PG compilation error with Visual Studio 2015/2017/2019

From f2b75be26e7c000ed279168750df104632a4d3b2 Mon Sep 17 00:00:00 2001
From: Davinder Singh <davindersingh2692@gmail.com>
Date: Wed, 8 Apr 2020 12:21:51 +0530
Subject: [PATCH] PG compilation error with VS 2015/2017/2019

This fix is to resolve undefined struct/union compilation error while accessing
_locale_name.
---
 src/backend/utils/adt/pg_locale.c | 63 ++++++++++++++++++++-----------
 1 file changed, 40 insertions(+), 23 deletions(-)

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 2562eb5416..1f739ab51a 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -990,6 +990,7 @@ IsoLocaleName(const char *winlocname)
 #ifdef _MSC_VER
 	static char iso_lc_messages[32];
 	_locale_t	loct = NULL;
+	size_t		rc;
 
 	if (pg_strcasecmp("c", winlocname) == 0 ||
 		pg_strcasecmp("posix", winlocname) == 0)
@@ -997,38 +998,54 @@ IsoLocaleName(const char *winlocname)
 		strcpy(iso_lc_messages, "C");
 		return iso_lc_messages;
 	}
-
+#if defined(_MSC_VER) && (_MSC_VER < 1900)
 	loct = _create_locale(LC_CTYPE, winlocname);
 	if (loct != NULL)
 	{
-		size_t		rc;
-		char	   *hyphen;
-
 		/* Locale names use only ASCII, any conversion locale suffices. */
 		rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
 						sizeof(iso_lc_messages), NULL);
 		_free_locale(loct);
-		if (rc == -1 || rc == sizeof(iso_lc_messages))
-			return NULL;
+	}
+	else
+		return NULL;
+#else   	/* _MSC_VER >= 1900 */
+	WCHAR		wc_locale_name[LOCALE_NAME_MAX_LENGTH];
+	WCHAR		buffer[LOCALE_NAME_MAX_LENGTH];
 
-		/*
-		 * Since the message catalogs sit on a case-insensitive filesystem, we
-		 * need not standardize letter case here.  So long as we do not ship
-		 * message catalogs for which it would matter, we also need not
-		 * translate the script/variant portion, e.g. uz-Cyrl-UZ to
-		 * uz_UZ@cyrillic.  Simply replace the hyphen with an underscore.
-		 *
-		 * Note that the locale name can be less-specific than the value we
-		 * would derive under earlier Visual Studio releases.  For example,
-		 * French_France.1252 yields just "fr".  This does not affect any of
-		 * the country-specific message catalogs available as of this writing
-		 * (pt_BR, zh_CN, zh_TW).
-		 */
-		hyphen = strchr(iso_lc_messages, '-');
-		if (hyphen)
-			*hyphen = '_';
-		return iso_lc_messages;
+	memset(wc_locale_name, 0, sizeof(wc_locale_name));
+	memset(buffer, 0, sizeof(buffer));
+
+	MultiByteToWideChar(CP_ACP, 0, winlocname, -1, wc_locale_name, LOCALE_NAME_MAX_LENGTH);
+
+	if ((GetLocaleInfoEx(wc_locale_name, LOCALE_SNAME,
+		(LPWSTR)&buffer, LOCALE_NAME_MAX_LENGTH)) > 0) {
+		rc = wchar2char(iso_lc_messages, buffer, sizeof(iso_lc_messages), NULL);
 	}
+	else
+		return NULL;
+#endif		/* _MSC_VER && _MSC_VER < 1900 */
+	char* hyphen;
+	if (rc == -1 || rc == sizeof(iso_lc_messages))
+		return NULL;
+
+	/*
+	 * Since the message catalogs sit on a case-insensitive filesystem, we
+	 * need not standardize letter case here.  So long as we do not ship
+	 * message catalogs for which it would matter, we also need not
+	 * translate the script/variant portion, e.g. uz-Cyrl-UZ to
+	 * uz_UZ@cyrillic.  Simply replace the hyphen with an underscore.
+	 *
+	 * Note that the locale name can be less-specific than the value we
+	 * would derive under earlier Visual Studio releases.  For example,
+	 * French_France.1252 yields just "fr".  This does not affect any of
+	 * the country-specific message catalogs available as of this writing
+	 * (pt_BR, zh_CN, zh_TW).
+	 */
+	hyphen = strchr(iso_lc_messages, '-');
+	if (hyphen)
+		*hyphen = '_';
+	return iso_lc_messages;
 #endif							/* _MSC_VER */
 	return NULL;				/* Not supported on this version of msvc/mingw */
 }
-- 
2.24.0.windows.2

From 4f0900616d4943537520d6f5bb62ca991558e9ab Mon Sep 17 00:00:00 2001
From: Davinder Singh <davindersingh2692@gmail.com>
Date: Thu, 9 Apr 2020 13:43:53 +0530
Subject: [PATCH] PG compilation error with VS 2015/2017/2019

This fix is to resolve undefined struct/union compilation error while
accessing _locale_name.
---
 src/backend/utils/adt/pg_locale.c | 65 +++++++++++++++++++------------
 1 file changed, 41 insertions(+), 24 deletions(-)

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 2562eb5416..52b1a0473e 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -989,7 +989,8 @@ IsoLocaleName(const char *winlocname)
 {
 #ifdef _MSC_VER
 	static char iso_lc_messages[32];
-	_locale_t	loct = NULL;
+	size_t		rc;
+	char*		hyphen;
 
 	if (pg_strcasecmp("c", winlocname) == 0 ||
 		pg_strcasecmp("posix", winlocname) == 0)
@@ -997,38 +998,54 @@ IsoLocaleName(const char *winlocname)
 		strcpy(iso_lc_messages, "C");
 		return iso_lc_messages;
 	}
+#if _WIN32_WINNT >= 0x0600
+	WCHAR		wc_locale_name[LOCALE_NAME_MAX_LENGTH];
+	WCHAR		buffer[LOCALE_NAME_MAX_LENGTH];
+
+	memset(wc_locale_name, 0, sizeof(wc_locale_name));
+	memset(buffer, 0, sizeof(buffer));
+	MultiByteToWideChar(CP_ACP, 0, winlocname, -1, wc_locale_name,
+						LOCALE_NAME_MAX_LENGTH);
+	if ((GetLocaleInfoEx(wc_locale_name, LOCALE_SNAME,
+		(LPWSTR)&buffer, LOCALE_NAME_MAX_LENGTH)) > 0) {
+		rc = wchar2char(iso_lc_messages, buffer, sizeof(iso_lc_messages),
+						NULL);
+	}
+#else   	/* _WIN32_WINNT < 0x0600 */
+	_locale_t	loct = NULL;
 
 	loct = _create_locale(LC_CTYPE, winlocname);
 	if (loct != NULL)
 	{
-		size_t		rc;
-		char	   *hyphen;
-
 		/* Locale names use only ASCII, any conversion locale suffices. */
 		rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
 						sizeof(iso_lc_messages), NULL);
 		_free_locale(loct);
-		if (rc == -1 || rc == sizeof(iso_lc_messages))
-			return NULL;
-
-		/*
-		 * Since the message catalogs sit on a case-insensitive filesystem, we
-		 * need not standardize letter case here.  So long as we do not ship
-		 * message catalogs for which it would matter, we also need not
-		 * translate the script/variant portion, e.g. uz-Cyrl-UZ to
-		 * uz_UZ@cyrillic.  Simply replace the hyphen with an underscore.
-		 *
-		 * Note that the locale name can be less-specific than the value we
-		 * would derive under earlier Visual Studio releases.  For example,
-		 * French_France.1252 yields just "fr".  This does not affect any of
-		 * the country-specific message catalogs available as of this writing
-		 * (pt_BR, zh_CN, zh_TW).
-		 */
-		hyphen = strchr(iso_lc_messages, '-');
-		if (hyphen)
-			*hyphen = '_';
-		return iso_lc_messages;
 	}
+#endif		/* _WIN32_WINNT >= 0x0600 */
+	else
+		return NULL;
+
+	if (rc == -1 || rc == sizeof(iso_lc_messages))
+		return NULL;
+
+	/*
+	 * Since the message catalogs sit on a case-insensitive filesystem, we
+	 * need not standardize letter case here.  So long as we do not ship
+	 * message catalogs for which it would matter, we also need not
+	 * translate the script/variant portion, e.g. uz-Cyrl-UZ to
+	 * uz_UZ@cyrillic.  Simply replace the hyphen with an underscore.
+	 *
+	 * Note that the locale name can be less-specific than the value we
+	 * would derive under earlier Visual Studio releases.  For example,
+	 * French_France.1252 yields just "fr".  This does not affect any of
+	 * the country-specific message catalogs available as of this writing
+	 * (pt_BR, zh_CN, zh_TW).
+	 */
+	hyphen = strchr(iso_lc_messages, '-');
+	if (hyphen)
+		*hyphen = '_';
+	return iso_lc_messages;
 #endif							/* _MSC_VER */
 	return NULL;				/* Not supported on this version of msvc/mingw */
 }
-- 
2.24.0.windows.2

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 2562eb5416..286e983ae8 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -989,46 +989,62 @@ IsoLocaleName(const char *winlocname)
 {
 #ifdef _MSC_VER
 	static char iso_lc_messages[32];
-	_locale_t	loct = NULL;
+	size_t		rc = -1;
+	char*		hyphen;
 
 	if (pg_strcasecmp("c", winlocname) == 0 ||
 		pg_strcasecmp("posix", winlocname) == 0)
 	{
-		strcpy(iso_lc_messages, "C");
-		return iso_lc_messages;
+		return "C";
 	}
+#if _WIN32_WINNT >= 0x0600
+	WCHAR		wc_locale_name[LOCALE_NAME_MAX_LENGTH];
+	WCHAR		buffer[LOCALE_NAME_MAX_LENGTH];
+
+	memset(wc_locale_name, 0, sizeof(wc_locale_name));
+	memset(buffer, 0, sizeof(buffer));
+	MultiByteToWideChar(CP_ACP, 0, winlocname, -1, wc_locale_name,
+						LOCALE_NAME_MAX_LENGTH);
+	if ((GetLocaleInfoEx(wc_locale_name, LOCALE_SNAME,
+		(LPWSTR)&buffer, LOCALE_NAME_MAX_LENGTH)) > 0) {
+		rc = wchar2char(iso_lc_messages, buffer, sizeof(iso_lc_messages),
+						NULL);
+	}
+#else   	/* _WIN32_WINNT < 0x0600 */
+	_locale_t	loct;
 
 	loct = _create_locale(LC_CTYPE, winlocname);
 	if (loct != NULL)
 	{
-		size_t		rc;
-		char	   *hyphen;
-
 		/* Locale names use only ASCII, any conversion locale suffices. */
 		rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
 						sizeof(iso_lc_messages), NULL);
 		_free_locale(loct);
-		if (rc == -1 || rc == sizeof(iso_lc_messages))
-			return NULL;
-
-		/*
-		 * Since the message catalogs sit on a case-insensitive filesystem, we
-		 * need not standardize letter case here.  So long as we do not ship
-		 * message catalogs for which it would matter, we also need not
-		 * translate the script/variant portion, e.g. uz-Cyrl-UZ to
-		 * uz_UZ@cyrillic.  Simply replace the hyphen with an underscore.
-		 *
-		 * Note that the locale name can be less-specific than the value we
-		 * would derive under earlier Visual Studio releases.  For example,
-		 * French_France.1252 yields just "fr".  This does not affect any of
-		 * the country-specific message catalogs available as of this writing
-		 * (pt_BR, zh_CN, zh_TW).
-		 */
-		hyphen = strchr(iso_lc_messages, '-');
-		if (hyphen)
-			*hyphen = '_';
-		return iso_lc_messages;
 	}
+#endif		/* _WIN32_WINNT >= 0x0600 */
+	else
+		return NULL;
+
+	if (rc == -1 || rc == sizeof(iso_lc_messages))
+		return NULL;
+
+	/*
+	 * Since the message catalogs sit on a case-insensitive filesystem, we
+	 * need not standardize letter case here.  So long as we do not ship
+	 * message catalogs for which it would matter, we also need not
+	 * translate the script/variant portion, e.g. uz-Cyrl-UZ to
+	 * uz_UZ@cyrillic.  Simply replace the hyphen with an underscore.
+	 *
+	 * Note that the locale name can be less-specific than the value we
+	 * would derive under earlier Visual Studio releases.  For example,
+	 * French_France.1252 yields just "fr".  This does not affect any of
+	 * the country-specific message catalogs available as of this writing
+	 * (pt_BR, zh_CN, zh_TW).
+	 */
+	hyphen = strchr(iso_lc_messages, '-');
+	if (hyphen)
+		*hyphen = '_';
+	return iso_lc_messages;
 #endif							/* _MSC_VER */
 	return NULL;				/* Not supported on this version of msvc/mingw */
 }

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 2562eb5416..1de93023a5 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -988,26 +988,61 @@ static char *
 IsoLocaleName(const char *winlocname)
 {
 #ifdef _MSC_VER
-	static char iso_lc_messages[32];
+	static char iso_lc_messages[LOCALE_NAME_MAX_LENGTH];
 	_locale_t	loct = NULL;
+	size_t		rc ;
+	char*		hyphen;
 
 	if (pg_strcasecmp("c", winlocname) == 0 ||
 		pg_strcasecmp("posix", winlocname) == 0)
 	{
-		strcpy(iso_lc_messages, "C");
-		return iso_lc_messages;
+		return "C";
 	}
-
 	loct = _create_locale(LC_CTYPE, winlocname);
 	if (loct != NULL)
 	{
-		size_t		rc;
-		char	   *hyphen;
+#if _WIN32_WINNT >= 0x0600
+		WCHAR		wc_locale_name[LOCALE_NAME_MAX_LENGTH];
+		WCHAR		buffer[LOCALE_NAME_MAX_LENGTH];
+		char		loc_name[LOCALE_NAME_MAX_LENGTH];
+		char*		tmp;
+		size_t		cp_index;
+
+		/*
+		 * We know input locale is valid and has following syntax
+		 * <Language>[_<Country>[.<CodePage>]]
+		 * GetLocaleInfoEx can only take locale name without code-page
+		 * so we are trimming the unwanted part from the locale name.
+		 */
+		tmp = strchr(winlocname, '.');
+		if (tmp != NULL) {
+			cp_index = (size_t)(tmp - winlocname);
+			strncpy(loc_name, winlocname, cp_index);
+			loc_name[cp_index] = '\0';
+		}
+		else {
+			// assuming only locale name is given as input string.
+			strcpy(loc_name, winlocname);
+		}
 
+		memset(wc_locale_name, 0, sizeof(wc_locale_name));
+		memset(buffer, 0, sizeof(buffer));
+		MultiByteToWideChar(CP_ACP, 0, loc_name, -1, wc_locale_name,
+							LOCALE_NAME_MAX_LENGTH);
+		if ((GetLocaleInfoEx(wc_locale_name, LOCALE_SNAME,
+			(LPWSTR)&buffer, LOCALE_NAME_MAX_LENGTH)) > 0) {
+			rc = wchar2char(iso_lc_messages, buffer, sizeof(iso_lc_messages),
+							NULL);
+		}
+		else
+			return NULL;
+#else   	/* _WIN32_WINNT < 0x0600 */
 		/* Locale names use only ASCII, any conversion locale suffices. */
 		rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
 						sizeof(iso_lc_messages), NULL);
 		_free_locale(loct);
+#endif		/* _WIN32_WINNT >= 0x0600 */
+
 		if (rc == -1 || rc == sizeof(iso_lc_messages))
 			return NULL;
 

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 2562eb5416..253f18488f 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -988,25 +988,60 @@ static char *
 IsoLocaleName(const char *winlocname)
 {
 #ifdef _MSC_VER
-	static char iso_lc_messages[32];
-	_locale_t	loct = NULL;
+	static char iso_lc_messages[LOCALE_NAME_MAX_LENGTH];
+	_locale_t	loct;
 
 	if (pg_strcasecmp("c", winlocname) == 0 ||
 		pg_strcasecmp("posix", winlocname) == 0)
 	{
-		strcpy(iso_lc_messages, "C");
-		return iso_lc_messages;
+		return "C";
 	}
-
 	loct = _create_locale(LC_CTYPE, winlocname);
 	if (loct != NULL)
 	{
 		size_t		rc;
-		char	   *hyphen;
+		char*		hyphen;
+
+#if _WIN32_WINNT >= 0x0600
+		WCHAR		wc_locale_name[LOCALE_NAME_MAX_LENGTH];
+		WCHAR		buffer[LOCALE_NAME_MAX_LENGTH];
+		char		loc_name[LOCALE_NAME_MAX_LENGTH];
+		char*		tmp;
+
+		/*
+		 * We know input locale is valid and has following syntax
+		 * <Language>[_<Country>[.<CodePage>]]
+		 * GetLocaleInfoEx can only take locale name without code-page
+		 * so we are trimming the unwanted part from the locale name.
+		 */
+		tmp = strchr(winlocname, '.');
+		if (tmp != NULL) {
+			size_t		cp_index;
+			cp_index = (size_t)(tmp - winlocname);
+			strncpy(loc_name, winlocname, cp_index);
+			loc_name[cp_index] = '\0';
+		}
+		else {
+			// assuming only locale name is given as input string.
+			strcpy(loc_name, winlocname);
+		}
 
+		memset(wc_locale_name, 0, sizeof(wc_locale_name));
+		memset(buffer, 0, sizeof(buffer));
+		MultiByteToWideChar(CP_ACP, 0, loc_name, -1, wc_locale_name,
+							LOCALE_NAME_MAX_LENGTH);
+		if ((GetLocaleInfoEx(wc_locale_name, LOCALE_SNAME,
+			(LPWSTR)&buffer, LOCALE_NAME_MAX_LENGTH)) > 0) {
+			rc = wchar2char(iso_lc_messages, buffer, sizeof(iso_lc_messages),
+							NULL);
+		}
+		else
+			return NULL;
+#else   	/* _WIN32_WINNT < 0x0600 */
 		/* Locale names use only ASCII, any conversion locale suffices. */
 		rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
 						sizeof(iso_lc_messages), NULL);
+#endif		/* _WIN32_WINNT >= 0x0600 */
 		_free_locale(loct);
 		if (rc == -1 || rc == sizeof(iso_lc_messages))
 			return NULL;

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 2562eb5..fdc2c89 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -971,43 +971,72 @@ cache_locale_time(void)
  * string.  Furthermore, msvcr110.dll changed the undocumented _locale_t
  * content to carry locale names instead of locale identifiers.
  *
- * MinGW headers declare _create_locale(), but msvcrt.dll lacks that symbol.
- * 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.
+ * 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 or
+ * using GetLocaleInfoEx() from Windows Vista/2008.
  *
  * This function returns a pointer to a static buffer bearing the converted
  * name or NULL if conversion fails.
  *
- * [1] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373763.aspx
- * [2] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373814.aspx
+ * [1] https://docs.microsoft.com/en-us/windows/win32/intl/locale-identifiers
+ * [2] https://docs.microsoft.com/en-us/windows/win32/intl/locale-names
  */
 static char *
 IsoLocaleName(const char *winlocname)
 {
-#ifdef _MSC_VER
-	static char iso_lc_messages[32];
-	_locale_t	loct = NULL;
+#if defined(_MSC_VER) || _WIN32_WINNT >= 0x0600
+	static char iso_lc_messages[LOCALE_NAME_MAX_LENGTH];
 
 	if (pg_strcasecmp("c", winlocname) == 0 ||
 		pg_strcasecmp("posix", winlocname) == 0)
 	{
-		strcpy(iso_lc_messages, "C");
-		return iso_lc_messages;
+		return "C";
 	}
-
-	loct = _create_locale(LC_CTYPE, winlocname);
-	if (loct != NULL)
+	else
 	{
 		size_t		rc;
 		char	   *hyphen;
+#if _WIN32_WINNT >= 0x0600
+		WCHAR		wc_locale_name[LOCALE_NAME_MAX_LENGTH];
+		WCHAR		buffer[LOCALE_NAME_MAX_LENGTH];
+		char	   *period;
+		int			index;
+
+		/*
+		 * Valid locales have the following syntax:
+		 * <Language>[_<Country>[.<CodePage>]]
+		 * GetLocaleInfoEx can only take locale name without code-page,
+		 * so we are trimming that unwanted part from the locale name.
+		 */
+		period = strchr(winlocname, '.');
+		if (period != NULL)
+			index = period - winlocname;
+		else
+			index = pg_mbstrlen(winlocname);
+
+		memset(wc_locale_name, 0, sizeof(wc_locale_name));
+		memset(buffer, 0, sizeof(buffer));
+		MultiByteToWideChar(CP_ACP, 0, winlocname, index, wc_locale_name,
+							LOCALE_NAME_MAX_LENGTH);
+		GetLocaleInfoEx(wc_locale_name, LOCALE_SNAME, (LPWSTR) &buffer,
+						LOCALE_NAME_MAX_LENGTH);
 
 		/* Locale names use only ASCII, any conversion locale suffices. */
-		rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
-						sizeof(iso_lc_messages), NULL);
+		rc = wchar2char(iso_lc_messages, buffer, sizeof(iso_lc_messages), NULL);
+#else   	/* _WIN32_WINNT < 0x0600 */
+		_locale_t	loct;
+
+		loct = _create_locale(LC_CTYPE, winlocname);
+		if (loct != NULL)
+			rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
+							sizeof(iso_lc_messages), NULL);
 		_free_locale(loct);
+#endif		/* _WIN32_WINNT >= 0x0600 */
+
 		if (rc == -1 || rc == sizeof(iso_lc_messages))
 			return NULL;
 
@@ -1029,7 +1058,7 @@ IsoLocaleName(const char *winlocname)
 			*hyphen = '_';
 		return iso_lc_messages;
 	}
-#endif							/* _MSC_VER */
+#endif							/* defined(_MSC_VER) || _WIN32_WINNT >= 0x0600 */
 	return NULL;				/* Not supported on this version of msvc/mingw */
 }
 #endif							/* WIN32 && LC_MESSAGES */

diff --git a/src/include/port.h b/src/include/port.h
index 20a5de1b7a..3b6d7ef513 100644
--- a/src/include/port.h
+++ b/src/include/port.h
@@ -521,4 +521,38 @@ extern char *wait_result_to_str(int exit_status);
 extern bool wait_result_is_signal(int exit_status, int signum);
 extern bool wait_result_is_any_signal(int exit_status, bool include_command_not_found);
 
+#if _MSC_VER >= 1800
+	//From VS2012.
+typedef struct localerefcount
+{
+	char *locale;
+	wchar_t *wlocale;
+	int *refcount;
+	int *wrefcount;
+} locrefcount;
+
+	//From VS2012.
+typedef struct __crt_locale_data
+{
+	int refcount;
+	unsigned int lc_codepage;
+	unsigned int lc_collate_cp;
+	unsigned int lc_time_cp;
+	locrefcount lc_category[6];
+	int lc_clike;
+	int mb_cur_max;
+	int * lconv_intl_refcount;
+	int * lconv_num_refcount;
+	int * lconv_mon_refcount;
+	struct lconv * lconv;
+	int * ctype1_refcount;
+	unsigned short * ctype1;
+	const unsigned short * pctype;
+	const unsigned char * pclmap;
+	const unsigned char * pcumap;
+	struct __lc_time_data * lc_time_curr;
+	wchar_t * locale_name[6];
+} threadlocinfo;
+#endif
+
 #endif							/* PG_PORT_H */

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 2562eb5..7ff29a7 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -971,43 +971,113 @@ cache_locale_time(void)
  * string.  Furthermore, msvcr110.dll changed the undocumented _locale_t
  * content to carry locale names instead of locale identifiers.
  *
- * MinGW headers declare _create_locale(), but msvcrt.dll lacks that symbol.
- * 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.
+ * 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 or
+ * using EnumSystemLocalesEx() from Windows Vista/2008.
  *
  * This function returns a pointer to a static buffer bearing the converted
  * name or NULL if conversion fails.
  *
- * [1] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373763.aspx
- * [2] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373814.aspx
+ * [1] https://docs.microsoft.com/en-us/windows/win32/intl/locale-identifiers
+ * [2] https://docs.microsoft.com/en-us/windows/win32/intl/locale-names
  */
+#if _WIN32_WINNT >= 0x0600
+/*
+ * Callback function for EnumSystemLocalesEx.
+ * Stop enumarating if a match is found for a locale with the format
+ * <Language>_<Country>.
+ */
+static BOOL CALLBACK
+enum_locales_fn(LPWSTR pStr, DWORD dwFlags, LPARAM lparam)
+{
+	WCHAR	**argv = (WCHAR **) lparam;
+	WCHAR	test_locale[LOCALE_NAME_MAX_LENGTH];
+
+	memset(test_locale, 0, sizeof(test_locale));
+	if (GetLocaleInfoEx(pStr, LOCALE_SENGLISHLANGUAGENAME,
+						test_locale, LOCALE_NAME_MAX_LENGTH) > 0)
+	{
+		wcscat(test_locale, L"_");
+		size_t		len = wcslen(test_locale);
+		if (GetLocaleInfoEx(pStr, LOCALE_SENGLISHCOUNTRYNAME,
+							test_locale + len, LOCALE_NAME_MAX_LENGTH - len) > 0)
+		{
+			if (wcsncmp(argv[0], test_locale, wcslen(test_locale)) == 0)
+			{
+				wcscpy(argv[1], pStr);
+				return FALSE;
+			}
+		}
+	}
+	return TRUE;
+}
+#endif		/* _WIN32_WINNT >= 0x0600 */
+
 static char *
 IsoLocaleName(const char *winlocname)
 {
-#ifdef _MSC_VER
-	static char iso_lc_messages[32];
-	_locale_t	loct = NULL;
+#if defined(_MSC_VER) || _WIN32_WINNT >= 0x0600
+	static char iso_lc_messages[LOCALE_NAME_MAX_LENGTH];
 
 	if (pg_strcasecmp("c", winlocname) == 0 ||
 		pg_strcasecmp("posix", winlocname) == 0)
 	{
-		strcpy(iso_lc_messages, "C");
-		return iso_lc_messages;
+		return "C";
 	}
-
-	loct = _create_locale(LC_CTYPE, winlocname);
-	if (loct != NULL)
+	else
 	{
 		size_t		rc;
 		char	   *hyphen;
+#if _WIN32_WINNT >= 0x0600
+		WCHAR		wc_locale_name[LOCALE_NAME_MAX_LENGTH];
+		WCHAR		buffer[LOCALE_NAME_MAX_LENGTH];
+		char	   *period;
+		int			len;
+
+		/*
+		 * Valid locales have the following syntax:
+		 * <Language>[_<Country>[.<CodePage>]]
+		 * GetLocaleInfoEx can only take locale name without code-page.
+		 */
+		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 (GetLocaleInfoEx(wc_locale_name, LOCALE_SNAME, (LPWSTR) &buffer,
+						LOCALE_NAME_MAX_LENGTH) <= 0)
+		{
+			/* Enumerate all locales supported by the system until match. */
+			WCHAR	  *argv[2];
+
+			argv[0] = wc_locale_name;
+			argv[1] = buffer;
+			EnumSystemLocalesEx(enum_locales_fn, LOCALE_WINDOWS, (LPARAM) argv,
+								NULL);
+		}
 
 		/* Locale names use only ASCII, any conversion locale suffices. */
-		rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
-						sizeof(iso_lc_messages), NULL);
+		rc = wchar2char(iso_lc_messages, buffer, sizeof(iso_lc_messages),
+						NULL);
+#else   	/* _WIN32_WINNT < 0x0600 */
+		_locale_t	loct;
+
+		loct = _create_locale(LC_CTYPE, winlocname);
+		if (loct != NULL)
+			rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
+							sizeof(iso_lc_messages), NULL);
 		_free_locale(loct);
+#endif		/* _WIN32_WINNT >= 0x0600 */
+
 		if (rc == -1 || rc == sizeof(iso_lc_messages))
 			return NULL;
 
@@ -1029,7 +1099,7 @@ IsoLocaleName(const char *winlocname)
 			*hyphen = '_';
 		return iso_lc_messages;
 	}
-#endif							/* _MSC_VER */
+#endif							/* defined(_MSC_VER) || _WIN32_WINNT >= 0x0600 */
 	return NULL;				/* Not supported on this version of msvc/mingw */
 }
 #endif							/* WIN32 && LC_MESSAGES */

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 2562eb5..401dfde 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -971,43 +971,135 @@ cache_locale_time(void)
  * string.  Furthermore, msvcr110.dll changed the undocumented _locale_t
  * content to carry locale names instead of locale identifiers.
  *
- * MinGW headers declare _create_locale(), but msvcrt.dll lacks that symbol.
- * 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.
+ * 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 or
+ * using EnumSystemLocalesEx() from Windows Vista/2008.
  *
  * This function returns a pointer to a static buffer bearing the converted
  * name or NULL if conversion fails.
  *
- * [1] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373763.aspx
- * [2] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373814.aspx
+ * [1] https://docs.microsoft.com/en-us/windows/win32/intl/locale-identifiers
+ * [2] https://docs.microsoft.com/en-us/windows/win32/intl/locale-names
  */
+#if _WIN32_WINNT >= 0x0600
+/*
+ * Callback function for EnumSystemLocalesEx.
+ * Stop enumarating if a match is found for a locale with the format
+ * <Language>_<Country>.
+ */
+static BOOL CALLBACK
+enum_locales_fn(LPWSTR pStr, DWORD dwFlags, LPARAM lparam)
+{
+	wchar_t		test_locale[LOCALE_NAME_MAX_LENGTH];
+
+	(void)(dwFlags);
+	memset(test_locale, 0, sizeof(test_locale));
+	if (GetLocaleInfoEx(pStr, LOCALE_SENGLISHLANGUAGENAME,
+						test_locale, LOCALE_NAME_MAX_LENGTH) > 0)
+	{
+		wchar_t	   *hyphen;
+		wchar_t	   *underscore;
+		wchar_t	  **argv;
+
+		argv = (wchar_t**) lparam;
+		hyphen = wcsrchr(pStr, '-');
+		underscore = wcsrchr(argv[0], '_');
+		if (hyphen == NULL || underscore == NULL)
+		{
+			/* Compare <Language> only */
+			if (_wcsicmp(argv[0], test_locale) == 0)
+			{
+				wcscpy(argv[1], pStr);
+				return FALSE;
+			}
+		}
+		else
+		{
+			size_t		len;
+
+			/* Comparing with a full string <Language>_<Country> */
+			wcscat(test_locale, L"_");
+			len = wcslen(test_locale);
+			if (GetLocaleInfoEx(pStr, LOCALE_SENGLISHCOUNTRYNAME,
+				test_locale + len, LOCALE_NAME_MAX_LENGTH - len) > 0)
+			{
+				if (_wcsicmp(argv[0], test_locale) == 0)
+				{
+					wcscpy(argv[1], pStr);
+					return FALSE;
+				}
+			}
+		}
+	}
+	return TRUE;
+}
+#endif							/* _WIN32_WINNT >= 0x0600 */
+
 static char *
 IsoLocaleName(const char *winlocname)
 {
-#ifdef _MSC_VER
-	static char iso_lc_messages[32];
-	_locale_t	loct = NULL;
+#if defined(_MSC_VER) || _WIN32_WINNT >= 0x0600
+	static char	iso_lc_messages[LOCALE_NAME_MAX_LENGTH];
 
 	if (pg_strcasecmp("c", winlocname) == 0 ||
 		pg_strcasecmp("posix", winlocname) == 0)
 	{
-		strcpy(iso_lc_messages, "C");
-		return iso_lc_messages;
+		return "C";
 	}
-
-	loct = _create_locale(LC_CTYPE, winlocname);
-	if (loct != NULL)
+	else
 	{
 		size_t		rc;
 		char	   *hyphen;
+#if _WIN32_WINNT >= 0x0600
+		wchar_t		wc_locale_name[LOCALE_NAME_MAX_LENGTH];
+		wchar_t		buffer[LOCALE_NAME_MAX_LENGTH];
+		char	   *period;
+		int			len;
+
+		/*
+		 * Valid locales have the following syntax:
+		 * <Language>[_<Country>[.<CodePage>]]
+		 * GetLocaleInfoEx can only take locale name without code-page.
+		 */
+		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 (GetLocaleInfoEx(wc_locale_name, LOCALE_SNAME, (LPWSTR) &buffer,
+						LOCALE_NAME_MAX_LENGTH) <= 0)
+		{
+			/* Enumerate all locales supported by the system, until match. */
+			wchar_t	  *argv[2];
+
+			argv[0] = wc_locale_name;
+			argv[1] = buffer;
+			EnumSystemLocalesEx(enum_locales_fn, LOCALE_WINDOWS, (LPARAM) argv,
+								NULL);
+		}
 
 		/* Locale names use only ASCII, any conversion locale suffices. */
-		rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
-						sizeof(iso_lc_messages), NULL);
+		rc = wchar2char(iso_lc_messages, buffer, sizeof(iso_lc_messages),
+						NULL);
+#else							/* _WIN32_WINNT < 0x0600 */
+		_locale_t	loct;
+
+		loct = _create_locale(LC_CTYPE, winlocname);
+		if (loct != NULL)
+			rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
+							sizeof(iso_lc_messages), NULL);
 		_free_locale(loct);
+#endif							/* _WIN32_WINNT >= 0x0600 */
+
 		if (rc == -1 || rc == sizeof(iso_lc_messages))
 			return NULL;
 
@@ -1029,7 +1121,7 @@ IsoLocaleName(const char *winlocname)
 			*hyphen = '_';
 		return iso_lc_messages;
 	}
-#endif							/* _MSC_VER */
+#endif							/* defined(_MSC_VER) || _WIN32_WINNT >= 0x0600 */
 	return NULL;				/* Not supported on this version of msvc/mingw */
 }
 #endif							/* WIN32 && LC_MESSAGES */

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 2562eb5416..ef151a444d 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -971,43 +971,138 @@ cache_locale_time(void)
  * string.  Furthermore, msvcr110.dll changed the undocumented _locale_t
  * content to carry locale names instead of locale identifiers.
  *
- * MinGW headers declare _create_locale(), but msvcrt.dll lacks that symbol.
- * 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.
+ * 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 or
+ * using EnumSystemLocalesEx() from Windows Vista/2008.
  *
  * This function returns a pointer to a static buffer bearing the converted
  * name or NULL if conversion fails.
  *
- * [1] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373763.aspx
- * [2] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373814.aspx
+ * [1] https://docs.microsoft.com/en-us/windows/win32/intl/locale-identifiers
+ * [2] https://docs.microsoft.com/en-us/windows/win32/intl/locale-names
  */
+#if _WIN32_WINNT >= 0x0600
+/*
+ * Callback function for EnumSystemLocalesEx.
+ * Stop enumarating if a match is found for a locale with the format
+ * <Language>_<Country>.
+ */
+static BOOL CALLBACK
+enum_locales_fn(LPWSTR pStr, DWORD dwFlags, LPARAM lparam)
+{
+	wchar_t		test_locale[LOCALE_NAME_MAX_LENGTH];
+
+	(void)(dwFlags);
+	memset(test_locale, 0, sizeof(test_locale));
+	if (GetLocaleInfoEx(pStr, LOCALE_SENGLISHLANGUAGENAME,
+						test_locale, LOCALE_NAME_MAX_LENGTH) > 0)
+	{
+		wchar_t	   *hyphen;
+		wchar_t	   *underscore;
+		wchar_t	  **argv;
+
+		argv = (wchar_t**) lparam;
+		hyphen = wcsrchr(pStr, '-');
+		underscore = wcsrchr(argv[0], '_');
+		if (hyphen == NULL || underscore == NULL)
+		{
+			/* Compare <Language> only */
+			if (_wcsicmp(argv[0], test_locale) == 0)
+			{
+				wcscpy(argv[1], pStr);
+				return FALSE;
+			}
+		}
+		else
+		{
+			size_t		len;
+
+			/* Comparing with a full string <Language>_<Country> */
+			wcscat(test_locale, L"_");
+			len = wcslen(test_locale);
+			if (GetLocaleInfoEx(pStr, LOCALE_SENGLISHCOUNTRYNAME,
+				test_locale + len, LOCALE_NAME_MAX_LENGTH - len) > 0)
+			{
+				if (_wcsicmp(argv[0], test_locale) == 0)
+				{
+					wcscpy(argv[1], pStr);
+					return FALSE;
+				}
+			}
+		}
+	}
+	return TRUE;
+}
+#endif							/* _WIN32_WINNT >= 0x0600 */
+
 static char *
 IsoLocaleName(const char *winlocname)
 {
-#ifdef _MSC_VER
-	static char iso_lc_messages[32];
-	_locale_t	loct = NULL;
+#if defined(_MSC_VER) || _WIN32_WINNT >= 0x0600
+	static char	iso_lc_messages[LOCALE_NAME_MAX_LENGTH];
 
 	if (pg_strcasecmp("c", winlocname) == 0 ||
 		pg_strcasecmp("posix", winlocname) == 0)
 	{
-		strcpy(iso_lc_messages, "C");
-		return iso_lc_messages;
+		return "C";
 	}
-
-	loct = _create_locale(LC_CTYPE, winlocname);
-	if (loct != NULL)
+	else
 	{
 		size_t		rc;
 		char	   *hyphen;
+#if _WIN32_WINNT >= 0x0600
+		wchar_t		wc_locale_name[LOCALE_NAME_MAX_LENGTH];
+		wchar_t		buffer[LOCALE_NAME_MAX_LENGTH];
+		char	   *period;
+		int			len;
+
+		/*
+		 * Valid locales have the following syntax:
+		 * <Language>[_<Country>[.<CodePage>]]
+		 * GetLocaleInfoEx can only take locale name without code-page.
+		 */
+		period = strchr(winlocname, '.');
+		if (period != NULL)
+			len = period - winlocname;
+		else
+			len = wcslen(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 (GetLocaleInfoEx(wc_locale_name, LOCALE_SNAME, (LPWSTR) &buffer,
+						LOCALE_NAME_MAX_LENGTH) <= 0)
+		{
+			/* Enumerate all locales supported by the system, until match. */
+			wchar_t	  *argv[2];
+
+			argv[0] = wc_locale_name;
+			argv[1] = buffer;
+			EnumSystemLocalesEx(enum_locales_fn, LOCALE_WINDOWS, (LPARAM) argv,
+								NULL);
+		}
 
 		/* Locale names use only ASCII, any conversion locale suffices. */
-		rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
-						sizeof(iso_lc_messages), NULL);
-		_free_locale(loct);
+		rc = wchar2char(iso_lc_messages, buffer, sizeof(iso_lc_messages),
+						NULL);
+#else							/* _WIN32_WINNT < 0x0600 */
+		_locale_t	loct;
+
+		loct = _create_locale(LC_CTYPE, winlocname);
+		if (loct != NULL)
+		{
+			rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
+							sizeof(iso_lc_messages), NULL);
+		    _free_locale(loct);
+		} else
+			rc = -1;
+#endif							/* _WIN32_WINNT >= 0x0600 */
+
 		if (rc == -1 || rc == sizeof(iso_lc_messages))
 			return NULL;
 
@@ -1029,7 +1124,7 @@ IsoLocaleName(const char *winlocname)
 			*hyphen = '_';
 		return iso_lc_messages;
 	}
-#endif							/* _MSC_VER */
+#endif							/* defined(_MSC_VER) || _WIN32_WINNT >= 0x0600 */
 	return NULL;				/* Not supported on this version of msvc/mingw */
 }
 #endif							/* WIN32 && LC_MESSAGES */

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 2562eb5416..e0271a4fb4 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -971,43 +971,139 @@ cache_locale_time(void)
  * string.  Furthermore, msvcr110.dll changed the undocumented _locale_t
  * content to carry locale names instead of locale identifiers.
  *
- * MinGW headers declare _create_locale(), but msvcrt.dll lacks that symbol.
- * 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.
+ * 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 or
+ * using EnumSystemLocalesEx() from Windows Vista/2008.
  *
  * This function returns a pointer to a static buffer bearing the converted
  * name or NULL if conversion fails.
  *
- * [1] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373763.aspx
- * [2] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373814.aspx
+ * [1] https://docs.microsoft.com/en-us/windows/win32/intl/locale-identifiers
+ * [2] https://docs.microsoft.com/en-us/windows/win32/intl/locale-names
  */
+#if _WIN32_WINNT >= 0x0600
+/*
+ * Callback function for EnumSystemLocalesEx.
+ * Stop enumarating if a match is found for a locale with the format
+ * <Language>_<Country>.
+ */
+static BOOL CALLBACK
+enum_locales_fn(LPWSTR pStr, DWORD dwFlags, LPARAM lparam)
+{
+	wchar_t		test_locale[LOCALE_NAME_MAX_LENGTH];
+
+	(void)(dwFlags);
+	memset(test_locale, 0, sizeof(test_locale));
+	if (GetLocaleInfoEx(pStr, LOCALE_SENGLISHLANGUAGENAME,
+						test_locale, LOCALE_NAME_MAX_LENGTH) > 0)
+	{
+		wchar_t	   *hyphen;
+		wchar_t	   *underscore;
+		wchar_t	  **argv;
+
+		argv = (wchar_t**) lparam;
+		hyphen = wcsrchr(pStr, '-');
+		underscore = wcsrchr(argv[0], '_');
+		if (hyphen == NULL || underscore == NULL)
+		{
+			/* Compare <Language> only */
+			if (_wcsicmp(argv[0], test_locale) == 0)
+			{
+				wcscpy(argv[1], pStr);
+				return FALSE;
+			}
+		}
+		else
+		{
+			size_t		len;
+
+			/* Comparing with a full string <Language>_<Country> */
+			wcscat(test_locale, L"_");
+			len = wcslen(test_locale);
+			if (GetLocaleInfoEx(pStr, LOCALE_SENGLISHCOUNTRYNAME,
+				test_locale + len, LOCALE_NAME_MAX_LENGTH - len) > 0)
+			{
+				if (_wcsicmp(argv[0], test_locale) == 0)
+				{
+					wcscpy(argv[1], pStr);
+					return FALSE;
+				}
+			}
+		}
+	}
+	return TRUE;
+}
+#endif							/* _WIN32_WINNT >= 0x0600 */
+
 static char *
 IsoLocaleName(const char *winlocname)
 {
-#ifdef _MSC_VER
-	static char iso_lc_messages[32];
-	_locale_t	loct = NULL;
+#if defined(_MSC_VER) || _WIN32_WINNT >= 0x0600
+	static char	iso_lc_messages[LOCALE_NAME_MAX_LENGTH];
 
 	if (pg_strcasecmp("c", winlocname) == 0 ||
 		pg_strcasecmp("posix", winlocname) == 0)
 	{
-		strcpy(iso_lc_messages, "C");
-		return iso_lc_messages;
+		return "C";
 	}
-
-	loct = _create_locale(LC_CTYPE, winlocname);
-	if (loct != NULL)
+	else
 	{
 		size_t		rc;
 		char	   *hyphen;
+#if _WIN32_WINNT >= 0x0600
+		wchar_t		wc_locale_name[LOCALE_NAME_MAX_LENGTH];
+		wchar_t		buffer[LOCALE_NAME_MAX_LENGTH];
+		char	   *period;
+		int			len;
+
+		/*
+		 * Valid locales have the following syntax:
+		 * <Language>[_<Country>[.<CodePage>]]
+		 * GetLocaleInfoEx can only take locale name without code-page.
+		 */
+		period = strchr(winlocname, '.');
+		if (period != NULL)
+			len = period - winlocname;
+		else
+			len = wcslen(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 (GetLocaleInfoEx(wc_locale_name, LOCALE_SNAME, (LPWSTR) &buffer,
+						LOCALE_NAME_MAX_LENGTH) <= 0)
+		{
+			/* Enumerate all locales supported by the system, until match. */
+			wchar_t	  *argv[2];
+
+			argv[0] = wc_locale_name;
+			argv[1] = buffer;
+			EnumSystemLocalesEx(enum_locales_fn, LOCALE_WINDOWS, (LPARAM) argv,
+								NULL);
+		}
 
 		/* Locale names use only ASCII, any conversion locale suffices. */
-		rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
-						sizeof(iso_lc_messages), NULL);
-		_free_locale(loct);
+		rc = wchar2char(iso_lc_messages, buffer, sizeof(iso_lc_messages),
+						NULL);
+#else							/* _WIN32_WINNT < 0x0600 */
+		_locale_t	loct;
+
+		loct = _create_locale(LC_CTYPE, winlocname);
+		if (loct != NULL)
+		{
+			rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
+							sizeof(iso_lc_messages), NULL);
+		    _free_locale(loct);
+		}
+		else
+			rc = -1;
+#endif							/* _WIN32_WINNT >= 0x0600 */
+
 		if (rc == -1 || rc == sizeof(iso_lc_messages))
 			return NULL;
 
@@ -1029,7 +1125,7 @@ IsoLocaleName(const char *winlocname)
 			*hyphen = '_';
 		return iso_lc_messages;
 	}
-#endif							/* _MSC_VER */
+#endif							/* defined(_MSC_VER) || _WIN32_WINNT >= 0x0600 */
 	return NULL;				/* Not supported on this version of msvc/mingw */
 }
 #endif							/* WIN32 && LC_MESSAGES */

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 2562eb5..9e231f9 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -971,45 +971,143 @@ cache_locale_time(void)
  * string.  Furthermore, msvcr110.dll changed the undocumented _locale_t
  * content to carry locale names instead of locale identifiers.
  *
- * MinGW headers declare _create_locale(), but msvcrt.dll lacks that symbol.
- * 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.
+ * 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 or
+ * using EnumSystemLocalesEx() from Windows Vista/2008.
  *
  * This function returns a pointer to a static buffer bearing the converted
  * name or NULL if conversion fails.
  *
- * [1] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373763.aspx
- * [2] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373814.aspx
+ * [1] https://docs.microsoft.com/en-us/windows/win32/intl/locale-identifiers
+ * [2] https://docs.microsoft.com/en-us/windows/win32/intl/locale-names
  */
+#if _WIN32_WINNT >= 0x0600
+/*
+ * Callback function for EnumSystemLocalesEx.
+ * Stop enumarating if a match is found for a locale with the format
+ * <Language>[_<Country]>, e.g. English[_United States]
+ */
+static BOOL CALLBACK
+enum_locales_fn(LPWSTR pStr, DWORD dwFlags, LPARAM lparam)
+{
+	wchar_t		test_locale[LOCALE_NAME_MAX_LENGTH];
+
+	(void)(dwFlags);
+	memset(test_locale, 0, sizeof(test_locale));
+	if (GetLocaleInfoEx(pStr, LOCALE_SENGLISHLANGUAGENAME,
+						test_locale, LOCALE_NAME_MAX_LENGTH))
+	{
+		wchar_t	   *hyphen;
+		wchar_t	   *underscore;
+		wchar_t	  **argv;
+
+		argv = (wchar_t**) lparam;
+		hyphen = wcsrchr(pStr, '-');
+		underscore = wcsrchr(argv[0], '_');
+		if (hyphen == NULL || underscore == NULL)
+		{
+			/* Compare <Language> only, e.g. English */
+			if (_wcsicmp(argv[0], test_locale) == 0)
+			{
+				wcscpy(argv[1], pStr);
+				return FALSE;
+			}
+		}
+		else
+		{
+			size_t		len;
+
+			/*
+			 * Comparing with a full string <Language>_<Country>, e.g.
+			 * English_United States
+			 */
+			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);
+					return FALSE;
+				}
+			}
+		}
+	}
+	return TRUE;
+}
+#endif							/* _WIN32_WINNT >= 0x0600 */
+
 static char *
 IsoLocaleName(const char *winlocname)
 {
-#ifdef _MSC_VER
-	static char iso_lc_messages[32];
-	_locale_t	loct = NULL;
+#if defined(_MSC_VER) || _WIN32_WINNT >= 0x0600
+	static char	iso_lc_messages[LOCALE_NAME_MAX_LENGTH];
 
 	if (pg_strcasecmp("c", winlocname) == 0 ||
 		pg_strcasecmp("posix", winlocname) == 0)
-	{
 		strcpy(iso_lc_messages, "C");
-		return iso_lc_messages;
-	}
-
-	loct = _create_locale(LC_CTYPE, winlocname);
-	if (loct != NULL)
+	else
 	{
 		size_t		rc;
 		char	   *hyphen;
+#if _WIN32_WINNT >= 0x0600
+		wchar_t		wc_locale_name[LOCALE_NAME_MAX_LENGTH];
+		wchar_t		buffer[LOCALE_NAME_MAX_LENGTH];
+		char	   *period;
+		int			len;
+
+		/*
+		 * Valid locales have the following syntax:
+		 * <Language>[_<Country>[.<CodePage>]]
+		 * GetLocaleInfoEx can only take locale name without code-page.
+		 */
+		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);
+		/* Is it already a IETF-standardized string, e.g. en-US, en_US */
+		if (!GetLocaleInfoEx(wc_locale_name, LOCALE_SNAME, (LPWSTR) &buffer,
+						LOCALE_NAME_MAX_LENGTH))
+		{
+			/* Enumerate all locales supported by the system, until match. */
+			wchar_t	  *argv[2];
+
+			argv[0] = wc_locale_name;
+			argv[1] = buffer;
+			EnumSystemLocalesEx(enum_locales_fn, LOCALE_WINDOWS, (LPARAM) argv,
+								NULL);
+		}
 
 		/* Locale names use only ASCII, any conversion locale suffices. */
-		rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
-						sizeof(iso_lc_messages), NULL);
-		_free_locale(loct);
+		rc = wchar2char(iso_lc_messages, buffer, sizeof(iso_lc_messages),
+						NULL);
+#else							/* _WIN32_WINNT < 0x0600 */
+		_locale_t	loct;
+
+		loct = _create_locale(LC_CTYPE, winlocname);
+		if (loct != NULL)
+		{
+			rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
+							sizeof(iso_lc_messages), NULL);
+			_free_locale(loct);
+		}
+		else
+			rc = -1;
+#endif							/* _WIN32_WINNT >= 0x0600 */
+
 		if (rc == -1 || rc == sizeof(iso_lc_messages))
-			return NULL;
+			iso_lc_messages[0] = '\0';
 
 		/*
 		 * Since the message catalogs sit on a case-insensitive filesystem, we
@@ -1027,9 +1125,10 @@ IsoLocaleName(const char *winlocname)
 		hyphen = strchr(iso_lc_messages, '-');
 		if (hyphen)
 			*hyphen = '_';
+		elog(DEBUG3, "IsoLocaleName() executed; locale: \"%s\"", iso_lc_messages);
 		return iso_lc_messages;
 	}
-#endif							/* _MSC_VER */
+#endif							/* defined(_MSC_VER) || _WIN32_WINNT >= 0x0600 */
 	return NULL;				/* Not supported on this version of msvc/mingw */
 }
 #endif							/* WIN32 && LC_MESSAGES */

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 2562eb5416..5da31de23e 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -971,25 +971,89 @@ cache_locale_time(void)
  * string.  Furthermore, msvcr110.dll changed the undocumented _locale_t
  * content to carry locale names instead of locale identifiers.
  *
- * MinGW headers declare _create_locale(), but msvcrt.dll lacks that symbol.
- * 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.
+ * 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 or
+ * using EnumSystemLocalesEx() from Windows Vista/2008.
  *
  * This function returns a pointer to a static buffer bearing the converted
  * name or NULL if conversion fails.
  *
- * [1] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373763.aspx
- * [2] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373814.aspx
+ * [1] https://docs.microsoft.com/en-us/windows/win32/intl/locale-identifiers
+ * [2] https://docs.microsoft.com/en-us/windows/win32/intl/locale-names
  */
+
+#if _MSC_VER >= 1900
+/*
+ * Callback function for EnumSystemLocalesEx.
+ * Stop enumarating if a match is found for a locale with the format
+ * <Language>[_<Country]>, e.g. English[_United States]
+ */
+static BOOL CALLBACK
+enum_locales_fn(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));
+	if (GetLocaleInfoEx(pStr, LOCALE_SENGLISHLANGUAGENAME,
+						test_locale, LOCALE_NAME_MAX_LENGTH))
+	{
+		wchar_t	   *hyphen;
+		wchar_t	   *underscore;
+
+		hyphen = wcsrchr(pStr, '-');
+		underscore = wcsrchr(argv[0], '_');
+		if (hyphen == NULL || underscore == NULL)
+		{
+			/* Compare <Language> only, e.g. English */
+			if (_wcsicmp(argv[0], test_locale) == 0)
+			{
+				wcscpy(argv[1], pStr);
+				*argv[2] = (wchar_t) 1;
+				return FALSE;
+			}
+		}
+		else
+		{
+			size_t		len;
+
+			/*
+			 * Comparing with a full string <Language>_<Country>, e.g.
+			 * English_United States
+			 */
+			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;
+}
+#endif							/* _MSC_VER >= 1900 */
+
 static char *
 IsoLocaleName(const char *winlocname)
 {
-#ifdef _MSC_VER
-	static char iso_lc_messages[32];
-	_locale_t	loct = NULL;
+#if defined(_MSC_VER)
+	static char	iso_lc_messages[LOCALE_NAME_MAX_LENGTH];
 
 	if (pg_strcasecmp("c", winlocname) == 0 ||
 		pg_strcasecmp("posix", winlocname) == 0)
@@ -997,17 +1061,68 @@ IsoLocaleName(const char *winlocname)
 		strcpy(iso_lc_messages, "C");
 		return iso_lc_messages;
 	}
-
-	loct = _create_locale(LC_CTYPE, winlocname);
-	if (loct != NULL)
+	else
 	{
-		size_t		rc;
+		size_t		rc = -1;
 		char	   *hyphen;
+#if _MSC_VER >= 1900
+		wchar_t		wc_locale_name[LOCALE_NAME_MAX_LENGTH];
+		wchar_t		buffer[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);
+
+		/* Is it already a IETF-standardized string, e.g. en-US, en_US */
+		ret_val = GetLocaleInfoEx(wc_locale_name, LOCALE_SNAME, (LPWSTR)&buffer,
+								  LOCALE_NAME_MAX_LENGTH);
+		if (!ret_val)
+		{
+			/* Enumerate all locales supported by the system, until match. */
+			wchar_t	  *argv[3];
+
+			argv[0] = wc_locale_name;
+			argv[1] = buffer;
+			argv[2] = (wchar_t *) &ret_val;
+			EnumSystemLocalesEx(enum_locales_fn, LOCALE_WINDOWS, (LPARAM) argv,
+								NULL);
+		}
+
+		if (ret_val)
+		{
+			/* Locale names use only ASCII, any conversion locale suffices. */
+			rc = wchar2char(iso_lc_messages, buffer, sizeof(iso_lc_messages),
+							NULL);
+		}
+#else							/* _MSC_VER < 1900 */
+		_locale_t	loct;
+
+		loct = _create_locale(LC_CTYPE, winlocname);
+		if (loct != NULL)
+		{
+			rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
+							sizeof(iso_lc_messages), NULL);
+			_free_locale(loct);
+		}
+#endif							/* _MSC_VER >= 1900 */
 
-		/* Locale names use only ASCII, any conversion locale suffices. */
-		rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
-						sizeof(iso_lc_messages), NULL);
-		_free_locale(loct);
 		if (rc == -1 || rc == sizeof(iso_lc_messages))
 			return NULL;
 
@@ -1027,9 +1142,10 @@ IsoLocaleName(const char *winlocname)
 		hyphen = strchr(iso_lc_messages, '-');
 		if (hyphen)
 			*hyphen = '_';
+		elog(DEBUG3, "IsoLocaleName() executed; locale: \"%s\"", iso_lc_messages);
 		return iso_lc_messages;
 	}
-#endif							/* _MSC_VER */
+#endif							/* defined(_MSC_VER) */
 	return NULL;				/* Not supported on this version of msvc/mingw */
 }
 #endif							/* WIN32 && LC_MESSAGES */

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 2562eb5416..3cded4cc81 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -971,43 +971,155 @@ cache_locale_time(void)
  * string.  Furthermore, msvcr110.dll changed the undocumented _locale_t
  * content to carry locale names instead of locale identifiers.
  *
- * MinGW headers declare _create_locale(), but msvcrt.dll lacks that symbol.
- * 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.
+ * 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 or
+ * using EnumSystemLocalesEx() from Windows Vista/2008.
  *
  * This function returns a pointer to a static buffer bearing the converted
  * name or NULL if conversion fails.
  *
- * [1] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373763.aspx
- * [2] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373814.aspx
+ * [1] https://docs.microsoft.com/en-us/windows/win32/intl/locale-identifiers
+ * [2] https://docs.microsoft.com/en-us/windows/win32/intl/locale-names
  */
+
+#if _MSC_VER >= 1900
+/*
+ * Callback function for EnumSystemLocalesEx.
+ * Stop enumarating if a match is found for a locale with the format
+ * <Language>[_<Country]>, e.g. English[_United States]
+ */
+static BOOL CALLBACK
+enum_locales_fn(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));
+	if (GetLocaleInfoEx(pStr, LOCALE_SENGLISHLANGUAGENAME,
+						test_locale, LOCALE_NAME_MAX_LENGTH))
+	{
+		if (wcsrchr(pStr, '-') == NULL || wcsrchr(argv[0], '_') == NULL)
+		{
+			/* Compare <Language> only, e.g. English */
+			if (_wcsicmp(argv[0], test_locale) == 0)
+			{
+				wcscpy(argv[1], pStr);
+				*argv[2] = (wchar_t) 1;
+				return FALSE;
+			}
+		}
+		else
+		{
+			size_t		len;
+
+			/*
+			 * Comparing with a full string <Language>_<Country>, e.g.
+			 * English_United States
+			 */
+			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;
+}
+#endif							/* _MSC_VER >= 1900 */
+
 static char *
 IsoLocaleName(const char *winlocname)
 {
-#ifdef _MSC_VER
-	static char iso_lc_messages[32];
-	_locale_t	loct = NULL;
+#if defined(_MSC_VER)
+	static char	iso_lc_messages[LOCALE_NAME_MAX_LENGTH];
 
 	if (pg_strcasecmp("c", winlocname) == 0 ||
 		pg_strcasecmp("posix", winlocname) == 0)
 	{
-		strcpy(iso_lc_messages, "C");
+		iso_lc_messages[0] = 'C';
+		iso_lc_messages[1] = '\0';
+
 		return iso_lc_messages;
 	}
-
-	loct = _create_locale(LC_CTYPE, winlocname);
-	if (loct != NULL)
+	else
 	{
-		size_t		rc;
+		size_t		rc = -1;
 		char	   *hyphen;
+#if _MSC_VER >= 1900
+		wchar_t		wc_locale_name[LOCALE_NAME_MAX_LENGTH];
+		wchar_t		buffer[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);
+
+		/* Is it already a IETF-standardized string, e.g. en-US, en_US */
+		ret_val = GetLocaleInfoEx(wc_locale_name, LOCALE_SNAME, (LPWSTR)&buffer,
+								  LOCALE_NAME_MAX_LENGTH);
+		if (!ret_val)
+		{
+			/* Enumerate all locales supported by the system, until match. */
+			wchar_t	  *argv[3];
+
+			argv[0] = wc_locale_name;
+			argv[1] = buffer;
+			argv[2] = (wchar_t *) &ret_val;
+			EnumSystemLocalesEx(enum_locales_fn, LOCALE_WINDOWS, (LPARAM) argv,
+								NULL);
+		}
+
+		if (ret_val)
+		{
+			/* Locale names use only ASCII, any conversion locale suffices. */
+			rc = wchar2char(iso_lc_messages, buffer, sizeof(iso_lc_messages),
+							NULL);
+		}
+#else							/* _MSC_VER < 1900 */
+		_locale_t	loct;
+
+		loct = _create_locale(LC_CTYPE, winlocname);
+		if (loct != NULL)
+		{
+			rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
+							sizeof(iso_lc_messages), NULL);
+			_free_locale(loct);
+		}
+#endif							/* _MSC_VER >= 1900 */
 
-		/* Locale names use only ASCII, any conversion locale suffices. */
-		rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
-						sizeof(iso_lc_messages), NULL);
-		_free_locale(loct);
 		if (rc == -1 || rc == sizeof(iso_lc_messages))
 			return NULL;
 
@@ -1027,9 +1139,10 @@ IsoLocaleName(const char *winlocname)
 		hyphen = strchr(iso_lc_messages, '-');
 		if (hyphen)
 			*hyphen = '_';
+		elog(DEBUG3, "IsoLocaleName() executed; locale: \"%s\"", iso_lc_messages);
 		return iso_lc_messages;
 	}
-#endif							/* _MSC_VER */
+#endif							/* defined(_MSC_VER) */
 	return NULL;				/* Not supported on this version of msvc/mingw */
 }
 #endif							/* WIN32 && LC_MESSAGES */

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 2562eb5..3ae60f4 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -234,6 +234,7 @@ pg_perm_setlocale(int category, const char *locale)
 			result = IsoLocaleName(locale);
 			if (result == NULL)
 				result = (char *) locale;
+			elog(DEBUG3, "IsoLocaleName() executed; locale: \"%s\"", result);
 #endif							/* WIN32 */
 			break;
 #endif							/* LC_MESSAGES */
@@ -971,25 +972,97 @@ cache_locale_time(void)
  * string.  Furthermore, msvcr110.dll changed the undocumented _locale_t
  * content to carry locale names instead of locale identifiers.
  *
- * MinGW headers declare _create_locale(), but msvcrt.dll lacks that symbol.
- * 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.
+ * 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
+ * or using EnumSystemLocalesEx() from Windows Vista/2008.
  *
  * This function returns a pointer to a static buffer bearing the converted
  * name or NULL if conversion fails.
  *
- * [1] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373763.aspx
- * [2] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373814.aspx
+ * [1] https://docs.microsoft.com/en-us/windows/win32/intl/locale-identifiers
+ * [2] https://docs.microsoft.com/en-us/windows/win32/intl/locale-names
  */
+
+#if _MSC_VER >= 1900
+/*
+ * Callback function for EnumSystemLocalesEx() in IsoLocaleName().
+ *
+ * This search is done by enumerating all system locales, trying to match a
+ * locale 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 IETF-standardized format 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;
+}
+#endif							/* _MSC_VER >= 1900 */
+
 static char *
 IsoLocaleName(const char *winlocname)
 {
-#ifdef _MSC_VER
-	static char iso_lc_messages[32];
-	_locale_t	loct = NULL;
+#if defined(_MSC_VER)
+	static char	iso_lc_messages[LOCALE_NAME_MAX_LENGTH];
 
 	if (pg_strcasecmp("c", winlocname) == 0 ||
 		pg_strcasecmp("posix", winlocname) == 0)
@@ -997,17 +1070,73 @@ IsoLocaleName(const char *winlocname)
 		strcpy(iso_lc_messages, "C");
 		return iso_lc_messages;
 	}
-
-	loct = _create_locale(LC_CTYPE, winlocname);
-	if (loct != NULL)
+	else
 	{
-		size_t		rc;
+		size_t		rc = -1;
 		char	   *hyphen;
+#if _MSC_VER >= 1900
+		wchar_t		wc_locale_name[LOCALE_NAME_MAX_LENGTH];
+		wchar_t		buffer[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 an IETF-standardized 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
+			 * county names.
+			 */
+			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)
+		{
+			/* Locale names use only ASCII, any conversion locale suffices. */
+			rc = wchar2char(iso_lc_messages, buffer, sizeof(iso_lc_messages),
+							NULL);
+		}
+#else							/* _MSC_VER < 1900 */
+		_locale_t	loct;
+
+		loct = _create_locale(LC_CTYPE, winlocname);
+		if (loct != NULL)
+		{
+			rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
+							sizeof(iso_lc_messages), NULL);
+			_free_locale(loct);
+		}
+#endif							/* _MSC_VER >= 1900 */
 
-		/* Locale names use only ASCII, any conversion locale suffices. */
-		rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
-						sizeof(iso_lc_messages), NULL);
-		_free_locale(loct);
 		if (rc == -1 || rc == sizeof(iso_lc_messages))
 			return NULL;
 
@@ -1029,7 +1158,7 @@ IsoLocaleName(const char *winlocname)
 			*hyphen = '_';
 		return iso_lc_messages;
 	}
-#endif							/* _MSC_VER */
+#endif							/* defined(_MSC_VER) */
 	return NULL;				/* Not supported on this version of msvc/mingw */
 }
 #endif							/* WIN32 && LC_MESSAGES */

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 2562eb5..a9d5f46 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -234,6 +234,7 @@ pg_perm_setlocale(int category, const char *locale)
 			result = IsoLocaleName(locale);
 			if (result == NULL)
 				result = (char *) locale;
+			elog(DEBUG3, "IsoLocaleName() executed; locale: \"%s\"", result);
 #endif							/* WIN32 */
 			break;
 #endif							/* LC_MESSAGES */
@@ -971,25 +972,106 @@ cache_locale_time(void)
  * string.  Furthermore, msvcr110.dll changed the undocumented _locale_t
  * content to carry locale names instead of locale identifiers.
  *
- * MinGW headers declare _create_locale(), but msvcrt.dll lacks that symbol.
- * 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.
+ * 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 loacle 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] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373763.aspx
- * [2] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373814.aspx
+ * [1] https://docs.microsoft.com/en-us/windows/win32/intl/locale-identifiers
+ * [2] https://docs.microsoft.com/en-us/windows/win32/intl/locale-names
  */
+
+#if _MSC_VER >= 1900
+/*
+ * Callback function for EnumSystemLocalesEx() in IsoLocaleName().
+ *
+ * This search is done by enumerating all system locales, trying to match a
+ * locale 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;
+}
+#endif							/* _MSC_VER >= 1900 */
+
 static char *
 IsoLocaleName(const char *winlocname)
 {
-#ifdef _MSC_VER
-	static char iso_lc_messages[32];
-	_locale_t	loct = NULL;
+#if defined(_MSC_VER)
+	static char iso_lc_messages[LOCALE_NAME_MAX_LENGTH];
 
 	if (pg_strcasecmp("c", winlocname) == 0 ||
 		pg_strcasecmp("posix", winlocname) == 0)
@@ -997,17 +1079,74 @@ IsoLocaleName(const char *winlocname)
 		strcpy(iso_lc_messages, "C");
 		return iso_lc_messages;
 	}
-
-	loct = _create_locale(LC_CTYPE, winlocname);
-	if (loct != NULL)
+	else
 	{
-		size_t		rc;
+		size_t		rc = -1;
 		char	   *hyphen;
+#if _MSC_VER >= 1900
+		wchar_t		wc_locale_name[LOCALE_NAME_MAX_LENGTH];
+		wchar_t		buffer[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 an 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
+			 * county names.
+			 */
+			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)
+		{
+			/* Locale names use only ASCII, any conversion locale suffices. */
+			rc = wchar2char(iso_lc_messages, buffer, sizeof(iso_lc_messages),
+							NULL);
+		}
+#else							/* _MSC_VER < 1900 */
+		_locale_t	loct;
+
+		loct = _create_locale(LC_CTYPE, winlocname);
+		if (loct != NULL)
+		{
+			rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
+							sizeof(iso_lc_messages), NULL);
+			_free_locale(loct);
+		}
+#endif							/* _MSC_VER >= 1900 */
 
-		/* Locale names use only ASCII, any conversion locale suffices. */
-		rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
-						sizeof(iso_lc_messages), NULL);
-		_free_locale(loct);
 		if (rc == -1 || rc == sizeof(iso_lc_messages))
 			return NULL;
 
@@ -1029,7 +1168,7 @@ IsoLocaleName(const char *winlocname)
 			*hyphen = '_';
 		return iso_lc_messages;
 	}
-#endif							/* _MSC_VER */
+#endif							/* defined(_MSC_VER) */
 	return NULL;				/* Not supported on this version of msvc/mingw */
 }
 #endif							/* WIN32 && LC_MESSAGES */

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index b9e01b6..10eb0ab 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -220,6 +220,7 @@ pg_perm_setlocale(int category, const char *locale)
 			result = IsoLocaleName(locale);
 			if (result == NULL)
 				result = (char *) locale;
+			elog(DEBUG3, "IsoLocaleName() executed; locale: \"%s\"", result);
 #endif							/* WIN32 */
 			break;
 #endif							/* LC_MESSAGES */
@@ -953,25 +954,106 @@ cache_locale_time(void)
  * string.  Furthermore, msvcr110.dll changed the undocumented _locale_t
  * content to carry locale names instead of locale identifiers.
  *
- * MinGW headers declare _create_locale(), but msvcrt.dll lacks that symbol.
- * 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.
+ * 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 loacle 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] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373763.aspx
- * [2] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373814.aspx
+ * [1] https://docs.microsoft.com/en-us/windows/win32/intl/locale-identifiers
+ * [2] https://docs.microsoft.com/en-us/windows/win32/intl/locale-names
  */
+
+#if _MSC_VER >= 1900
+/*
+ * Callback function for EnumSystemLocalesEx() in IsoLocaleName().
+ *
+ * This search is done by enumerating all system locales, trying to match a
+ * locale 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;
+}
+#endif							/* _MSC_VER >= 1900 */
+
 static char *
 IsoLocaleName(const char *winlocname)
 {
 #if (_MSC_VER >= 1400)			/* VC8.0 or later */
-	static char iso_lc_messages[32];
-	_locale_t	loct = NULL;
+	static char iso_lc_messages[LOCALE_NAME_MAX_LENGTH];
 
 	if (pg_strcasecmp("c", winlocname) == 0 ||
 		pg_strcasecmp("posix", winlocname) == 0)
@@ -979,18 +1061,74 @@ IsoLocaleName(const char *winlocname)
 		strcpy(iso_lc_messages, "C");
 		return iso_lc_messages;
 	}
-
-	loct = _create_locale(LC_CTYPE, winlocname);
-	if (loct != NULL)
+	else
 	{
 #if (_MSC_VER >= 1700)			/* Visual Studio 2012 or later */
-		size_t		rc;
+		size_t		rc = -1;
 		char	   *hyphen;
+#if (_MSC_VER >= 1900)			/* Visual Studio 2015 or later */
+		wchar_t		wc_locale_name[LOCALE_NAME_MAX_LENGTH];
+		wchar_t		buffer[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 an 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
+			 * county names.
+			 */
+			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)
+		{
+			/* Locale names use only ASCII, any conversion locale suffices. */
+			rc = wchar2char(iso_lc_messages, buffer, sizeof(iso_lc_messages),
+							NULL);
+		}
+#else							/* Visual Studio 2015 or later */
+		_locale_t	loct;
+
+		loct = _create_locale(LC_CTYPE, winlocname);
+		if (loct != NULL)
+		{
+			rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
+							sizeof(iso_lc_messages), NULL);
+			_free_locale(loct);
+		}
+#endif							/* Visual Studio 2015 or later */
 
-		/* Locale names use only ASCII, any conversion locale suffices. */
-		rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
-						sizeof(iso_lc_messages), NULL);
-		_free_locale(loct);
 		if (rc == -1 || rc == sizeof(iso_lc_messages))
 			return NULL;
 
@@ -1010,22 +1148,27 @@ IsoLocaleName(const char *winlocname)
 		hyphen = strchr(iso_lc_messages, '-');
 		if (hyphen)
 			*hyphen = '_';
-#else
+#else							/* Visual Studio 2012 or later */
 		char		isolang[32],
 					isocrty[32];
 		LCID		lcid;
+		_locale_t   loct;
 
-		lcid = loct->locinfo->lc_handle[LC_CTYPE];
-		if (lcid == 0)
-			lcid = MAKELCID(MAKELANGID(LANG_ENGLISH, SUBLANG_ENGLISH_US), SORT_DEFAULT);
-		_free_locale(loct);
+		loct = _create_locale(LC_CTYPE, winlocname);
+		if (loct != NULL)
+		{
+			lcid = loct->locinfo->lc_handle[LC_CTYPE];
+			if (lcid == 0)
+				lcid = MAKELCID(MAKELANGID(LANG_ENGLISH, SUBLANG_ENGLISH_US), SORT_DEFAULT);
+			_free_locale(loct);
+		}
 
 		if (!GetLocaleInfoA(lcid, LOCALE_SISO639LANGNAME, isolang, sizeof(isolang)))
 			return NULL;
 		if (!GetLocaleInfoA(lcid, LOCALE_SISO3166CTRYNAME, isocrty, sizeof(isocrty)))
 			return NULL;
 		snprintf(iso_lc_messages, sizeof(iso_lc_messages) - 1, "%s_%s", isolang, isocrty);
-#endif
+#endif							/* Visual Studio 2012 or later */
 		return iso_lc_messages;
 	}
 	return NULL;

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index e0ebea7..d4c30c9 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -215,6 +215,7 @@ pg_perm_setlocale(int category, const char *locale)
 			result = IsoLocaleName(locale);
 			if (result == NULL)
 				result = (char *) locale;
+			elog(DEBUG3, "IsoLocaleName() executed; locale: \"%s\"", result);
 #endif   /* WIN32 */
 			break;
 #endif   /* LC_MESSAGES */
@@ -948,25 +949,106 @@ cache_locale_time(void)
  * string.  Furthermore, msvcr110.dll changed the undocumented _locale_t
  * content to carry locale names instead of locale identifiers.
  *
- * MinGW headers declare _create_locale(), but msvcrt.dll lacks that symbol.
- * 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.
+ * 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 loacle 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] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373763.aspx
- * [2] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373814.aspx
+ * [1] https://docs.microsoft.com/en-us/windows/win32/intl/locale-identifiers
+ * [2] https://docs.microsoft.com/en-us/windows/win32/intl/locale-names
  */
+
+#if _MSC_VER >= 1900
+/*
+ * Callback function for EnumSystemLocalesEx() in IsoLocaleName().
+ *
+ * This search is done by enumerating all system locales, trying to match a
+ * locale 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;
+}
+#endif							/* _MSC_VER >= 1900 */
+
 static char *
 IsoLocaleName(const char *winlocname)
 {
 #if (_MSC_VER >= 1400)			/* VC8.0 or later */
-	static char iso_lc_messages[32];
-	_locale_t	loct = NULL;
+	static char iso_lc_messages[LOCALE_NAME_MAX_LENGTH];
 
 	if (pg_strcasecmp("c", winlocname) == 0 ||
 		pg_strcasecmp("posix", winlocname) == 0)
@@ -974,18 +1056,74 @@ IsoLocaleName(const char *winlocname)
 		strcpy(iso_lc_messages, "C");
 		return iso_lc_messages;
 	}
-
-	loct = _create_locale(LC_CTYPE, winlocname);
-	if (loct != NULL)
+	else
 	{
 #if (_MSC_VER >= 1700)			/* Visual Studio 2012 or later */
-		size_t		rc;
+		size_t		rc = -1;
 		char	   *hyphen;
+#if (_MSC_VER >= 1900)			/* Visual Studio 2015 or later */
+		wchar_t		wc_locale_name[LOCALE_NAME_MAX_LENGTH];
+		wchar_t		buffer[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);
 
-		/* Locale names use only ASCII, any conversion locale suffices. */
-		rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
-						sizeof(iso_lc_messages), NULL);
-		_free_locale(loct);
+		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 an 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
+			 * county names.
+			 */
+			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)
+		{
+			/* Locale names use only ASCII, any conversion locale suffices. */
+			rc = wchar2char(iso_lc_messages, buffer, sizeof(iso_lc_messages),
+							NULL);
+		}
+#else							/* Visual Studio 2015 or later */
+		_locale_t   loct;
+
+		loct = _create_locale(LC_CTYPE, winlocname);
+		if (loct != NULL)
+		{
+			rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
+							sizeof(iso_lc_messages), NULL);
+			_free_locale(loct);
+		}
+#endif							/* Visual Studio 2015 or later */
 		if (rc == -1 || rc == sizeof(iso_lc_messages))
 			return NULL;
 
@@ -1005,22 +1143,27 @@ IsoLocaleName(const char *winlocname)
 		hyphen = strchr(iso_lc_messages, '-');
 		if (hyphen)
 			*hyphen = '_';
-#else
+#else							/* Visual Studio 2012 or later */
 		char		isolang[32],
 					isocrty[32];
 		LCID		lcid;
+		_locale_t   loct;
 
-		lcid = loct->locinfo->lc_handle[LC_CTYPE];
-		if (lcid == 0)
-			lcid = MAKELCID(MAKELANGID(LANG_ENGLISH, SUBLANG_ENGLISH_US), SORT_DEFAULT);
-		_free_locale(loct);
+		loct = _create_locale(LC_CTYPE, winlocname);
+		if (loct != NULL)
+		{
+			lcid = loct->locinfo->lc_handle[LC_CTYPE];
+			if (lcid == 0)
+				lcid = MAKELCID(MAKELANGID(LANG_ENGLISH, SUBLANG_ENGLISH_US), SORT_DEFAULT);
+			_free_locale(loct);
+		}
 
 		if (!GetLocaleInfoA(lcid, LOCALE_SISO639LANGNAME, isolang, sizeof(isolang)))
 			return NULL;
 		if (!GetLocaleInfoA(lcid, LOCALE_SISO3166CTRYNAME, isocrty, sizeof(isocrty)))
 			return NULL;
 		snprintf(iso_lc_messages, sizeof(iso_lc_messages) - 1, "%s_%s", isolang, isocrty);
-#endif
+#endif							/* Visual Studio 2012 or later */
 		return iso_lc_messages;
 	}
 	return NULL;

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index e0ebea7..f405f06 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -215,6 +215,7 @@ pg_perm_setlocale(int category, const char *locale)
 			result = IsoLocaleName(locale);
 			if (result == NULL)
 				result = (char *) locale;
+			elog(DEBUG3, "IsoLocaleName() executed; locale: \"%s\"", result);
 #endif   /* WIN32 */
 			break;
 #endif   /* LC_MESSAGES */
@@ -948,19 +949,168 @@ cache_locale_time(void)
  * string.  Furthermore, msvcr110.dll changed the undocumented _locale_t
  * content to carry locale names instead of locale identifiers.
  *
- * MinGW headers declare _create_locale(), but msvcrt.dll lacks that symbol.
- * 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.
+ * 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 loacle 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] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373763.aspx
- * [2] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373814.aspx
+ * [1] https://docs.microsoft.com/en-us/windows/win32/intl/locale-identifiers
+ * [2] https://docs.microsoft.com/en-us/windows/win32/intl/locale-names
+ */
+
+#if _MSC_VER >= 1900
+/*
+ * 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.
+ *
+ * BEWARE: this function is WIN32 specific, so wchar_t are UTF-16.
+ */
+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
+ * that identifies an LCID based on its language and location. The returned
+ * value is the size of the ISO locale name, where -1 means that no valid
+ * conversion was found.
  */
+static size_t
+get_iso_localename(const char *winlocname, char *isolocname)
+{
+	wchar_t		wc_locale_name[LOCALE_NAME_MAX_LENGTH];
+	wchar_t		buffer[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 an 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
+		 * county 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)
+	{
+		/* Locale names use only ASCII, any conversion locale suffices. */
+		return wchar2char(isolocname, buffer, sizeof(isolocname),
+						  NULL);
+	}
+
+	return (size_t) -1;
+}
+#endif							/* _MSC_VER >= 1900 */
+
 static char *
 IsoLocaleName(const char *winlocname)
 {
@@ -982,10 +1132,14 @@ IsoLocaleName(const char *winlocname)
 		size_t		rc;
 		char	   *hyphen;
 
+#if (_MSC_VER >= 1900)			/* Visual Studio 2015 or later */
+		rc = get_iso_localename(winlocname, iso_lc_messages);
+#else
 		/* Locale names use only ASCII, any conversion locale suffices. */
 		rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
 						sizeof(iso_lc_messages), NULL);
 		_free_locale(loct);
+#endif							/* Visual Studio 2015 or later */
 		if (rc == -1 || rc == sizeof(iso_lc_messages))
 			return NULL;
 
@@ -1020,7 +1174,7 @@ IsoLocaleName(const char *winlocname)
 		if (!GetLocaleInfoA(lcid, LOCALE_SISO3166CTRYNAME, isocrty, sizeof(isocrty)))
 			return NULL;
 		snprintf(iso_lc_messages, sizeof(iso_lc_messages) - 1, "%s_%s", isolang, isocrty);
-#endif
+#endif							/* Visual Studio 2012 or later */
 		return iso_lc_messages;
 	}
 	return NULL;

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index b9e01b6..1911989 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -220,6 +220,7 @@ pg_perm_setlocale(int category, const char *locale)
 			result = IsoLocaleName(locale);
 			if (result == NULL)
 				result = (char *) locale;
+			elog(DEBUG3, "IsoLocaleName() executed; locale: \"%s\"", result);
 #endif							/* WIN32 */
 			break;
 #endif							/* LC_MESSAGES */
@@ -953,19 +954,168 @@ cache_locale_time(void)
  * string.  Furthermore, msvcr110.dll changed the undocumented _locale_t
  * content to carry locale names instead of locale identifiers.
  *
- * MinGW headers declare _create_locale(), but msvcrt.dll lacks that symbol.
- * 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.
+ * 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 loacle 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] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373763.aspx
- * [2] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373814.aspx
+ * [1] https://docs.microsoft.com/en-us/windows/win32/intl/locale-identifiers
+ * [2] https://docs.microsoft.com/en-us/windows/win32/intl/locale-names
+ */
+
+#if _MSC_VER >= 1900
+/*
+ * 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.
+ *
+ * BEWARE: this function is WIN32 specific, so wchar_t are UTF-16.
  */
+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
+ * that identifies an LCID based on its language and location. The returned
+ * value is the size of the ISO locale name, where -1 means that no valid
+ * conversion was found.
+ */
+static size_t
+get_iso_localename(const char *winlocname, char *isolocname)
+{
+	wchar_t		wc_locale_name[LOCALE_NAME_MAX_LENGTH];
+	wchar_t		buffer[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 an 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
+		 * county 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)
+	{
+		/* Locale names use only ASCII, any conversion locale suffices. */
+		return wchar2char(isolocname, buffer, sizeof(isolocname),
+						  NULL);
+	}
+
+	return (size_t) -1;
+}
+#endif							/* _MSC_VER >= 1900 */
+
 static char *
 IsoLocaleName(const char *winlocname)
 {
@@ -987,10 +1137,14 @@ IsoLocaleName(const char *winlocname)
 		size_t		rc;
 		char	   *hyphen;
 
+#if (_MSC_VER >= 1900)			/* Visual Studio 2015 or later */
+		rc = get_iso_localename(winlocname, iso_lc_messages);
+#else
 		/* Locale names use only ASCII, any conversion locale suffices. */
 		rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
 						sizeof(iso_lc_messages), NULL);
 		_free_locale(loct);
+#endif							/* Visual Studio 2015 or later */
 		if (rc == -1 || rc == sizeof(iso_lc_messages))
 			return NULL;
 
@@ -1010,7 +1164,7 @@ IsoLocaleName(const char *winlocname)
 		hyphen = strchr(iso_lc_messages, '-');
 		if (hyphen)
 			*hyphen = '_';
-#else
+#else							/* Visual Studio 2012 or later */
 		char		isolang[32],
 					isocrty[32];
 		LCID		lcid;

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 2562eb5..24a55f3 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -234,6 +234,7 @@ pg_perm_setlocale(int category, const char *locale)
 			result = IsoLocaleName(locale);
 			if (result == NULL)
 				result = (char *) locale;
+			elog(DEBUG3, "IsoLocaleName() executed; locale: \"%s\"", result);
 #endif							/* WIN32 */
 			break;
 #endif							/* LC_MESSAGES */
@@ -971,25 +972,173 @@ cache_locale_time(void)
  * string.  Furthermore, msvcr110.dll changed the undocumented _locale_t
  * content to carry locale names instead of locale identifiers.
  *
- * MinGW headers declare _create_locale(), but msvcrt.dll lacks that symbol.
- * 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.
+ * 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 loacle 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] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373763.aspx
- * [2] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373814.aspx
+ * [1] https://docs.microsoft.com/en-us/windows/win32/intl/locale-identifiers
+ * [2] https://docs.microsoft.com/en-us/windows/win32/intl/locale-names
  */
+
+#if _MSC_VER >= 1900
+/*
+ * 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.
+ *
+ * BEWARE: this function is WIN32 specific, so wchar_t are UTF-16.
+ */
+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
+ * that identifies an LCID based on its language and location. The returned
+ * value is the size of the ISO locale name, where -1 means that no valid
+ * conversion was found.
+ */
+static size_t
+get_iso_localename(const char *winlocname, char *isolocname)
+{
+	wchar_t		wc_locale_name[LOCALE_NAME_MAX_LENGTH];
+	wchar_t		buffer[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 an 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
+		 * county 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)
+	{
+		/* Locale names use only ASCII, any conversion locale suffices. */
+		return wchar2char(isolocname, buffer, sizeof(isolocname),
+						NULL);
+	}
+
+	return (size_t) -1;
+}
+#endif							/* _MSC_VER >= 1900 */
+
 static char *
 IsoLocaleName(const char *winlocname)
 {
-#ifdef _MSC_VER
-	static char iso_lc_messages[32];
-	_locale_t	loct = NULL;
+#if defined(_MSC_VER)
+	static char iso_lc_messages[LOCALE_NAME_MAX_LENGTH];
 
 	if (pg_strcasecmp("c", winlocname) == 0 ||
 		pg_strcasecmp("posix", winlocname) == 0)
@@ -997,17 +1146,25 @@ IsoLocaleName(const char *winlocname)
 		strcpy(iso_lc_messages, "C");
 		return iso_lc_messages;
 	}
-
-	loct = _create_locale(LC_CTYPE, winlocname);
-	if (loct != NULL)
+	else
 	{
-		size_t		rc;
+		size_t		rc = -1;
 		char	   *hyphen;
 
-		/* Locale names use only ASCII, any conversion locale suffices. */
-		rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
-						sizeof(iso_lc_messages), NULL);
-		_free_locale(loct);
+#if (_MSC_VER >= 1900)			/* Visual Studio 2015 or later */
+		rc = get_iso_localename(winlocname, iso_lc_messages);
+#else
+		_locale_t	loct;
+
+		loct = _create_locale(LC_CTYPE, winlocname);
+		if (loct != NULL)
+		{
+			rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
+							sizeof(iso_lc_messages), NULL);
+			_free_locale(loct);
+		}
+#endif							/* Visual Studio 2015 or later */
+
 		if (rc == -1 || rc == sizeof(iso_lc_messages))
 			return NULL;
 
@@ -1029,7 +1186,7 @@ IsoLocaleName(const char *winlocname)
 			*hyphen = '_';
 		return iso_lc_messages;
 	}
-#endif							/* _MSC_VER */
+#endif							/* defined(_MSC_VER) */
 	return NULL;				/* Not supported on this version of msvc/mingw */
 }
 #endif							/* WIN32 && LC_MESSAGES */

From 6d89ecc3171be8be317b1d687909bd1dc0cfed4f Mon Sep 17 00:00:00 2001
From: Amit Kapila <akapila@postgresql.org>
Date: Tue, 5 May 2020 15:26:12 +0530
Subject: [PATCH v17] Fix the MSVC build for versions 2015 and later.

Visual Studio 2015 and later versions should still be able to do the same
as Visual Studio 2012, but the declaration of locale_name is missing in
_locale_t, causing the 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.

In passing, change the documentation references to the now obsolete links.

Note that this problem occurs only with NLS enabled builds.

Author: Juan José Santamaría Flecha, Davinder Singh and Amit Kapila
Reviewed-by: Ranier Vilela and Amit Kapila
Backpatch-through: 9.5
Discussion: https://postgr.es/m/CAHzhFSFoJEWezR96um4-rg5W6m2Rj9Ud2CNZvV4NWc9tXV7aXQ@mail.gmail.com
---
 src/backend/utils/adt/pg_locale.c | 197 ++++++++++++++++++++++++++++++++++----
 1 file changed, 177 insertions(+), 20 deletions(-)

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 2562eb5..a995238 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -234,6 +234,7 @@ pg_perm_setlocale(int category, const char *locale)
 			result = IsoLocaleName(locale);
 			if (result == NULL)
 				result = (char *) locale;
+			elog(DEBUG3, "IsoLocaleName() executed; locale: \"%s\"", result);
 #endif							/* WIN32 */
 			break;
 #endif							/* LC_MESSAGES */
@@ -971,25 +972,172 @@ cache_locale_time(void)
  * string.  Furthermore, msvcr110.dll changed the undocumented _locale_t
  * content to carry locale names instead of locale identifiers.
  *
- * MinGW headers declare _create_locale(), but msvcrt.dll lacks that symbol.
- * 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.
+ * 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] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373763.aspx
- * [2] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373814.aspx
+ * [1] https://docs.microsoft.com/en-us/windows/win32/intl/locale-identifiers
+ * [2] https://docs.microsoft.com/en-us/windows/win32/intl/locale-names
  */
+
+#if _MSC_VER >= 1900
+/*
+ * 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 the size of the ISO locale name, where -1 means that no valid
+ * conversion was found.
+ */
+static size_t
+get_iso_localename(const char *winlocname, char *isolocname)
+{
+	wchar_t		wc_locale_name[LOCALE_NAME_MAX_LENGTH];
+	wchar_t		buffer[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 an 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)
+	{
+		/* Locale names use only ASCII, any conversion locale suffices. */
+		return wchar2char(isolocname, buffer, sizeof(isolocname),
+						  NULL);
+	}
+
+	return (size_t) -1;
+}
+#endif							/* _MSC_VER >= 1900 */
+
 static char *
 IsoLocaleName(const char *winlocname)
 {
-#ifdef _MSC_VER
-	static char iso_lc_messages[32];
-	_locale_t	loct = NULL;
+#if defined(_MSC_VER)
+	static char iso_lc_messages[LOCALE_NAME_MAX_LENGTH];
 
 	if (pg_strcasecmp("c", winlocname) == 0 ||
 		pg_strcasecmp("posix", winlocname) == 0)
@@ -997,17 +1145,26 @@ IsoLocaleName(const char *winlocname)
 		strcpy(iso_lc_messages, "C");
 		return iso_lc_messages;
 	}
-
-	loct = _create_locale(LC_CTYPE, winlocname);
-	if (loct != NULL)
+	else
 	{
-		size_t		rc;
+		size_t		rc = -1;
 		char	   *hyphen;
 
-		/* Locale names use only ASCII, any conversion locale suffices. */
-		rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
-						sizeof(iso_lc_messages), NULL);
-		_free_locale(loct);
+#if (_MSC_VER >= 1900)			/* Visual Studio 2015 or later */
+		rc = get_iso_localename(winlocname, iso_lc_messages);
+#else
+		_locale_t	loct;
+
+		loct = _create_locale(LC_CTYPE, winlocname);
+		if (loct != NULL)
+		{
+			/* Locale names use only ASCII, any conversion locale suffices. */
+			rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
+							sizeof(iso_lc_messages), NULL);
+			_free_locale(loct);
+		}
+#endif							/* Visual Studio 2015 or later */
+
 		if (rc == -1 || rc == sizeof(iso_lc_messages))
 			return NULL;
 
@@ -1029,7 +1186,7 @@ IsoLocaleName(const char *winlocname)
 			*hyphen = '_';
 		return iso_lc_messages;
 	}
-#endif							/* _MSC_VER */
+#endif							/* defined(_MSC_VER) */
 	return NULL;				/* Not supported on this version of msvc/mingw */
 }
 #endif							/* WIN32 && LC_MESSAGES */
-- 
1.8.3.1

From 6e684dbd4d81047a44d4993a92d79555bf66451a Mon Sep 17 00:00:00 2001
From: Amit Kapila <akapila@postgresql.org>
Date: Tue, 5 May 2020 15:35:07 +0530
Subject: [PATCH v17] Fix the MSVC build for versions 2015 and later.

Visual Studio 2015 and later versions should still be able to do the same
as Visual Studio 2012, but the declaration of locale_name is missing in
_locale_t, causing the 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.

In passing, change the documentation references to the now obsolete links.

Note that this problem occurs only with NLS enabled builds.

Author: Juan José Santamaría Flecha, Davinder Singh and Amit Kapila
Reviewed-by: Ranier Vilela and Amit Kapila
Backpatch-through: 9.5
Discussion: https://postgr.es/m/CAHzhFSFoJEWezR96um4-rg5W6m2Rj9Ud2CNZvV4NWc9tXV7aXQ@mail.gmail.com
---
 src/backend/utils/adt/pg_locale.c | 183 ++++++++++++++++++++++++++++++++++++--
 1 file changed, 175 insertions(+), 8 deletions(-)

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 2376bda..bb929c5 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -224,6 +224,7 @@ pg_perm_setlocale(int category, const char *locale)
 			result = IsoLocaleName(locale);
 			if (result == NULL)
 				result = (char *) locale;
+			elog(DEBUG3, "IsoLocaleName() executed; locale: \"%s\"", result);
 #endif							/* WIN32 */
 			break;
 #endif							/* LC_MESSAGES */
@@ -957,20 +958,182 @@ cache_locale_time(void)
  * string.  Furthermore, msvcr110.dll changed the undocumented _locale_t
  * content to carry locale names instead of locale identifiers.
  *
- * MinGW headers declare _create_locale(), but msvcrt.dll lacks that symbol.
- * 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.
+ * 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] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373763.aspx
- * [2] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373814.aspx
+ * [1] https://docs.microsoft.com/en-us/windows/win32/intl/locale-identifiers
+ * [2] https://docs.microsoft.com/en-us/windows/win32/intl/locale-names
+ */
+
+#if _MSC_VER >= 1900
+/*
+ * 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.
  */
 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 an 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;
+}
+#endif							/* _MSC_VER >= 1900 */
+
+static char *
 IsoLocaleName(const char *winlocname)
 {
 #if (_MSC_VER >= 1400)			/* VC8.0 or later */
@@ -984,6 +1147,9 @@ IsoLocaleName(const char *winlocname)
 		return iso_lc_messages;
 	}
 
+#if (_MSC_VER >= 1900)			/* Visual Studio 2015 or later */
+	return get_iso_localename(winlocname);
+#else
 	loct = _create_locale(LC_CTYPE, winlocname);
 	if (loct != NULL)
 	{
@@ -1033,6 +1199,7 @@ IsoLocaleName(const char *winlocname)
 		return iso_lc_messages;
 	}
 	return NULL;
+#endif							/* Visual Studio 2015 or later */
 #else
 	return NULL;				/* Not supported on this version of msvc/mingw */
 #endif							/* _MSC_VER >= 1400 */
-- 
1.8.3.1

From 30abac48ac92c9a99e93949d96c7760c705e9f80 Mon Sep 17 00:00:00 2001
From: Amit Kapila <akapila@postgresql.org>
Date: Tue, 5 May 2020 16:31:07 +0530
Subject: [PATCH v17] Fix the MSVC build for versions 2015 and later.

Visual Studio 2015 and later versions should still be able to do the same
as Visual Studio 2012, but the declaration of locale_name is missing in
_locale_t, causing the 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.

In passing, change the documentation references to the now obsolete links.

Note that this problem occurs only with NLS enabled builds.

Author: Juan José Santamaría Flecha, Davinder Singh and Amit Kapila
Reviewed-by: Ranier Vilela and Amit Kapila
Backpatch-through: 9.5
Discussion: https://postgr.es/m/CAHzhFSFoJEWezR96um4-rg5W6m2Rj9Ud2CNZvV4NWc9tXV7aXQ@mail.gmail.com
---
 src/backend/utils/adt/pg_locale.c | 183 ++++++++++++++++++++++++++++++++++++--
 1 file changed, 175 insertions(+), 8 deletions(-)

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 79489a7..ff2969c 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -215,6 +215,7 @@ pg_perm_setlocale(int category, const char *locale)
 			result = IsoLocaleName(locale);
 			if (result == NULL)
 				result = (char *) locale;
+			elog(DEBUG3, "IsoLocaleName() executed; locale: \"%s\"", result);
 #endif   /* WIN32 */
 			break;
 #endif   /* LC_MESSAGES */
@@ -948,20 +949,182 @@ cache_locale_time(void)
  * string.  Furthermore, msvcr110.dll changed the undocumented _locale_t
  * content to carry locale names instead of locale identifiers.
  *
- * MinGW headers declare _create_locale(), but msvcrt.dll lacks that symbol.
- * 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.
+ * 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] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373763.aspx
- * [2] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373814.aspx
+ * [1] https://docs.microsoft.com/en-us/windows/win32/intl/locale-identifiers
+ * [2] https://docs.microsoft.com/en-us/windows/win32/intl/locale-names
+ */
+
+#if _MSC_VER >= 1900
+/*
+ * 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.
  */
 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 an 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;
+}
+#endif							/* _MSC_VER >= 1900 */
+
+static char *
 IsoLocaleName(const char *winlocname)
 {
 #if (_MSC_VER >= 1400)			/* VC8.0 or later */
@@ -975,6 +1138,9 @@ IsoLocaleName(const char *winlocname)
 		return iso_lc_messages;
 	}
 
+#if (_MSC_VER >= 1900)			/* Visual Studio 2015 or later */
+	return get_iso_localename(winlocname);
+#else
 	loct = _create_locale(LC_CTYPE, winlocname);
 	if (loct != NULL)
 	{
@@ -1024,6 +1190,7 @@ IsoLocaleName(const char *winlocname)
 		return iso_lc_messages;
 	}
 	return NULL;
+#endif							/* Visual Studio 2015 or later */
 #else
 	return NULL;				/* Not supported on this version of msvc/mingw */
 #endif   /* _MSC_VER >= 1400 */
-- 
1.8.3.1

From ef8eff4ea52305e095dff0f461f1ed16e109eb2b Mon Sep 17 00:00:00 2001
From: Amit Kapila <akapila@postgresql.org>
Date: Tue, 5 May 2020 15:26:12 +0530
Subject: [PATCH v17] Fix the MSVC build for versions 2015 and later.

Visual Studio 2015 and later versions should still be able to do the same
as Visual Studio 2012, but the declaration of locale_name is missing in
_locale_t, causing the 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.

In passing, change the documentation references to the now obsolete links.

Note that this problem occurs only with NLS enabled builds.

Author: Juan José Santamaría Flecha, Davinder Singh and Amit Kapila
Reviewed-by: Ranier Vilela and Amit Kapila
Backpatch-through: 9.5
Discussion: https://postgr.es/m/CAHzhFSFoJEWezR96um4-rg5W6m2Rj9Ud2CNZvV4NWc9tXV7aXQ@mail.gmail.com
---
 src/backend/utils/adt/pg_locale.c | 236 ++++++++++++++++++++++++++++++++------
 1 file changed, 203 insertions(+), 33 deletions(-)

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 2562eb5..11d05c7 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -234,6 +234,7 @@ pg_perm_setlocale(int category, const char *locale)
 			result = IsoLocaleName(locale);
 			if (result == NULL)
 				result = (char *) locale;
+			elog(DEBUG3, "IsoLocaleName() executed; locale: \"%s\"", result);
 #endif							/* WIN32 */
 			break;
 #endif							/* LC_MESSAGES */
@@ -971,65 +972,234 @@ cache_locale_time(void)
  * string.  Furthermore, msvcr110.dll changed the undocumented _locale_t
  * content to carry locale names instead of locale identifiers.
  *
- * MinGW headers declare _create_locale(), but msvcrt.dll lacks that symbol.
- * 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.
+ * 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] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373763.aspx
- * [2] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373814.aspx
+ * [1] https://docs.microsoft.com/en-us/windows/win32/intl/locale-identifiers
+ * [2] https://docs.microsoft.com/en-us/windows/win32/intl/locale-names
+ */
+
+#if _MSC_VER >= 1900
+/*
+ * 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.
  */
 static char *
-IsoLocaleName(const char *winlocname)
+get_iso_localename(const char *winlocname)
 {
-#ifdef _MSC_VER
-	static char iso_lc_messages[32];
-	_locale_t	loct = NULL;
+	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;
 
-	if (pg_strcasecmp("c", winlocname) == 0 ||
-		pg_strcasecmp("posix", winlocname) == 0)
+	/*
+	 * 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 an 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)
 	{
-		strcpy(iso_lc_messages, "C");
-		return iso_lc_messages;
+		/*
+		 * 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);
 	}
 
-	loct = _create_locale(LC_CTYPE, winlocname);
-	if (loct != NULL)
+	if (ret_val)
 	{
 		size_t		rc;
 		char	   *hyphen;
 
 		/* Locale names use only ASCII, any conversion locale suffices. */
-		rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
-						sizeof(iso_lc_messages), NULL);
-		_free_locale(loct);
+		rc = wchar2char(iso_lc_messages, buffer, sizeof(iso_lc_messages), NULL);
 		if (rc == -1 || rc == sizeof(iso_lc_messages))
 			return NULL;
 
 		/*
-		 * Since the message catalogs sit on a case-insensitive filesystem, we
-		 * need not standardize letter case here.  So long as we do not ship
-		 * message catalogs for which it would matter, we also need not
-		 * translate the script/variant portion, e.g. uz-Cyrl-UZ to
-		 * uz_UZ@cyrillic.  Simply replace the hyphen with an underscore.
-		 *
-		 * Note that the locale name can be less-specific than the value we
-		 * would derive under earlier Visual Studio releases.  For example,
-		 * French_France.1252 yields just "fr".  This does not affect any of
-		 * the country-specific message catalogs available as of this writing
-		 * (pt_BR, zh_CN, zh_TW).
+		 * Simply replace the hyphen with an underscore.  See comments in
+		 * IsoLocaleName.
 		 */
 		hyphen = strchr(iso_lc_messages, '-');
 		if (hyphen)
 			*hyphen = '_';
 		return iso_lc_messages;
 	}
-#endif							/* _MSC_VER */
+
+	return NULL;
+}
+#endif							/* _MSC_VER >= 1900 */
+
+static char *
+IsoLocaleName(const char *winlocname)
+{
+#if defined(_MSC_VER)
+	static char iso_lc_messages[LOCALE_NAME_MAX_LENGTH];
+
+	if (pg_strcasecmp("c", winlocname) == 0 ||
+		pg_strcasecmp("posix", winlocname) == 0)
+	{
+		strcpy(iso_lc_messages, "C");
+		return iso_lc_messages;
+	}
+	else
+	{
+#if (_MSC_VER >= 1900)			/* Visual Studio 2015 or later */
+		return get_iso_localename(winlocname);
+#else
+		_locale_t	loct;
+
+		loct = _create_locale(LC_CTYPE, winlocname);
+		if (loct != NULL)
+		{
+			size_t		rc;
+			char	   *hyphen;
+
+			/* Locale names use only ASCII, any conversion locale suffices. */
+			rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
+							sizeof(iso_lc_messages), NULL);
+			_free_locale(loct);
+			if (rc == -1 || rc == sizeof(iso_lc_messages))
+				return NULL;
+
+			/*
+			 * Since the message catalogs sit on a case-insensitive
+			 * filesystem, we need not standardize letter case here.  So long
+			 * as we do not ship message catalogs for which it would matter,
+			 * we also need not translate the script/variant portion, e.g.
+			 * uz-Cyrl-UZ to uz_UZ@cyrillic.  Simply replace the hyphen with
+			 * an underscore.
+			 *
+			 * Note that the locale name can be less-specific than the value
+			 * we would derive under earlier Visual Studio releases.  For
+			 * example, French_France.1252 yields just "fr".  This does not
+			 * affect any of the country-specific message catalogs available
+			 * as of this writing (pt_BR, zh_CN, zh_TW).
+			 */
+			hyphen = strchr(iso_lc_messages, '-');
+			if (hyphen)
+				*hyphen = '_';
+			return iso_lc_messages;
+		}
+#endif							/* Visual Studio 2015 or later */
+	}
+#endif							/* defined(_MSC_VER) */
 	return NULL;				/* Not supported on this version of msvc/mingw */
 }
 #endif							/* WIN32 && LC_MESSAGES */
-- 
1.8.3.1

From 30abac48ac92c9a99e93949d96c7760c705e9f80 Mon Sep 17 00:00:00 2001
From: Amit Kapila <akapila@postgresql.org>
Date: Tue, 5 May 2020 16:31:07 +0530
Subject: [PATCH v17] Fix the MSVC build for versions 2015 and later.

Visual Studio 2015 and later versions should still be able to do the same
as Visual Studio 2012, but the declaration of locale_name is missing in
_locale_t, causing the 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.

In passing, change the documentation references to the now obsolete links.

Note that this problem occurs only with NLS enabled builds.

Author: Juan José Santamaría Flecha, Davinder Singh and Amit Kapila
Reviewed-by: Ranier Vilela and Amit Kapila
Backpatch-through: 9.5
Discussion: https://postgr.es/m/CAHzhFSFoJEWezR96um4-rg5W6m2Rj9Ud2CNZvV4NWc9tXV7aXQ@mail.gmail.com
---
 src/backend/utils/adt/pg_locale.c | 183 ++++++++++++++++++++++++++++++++++++--
 1 file changed, 175 insertions(+), 8 deletions(-)

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 79489a7..ff2969c 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -215,6 +215,7 @@ pg_perm_setlocale(int category, const char *locale)
 			result = IsoLocaleName(locale);
 			if (result == NULL)
 				result = (char *) locale;
+			elog(DEBUG3, "IsoLocaleName() executed; locale: \"%s\"", result);
 #endif   /* WIN32 */
 			break;
 #endif   /* LC_MESSAGES */
@@ -948,20 +949,182 @@ cache_locale_time(void)
  * string.  Furthermore, msvcr110.dll changed the undocumented _locale_t
  * content to carry locale names instead of locale identifiers.
  *
- * MinGW headers declare _create_locale(), but msvcrt.dll lacks that symbol.
- * 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.
+ * 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] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373763.aspx
- * [2] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373814.aspx
+ * [1] https://docs.microsoft.com/en-us/windows/win32/intl/locale-identifiers
+ * [2] https://docs.microsoft.com/en-us/windows/win32/intl/locale-names
+ */
+
+#if _MSC_VER >= 1900
+/*
+ * 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.
  */
 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 an 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;
+}
+#endif							/* _MSC_VER >= 1900 */
+
+static char *
 IsoLocaleName(const char *winlocname)
 {
 #if (_MSC_VER >= 1400)			/* VC8.0 or later */
@@ -975,6 +1138,9 @@ IsoLocaleName(const char *winlocname)
 		return iso_lc_messages;
 	}
 
+#if (_MSC_VER >= 1900)			/* Visual Studio 2015 or later */
+	return get_iso_localename(winlocname);
+#else
 	loct = _create_locale(LC_CTYPE, winlocname);
 	if (loct != NULL)
 	{
@@ -1024,6 +1190,7 @@ IsoLocaleName(const char *winlocname)
 		return iso_lc_messages;
 	}
 	return NULL;
+#endif							/* Visual Studio 2015 or later */
 #else
 	return NULL;				/* Not supported on this version of msvc/mingw */
 #endif   /* _MSC_VER >= 1400 */
-- 
1.8.3.1

From 6e684dbd4d81047a44d4993a92d79555bf66451a Mon Sep 17 00:00:00 2001
From: Amit Kapila <akapila@postgresql.org>
Date: Tue, 5 May 2020 15:35:07 +0530
Subject: [PATCH v17] Fix the MSVC build for versions 2015 and later.

Visual Studio 2015 and later versions should still be able to do the same
as Visual Studio 2012, but the declaration of locale_name is missing in
_locale_t, causing the 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.

In passing, change the documentation references to the now obsolete links.

Note that this problem occurs only with NLS enabled builds.

Author: Juan José Santamaría Flecha, Davinder Singh and Amit Kapila
Reviewed-by: Ranier Vilela and Amit Kapila
Backpatch-through: 9.5
Discussion: https://postgr.es/m/CAHzhFSFoJEWezR96um4-rg5W6m2Rj9Ud2CNZvV4NWc9tXV7aXQ@mail.gmail.com
---
 src/backend/utils/adt/pg_locale.c | 183 ++++++++++++++++++++++++++++++++++++--
 1 file changed, 175 insertions(+), 8 deletions(-)

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 2376bda..bb929c5 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -224,6 +224,7 @@ pg_perm_setlocale(int category, const char *locale)
 			result = IsoLocaleName(locale);
 			if (result == NULL)
 				result = (char *) locale;
+			elog(DEBUG3, "IsoLocaleName() executed; locale: \"%s\"", result);
 #endif							/* WIN32 */
 			break;
 #endif							/* LC_MESSAGES */
@@ -957,20 +958,182 @@ cache_locale_time(void)
  * string.  Furthermore, msvcr110.dll changed the undocumented _locale_t
  * content to carry locale names instead of locale identifiers.
  *
- * MinGW headers declare _create_locale(), but msvcrt.dll lacks that symbol.
- * 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.
+ * 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] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373763.aspx
- * [2] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373814.aspx
+ * [1] https://docs.microsoft.com/en-us/windows/win32/intl/locale-identifiers
+ * [2] https://docs.microsoft.com/en-us/windows/win32/intl/locale-names
+ */
+
+#if _MSC_VER >= 1900
+/*
+ * 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.
  */
 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 an 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;
+}
+#endif							/* _MSC_VER >= 1900 */
+
+static char *
 IsoLocaleName(const char *winlocname)
 {
 #if (_MSC_VER >= 1400)			/* VC8.0 or later */
@@ -984,6 +1147,9 @@ IsoLocaleName(const char *winlocname)
 		return iso_lc_messages;
 	}
 
+#if (_MSC_VER >= 1900)			/* Visual Studio 2015 or later */
+	return get_iso_localename(winlocname);
+#else
 	loct = _create_locale(LC_CTYPE, winlocname);
 	if (loct != NULL)
 	{
@@ -1033,6 +1199,7 @@ IsoLocaleName(const char *winlocname)
 		return iso_lc_messages;
 	}
 	return NULL;
+#endif							/* Visual Studio 2015 or later */
 #else
 	return NULL;				/* Not supported on this version of msvc/mingw */
 #endif							/* _MSC_VER >= 1400 */
-- 
1.8.3.1