From 9a62ff1adcb957da7b3cde6ddc4113a9f5582318 Mon Sep 17 00:00:00 2001
From: Paul Monson <paulmon@microsoft.com>
Date: Thu, 2 May 2019 17:59:00 -0700
Subject: [PATCH 1/4] bpo-36799: time.tzname returns empty string on Windows if
 default codepage is a Unicode codepage

---
 Modules/timemodule.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/Modules/timemodule.c b/Modules/timemodule.c
index 3df17ac4fb68f5..2caba3b37bcdcd 100644
--- a/Modules/timemodule.c
+++ b/Modules/timemodule.c
@@ -1619,9 +1619,28 @@ init_timezone(PyObject *m)
     And I'm lazy and hate C so nyer.
      */
 #ifdef HAVE_DECL_TZNAME
+#ifdef MS_WINDOWS
+#	include <locale.h>
+	// https://bugs.python.org/issue36778
+	// workaround bug in UCRT
+	// strptime fails if the current locale is a Unicode locale
+	int cp = GetACP();
+	char* save_locale = NULL;
+	if (cp == CP_UTF8 || cp == CP_UTF7)
+	{
+		save_locale = setlocale(LC_CTYPE, NULL);
+		setlocale(LC_CTYPE, "C");
+	}
+#endif
     PyObject *otz0, *otz1;
     tzset();
     PyModule_AddIntConstant(m, "timezone", _Py_timezone);
+#ifdef MS_WINDOWS
+	if (cp == CP_UTF8 || cp == CP_UTF7)
+	{
+		setlocale(LC_CTYPE, save_locale);
+	}
+#endif
 #ifdef HAVE_ALTZONE
     PyModule_AddIntConstant(m, "altzone", altzone);
 #else

From 634776e56acce0ab6d10dce268a6a1f4eff51bff Mon Sep 17 00:00:00 2001
From: Paul Monson <paulmon@microsoft.com>
Date: Thu, 23 May 2019 13:03:54 -0700
Subject: [PATCH 2/4] fix tznames without changing locale

---
 Modules/timemodule.c | 33 ++++++++++++++-------------------
 1 file changed, 14 insertions(+), 19 deletions(-)

diff --git a/Modules/timemodule.c b/Modules/timemodule.c
index 2caba3b37bcdcd..8abc62f653286f 100644
--- a/Modules/timemodule.c
+++ b/Modules/timemodule.c
@@ -1619,34 +1619,28 @@ init_timezone(PyObject *m)
     And I'm lazy and hate C so nyer.
      */
 #ifdef HAVE_DECL_TZNAME
-#ifdef MS_WINDOWS
-#	include <locale.h>
-	// https://bugs.python.org/issue36778
-	// workaround bug in UCRT
-	// strptime fails if the current locale is a Unicode locale
-	int cp = GetACP();
-	char* save_locale = NULL;
-	if (cp == CP_UTF8 || cp == CP_UTF7)
-	{
-		save_locale = setlocale(LC_CTYPE, NULL);
-		setlocale(LC_CTYPE, "C");
-	}
-#endif
     PyObject *otz0, *otz1;
     tzset();
     PyModule_AddIntConstant(m, "timezone", _Py_timezone);
-#ifdef MS_WINDOWS
-	if (cp == CP_UTF8 || cp == CP_UTF7)
-	{
-		setlocale(LC_CTYPE, save_locale);
-	}
-#endif
 #ifdef HAVE_ALTZONE
     PyModule_AddIntConstant(m, "altzone", altzone);
 #else
     PyModule_AddIntConstant(m, "altzone", _Py_timezone-3600);
 #endif
     PyModule_AddIntConstant(m, "daylight", _Py_daylight);
+#ifdef MS_WINDOWS
+    TIME_ZONE_INFORMATION tzinfo = {0};
+    GetTimeZoneInformation(&tzinfo);
+    otz0 = PyUnicode_FromWideChar(tzinfo.StandardName, -1);
+    if (otz0 == NULL) {
+        return -1;
+    }
+    otz1 = PyUnicode_FromWideChar(tzinfo.DaylightName, -1);
+    if (otz1 == NULL) {
+        Py_DECREF(otz0);
+        return -1;
+    }
+#else
     otz0 = PyUnicode_DecodeLocale(_Py_tzname[0], "surrogateescape");
     if (otz0 == NULL) {
         return -1;
@@ -1656,6 +1650,7 @@ init_timezone(PyObject *m)
         Py_DECREF(otz0);
         return -1;
     }
+#endif // MS_WINDOWS
     PyObject *tzname_obj = Py_BuildValue("(NN)", otz0, otz1);
     if (tzname_obj == NULL) {
         return -1;

From 1c78c19f6f1a35647fceeb271692111b3e291f55 Mon Sep 17 00:00:00 2001
From: Paul Monson <paulmon@microsoft.com>
Date: Tue, 11 Jun 2019 15:43:20 -0700
Subject: [PATCH 3/4] add news item

---
 .../next/Windows/2019-06-11-15-41-34.bpo-36779.0TMw6f.rst     | 4 ++++
 1 file changed, 4 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Windows/2019-06-11-15-41-34.bpo-36779.0TMw6f.rst

diff --git a/Misc/NEWS.d/next/Windows/2019-06-11-15-41-34.bpo-36779.0TMw6f.rst b/Misc/NEWS.d/next/Windows/2019-06-11-15-41-34.bpo-36779.0TMw6f.rst
new file mode 100644
index 00000000000000..52663157478f3a
--- /dev/null
+++ b/Misc/NEWS.d/next/Windows/2019-06-11-15-41-34.bpo-36779.0TMw6f.rst
@@ -0,0 +1,4 @@
+If the default ANSI code page on Windows is CP_UTF7, or CP_UTF8 tzset()
+initializes tzname[0] and tzname[1] to empty strings.  By getting the time
+zone name information directly from GetTimeZoneInformation Python can set
+the value of time.tzname correctly.

From ce08e582dc13e669aa5a32d0857cc46c0fcfbdef Mon Sep 17 00:00:00 2001
From: Steve Dower <steve.dower@python.org>
Date: Wed, 12 Jun 2019 15:54:49 -0700
Subject: [PATCH 4/4] Simplify NEWS

---
 .../next/Windows/2019-06-11-15-41-34.bpo-36779.0TMw6f.rst   | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/Misc/NEWS.d/next/Windows/2019-06-11-15-41-34.bpo-36779.0TMw6f.rst b/Misc/NEWS.d/next/Windows/2019-06-11-15-41-34.bpo-36779.0TMw6f.rst
index 52663157478f3a..618cfcae7b8993 100644
--- a/Misc/NEWS.d/next/Windows/2019-06-11-15-41-34.bpo-36779.0TMw6f.rst
+++ b/Misc/NEWS.d/next/Windows/2019-06-11-15-41-34.bpo-36779.0TMw6f.rst
@@ -1,4 +1,2 @@
-If the default ANSI code page on Windows is CP_UTF7, or CP_UTF8 tzset()
-initializes tzname[0] and tzname[1] to empty strings.  By getting the time
-zone name information directly from GetTimeZoneInformation Python can set
-the value of time.tzname correctly.
+Ensure ``time.tzname`` is correct on Windows when the active code page is
+set to CP_UTF7 or CP_UTF8.