win32_port.h b/src/include/port/win32_port.h
index 5121c0c626..13ed144a8f 100644
--- a/src/include/port/win32_port.h
+++ b/src/include/port/win32_port.h
@@ -437,15 +437,6 @@ extern int	_pgstat64(const char *name, struct stat *buf);
 #undef setlocale
 #endif
 
-/*
- * Define our own wrapper macro around setlocale() to work around bugs in
- * Windows' native setlocale() function.
- */
-extern char *pgwin32_setlocale(int category, const char *locale);
-
-#define setlocale(a,b) pgwin32_setlocale(a,b)
-
-
 /* In backend/port/win32/signal.c */
 extern PGDLLIMPORT volatile int pg_signal_queue;
 extern PGDLLIMPORT int pg_signal_mask;
diff --git a/src/port/win32setlocale.c b/src/port/win32setlocale.c
deleted file mode 100644
index aadd09a4e9..0000000000
--- a/src/port/win32setlocale.c
+++ /dev/null
@@ -1,193 +0,0 @@
-/*-------------------------------------------------------------------------
- *
- * win32setlocale.c
- *		Wrapper to work around bugs in Windows setlocale() implementation
- *
- * Copyright (c) 2011-2022, PostgreSQL Global Development Group
- *
- * IDENTIFICATION
- *	  src/port/win32setlocale.c
- *
- *
- * The setlocale() function in Windows is broken in two ways. First, it
- * has a problem with locale names that have a dot in the country name. For
- * example:
- *
- * "Chinese (Traditional)_Hong Kong S.A.R..950"
- *
- * For some reason, setlocale() doesn't accept that as argument, even though
- * setlocale(LC_ALL, NULL) returns exactly that. Fortunately, it accepts
- * various alternative names for such countries, so to work around the broken
- * setlocale() function, we map the troublemaking locale names to accepted
- * aliases, before calling setlocale().
- *
- * The second problem is that the locale name for "Norwegian (Bokm&aring;l)"
- * contains a non-ASCII character. That's problematic, because it's not clear
- * what encoding the locale name itself is supposed to be in, when you
- * haven't yet set a locale. Also, it causes problems when the cluster
- * contains databases with different encodings, as the locale name is stored
- * in the pg_database system catalog. To work around that, when setlocale()
- * returns that locale name, map it to a pure-ASCII alias for the same
- * locale.
- *-------------------------------------------------------------------------
- */
-
-#include "c.h"
-
-#undef setlocale
-
-struct locale_map
-{
-	/*
-	 * String in locale name to replace. Can be a single string (end is NULL),
-	 * or separate start and end strings. If two strings are given, the locale
-	 * name must contain both of them, and everything between them is
-	 * replaced. This is used for a poor-man's regexp search, allowing
-	 * replacement of "start.*end".
-	 */
-	const char *locale_name_start;
-	const char *locale_name_end;
-
-	const char *replacement;	/* string to replace the match with */
-};
-
-/*
- * Mappings applied before calling setlocale(), to the argument.
- */
-static const struct locale_map locale_map_argument[] = {
-	/*
-	 * "HKG" is listed here:
-	 * http://msdn.microsoft.com/en-us/library/cdax410z%28v=vs.71%29.aspx
-	 * (Country/Region Strings).
-	 *
-	 * "ARE" is the ISO-3166 three-letter code for U.A.E. It is not on the
-	 * above list, but seems to work anyway.
-	 */
-	{"Hong Kong S.A.R.", NULL, "HKG"},
-	{"U.A.E.", NULL, "ARE"},
-
-	/*
-	 * The ISO-3166 country code for Macau S.A.R. is MAC, but Windows doesn't
-	 * seem to recognize that. And Macau isn't listed in the table of accepted
-	 * abbreviations linked above. Fortunately, "ZHM" seems to be accepted as
-	 * an alias for "Chinese (Traditional)_Macau S.A.R..950". I'm not sure
-	 * where "ZHM" comes from, must be some legacy naming scheme. But hey, it
-	 * works.
-	 *
-	 * Note that unlike HKG and ARE, ZHM is an alias for the *whole* locale
-	 * name, not just the country part.
-	 *
-	 * Some versions of Windows spell it "Macau", others "Macao".
-	 */
-	{"Chinese (Traditional)_Macau S.A.R..950", NULL, "ZHM"},
-	{"Chinese_Macau S.A.R..950", NULL, "ZHM"},
-	{"Chinese (Traditional)_Macao S.A.R..950", NULL, "ZHM"},
-	{"Chinese_Macao S.A.R..950", NULL, "ZHM"},
-	{NULL, NULL, NULL}
-};
-
-/*
- * Mappings applied after calling setlocale(), to its return value.
- */
-static const struct locale_map locale_map_result[] = {
-	/*
-	 * "Norwegian (Bokm&aring;l)" locale name contains the a-ring character.
-	 * Map it to a pure-ASCII alias.
-	 *
-	 * It's not clear what encoding setlocale() uses when it returns the
-	 * locale name, so to play it safe, we search for "Norwegian (Bok*l)".
-	 *
-	 * Just to make life even more complicated, some versions of Windows spell
-	 * the locale name without parentheses.  Translate that too.
-	 */
-	{"Norwegian (Bokm", "l)_Norway", "Norwegian_Norway"},
-	{"Norwegian Bokm", "l_Norway", "Norwegian_Norway"},
-	{NULL, NULL, NULL}
-};
-
-#define MAX_LOCALE_NAME_LEN		100
-
-static const char *
-map_locale(const struct locale_map *map, const char *locale)
-{
-	static char aliasbuf[MAX_LOCALE_NAME_LEN];
-	int			i;
-
-	/* Check if the locale name matches any of the problematic ones. */
-	for (i = 0; map[i].locale_name_start != NULL; i++)
-	{
-		const char *needle_start = map[i].locale_name_start;
-		const char *needle_end = map[i].locale_name_end;
-		const char *replacement = map[i].replacement;
-		char	   *match;
-		char	   *match_start = NULL;
-		char	   *match_end = NULL;
-
-		match = strstr(locale, needle_start);
-		if (match)
-		{
-			/*
-			 * Found a match for the first part. If this was a two-part
-			 * replacement, find the second part.
-			 */
-			match_start = match;
-			if (needle_end)
-			{
-				match = strstr(match_start + strlen(needle_start), needle_end);
-				if (match)
-					match_end = match + strlen(needle_end);
-				else
-					match_start = NULL;
-			}
-			else
-				match_end = match_start + strlen(needle_start);
-		}
-
-		if (match_start)
-		{
-			/* Found a match. Replace the matched string. */
-			int			matchpos = match_start - locale;
-			int			replacementlen = strlen(replacement);
-			char	   *rest = match_end;
-			int			restlen = strlen(rest);
-
-			/* check that the result fits in the static buffer */
-			if (matchpos + replacementlen + restlen + 1 > MAX_LOCALE_NAME_LEN)
-				return NULL;
-
-			memcpy(&aliasbuf[0], &locale[0], matchpos);
-			memcpy(&aliasbuf[matchpos], replacement, replacementlen);
-			/* includes null terminator */
-			memcpy(&aliasbuf[matchpos + replacementlen], rest, restlen + 1);
-
-			return aliasbuf;
-		}
-	}
-
-	/* no match, just return the original string */
-	return locale;
-}
-
-char *
-pgwin32_setlocale(int category, const char *locale)
-{
-	const char *argument;
-	char	   *result;
-
-	if (locale == NULL)
-		argument = NULL;
-	else
-		argument = map_locale(locale_map_argument, locale);
-
-	/* Call the real setlocale() function */
-	result = setlocale(category, argument);
-
-	/*
-	 * setlocale() is specified to return a "char *" that the caller is
-	 * forbidden to modify, so casting away the "const" is innocuous.
-	 */
-	if (result)
-		result = unconstify(char *, map_locale(locale_map_result, result));
-
-	return result;
-}
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index e4feda10fd..1bc35ef926 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -108,7 +108,7 @@ sub mkvcbuild
 	  pqsignal.c mkdtemp.c qsort.c qsort_arg.c bsearch_arg.c quotes.c system.c
 	  strerror.c tar.c
 	  win32env.c win32error.c win32ntdll.c
-	  win32security.c win32setlocale.c win32stat.c);
+	  win32security.c win32stat.c);
 
 	push(@pgportfiles, 'strtof.c') if ($vsVersion < '14.00');
 
-- 
2.35.1

From b007eb45e575956d5035f4152f72177abddc2762 Mon Sep 17 00:00:00 2001
From: Thomas Munro <thomas.munro@gmail.com>
Date: Tue, 19 Jul 2022 06:31:17 +1200
Subject: [PATCH v3 1/3] Default to BCP 47 locale in initdb on Windows.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Avoid selecting traditional Windows locale names written with English
words, because they are unstable and not recommended for use in
databases.  Since setlocale() returns such names, on Windows use
GetUserDefaultLocaleName() if the user didn't provide an explicit
locale.

Also update the documentation to recommend BCP 47 over the traditional
names when providing explicit values to initdb.

Reviewed-by: Juan José Santamaría Flecha <juanjo.santamaria@gmail.com>
Discussion: https://postgr.es/m/CA%2BhUKGJ%3DXThErgAQRoqfCy1bKPxXVuF0%3D2zDbB%2BSxDs59pv7Fw%40mail.gmail.com
---
 doc/src/sgml/charset.sgml | 10 ++++++++--
 src/bin/initdb/initdb.c   | 31 +++++++++++++++++++++++++++++--
 2 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/doc/src/sgml/charset.sgml b/doc/src/sgml/charset.sgml
index 445fd175d8..b656ca489f 100644
--- a/doc/src/sgml/charset.sgml
+++ b/doc/src/sgml/charset.sgml
@@ -83,8 +83,14 @@ initdb --locale=sv_SE
     system under what names depends on what was provided by the operating
     system vendor and what was installed.  On most Unix systems, the command
     <literal>locale -a</literal> will provide a list of available locales.
-    Windows uses more verbose locale names, such as <literal>German_Germany</literal>
-    or <literal>Swedish_Sweden.1252</literal>, but the principles are the same.
+   </para>
+
+   <para>
+    Windows uses BCP 47 language tags, like ICU.
+    For example, <literal>sv-SE</literal> represents Swedish as spoken in Sweden.
+    Windows also supports more verbose locale names based on English words,
+    such as <literal>German_Germany</literal> or <literal>Swedish_Sweden.1252</literal>,
+    but these are not recommended.
    </para>
 
    <para>
diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index 89b888eaa5..3af08b7b99 100644
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -59,6 +59,10 @@
 #include "sys/mman.h"
 #endif
 
+#ifdef WIN32
+#include <winnls.h>
+#endif
+
 #include "access/xlog_internal.h"
 #include "catalog/pg_authid_d.h"
 #include "catalog/pg_class_d.h" /* pgrminclude ignore */
@@ -2007,6 +2011,7 @@ locale_date_order(const char *locale)
 static void
 check_locale_name(int category, const char *locale, char **canonname)
 {
+	char	   *locale_copy;
 	char	   *save;
 	char	   *res;
 
@@ -2022,10 +2027,30 @@ check_locale_name(int category, const char *locale, char **canonname)
 
 	/* for setlocale() call */
 	if (!locale)
-		locale = "";
+	{
+#ifdef WIN32
+		wchar_t		wide_name[LOCALE_NAME_MAX_LENGTH];
+		char		name[LOCALE_NAME_MAX_LENGTH];
+
+		/* use Windows API to find the default in BCP47 format */
+		if (GetUserDefaultLocaleName(wide_name, LOCALE_NAME_MAX_LENGTH) == 0)
+			pg_fatal("failed to get default locale name: error code %lu",
+					 GetLastError());
+		if (WideCharToMultiByte(CP_ACP, 0, wide_name, -1, name,
+								LOCALE_NAME_MAX_LENGTH, NULL, NULL) == 0)
+			pg_fatal("failed to convert locale name: error code %lu",
+					 GetLastError());
+		locale_copy = pg_strdup(name);
+#else
+		/* use environment to find the default */
+		locale_copy = pg_strdup("");
+#endif
+	}
+	else
+		locale_copy = pg_strdup(locale);
 
 	/* set the locale with setlocale, to see if it accepts it. */
-	res = setlocale(category, locale);
+	res = setlocale(category, locale_copy);
 
 	/* save canonical name if requested. */
 	if (res && canonname)
@@ -2054,6 +2079,8 @@ check_locale_name(int category, const char *locale, char **canonname)
 			pg_fatal("invalid locale settings; check LANG and LC_* environment variables");
 		}
 	}
+
+	free(locale_copy);
 }
 
 /*
-- 
2.30.2

From 430fda564b3a36f346a672668e5181f43132368e Mon Sep 17 00:00:00 2001
From: Thomas Munro <thomas.munro@gmail.com>
Date: Wed, 20 Jul 2022 22:38:50 +1200
Subject: [PATCH v3 2/3] Default to UTF-8 in initdb on Windows.

---
 src/backend/utils/adt/pg_locale.c | 13 ++++++++++++-
 src/bin/initdb/initdb.c           |  4 +++-
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 607a4b7340..6242dc094d 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -1687,8 +1687,19 @@ get_collation_actual_version(char collprovider, const char *collcollate)
 		 */
 		NLSVERSIONINFOEX version = {sizeof(NLSVERSIONINFOEX)};
 		WCHAR		wide_collcollate[LOCALE_NAME_MAX_LENGTH];
+		char		copy_collcollate[LOCALE_NAME_MAX_LENGTH];
 
-		MultiByteToWideChar(CP_ACP, 0, collcollate, -1, wide_collcollate,
+		/* Trim off encoding, if there is one */
+		strlcpy(copy_collcollate, collcollate, sizeof(copy_collcollate));
+		for (char *p = copy_collcollate; *p; ++p)
+		{
+			if (*p == '.')
+			{
+				*p = 0;
+				break;
+			}
+		}
+		MultiByteToWideChar(CP_ACP, 0, copy_collcollate, -1, wide_collcollate,
 							LOCALE_NAME_MAX_LENGTH);
 		if (!GetNLSVersionEx(COMPARE_STRING, wide_collcollate, &version))
 		{
diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index 3af08b7b99..1170b80d75 100644
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -2040,7 +2040,9 @@ check_locale_name(int category, const char *locale, char **canonname)
 								LOCALE_NAME_MAX_LENGTH, NULL, NULL) == 0)
 			pg_fatal("failed to convert locale name: error code %lu",
 					 GetLastError());
-		locale_copy = pg_strdup(name);
+		/* default to UTF-8, no matter what the system default codepage is */
+		locale_copy = pg_malloc(strlen(name) + sizeof(".UTF-8") + 1);
+		sprintf(locale_copy, "%s.UTF-8", name);
 #else
 		/* use environment to find the default */
 		locale_copy = pg_strdup("");
-- 
2.30.2

From 5281778fbcd20155fd4613732c00e140f7745842 Mon Sep 17 00:00:00 2001
From: Thomas Munro <thomas.munro@gmail.com>
Date: Tue, 19 Jul 2022 08:53:08 +1200
Subject: [PATCH v3 3/3] Remove support for old Windows locale names.

We now use BCP 47 locale names by default and also advise those for
explicit use.  Remove support for munging the old unstable and
unsystematic English word-style locale names.

If you explicitly provide a traditional value like "English_United
States.1521", it will still work, but we won't do any kind of cleanup on
the name.  This should be enough to work with pg_upgrade'd systems from
before we started using BCP 47.

XXX Is that true?
---
 configure                         |   6 -
 configure.ac                      |   1 -
 doc/src/sgml/charset.sgml         |   2 +-
 src/backend/utils/adt/pg_locale.c | 231 +++---------------------------
 src/include/port/win32_port.h     |   9 --
 src/port/win32setlocale.c         | 193 -------------------------
 src/tools/msvc/Mkvcbuild.pm       |   2 +-
 7 files changed, 19 insertions(+), 425 deletions(-)
 delete mode 100644 src/port/win32setlocale.c

diff --git a/configure b/configure
index 59fa82b8d7..d0da0c0a40 100755
--- a/configure
+++ b/configure
@@ -17180,12 +17180,6 @@ esac
  ;;
 esac
 
-  case " $LIBOBJS " in
-  *" win32setlocale.$ac_objext "* ) ;;
-  *) LIBOBJS="$LIBOBJS win32setlocale.$ac_objext"
- ;;
-esac
-
   case " $LIBOBJS " in
   *" win32stat.$ac_objext "* ) ;;
   *) LIBOBJS="$LIBOBJS win32stat.$ac_objext"
diff --git a/configure.ac b/configure.ac
index 612dabf698..c0906429be 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1996,7 +1996,6 @@ if test "$PORTNAME" = "win32"; then
   AC_LIBOBJ(win32error)
   AC_LIBOBJ(win32ntdll)
   AC_LIBOBJ(win32security)
-  AC_LIBOBJ(win32setlocale)
   AC_LIBOBJ(win32stat)
   AC_DEFINE([HAVE_SYMLINK], 1,
             [Define to 1 if you have the `symlink' function.])
diff --git a/doc/src/sgml/charset.sgml b/doc/src/sgml/charset.sgml
index b656ca489f..3c12f3f344 100644
--- a/doc/src/sgml/charset.sgml
+++ b/doc/src/sgml/charset.sgml
@@ -90,7 +90,7 @@ initdb --locale=sv_SE
     For example, <literal>sv-SE</literal> represents Swedish as spoken in Sweden.
     Windows also supports more verbose locale names based on English words,
     such as <literal>German_Germany</literal> or <literal>Swedish_Sweden.1252</literal>,
-    but these are not recommended.
+    but these should not be used in PostgreSQL.
    </para>
 
    <para>
diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 6242dc094d..f7f51a7055 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -118,7 +118,7 @@ static HTAB *collation_cache = NULL;
 
 
 #if defined(WIN32) && defined(LC_MESSAGES)
-static char *IsoLocaleName(const char *);	/* MSVC specific */
+static char *PosixLocaleName(const char *);
 #endif
 
 #ifdef USE_ICU
@@ -204,10 +204,7 @@ pg_perm_setlocale(int category, const char *locale)
 		case LC_MESSAGES:
 			envvar = "LC_MESSAGES";
 #ifdef WIN32
-			result = IsoLocaleName(locale);
-			if (result == NULL)
-				result = (char *) locale;
-			elog(DEBUG3, "IsoLocaleName() executed; locale: \"%s\"", result);
+			locale = PosixLocaleName(locale);
 #endif							/* WIN32 */
 			break;
 #endif							/* LC_MESSAGES */
@@ -905,218 +902,35 @@ cache_locale_time(void)
 
 #if defined(WIN32) && defined(LC_MESSAGES)
 /*
- * Convert a Windows setlocale() argument to a Unix-style one.
+ * Convert a Windows BCP 47 locale name to a POSIX one.
  *
  * Regardless of platform, we install message catalogs under a Unix-style
  * LL[_CC][.ENCODING][@VARIANT] naming convention.  Only LC_MESSAGES settings
  * following that style will elicit localized interface strings.
  *
- * Before Visual Studio 2012 (msvcr110.dll), Windows setlocale() accepted "C"
- * (but not "c") and strings of the form <Language>[_<Country>][.<CodePage>],
- * case-insensitive.  setlocale() returns the fully-qualified form; for
- * example, setlocale("thaI") returns "Thai_Thailand.874".  Internally,
- * setlocale() and _create_locale() select a "locale identifier"[1] and store
- * it in an undocumented _locale_t field.  From that LCID, we can retrieve the
- * ISO 639 language and the ISO 3166 country.  Character encoding does not
- * matter, because the server and client encodings govern that.
- *
- * Windows Vista introduced the "locale name" concept[2], closely following
- * RFC 4646.  Locale identifiers are now deprecated.  Starting with Visual
- * Studio 2012, setlocale() accepts locale names in addition to the strings it
- * accepted historically.  It does not standardize them; setlocale("Th-tH")
- * returns "Th-tH".  setlocale(category, "") still returns a traditional
- * string.  Furthermore, msvcr110.dll changed the undocumented _locale_t
- * content to carry locale names instead of locale identifiers.
- *
- * Visual Studio 2015 should still be able to do the same as Visual Studio
- * 2012, but the declaration of locale_name is missing in _locale_t, causing
- * this code compilation to fail, hence this falls back instead on to
- * enumerating all system locales by using EnumSystemLocalesEx to find the
- * required locale name.  If the input argument is in Unix-style then we can
- * get ISO Locale name directly by using GetLocaleInfoEx() with LCType as
- * LOCALE_SNAME.
- *
- * MinGW headers declare _create_locale(), but msvcrt.dll lacks that symbol in
- * releases before Windows 8. IsoLocaleName() always fails in a MinGW-built
- * postgres.exe, so only Unix-style values of the lc_messages GUC can elicit
- * localized messages. In particular, every lc_messages setting that initdb
- * can select automatically will yield only C-locale messages. XXX This could
- * be fixed by running the fully-qualified locale name through a lookup table.
- *
- * This function returns a pointer to a static buffer bearing the converted
- * name or NULL if conversion fails.
- *
- * [1] https://docs.microsoft.com/en-us/windows/win32/intl/locale-identifiers
- * [2] https://docs.microsoft.com/en-us/windows/win32/intl/locale-names
- */
-
-/*
- * Callback function for EnumSystemLocalesEx() in get_iso_localename().
- *
- * This function enumerates all system locales, searching for one that matches
- * an input with the format: <Language>[_<Country>], e.g.
- * English[_United States]
- *
- * The input is a three wchar_t array as an LPARAM. The first element is the
- * locale_name we want to match, the second element is an allocated buffer
- * where the Unix-style locale is copied if a match is found, and the third
- * element is the search status, 1 if a match was found, 0 otherwise.
- */
-static BOOL CALLBACK
-search_locale_enum(LPWSTR pStr, DWORD dwFlags, LPARAM lparam)
-{
-	wchar_t		test_locale[LOCALE_NAME_MAX_LENGTH];
-	wchar_t   **argv;
-
-	(void) (dwFlags);
-
-	argv = (wchar_t **) lparam;
-	*argv[2] = (wchar_t) 0;
-
-	memset(test_locale, 0, sizeof(test_locale));
-
-	/* Get the name of the <Language> in English */
-	if (GetLocaleInfoEx(pStr, LOCALE_SENGLISHLANGUAGENAME,
-						test_locale, LOCALE_NAME_MAX_LENGTH))
-	{
-		/*
-		 * If the enumerated locale does not have a hyphen ("en") OR the
-		 * lc_message input does not have an underscore ("English"), we only
-		 * need to compare the <Language> tags.
-		 */
-		if (wcsrchr(pStr, '-') == NULL || wcsrchr(argv[0], '_') == NULL)
-		{
-			if (_wcsicmp(argv[0], test_locale) == 0)
-			{
-				wcscpy(argv[1], pStr);
-				*argv[2] = (wchar_t) 1;
-				return FALSE;
-			}
-		}
-
-		/*
-		 * We have to compare a full <Language>_<Country> tag, so we append
-		 * the underscore and name of the country/region in English, e.g.
-		 * "English_United States".
-		 */
-		else
-		{
-			size_t		len;
-
-			wcscat(test_locale, L"_");
-			len = wcslen(test_locale);
-			if (GetLocaleInfoEx(pStr, LOCALE_SENGLISHCOUNTRYNAME,
-								test_locale + len,
-								LOCALE_NAME_MAX_LENGTH - len))
-			{
-				if (_wcsicmp(argv[0], test_locale) == 0)
-				{
-					wcscpy(argv[1], pStr);
-					*argv[2] = (wchar_t) 1;
-					return FALSE;
-				}
-			}
-		}
-	}
-
-	return TRUE;
-}
-
-/*
- * This function converts a Windows locale name to an ISO formatted version
- * for Visual Studio 2015 or greater.
- *
- * Returns NULL, if no valid conversion was found.
+ * Historically, verbose, but unsystematic and unstable names like
+ * "Thai_Thailand.874" were supported, but now only BCP 47 input is expected.
+ * That means we just need to be able to convert "en-US" to "en_US".
  */
 static char *
-get_iso_localename(const char *winlocname)
+PosixLocaleName(const char *winlocname)
 {
-	wchar_t		wc_locale_name[LOCALE_NAME_MAX_LENGTH];
-	wchar_t		buffer[LOCALE_NAME_MAX_LENGTH];
-	static char iso_lc_messages[LOCALE_NAME_MAX_LENGTH];
-	char	   *period;
-	int			len;
-	int			ret_val;
-
-	/*
-	 * Valid locales have the following syntax:
-	 * <Language>[_<Country>[.<CodePage>]]
-	 *
-	 * GetLocaleInfoEx can only take locale name without code-page and for the
-	 * purpose of this API the code-page doesn't matter.
-	 */
-	period = strchr(winlocname, '.');
-	if (period != NULL)
-		len = period - winlocname;
-	else
-		len = pg_mbstrlen(winlocname);
-
-	memset(wc_locale_name, 0, sizeof(wc_locale_name));
-	memset(buffer, 0, sizeof(buffer));
-	MultiByteToWideChar(CP_ACP, 0, winlocname, len, wc_locale_name,
-						LOCALE_NAME_MAX_LENGTH);
-
-	/*
-	 * If the lc_messages is already a Unix-style string, we have a direct
-	 * match with LOCALE_SNAME, e.g. en-US, en_US.
-	 */
-	ret_val = GetLocaleInfoEx(wc_locale_name, LOCALE_SNAME, (LPWSTR) &buffer,
-							  LOCALE_NAME_MAX_LENGTH);
-	if (!ret_val)
-	{
-		/*
-		 * Search for a locale in the system that matches language and country
-		 * name.
-		 */
-		wchar_t    *argv[3];
-
-		argv[0] = wc_locale_name;
-		argv[1] = buffer;
-		argv[2] = (wchar_t *) &ret_val;
-		EnumSystemLocalesEx(search_locale_enum, LOCALE_WINDOWS, (LPARAM) argv,
-							NULL);
-	}
-
-	if (ret_val)
-	{
-		size_t		rc;
-		char	   *hyphen;
-
-		/* Locale names use only ASCII, any conversion locale suffices. */
-		rc = wchar2char(iso_lc_messages, buffer, sizeof(iso_lc_messages), NULL);
-		if (rc == -1 || rc == sizeof(iso_lc_messages))
-			return NULL;
-
-		/*
-		 * Simply replace the hyphen with an underscore.  See comments in
-		 * IsoLocaleName.
-		 */
-		hyphen = strchr(iso_lc_messages, '-');
-		if (hyphen)
-			*hyphen = '_';
-		return iso_lc_messages;
-	}
-
-	return NULL;
-}
-
-static char *
-IsoLocaleName(const char *winlocname)
-{
-#if defined(_MSC_VER)
-	static char iso_lc_messages[LOCALE_NAME_MAX_LENGTH];
+	char iso_lc_messages[LOCALE_NAME_MAX_LENGTH];
+	char *hyphen;
 
 	if (pg_strcasecmp("c", winlocname) == 0 ||
 		pg_strcasecmp("posix", winlocname) == 0)
 	{
 		strcpy(iso_lc_messages, "C");
-		return iso_lc_messages;
 	}
 	else
-		return get_iso_localename(winlocname);
-
-#endif							/* defined(_MSC_VER) */
-	return NULL;				/* Not supported on this version of msvc/mingw */
+	{
+		strlcpy(iso_lc_messages, winlocname, sizeof(iso_lc_messages));
+		hypen = strchr(iso_lc_messages, '-');
+		if (hyphen)
+			*hyphen = '_';
+	}
+	return pg_strcpy(iso_lc_messages);
 }
 #endif							/* WIN32 && LC_MESSAGES */
 
@@ -1680,11 +1494,6 @@ get_collation_actual_version(char collprovider, const char *collcollate)
 			ereport(ERROR,
 					(errmsg("could not load locale \"%s\"", collcollate)));
 #elif defined(WIN32)
-		/*
-		 * If we are targeting Windows Vista and above, we can ask for a name
-		 * given a collation name (earlier versions required a location code
-		 * that we don't have).
-		 */
 		NLSVERSIONINFOEX version = {sizeof(NLSVERSIONINFOEX)};
 		WCHAR		wide_collcollate[LOCALE_NAME_MAX_LENGTH];
 		char		copy_collcollate[LOCALE_NAME_MAX_LENGTH];
@@ -1703,13 +1512,7 @@ get_collation_actual_version(char collprovider, const char *collcollate)
 							LOCALE_NAME_MAX_LENGTH);
 		if (!GetNLSVersionEx(COMPARE_STRING, wide_collcollate, &version))
 		{
-			/*
-			 * GetNLSVersionEx() wants a language tag such as "en-US", not a
-			 * locale name like "English_United States.1252".  Until those
-			 * values can be prevented from entering the system, or 100%
-			 * reliably converted to the more useful tag format, tolerate the
-			 * resulting error and report that we have no version data.
-			 */
+			/* Old style locale names fail here, so ignore. */
 			if (GetLastError() == ERROR_INVALID_PARAMETER)
 				return NULL;
 
diff --git a/src/include/port/win32_port.h b/src/include/port/win32_port.h
index 4de5bf3bf6..a569433811 100644
--- a/src/include/port/win32_port.h
+++ b/src/include/port/win32_port.h
@@ -445,15 +445,6 @@ extern int	_pgstat64(const char *name, struct stat *buf);
 #undef setlocale
 #endif
 
-/*
- * Define our own wrapper macro around setlocale() to work around bugs in
- * Windows' native setlocale() function.
- */
-extern char *pgwin32_setlocale(int category, const char *locale);
-
-#define setlocale(a,b) pgwin32_setlocale(a,b)
-
-
 /* In backend/port/win32/signal.c */
 extern PGDLLIMPORT volatile int pg_signal_queue;
 extern PGDLLIMPORT int pg_signal_mask;
diff --git a/src/port/win32setlocale.c b/src/port/win32setlocale.c
deleted file mode 100644
index aadd09a4e9..0000000000
--- a/src/port/win32setlocale.c
+++ /dev/null
@@ -1,193 +0,0 @@
-/*-------------------------------------------------------------------------
- *
- * win32setlocale.c
- *		Wrapper to work around bugs in Windows setlocale() implementation
- *
- * Copyright (c) 2011-2022, PostgreSQL Global Development Group
- *
- * IDENTIFICATION
- *	  src/port/win32setlocale.c
- *
- *
- * The setlocale() function in Windows is broken in two ways. First, it
- * has a problem with locale names that have a dot in the country name. For
- * example:
- *
- * "Chinese (Traditional)_Hong Kong S.A.R..950"
- *
- * For some reason, setlocale() doesn't accept that as argument, even though
- * setlocale(LC_ALL, NULL) returns exactly that. Fortunately, it accepts
- * various alternative names for such countries, so to work around the broken
- * setlocale() function, we map the troublemaking locale names to accepted
- * aliases, before calling setlocale().
- *
- * The second problem is that the locale name for "Norwegian (Bokm&aring;l)"
- * contains a non-ASCII character. That's problematic, because it's not clear
- * what encoding the locale name itself is supposed to be in, when you
- * haven't yet set a locale. Also, it causes problems when the cluster
- * contains databases with different encodings, as the locale name is stored
- * in the pg_database system catalog. To work around that, when setlocale()
- * returns that locale name, map it to a pure-ASCII alias for the same
- * locale.
- *-------------------------------------------------------------------------
- */
-
-#include "c.h"
-
-#undef setlocale
-
-struct locale_map
-{
-	/*
-	 * String in locale name to replace. Can be a single string (end is NULL),
-	 * or separate start and end strings. If two strings are given, the locale
-	 * name must contain both of them, and everything between them is
-	 * replaced. This is used for a poor-man's regexp search, allowing
-	 * replacement of "start.*end".
-	 */
-	const char *locale_name_start;
-	const char *locale_name_end;
-
-	const char *replacement;	/* string to replace the match with */
-};
-
-/*
- * Mappings applied before calling setlocale(), to the argument.
- */
-static const struct locale_map locale_map_argument[] = {
-	/*
-	 * "HKG" is listed here:
-	 * http://msdn.microsoft.com/en-us/library/cdax410z%28v=vs.71%29.aspx
-	 * (Country/Region Strings).
-	 *
-	 * "ARE" is the ISO-3166 three-letter code for U.A.E. It is not on the
-	 * above list, but seems to work anyway.
-	 */
-	{"Hong Kong S.A.R.", NULL, "HKG"},
-	{"U.A.E.", NULL, "ARE"},
-
-	/*
-	 * The ISO-3166 country code for Macau S.A.R. is MAC, but Windows doesn't
-	 * seem to recognize that. And Macau isn't listed in the table of accepted
-	 * abbreviations linked above. Fortunately, "ZHM" seems to be accepted as
-	 * an alias for "Chinese (Traditional)_Macau S.A.R..950". I'm not sure
-	 * where "ZHM" comes from, must be some legacy naming scheme. But hey, it
-	 * works.
-	 *
-	 * Note that unlike HKG and ARE, ZHM is an alias for the *whole* locale
-	 * name, not just the country part.
-	 *
-	 * Some versions of Windows spell it "Macau", others "Macao".
-	 */
-	{"Chinese (Traditional)_Macau S.A.R..950", NULL, "ZHM"},
-	{"Chinese_Macau S.A.R..950", NULL, "ZHM"},
-	{"Chinese (Traditional)_Macao S.A.R..950", NULL, "ZHM"},
-	{"Chinese_Macao S.A.R..950", NULL, "ZHM"},
-	{NULL, NULL, NULL}
-};
-
-/*
- * Mappings applied after calling setlocale(), to its return value.
- */
-static const struct locale_map locale_map_result[] = {
-	/*
-	 * "Norwegian (Bokm&aring;l)" locale name contains the a-ring character.
-	 * Map it to a pure-ASCII alias.
-	 *
-	 * It's not clear what encoding setlocale() uses when it returns the
-	 * locale name, so to play it safe, we search for "Norwegian (Bok*l)".
-	 *
-	 * Just to make life even more complicated, some versions of Windows spell
-	 * the locale name without parentheses.  Translate that too.
-	 */
-	{"Norwegian (Bokm", "l)_Norway", "Norwegian_Norway"},
-	{"Norwegian Bokm", "l_Norway", "Norwegian_Norway"},
-	{NULL, NULL, NULL}
-};
-
-#define MAX_LOCALE_NAME_LEN		100
-
-static const char *
-map_locale(const struct locale_map *map, const char *locale)
-{
-	static char aliasbuf[MAX_LOCALE_NAME_LEN];
-	int			i;
-
-	/* Check if the locale name matches any of the problematic ones. */
-	for (i = 0; map[i].locale_name_start != NULL; i++)
-	{
-		const char *needle_start = map[i].locale_name_start;
-		const char *needle_end = map[i].locale_name_end;
-		const char *replacement = map[i].replacement;
-		char	   *match;
-		char	   *match_start = NULL;
-		char	   *match_end = NULL;
-
-		match = strstr(locale, needle_start);
-		if (match)
-		{
-			/*
-			 * Found a match for the first part. If this was a two-part
-			 * replacement, find the second part.
-			 */
-			match_start = match;
-			if (needle_end)
-			{
-				match = strstr(match_start + strlen(needle_start), needle_end);
-				if (match)
-					match_end = match + strlen(needle_end);
-				else
-					match_start = NULL;
-			}
-			else
-				match_end = match_start + strlen(needle_start);
-		}
-
-		if (match_start)
-		{
-			/* Found a match. Replace the matched string. */
-			int			matchpos = match_start - locale;
-			int			replacementlen = strlen(replacement);
-			char	   *rest = match_end;
-			int			restlen = strlen(rest);
-
-			/* check that the result fits in the static buffer */
-			if (matchpos + replacementlen + restlen + 1 > MAX_LOCALE_NAME_LEN)
-				return NULL;
-
-			memcpy(&aliasbuf[0], &locale[0], matchpos);
-			memcpy(&aliasbuf[matchpos], replacement, replacementlen);
-			/* includes null terminator */
-			memcpy(&aliasbuf[matchpos + replacementlen], rest, restlen + 1);
-
-			return aliasbuf;
-		}
-	}
-
-	/* no match, just return the original string */
-	return locale;
-}
-
-char *
-pgwin32_setlocale(int category, const char *locale)
-{
-	const char *argument;
-	char	   *result;
-
-	if (locale == NULL)
-		argument = NULL;
-	else
-		argument = map_locale(locale_map_argument, locale);
-
-	/* Call the real setlocale() function */
-	result = setlocale(category, argument);
-
-	/*
-	 * setlocale() is specified to return a "char *" that the caller is
-	 * forbidden to modify, so casting away the "const" is innocuous.
-	 */
-	if (result)
-		result = unconstify(char *, map_locale(locale_map_result, result));
-
-	return result;
-}
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index cc7a908d10..fff378d2b3 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -109,7 +109,7 @@ sub mkvcbuild
 	  pqsignal.c mkdtemp.c qsort.c qsort_arg.c bsearch_arg.c quotes.c system.c
 	  strerror.c tar.c
 	  win32env.c win32error.c win32ntdll.c
-	  win32security.c win32setlocale.c win32stat.c);
+	  win32security.c win32stat.c);
 
 	push(@pgportfiles, 'strtof.c') if ($vsVersion < '14.00');
 
-- 
2.30.2

From d015005cca08bc1c7ae487392ed7b5a4cfa58748 Mon Sep 17 00:00:00 2001
From: Thomas Munro <thomas.munro@gmail.com>
Date: Tue, 19 Jul 2022 06:31:17 +1200
Subject: [PATCH v4] Default to IETF BCP 47 locale names in initdb on Windows.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Avoid selecting traditional Windows locale names written with English
words, because (1) they are unstable and not recommended for use in
databases and (2) they may contain non-ASCII characters, which we can't
put in our shared catalogs.  Since setlocale() returns such names, on
Windows use GetUserDefaultLocaleName() if the user didn't provide an
explicit locale.  It returns BCP 47 strings like "en-US".

Also update the documentation to recommend BCP 47 over the traditional
names when providing explicit values to initdb.

Reviewed-by: Juan José Santamaría Flecha <juanjo.santamaria@gmail.com>
Discussion: https://postgr.es/m/CA%2BhUKGJ%3DXThErgAQRoqfCy1bKPxXVuF0%3D2zDbB%2BSxDs59pv7Fw%40mail.gmail.com
---
 doc/src/sgml/charset.sgml | 13 +++++++++++--
 src/bin/initdb/initdb.c   | 31 +++++++++++++++++++++++++++++--
 2 files changed, 40 insertions(+), 4 deletions(-)

diff --git a/doc/src/sgml/charset.sgml b/doc/src/sgml/charset.sgml
index 74783d148f..9a2cd5c2d5 100644
--- a/doc/src/sgml/charset.sgml
+++ b/doc/src/sgml/charset.sgml
@@ -83,8 +83,17 @@ initdb --locale=sv_SE
     system under what names depends on what was provided by the operating
     system vendor and what was installed.  On most Unix systems, the command
     <literal>locale -a</literal> will provide a list of available locales.
-    Windows uses more verbose locale names, such as <literal>German_Germany</literal>
-    or <literal>Swedish_Sweden.1252</literal>, but the principles are the same.
+   </para>
+
+   <para>
+    Windows uses BCP 47 language tags, like ICU.
+    For example, <literal>sv-SE</literal> represents Swedish as spoken in Sweden.
+    Windows also supports more verbose locale names based on full names
+    such as <literal>German_Germany</literal> or <literal>Swedish_Sweden.1252</literal>,
+    but these are not recommended because they are not stable across operating
+    system updates due to changes in geographical names, and may contain
+    non-ASCII characters which are not supported in PostgreSQL's shared
+    catalogs.
    </para>
 
    <para>
diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index 0c6f5ceb0a..021e847240 100644
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -64,6 +64,10 @@
 #include "sys/mman.h"
 #endif
 
+#ifdef WIN32
+#include <winnls.h>
+#endif
+
 #include "access/xlog_internal.h"
 #include "catalog/pg_authid_d.h"
 #include "catalog/pg_class_d.h" /* pgrminclude ignore */
@@ -2132,6 +2136,7 @@ locale_date_order(const char *locale)
 static void
 check_locale_name(int category, const char *locale, char **canonname)
 {
+	char	   *locale_copy;
 	char	   *save;
 	char	   *res;
 
@@ -2147,10 +2152,30 @@ check_locale_name(int category, const char *locale, char **canonname)
 
 	/* for setlocale() call */
 	if (!locale)
-		locale = "";
+	{
+#ifdef WIN32
+		wchar_t		wide_name[LOCALE_NAME_MAX_LENGTH];
+		char		name[LOCALE_NAME_MAX_LENGTH];
+
+		/* use Windows API to find the default in BCP47 format */
+		if (GetUserDefaultLocaleName(wide_name, LOCALE_NAME_MAX_LENGTH) == 0)
+			pg_fatal("failed to get default locale name: error code %lu",
+					 GetLastError());
+		if (WideCharToMultiByte(CP_ACP, 0, wide_name, -1, name,
+								LOCALE_NAME_MAX_LENGTH, NULL, NULL) == 0)
+			pg_fatal("failed to convert locale name: error code %lu",
+					 GetLastError());
+		locale_copy = pg_strdup(name);
+#else
+		/* use environment to find the default */
+		locale_copy = pg_strdup("");
+#endif
+	}
+	else
+		locale_copy = pg_strdup(locale);
 
 	/* set the locale with setlocale, to see if it accepts it. */
-	res = setlocale(category, locale);
+	res = setlocale(category, locale_copy);
 
 	/* save canonical name if requested. */
 	if (res && canonname)
@@ -2183,6 +2208,8 @@ check_locale_name(int category, const char *locale, char **canonname)
 			pg_fatal("invalid locale settings; check LANG and LC_* environment variables");
 		}
 	}
+
+	free(locale_copy);
 }
 
 /*
-- 
2.39.2

From fb33b7eb5482bae31b70bb54dbe77325b543a89c Mon Sep 17 00:00:00 2001
From: Thomas Munro <thomas.munro@gmail.com>
Date: Mon, 20 Nov 2023 14:24:35 +1300
Subject: [PATCH v5 1/2] MinGW has GetLocaleInfoEx().

To use BCP 47 locale names like "en-US" without a suffix ".encoding", we
need to be able to call GetLocaleInfoEx() to look up the encoding.  That
was previously gated for MSVC only, but MinGW has had the function for
many years.  Remove that gating, because otherwise our MinGW build farm
animals would fail when a later commit switches to using the new names by
default.

There are probably other places where _MSC_VER is being used as a proxy
for detecting MinGW with an out-of-date idea about missing functions.

Discussion: https://postgr.es/m/CA%2BhUKGLsV3vTjPp7bOZBr3JTKp3Brkr9V0Qfmc7UvpWcmAQL4A%40mail.gmail.com
---
 src/port/chklocale.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/src/port/chklocale.c b/src/port/chklocale.c
index 8cb81c8640e..a15b0d5349b 100644
--- a/src/port/chklocale.c
+++ b/src/port/chklocale.c
@@ -204,7 +204,6 @@ win32_langinfo(const char *ctype)
 	char	   *r = NULL;
 	char	   *codepage;
 
-#if defined(_MSC_VER)
 	uint32		cp;
 	WCHAR		wctype[LOCALE_NAME_MAX_LENGTH];
 
@@ -229,7 +228,6 @@ win32_langinfo(const char *ctype)
 		}
 	}
 	else
-#endif
 	{
 		/*
 		 * Locale format on Win32 is <Language>_<Country>.<CodePage>.  For
-- 
2.45.2

From dc726a61aace86bda62687e3aa1411753ba3f1a4 Mon Sep 17 00:00:00 2001
From: Thomas Munro <thomas.munro@gmail.com>
Date: Tue, 19 Jul 2022 06:31:17 +1200
Subject: [PATCH v5 2/2] Default to IETF BCP 47 locale names in initdb on
 Windows.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Avoid selecting traditional Windows locale names written with English
words, because (1) they are unstable and explicitly not recommended for
use in databases and (2) they may contain non-ASCII characters, which we
can't put in our shared catalogs.  Since setlocale() returns such names,
on Windows use GetUserDefaultLocaleName() if the user didn't provide an
explicit locale.  It returns BCP 47 strings like "en-US".

Also update the documentation to recommend BCP 47 over the traditional
names when providing explicit values to initdb.

Reviewed-by: Juan José Santamaría Flecha <juanjo.santamaria@gmail.com>
Reviewed-by:
Discussion: https://postgr.es/m/CA%2BhUKGJ%3DXThErgAQRoqfCy1bKPxXVuF0%3D2zDbB%2BSxDs59pv7Fw%40mail.gmail.com
---
 doc/src/sgml/charset.sgml | 13 +++++++++++--
 src/bin/initdb/initdb.c   | 31 +++++++++++++++++++++++++++++--
 2 files changed, 40 insertions(+), 4 deletions(-)

diff --git a/doc/src/sgml/charset.sgml b/doc/src/sgml/charset.sgml
index 834cb30c85a..adb21eb0799 100644
--- a/doc/src/sgml/charset.sgml
+++ b/doc/src/sgml/charset.sgml
@@ -83,8 +83,17 @@ initdb --locale=sv_SE
     system under what names depends on what was provided by the operating
     system vendor and what was installed.  On most Unix systems, the command
     <literal>locale -a</literal> will provide a list of available locales.
-    Windows uses more verbose locale names, such as <literal>German_Germany</literal>
-    or <literal>Swedish_Sweden.1252</literal>, but the principles are the same.
+   </para>
+
+   <para>
+    Windows uses BCP 47 language tags, like ICU.
+    For example, <literal>sv-SE</literal> represents Swedish as spoken in Sweden.
+    Windows also supports more verbose locale names based on full names
+    such as <literal>German_Germany</literal> or <literal>Swedish_Sweden.1252</literal>,
+    but these are not recommended because they are not stable across operating
+    system updates due to changes in geographical names, and may contain
+    non-ASCII characters which are not supported in PostgreSQL's shared
+    catalogs.
    </para>
 
    <para>
diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index f00718a0150..393232b6cec 100644
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -64,6 +64,10 @@
 #include "sys/mman.h"
 #endif
 
+#ifdef WIN32
+#include <winnls.h>
+#endif
+
 #include "access/xlog_internal.h"
 #include "catalog/pg_authid_d.h"
 #include "catalog/pg_class_d.h" /* pgrminclude ignore */
@@ -2132,6 +2136,7 @@ locale_date_order(const char *locale)
 static void
 check_locale_name(int category, const char *locale, char **canonname)
 {
+	char	   *locale_copy;
 	char	   *save;
 	char	   *res;
 
@@ -2147,10 +2152,30 @@ check_locale_name(int category, const char *locale, char **canonname)
 
 	/* for setlocale() call */
 	if (!locale)
-		locale = "";
+	{
+#ifdef WIN32
+		wchar_t		wide_name[LOCALE_NAME_MAX_LENGTH];
+		char		name[LOCALE_NAME_MAX_LENGTH];
+
+		/* use Windows API to find the default in BCP47 format */
+		if (GetUserDefaultLocaleName(wide_name, LOCALE_NAME_MAX_LENGTH) == 0)
+			pg_fatal("failed to get default locale name: error code %lu",
+					 GetLastError());
+		if (WideCharToMultiByte(CP_ACP, 0, wide_name, -1, name,
+								LOCALE_NAME_MAX_LENGTH, NULL, NULL) == 0)
+			pg_fatal("failed to convert locale name: error code %lu",
+					 GetLastError());
+		locale_copy = pg_strdup(name);
+#else
+		/* use environment to find the default */
+		locale_copy = pg_strdup("");
+#endif
+	}
+	else
+		locale_copy = pg_strdup(locale);
 
 	/* set the locale with setlocale, to see if it accepts it. */
-	res = setlocale(category, locale);
+	res = setlocale(category, locale_copy);
 
 	/* save canonical name if requested. */
 	if (res && canonname)
@@ -2183,6 +2208,8 @@ check_locale_name(int category, const char *locale, char **canonname)
 			pg_fatal("invalid locale settings; check LANG and LC_* environment variables");
 		}
 	}
+
+	free(locale_copy);
 }
 
 /*
-- 
2.45.2

From 886815244ab43092562ae3118cd5588a2fad5bb2 Mon Sep 17 00:00:00 2001
From: Thomas Munro <thomas.munro@gmail.com>
Date: Mon, 20 Nov 2023 14:24:35 +1300
Subject: [PATCH v6 1/5] MinGW has GetLocaleInfoEx().

To use BCP 47 locale names like "en-US" without a suffix ".encoding", we
need to be able to call GetLocaleInfoEx() to look up the encoding.  That
was previously gated for MSVC only, but MinGW has had the function for
many years.  Remove that gating, because otherwise our MinGW build farm
animals would fail when a later commit switches to using the new names by
default.

There are probably other places where _MSC_VER is being used as a proxy
for detecting MinGW with an out-of-date idea about missing functions.

Discussion: https://postgr.es/m/CA%2BhUKGLsV3vTjPp7bOZBr3JTKp3Brkr9V0Qfmc7UvpWcmAQL4A%40mail.gmail.com
---
 src/port/chklocale.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/src/port/chklocale.c b/src/port/chklocale.c
index 8cb81c8640..a15b0d5349 100644
--- a/src/port/chklocale.c
+++ b/src/port/chklocale.c
@@ -204,7 +204,6 @@ win32_langinfo(const char *ctype)
 	char	   *r = NULL;
 	char	   *codepage;
 
-#if defined(_MSC_VER)
 	uint32		cp;
 	WCHAR		wctype[LOCALE_NAME_MAX_LENGTH];
 
@@ -229,7 +228,6 @@ win32_langinfo(const char *ctype)
 		}
 	}
 	else
-#endif
 	{
 		/*
 		 * Locale format on Win32 is <Language>_<Country>.<CodePage>.  For
-- 
2.39.2

From 357751c04cdd3dc7dea1ee9409356d818af70d5d Mon Sep 17 00:00:00 2001
From: Thomas Munro <thomas.munro@gmail.com>
Date: Tue, 19 Jul 2022 06:31:17 +1200
Subject: [PATCH v6 2/5] Default to IETF BCP 47 locale names in initdb on
 Windows.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Avoid selecting traditional Windows locale names written with English
words, because (1) they are unstable and explicitly not recommended for
use in databases and (2) they may contain non-ASCII characters, which we
can't put in our shared catalogs.  Since setlocale() returns such names,
on Windows use GetUserDefaultLocaleName() if the user didn't provide an
explicit locale.  It returns BCP 47 strings like "en-US".

Also update the documentation to recommend BCP 47 over the traditional
names when providing explicit values to initdb.

Reviewed-by: Juan José Santamaría Flecha <juanjo.santamaria@gmail.com>
Reviewed-by:
Discussion: https://postgr.es/m/CA%2BhUKGJ%3DXThErgAQRoqfCy1bKPxXVuF0%3D2zDbB%2BSxDs59pv7Fw%40mail.gmail.com
---
 doc/src/sgml/charset.sgml | 13 +++++++++++--
 src/bin/initdb/initdb.c   | 31 +++++++++++++++++++++++++++++--
 2 files changed, 40 insertions(+), 4 deletions(-)

diff --git a/doc/src/sgml/charset.sgml b/doc/src/sgml/charset.sgml
index 834cb30c85..adb21eb079 100644
--- a/doc/src/sgml/charset.sgml
+++ b/doc/src/sgml/charset.sgml
@@ -83,8 +83,17 @@ initdb --locale=sv_SE
     system under what names depends on what was provided by the operating
     system vendor and what was installed.  On most Unix systems, the command
     <literal>locale -a</literal> will provide a list of available locales.
-    Windows uses more verbose locale names, such as <literal>German_Germany</literal>
-    or <literal>Swedish_Sweden.1252</literal>, but the principles are the same.
+   </para>
+
+   <para>
+    Windows uses BCP 47 language tags, like ICU.
+    For example, <literal>sv-SE</literal> represents Swedish as spoken in Sweden.
+    Windows also supports more verbose locale names based on full names
+    such as <literal>German_Germany</literal> or <literal>Swedish_Sweden.1252</literal>,
+    but these are not recommended because they are not stable across operating
+    system updates due to changes in geographical names, and may contain
+    non-ASCII characters which are not supported in PostgreSQL's shared
+    catalogs.
    </para>
 
    <para>
diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index f00718a015..393232b6ce 100644
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -64,6 +64,10 @@
 #include "sys/mman.h"
 #endif
 
+#ifdef WIN32
+#include <winnls.h>
+#endif
+
 #include "access/xlog_internal.h"
 #include "catalog/pg_authid_d.h"
 #include "catalog/pg_class_d.h" /* pgrminclude ignore */
@@ -2132,6 +2136,7 @@ locale_date_order(const char *locale)
 static void
 check_locale_name(int category, const char *locale, char **canonname)
 {
+	char	   *locale_copy;
 	char	   *save;
 	char	   *res;
 
@@ -2147,10 +2152,30 @@ check_locale_name(int category, const char *locale, char **canonname)
 
 	/* for setlocale() call */
 	if (!locale)
-		locale = "";
+	{
+#ifdef WIN32
+		wchar_t		wide_name[LOCALE_NAME_MAX_LENGTH];
+		char		name[LOCALE_NAME_MAX_LENGTH];
+
+		/* use Windows API to find the default in BCP47 format */
+		if (GetUserDefaultLocaleName(wide_name, LOCALE_NAME_MAX_LENGTH) == 0)
+			pg_fatal("failed to get default locale name: error code %lu",
+					 GetLastError());
+		if (WideCharToMultiByte(CP_ACP, 0, wide_name, -1, name,
+								LOCALE_NAME_MAX_LENGTH, NULL, NULL) == 0)
+			pg_fatal("failed to convert locale name: error code %lu",
+					 GetLastError());
+		locale_copy = pg_strdup(name);
+#else
+		/* use environment to find the default */
+		locale_copy = pg_strdup("");
+#endif
+	}
+	else
+		locale_copy = pg_strdup(locale);
 
 	/* set the locale with setlocale, to see if it accepts it. */
-	res = setlocale(category, locale);
+	res = setlocale(category, locale_copy);
 
 	/* save canonical name if requested. */
 	if (res && canonname)
@@ -2183,6 +2208,8 @@ check_locale_name(int category, const char *locale, char **canonname)
 			pg_fatal("invalid locale settings; check LANG and LC_* environment variables");
 		}
 	}
+
+	free(locale_copy);
 }
 
 /*
-- 
2.39.2

From a4b0b0324900d12d487370a08b4ddba20552e230 Mon Sep 17 00:00:00 2001
From: Thomas Munro <thomas.munro@gmail.com>
Date: Wed, 7 Aug 2024 10:23:05 +1200
Subject: [PATCH v6 3/5] Don't allow UTF-8 with non-UTF-8 locales on Windows.

Historically, we allowed contradictions such as:

initdb.exe --locale="French_France.1252" --encoding="UTF-8"

That's because Windows didn't support UTF-8 directly, and PostgreSQL
had to perform UTF-8 char -> wchar_t conversions at various places on
that OS, and still does.  Therefore it was never actually passing
UTF-8 text to operating system facilities.

In preparation for removing those code paths, harmonizing the code
and behavior with Unix builds, and adapting to modern Windows
interfaces, ban such contradictions.  Locale names should ideally be
specified as BCP 47 tags.  If UTF-8 is desired, the name should have
".UTF-8" on the end, but otherwise the traditional encoding of that
language is implied.  Now only the following are valid:

initdb.exe --locale="fr-FR" --encoding="WIN1252"
initdb.exe --locale="fr-FR.UTF-8" --encoding="UTF-8"
initdb.exe --locale="French_France.1252" --encoding="WIN1252"

(The last form is not recommended, but still accepted.)

XXX This will cause problems for clusters upgraded with pg_upgrade from
a system using locales with the wrong encoding.  We'll need a way to
translate to the correct modern locale names.

Discussion: https://postgr.es/m/CA%2BhUKGJ%3DXThErgAQRoqfCy1bKPxXVuF0%3D2zDbB%2BSxDs59pv7Fw%40mail.gmail.com
---
 src/backend/commands/dbcommands.c | 12 +-----------
 src/bin/initdb/initdb.c           | 11 -----------
 2 files changed, 1 insertion(+), 22 deletions(-)

diff --git a/src/backend/commands/dbcommands.c b/src/backend/commands/dbcommands.c
index 7026352bc9..566085fecc 100644
--- a/src/backend/commands/dbcommands.c
+++ b/src/backend/commands/dbcommands.c
@@ -1555,11 +1555,7 @@ createdb(ParseState *pstate, const CreatedbStmt *stmt)
  * 2. locale encoding = -1, which means that we couldn't determine the
  * locale's encoding and have to trust the user to get it right.
  *
- * 3. selected encoding is UTF8 and platform is win32. This is because
- * UTF8 is a pseudo codepage that is supported in all locales since it's
- * converted to UTF16 before being used.
- *
- * 4. selected encoding is SQL_ASCII, but only if you're a superuser. This
+ * 3. selected encoding is SQL_ASCII, but only if you're a superuser. This
  * is risky but we have historically allowed it --- notably, the
  * regression tests require it.
  *
@@ -1574,9 +1570,6 @@ check_encoding_locale_matches(int encoding, const char *collate, const char *cty
 	if (!(ctype_encoding == encoding ||
 		  ctype_encoding == PG_SQL_ASCII ||
 		  ctype_encoding == -1 ||
-#ifdef WIN32
-		  encoding == PG_UTF8 ||
-#endif
 		  (encoding == PG_SQL_ASCII && superuser())))
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
@@ -1589,9 +1582,6 @@ check_encoding_locale_matches(int encoding, const char *collate, const char *cty
 	if (!(collate_encoding == encoding ||
 		  collate_encoding == PG_SQL_ASCII ||
 		  collate_encoding == -1 ||
-#ifdef WIN32
-		  encoding == PG_UTF8 ||
-#endif
 		  (encoding == PG_SQL_ASCII && superuser())))
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index 393232b6ce..77bf815919 100644
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -2228,9 +2228,6 @@ check_locale_encoding(const char *locale, int user_enc)
 	if (!(locale_enc == user_enc ||
 		  locale_enc == PG_SQL_ASCII ||
 		  locale_enc == -1 ||
-#ifdef WIN32
-		  user_enc == PG_UTF8 ||
-#endif
 		  user_enc == PG_SQL_ASCII))
 	{
 		pg_log_error("encoding mismatch");
@@ -2695,13 +2692,6 @@ setup_locale_encoding(void)
 			 * Windows, UTF-8 works with any locale, so we can fall back to
 			 * UTF-8.
 			 */
-#ifdef WIN32
-			encodingid = PG_UTF8;
-			printf(_("Encoding \"%s\" implied by locale is not allowed as a server-side encoding.\n"
-					 "The default database encoding will be set to \"%s\" instead.\n"),
-				   pg_encoding_to_char(ctype_enc),
-				   pg_encoding_to_char(encodingid));
-#else
 			pg_log_error("locale \"%s\" requires unsupported encoding \"%s\"",
 						 lc_ctype, pg_encoding_to_char(ctype_enc));
 			pg_log_error_detail("Encoding \"%s\" is not allowed as a server-side encoding.",
@@ -2709,7 +2699,6 @@ setup_locale_encoding(void)
 			pg_log_error_hint("Rerun %s with a different locale selection.",
 							  progname);
 			exit(1);
-#endif
 		}
 		else
 		{
-- 
2.39.2

From 5e8689b50db21fe5adfcee15f54524eefe64c492 Mon Sep 17 00:00:00 2001
From: Thomas Munro <thomas.munro@gmail.com>
Date: Wed, 7 Aug 2024 10:36:15 +1200
Subject: [PATCH v6 4/5] Collate UTF-8 without wchar_t conversion in Windows.

Traditionally, Windows didn't support UTF-8 encoding in system
interfaces, and we had to convert to UTF-16 and use wcscoll_l().
Windows 10+ has UTF-8 support, and an earlier commit banned the use of
locales with encoding that doesn't match the database, so we can now
harmonize with the Unix code paths and just call strcoll_l().

Discussion: https://postgr.es/m/CA%2BhUKGJ%3DXThErgAQRoqfCy1bKPxXVuF0%3D2zDbB%2BSxDs59pv7Fw%40mail.gmail.com
---
 src/backend/utils/adt/pg_locale.c | 90 +------------------------------
 1 file changed, 1 insertion(+), 89 deletions(-)

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index cd3661e727..4d3c3e4e75 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -1804,78 +1804,6 @@ get_collation_actual_version(char collprovider, const char *collcollate)
 	return collversion;
 }
 
-/*
- * pg_strncoll_libc_win32_utf8
- *
- * Win32 does not have UTF-8. Convert UTF8 arguments to wide characters and
- * invoke wcscoll_l().
- */
-#ifdef WIN32
-static int
-pg_strncoll_libc_win32_utf8(const char *arg1, size_t len1, const char *arg2,
-							size_t len2, pg_locale_t locale)
-{
-	char		sbuf[TEXTBUFLEN];
-	char	   *buf = sbuf;
-	char	   *a1p,
-			   *a2p;
-	int			a1len = len1 * 2 + 2;
-	int			a2len = len2 * 2 + 2;
-	int			r;
-	int			result;
-
-	Assert(locale->provider == COLLPROVIDER_LIBC);
-	Assert(GetDatabaseEncoding() == PG_UTF8);
-#ifndef WIN32
-	Assert(false);
-#endif
-
-	if (a1len + a2len > TEXTBUFLEN)
-		buf = palloc(a1len + a2len);
-
-	a1p = buf;
-	a2p = buf + a1len;
-
-	/* API does not work for zero-length input */
-	if (len1 == 0)
-		r = 0;
-	else
-	{
-		r = MultiByteToWideChar(CP_UTF8, 0, arg1, len1,
-								(LPWSTR) a1p, a1len / 2);
-		if (!r)
-			ereport(ERROR,
-					(errmsg("could not convert string to UTF-16: error code %lu",
-							GetLastError())));
-	}
-	((LPWSTR) a1p)[r] = 0;
-
-	if (len2 == 0)
-		r = 0;
-	else
-	{
-		r = MultiByteToWideChar(CP_UTF8, 0, arg2, len2,
-								(LPWSTR) a2p, a2len / 2);
-		if (!r)
-			ereport(ERROR,
-					(errmsg("could not convert string to UTF-16: error code %lu",
-							GetLastError())));
-	}
-	((LPWSTR) a2p)[r] = 0;
-
-	errno = 0;
-	result = wcscoll_l((LPWSTR) a1p, (LPWSTR) a2p, locale->info.lt);
-	if (result == 2147483647)	/* _NLSCMPERROR; missing from mingw headers */
-		ereport(ERROR,
-				(errmsg("could not compare Unicode strings: %m")));
-
-	if (buf != sbuf)
-		pfree(buf);
-
-	return result;
-}
-#endif							/* WIN32 */
-
 /*
  * pg_strcoll_libc
  *
@@ -1891,17 +1819,7 @@ pg_strcoll_libc(const char *arg1, const char *arg2, pg_locale_t locale)
 	int			result;
 
 	Assert(locale->provider == COLLPROVIDER_LIBC);
-#ifdef WIN32
-	if (GetDatabaseEncoding() == PG_UTF8)
-	{
-		size_t		len1 = strlen(arg1);
-		size_t		len2 = strlen(arg2);
-
-		result = pg_strncoll_libc_win32_utf8(arg1, len1, arg2, len2, locale);
-	}
-	else
-#endif							/* WIN32 */
-		result = strcoll_l(arg1, arg2, locale->info.lt);
+	result = strcoll_l(arg1, arg2, locale->info.lt);
 
 	return result;
 }
@@ -1925,12 +1843,6 @@ pg_strncoll_libc(const char *arg1, size_t len1, const char *arg2, size_t len2,
 
 	Assert(locale->provider == COLLPROVIDER_LIBC);
 
-#ifdef WIN32
-	/* check for this case before doing the work for nul-termination */
-	if (GetDatabaseEncoding() == PG_UTF8)
-		return pg_strncoll_libc_win32_utf8(arg1, len1, arg2, len2, locale);
-#endif							/* WIN32 */
-
 	if (bufsize1 + bufsize2 > TEXTBUFLEN)
 		buf = palloc(bufsize1 + bufsize2);
 
-- 
2.39.2

From 05a451df747f219192fbf79d833ac50285048dbf Mon Sep 17 00:00:00 2001
From: Thomas Munro <thomas.munro@gmail.com>
Date: Wed, 7 Aug 2024 11:33:22 +1200
Subject: [PATCH v6 5/5] Format times without wchar_t conversion in Windows.

Previously we allowed the locale to be set to something that used an
encoding that didn't match the database.  We have disallowed that now,
so we can use strftime() directly.  And if we're going to touch that
code, we might as well use strftime_l() instead and skip some ugly
save/restore of global state.

strftime_l() is from POSIX 2008.  All supported systems have it, thought
Windows has a leading underscore.

For the CI MinGW cross-build warning check to pass, add -lucrt because
otherwise strftime_l() is not available.

Discussion: https://postgr.es/m/CA%2BhUKGJ%3DXThErgAQRoqfCy1bKPxXVuF0%3D2zDbB%2BSxDs59pv7Fw%40mail.gmail.com
---
 .cirrus.tasks.yml                 |   1 +
 src/backend/utils/adt/pg_locale.c | 147 ++++--------------------------
 src/include/port/win32_port.h     |   1 +
 3 files changed, 21 insertions(+), 128 deletions(-)

diff --git a/.cirrus.tasks.yml b/.cirrus.tasks.yml
index 1ce6c443a8..3bf81ed4af 100644
--- a/.cirrus.tasks.yml
+++ b/.cirrus.tasks.yml
@@ -753,6 +753,7 @@ task:
         --host=x86_64-w64-mingw32 \
         --enable-cassert \
         --without-icu \
+        LDFLAGS="-lucrt" \
         CC="ccache x86_64-w64-mingw32-gcc" \
         CXX="ccache x86_64-w64-mingw32-g++"
       make -s -j${BUILD_JOBS} clean
diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 4d3c3e4e75..5e64470b58 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -174,6 +174,8 @@ static void icu_set_collation_attributes(UCollator *collator, const char *loc,
 										 UErrorCode *status);
 #endif
 
+static void report_newlocale_failure(const char *localename);
+
 /*
  * POSIX doesn't define _l-variants of these functions, but several systems
  * have them.  We provide our own replacements here.
@@ -732,65 +734,6 @@ PGLC_localeconv(void)
 	return &CurrentLocaleConv;
 }
 
-#ifdef WIN32
-/*
- * On Windows, strftime() returns its output in encoding CP_ACP (the default
- * operating system codepage for the computer), which is likely different
- * from SERVER_ENCODING.  This is especially important in Japanese versions
- * of Windows which will use SJIS encoding, which we don't support as a
- * server encoding.
- *
- * So, instead of using strftime(), use wcsftime() to return the value in
- * wide characters (internally UTF16) and then convert to UTF8, which we
- * know how to handle directly.
- *
- * Note that this only affects the calls to strftime() in this file, which are
- * used to get the locale-aware strings. Other parts of the backend use
- * pg_strftime(), which isn't locale-aware and does not need to be replaced.
- */
-static size_t
-strftime_win32(char *dst, size_t dstlen,
-			   const char *format, const struct tm *tm)
-{
-	size_t		len;
-	wchar_t		wformat[8];		/* formats used below need 3 chars */
-	wchar_t		wbuf[MAX_L10N_DATA];
-
-	/*
-	 * Get a wchar_t version of the format string.  We only actually use
-	 * plain-ASCII formats in this file, so we can say that they're UTF8.
-	 */
-	len = MultiByteToWideChar(CP_UTF8, 0, format, -1,
-							  wformat, lengthof(wformat));
-	if (len == 0)
-		elog(ERROR, "could not convert format string from UTF-8: error code %lu",
-			 GetLastError());
-
-	len = wcsftime(wbuf, MAX_L10N_DATA, wformat, tm);
-	if (len == 0)
-	{
-		/*
-		 * wcsftime failed, possibly because the result would not fit in
-		 * MAX_L10N_DATA.  Return 0 with the contents of dst unspecified.
-		 */
-		return 0;
-	}
-
-	len = WideCharToMultiByte(CP_UTF8, 0, wbuf, len, dst, dstlen - 1,
-							  NULL, NULL);
-	if (len == 0)
-		elog(ERROR, "could not convert string to UTF-8: error code %lu",
-			 GetLastError());
-
-	dst[len] = '\0';
-
-	return len;
-}
-
-/* redefine strftime() */
-#define strftime(a,b,c,d) strftime_win32(a,b,c,d)
-#endif							/* WIN32 */
-
 /*
  * Subroutine for cache_locale_time().
  * Convert the given string from encoding "encoding" to the database
@@ -829,10 +772,7 @@ cache_locale_time(void)
 	bool		strftimefail = false;
 	int			encoding;
 	int			i;
-	char	   *save_lc_time;
-#ifdef WIN32
-	char	   *save_lc_ctype;
-#endif
+	locale_t	locale;
 
 	/* did we do this already? */
 	if (CurrentLCTimeValid)
@@ -840,50 +780,24 @@ cache_locale_time(void)
 
 	elog(DEBUG3, "cache_locale_time() executed; locale: \"%s\"", locale_time);
 
-	/*
-	 * As in PGLC_localeconv(), it's critical that we not throw error while
-	 * libc's locale settings have nondefault values.  Hence, we just call
-	 * strftime() within the critical section, and then convert and save its
-	 * results afterwards.
-	 */
-
-	/* Save prevailing value of time locale */
-	save_lc_time = setlocale(LC_TIME, NULL);
-	if (!save_lc_time)
-		elog(ERROR, "setlocale(NULL) failed");
-	save_lc_time = pstrdup(save_lc_time);
-
 #ifdef WIN32
-
-	/*
-	 * On Windows, it appears that wcsftime() internally uses LC_CTYPE, so we
-	 * must set it here.  This code looks the same as what PGLC_localeconv()
-	 * does, but the underlying reason is different: this does NOT determine
-	 * the encoding we'll get back from strftime_win32().
-	 */
-
-	/* Save prevailing value of ctype locale */
-	save_lc_ctype = setlocale(LC_CTYPE, NULL);
-	if (!save_lc_ctype)
-		elog(ERROR, "setlocale(NULL) failed");
-	save_lc_ctype = pstrdup(save_lc_ctype);
-
-	/* use lc_time to set the ctype */
-	setlocale(LC_CTYPE, locale_time);
+	locale = _create_locale(LC_ALL, locale_time);
+#else
+	locale = newlocale(LC_ALL, locale_time, NULL);
 #endif
+	if (!locale)
+		report_newlocale_failure(locale_time);
 
-	setlocale(LC_TIME, locale_time);
-
-	/* We use times close to current time as data for strftime(). */
+	/* We use times close to current time as data for strftime_l(). */
 	timenow = time(NULL);
 	timeinfo = localtime(&timenow);
 
-	/* Store the strftime results in MAX_L10N_DATA-sized portions of buf[] */
+	/* Store the strftime_l results in MAX_L10N_DATA-sized portions of buf[] */
 	bufptr = buf;
 
 	/*
 	 * MAX_L10N_DATA is sufficient buffer space for every known locale, and
-	 * POSIX defines no strftime() errors.  (Buffer space exhaustion is not an
+	 * POSIX defines no strftime_l() errors.  (Buffer space exhaustion is not an
 	 * error.)  An implementation might report errors (e.g. ENOMEM) by
 	 * returning 0 (or, less plausibly, a negative value) and setting errno.
 	 * Report errno just in case the implementation did that, but clear it in
@@ -895,10 +809,10 @@ cache_locale_time(void)
 	for (i = 0; i < 7; i++)
 	{
 		timeinfo->tm_wday = i;
-		if (strftime(bufptr, MAX_L10N_DATA, "%a", timeinfo) <= 0)
+		if (strftime_l(bufptr, MAX_L10N_DATA, "%a", timeinfo, locale) <= 0)
 			strftimefail = true;
 		bufptr += MAX_L10N_DATA;
-		if (strftime(bufptr, MAX_L10N_DATA, "%A", timeinfo) <= 0)
+		if (strftime_l(bufptr, MAX_L10N_DATA, "%A", timeinfo, locale) <= 0)
 			strftimefail = true;
 		bufptr += MAX_L10N_DATA;
 	}
@@ -908,39 +822,26 @@ cache_locale_time(void)
 	{
 		timeinfo->tm_mon = i;
 		timeinfo->tm_mday = 1;	/* make sure we don't have invalid date */
-		if (strftime(bufptr, MAX_L10N_DATA, "%b", timeinfo) <= 0)
+		if (strftime_l(bufptr, MAX_L10N_DATA, "%b", timeinfo, locale) <= 0)
 			strftimefail = true;
 		bufptr += MAX_L10N_DATA;
-		if (strftime(bufptr, MAX_L10N_DATA, "%B", timeinfo) <= 0)
+		if (strftime_l(bufptr, MAX_L10N_DATA, "%B", timeinfo, locale) <= 0)
 			strftimefail = true;
 		bufptr += MAX_L10N_DATA;
 	}
 
-	/*
-	 * Restore the prevailing locale settings; as in PGLC_localeconv(),
-	 * failure to do so is fatal.
-	 */
 #ifdef WIN32
-	if (!setlocale(LC_CTYPE, save_lc_ctype))
-		elog(FATAL, "failed to restore LC_CTYPE to \"%s\"", save_lc_ctype);
+	_free_locale(locale);
+#else
+	freelocale(locale);
 #endif
-	if (!setlocale(LC_TIME, save_lc_time))
-		elog(FATAL, "failed to restore LC_TIME to \"%s\"", save_lc_time);
 
 	/*
 	 * At this point we've done our best to clean up, and can throw errors, or
 	 * call functions that might throw errors, with a clean conscience.
 	 */
 	if (strftimefail)
-		elog(ERROR, "strftime() failed: %m");
-
-	/* Release the pstrdup'd locale names */
-	pfree(save_lc_time);
-#ifdef WIN32
-	pfree(save_lc_ctype);
-#endif
-
-#ifndef WIN32
+		elog(ERROR, "strftime_() failed: %m");
 
 	/*
 	 * As in PGLC_localeconv(), we must convert strftime()'s output from the
@@ -951,16 +852,6 @@ cache_locale_time(void)
 	if (encoding < 0)
 		encoding = PG_SQL_ASCII;
 
-#else
-
-	/*
-	 * On Windows, strftime_win32() always returns UTF8 data, so convert from
-	 * that if necessary.
-	 */
-	encoding = PG_UTF8;
-
-#endif							/* WIN32 */
-
 	bufptr = buf;
 
 	/* localized days */
diff --git a/src/include/port/win32_port.h b/src/include/port/win32_port.h
index 7ffe5891c6..87157a1095 100644
--- a/src/include/port/win32_port.h
+++ b/src/include/port/win32_port.h
@@ -450,6 +450,7 @@ extern int	_pglstat64(const char *name, struct stat *buf);
 #define isspace_l _isspace_l
 #define iswspace_l _iswspace_l
 #define strcoll_l _strcoll_l
+#define strftime_l _strftime_l
 #define strxfrm_l _strxfrm_l
 #define wcscoll_l _wcscoll_l
 
-- 
2.39.2