From 060cd714f798d94fc694e8ee9fc52fdc84430d24 Mon Sep 17 00:00:00 2001
From: AN Long <aisk@users.noreply.github.com>
Date: Sun, 20 Mar 2022 23:45:22 +0800
Subject: [PATCH 01/17] Add _winapi.LCMapStringEx

---
 Modules/_winapi.c          | 54 ++++++++++++++++++++++++++++++++++++++
 Modules/clinic/_winapi.c.h | 41 +++++++++++++++++++++++++++++
 2 files changed, 95 insertions(+)

diff --git a/Modules/_winapi.c b/Modules/_winapi.c
index 3e24d512cac384..94de2377c200f0 100644
--- a/Modules/_winapi.c
+++ b/Modules/_winapi.c
@@ -1512,6 +1512,29 @@ _winapi_PeekNamedPipe_impl(PyObject *module, HANDLE handle, int size)
     }
 }
 
+/*[clinic input]
+_winapi.LCMapStringEx
+
+    locale: LPCWSTR
+    flags: DWORD
+    src: LPCWSTR
+
+[clinic start generated code]*/
+
+static PyObject *
+_winapi_LCMapStringEx_impl(PyObject *module, LPCWSTR locale, DWORD flags,
+                           LPCWSTR src)
+/*[clinic end generated code: output=cf4713d80e2b47c9 input=9fe26f95d5ab0001]*/
+{
+
+    int dest_size = LCMapStringEx(locale, flags, src, wcslen(src), NULL, 0, NULL, NULL, 0);
+    wchar_t* dest = PyMem_NEW(wchar_t, dest_size);
+    LCMapStringEx(locale, flags, src, wcslen(src), dest, dest_size, NULL, NULL, 0);
+    PyObject *ret = PyUnicode_FromWideChar(dest, dest_size);
+    PyMem_DEL(dest);
+    return ret;
+}
+
 /*[clinic input]
 _winapi.ReadFile
 
@@ -2023,6 +2046,7 @@ static PyMethodDef winapi_functions[] = {
     _WINAPI_OPENFILEMAPPING_METHODDEF
     _WINAPI_OPENPROCESS_METHODDEF
     _WINAPI_PEEKNAMEDPIPE_METHODDEF
+    _WINAPI_LCMAPSTRINGEX_METHODDEF
     _WINAPI_READFILE_METHODDEF
     _WINAPI_SETNAMEDPIPEHANDLESTATE_METHODDEF
     _WINAPI_TERMINATEPROCESS_METHODDEF
@@ -2160,6 +2184,36 @@ static int winapi_exec(PyObject *m)
     WINAPI_CONSTANT(F_DWORD, FILE_TYPE_PIPE);
     WINAPI_CONSTANT(F_DWORD, FILE_TYPE_REMOTE);
 
+    WINAPI_CONSTANT("u", LOCALE_NAME_INVARIANT);
+    WINAPI_CONSTANT(F_DWORD, LOCALE_NAME_MAX_LENGTH);
+    WINAPI_CONSTANT("u", LOCALE_NAME_SYSTEM_DEFAULT);
+    WINAPI_CONSTANT("u", LOCALE_NAME_USER_DEFAULT);
+
+    WINAPI_CONSTANT(F_DWORD, LCMAP_BYTEREV);
+    WINAPI_CONSTANT(F_DWORD, LCMAP_FULLWIDTH);
+    WINAPI_CONSTANT(F_DWORD, LCMAP_HALFWIDTH);
+    WINAPI_CONSTANT(F_DWORD, LCMAP_HIRAGANA);
+    WINAPI_CONSTANT(F_DWORD, LCMAP_KATAKANA);
+    WINAPI_CONSTANT(F_DWORD, LCMAP_LINGUISTIC_CASING);
+    WINAPI_CONSTANT(F_DWORD, LCMAP_LOWERCASE);
+    WINAPI_CONSTANT(F_DWORD, LCMAP_HASH);
+    WINAPI_CONSTANT(F_DWORD, LCMAP_SIMPLIFIED_CHINESE);
+    WINAPI_CONSTANT(F_DWORD, LCMAP_SORTHANDLE);
+    WINAPI_CONSTANT(F_DWORD, LCMAP_SORTKEY);
+    WINAPI_CONSTANT(F_DWORD, LCMAP_TITLECASE);
+    WINAPI_CONSTANT(F_DWORD, LCMAP_TRADITIONAL_CHINESE);
+    WINAPI_CONSTANT(F_DWORD, LCMAP_UPPERCASE);
+    WINAPI_CONSTANT(F_DWORD, NORM_IGNORENONSPACE);
+    WINAPI_CONSTANT(F_DWORD, NORM_IGNORESYMBOLS);
+    WINAPI_CONSTANT(F_DWORD, LINGUISTIC_IGNORECASE);
+    WINAPI_CONSTANT(F_DWORD, LINGUISTIC_IGNOREDIACRITIC);
+    WINAPI_CONSTANT(F_DWORD, NORM_IGNORECASE);
+    WINAPI_CONSTANT(F_DWORD, NORM_IGNOREKANATYPE);
+    WINAPI_CONSTANT(F_DWORD, NORM_IGNOREWIDTH);
+    WINAPI_CONSTANT(F_DWORD, NORM_LINGUISTIC_CASING);
+    WINAPI_CONSTANT(F_DWORD, SORT_DIGITSASNUMBERS);
+    WINAPI_CONSTANT(F_DWORD, SORT_STRINGSORT);
+
     WINAPI_CONSTANT("i", NULL);
 
     return 0;
diff --git a/Modules/clinic/_winapi.c.h b/Modules/clinic/_winapi.c.h
index 4d89888af9054a..9f73c11785c704 100644
--- a/Modules/clinic/_winapi.c.h
+++ b/Modules/clinic/_winapi.c.h
@@ -820,6 +820,47 @@ _winapi_PeekNamedPipe(PyObject *module, PyObject *const *args, Py_ssize_t nargs)
     return return_value;
 }
 
+PyDoc_STRVAR(_winapi_LCMapStringEx__doc__,
+"LCMapStringEx($module, /, locale, flags, src)\n"
+"--\n"
+"\n");
+
+#define _WINAPI_LCMAPSTRINGEX_METHODDEF    \
+    {"LCMapStringEx", (PyCFunction)(void(*)(void))_winapi_LCMapStringEx, METH_FASTCALL|METH_KEYWORDS, _winapi_LCMapStringEx__doc__},
+
+static PyObject *
+_winapi_LCMapStringEx_impl(PyObject *module, LPCWSTR locale, DWORD flags,
+                           LPCWSTR src);
+
+static PyObject *
+_winapi_LCMapStringEx(PyObject *module, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
+{
+    PyObject *return_value = NULL;
+    static const char * const _keywords[] = {"locale", "flags", "src", NULL};
+    static _PyArg_Parser _parser = {"O&kO&:LCMapStringEx", _keywords, 0};
+    LPCWSTR locale;
+    DWORD flags;
+    LPCWSTR src;
+
+    if (!_PyArg_ParseStackAndKeywords(args, nargs, kwnames, &_parser,
+        _PyUnicode_WideCharString_Converter, &locale, &flags, _PyUnicode_WideCharString_Converter, &src)) {
+        goto exit;
+    }
+    return_value = _winapi_LCMapStringEx_impl(module, locale, flags, src);
+
+exit:
+    /* Cleanup for locale */
+    #if !USE_UNICODE_WCHAR_CACHE
+    PyMem_Free((void *)locale);
+    #endif /* USE_UNICODE_WCHAR_CACHE */
+    /* Cleanup for src */
+    #if !USE_UNICODE_WCHAR_CACHE
+    PyMem_Free((void *)src);
+    #endif /* USE_UNICODE_WCHAR_CACHE */
+
+    return return_value;
+}
+
 PyDoc_STRVAR(_winapi_ReadFile__doc__,
 "ReadFile($module, /, handle, size, overlapped=False)\n"
 "--\n"

From 6ecbc486a6bb4b05643c8b06e8533c899d5a7bc7 Mon Sep 17 00:00:00 2001
From: AN Long <aisk@users.noreply.github.com>
Date: Sun, 20 Mar 2022 23:45:44 +0800
Subject: [PATCH 02/17] Using _winapi.LCMapStringEx in ntpath.normcase

---
 Lib/ntpath.py           | 9 +++++++--
 Lib/test/test_ntpath.py | 1 +
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/Lib/ntpath.py b/Lib/ntpath.py
index 041ebc75cb127c..98fc6553d62deb 100644
--- a/Lib/ntpath.py
+++ b/Lib/ntpath.py
@@ -17,6 +17,7 @@
 defpath = '.;C:\\bin'
 devnull = 'nul'
 
+import _winapi
 import os
 import sys
 import stat
@@ -47,9 +48,13 @@ def normcase(s):
     Makes all characters lowercase and all slashes into backslashes."""
     s = os.fspath(s)
     if isinstance(s, bytes):
-        return s.replace(b'/', b'\\').lower()
+        return _winapi.LCMapStringEx(_winapi.LOCALE_NAME_INVARIANT,
+                                     _winapi.LCMAP_LOWERCASE,
+                                     s.replace(b'/', b'\\'))
     else:
-        return s.replace('/', '\\').lower()
+        return _winapi.LCMapStringEx(_winapi.LOCALE_NAME_INVARIANT,
+                                     _winapi.LCMAP_LOWERCASE,
+                                     s.replace('/', '\\'))
 
 
 # Return whether a path is absolute.
diff --git a/Lib/test/test_ntpath.py b/Lib/test/test_ntpath.py
index 7211ed861762b4..9799400a716447 100644
--- a/Lib/test/test_ntpath.py
+++ b/Lib/test/test_ntpath.py
@@ -852,6 +852,7 @@ def _check_function(self, func):
 
     def test_path_normcase(self):
         self._check_function(self.path.normcase)
+        self.assertEqual(ntpath.normcase('\u03a9\u2126'), 'ωΩ')
 
     def test_path_isabs(self):
         self._check_function(self.path.isabs)

From c1429b90227ef69647fd29c74e736dbced913e4b Mon Sep 17 00:00:00 2001
From: "blurb-it[bot]" <43283697+blurb-it[bot]@users.noreply.github.com>
Date: Sun, 20 Mar 2022 15:47:37 +0000
Subject: [PATCH 03/17] =?UTF-8?q?=F0=9F=93=9C=F0=9F=A4=96=20Added=20by=20b?=
 =?UTF-8?q?lurb=5Fit.?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../next/Windows/2022-03-20-15-47-35.bpo-42658.16eXtb.rst      | 3 +++
 1 file changed, 3 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Windows/2022-03-20-15-47-35.bpo-42658.16eXtb.rst

diff --git a/Misc/NEWS.d/next/Windows/2022-03-20-15-47-35.bpo-42658.16eXtb.rst b/Misc/NEWS.d/next/Windows/2022-03-20-15-47-35.bpo-42658.16eXtb.rst
new file mode 100644
index 00000000000000..91816de244acad
--- /dev/null
+++ b/Misc/NEWS.d/next/Windows/2022-03-20-15-47-35.bpo-42658.16eXtb.rst
@@ -0,0 +1,3 @@
+Using Windows function `LCMapStringEx` in `ntpath.normcase` instead of `str.lower` to deal with non ASCII characters.
+
+The `LCMapStringEx` is added in `_winapi` module also.

From 81be381e08bb4394258aff96a329eba20d552cc1 Mon Sep 17 00:00:00 2001
From: AN Long <aisk@users.noreply.github.com>
Date: Tue, 22 Mar 2022 00:30:05 +0800
Subject: [PATCH 04/17] Changes from review

---
 Lib/ntpath.py     | 33 +++++++++++++++++++++++----------
 Modules/_winapi.c | 42 ++++++++++++++++++++++++++++++++++++------
 2 files changed, 59 insertions(+), 16 deletions(-)

diff --git a/Lib/ntpath.py b/Lib/ntpath.py
index 98fc6553d62deb..39d0cdbff1001a 100644
--- a/Lib/ntpath.py
+++ b/Lib/ntpath.py
@@ -17,13 +17,34 @@
 defpath = '.;C:\\bin'
 devnull = 'nul'
 
-import _winapi
 import os
 import sys
 import stat
 import genericpath
 from genericpath import *
 
+
+try:
+    import _winapi
+
+    def _normcase(s):
+        is_bytes = isinstance(s, bytes)
+        if is_bytes:
+            s = os.fsdecode(s)
+        s = _winapi.LCMapStringEx(_winapi.LOCALE_NAME_INVARIANT,
+                                  _winapi.LCMAP_LOWERCASE,
+                                  s.replace('/', '\\'))
+        if is_bytes:
+            s = os.fsencode(s)
+        return s
+except ImportError:
+    def _normcase(s):
+        if isinstance(s, bytes):
+            return s.replace(b'/', b'\\').lower()
+        return s.replace('/', '\\').lower()
+
+
+
 __all__ = ["normcase","isabs","join","splitdrive","split","splitext",
            "basename","dirname","commonprefix","getsize","getmtime",
            "getatime","getctime", "islink","exists","lexists","isdir","isfile",
@@ -46,15 +67,7 @@ def normcase(s):
     """Normalize case of pathname.
 
     Makes all characters lowercase and all slashes into backslashes."""
-    s = os.fspath(s)
-    if isinstance(s, bytes):
-        return _winapi.LCMapStringEx(_winapi.LOCALE_NAME_INVARIANT,
-                                     _winapi.LCMAP_LOWERCASE,
-                                     s.replace(b'/', b'\\'))
-    else:
-        return _winapi.LCMapStringEx(_winapi.LOCALE_NAME_INVARIANT,
-                                     _winapi.LCMAP_LOWERCASE,
-                                     s.replace('/', '\\'))
+    return _normcase(os.fspath(s))
 
 
 # Return whether a path is absolute.
diff --git a/Modules/_winapi.c b/Modules/_winapi.c
index 94de2377c200f0..a10649c06cab54 100644
--- a/Modules/_winapi.c
+++ b/Modules/_winapi.c
@@ -1526,12 +1526,46 @@ _winapi_LCMapStringEx_impl(PyObject *module, LPCWSTR locale, DWORD flags,
                            LPCWSTR src)
 /*[clinic end generated code: output=cf4713d80e2b47c9 input=9fe26f95d5ab0001]*/
 {
+    if (flags & LCMAP_SORTHANDLE) {
+        PyErr_SetString(PyExc_ValueError, "LCMAP_SORTHANDLE is not supported");
+        return NULL;
+    }
+    if (flags & LCMAP_HASH) {
+        PyErr_SetString(PyExc_ValueError, "LCMAP_HASH is not supported");
+        return NULL;
+    }
+    if (flags & LCMAP_BYTEREV) {
+        PyErr_SetString(PyExc_ValueError, "LCMAP_BYTEREV is not supported");
+        return NULL;
+    }
+    if (flags & LCMAP_SORTKEY) {
+        PyErr_SetString(PyExc_ValueError, "LCMAP_SORTKEY is not supported");
+        return NULL;
+    }
+
+    int dest_size = LCMapStringEx(locale, flags, src, wcslen(src), NULL, 0,
+                                  NULL, NULL, 0);
+    if (dest_size == 0) {
+        PyErr_SetFromWindowsErr(0);
+        return NULL;
+    }
 
-    int dest_size = LCMapStringEx(locale, flags, src, wcslen(src), NULL, 0, NULL, NULL, 0);
     wchar_t* dest = PyMem_NEW(wchar_t, dest_size);
-    LCMapStringEx(locale, flags, src, wcslen(src), dest, dest_size, NULL, NULL, 0);
+    if (dest == NULL) {
+        return PyErr_NoMemory();
+    }
+
+    int nmapped = LCMapStringEx(locale, flags, src, wcslen(src), dest, dest_size,
+                                NULL, NULL, 0);
+    if (nmapped == 0) {
+        PyErr_SetFromWindowsErr(0);
+        PyMem_DEL(dest);
+        return NULL;
+    }
+
     PyObject *ret = PyUnicode_FromWideChar(dest, dest_size);
     PyMem_DEL(dest);
+
     return ret;
 }
 
@@ -2189,17 +2223,13 @@ static int winapi_exec(PyObject *m)
     WINAPI_CONSTANT("u", LOCALE_NAME_SYSTEM_DEFAULT);
     WINAPI_CONSTANT("u", LOCALE_NAME_USER_DEFAULT);
 
-    WINAPI_CONSTANT(F_DWORD, LCMAP_BYTEREV);
     WINAPI_CONSTANT(F_DWORD, LCMAP_FULLWIDTH);
     WINAPI_CONSTANT(F_DWORD, LCMAP_HALFWIDTH);
     WINAPI_CONSTANT(F_DWORD, LCMAP_HIRAGANA);
     WINAPI_CONSTANT(F_DWORD, LCMAP_KATAKANA);
     WINAPI_CONSTANT(F_DWORD, LCMAP_LINGUISTIC_CASING);
     WINAPI_CONSTANT(F_DWORD, LCMAP_LOWERCASE);
-    WINAPI_CONSTANT(F_DWORD, LCMAP_HASH);
     WINAPI_CONSTANT(F_DWORD, LCMAP_SIMPLIFIED_CHINESE);
-    WINAPI_CONSTANT(F_DWORD, LCMAP_SORTHANDLE);
-    WINAPI_CONSTANT(F_DWORD, LCMAP_SORTKEY);
     WINAPI_CONSTANT(F_DWORD, LCMAP_TITLECASE);
     WINAPI_CONSTANT(F_DWORD, LCMAP_TRADITIONAL_CHINESE);
     WINAPI_CONSTANT(F_DWORD, LCMAP_UPPERCASE);

From 6108d201387aaedae8eca9635fa6e7768d1dc3de Mon Sep 17 00:00:00 2001
From: AN Long <aisk@users.noreply.github.com>
Date: Tue, 22 Mar 2022 00:50:53 +0800
Subject: [PATCH 05/17] Update for comments

---
 .../2022-03-20-15-47-35.bpo-42658.16eXtb.rst  |  4 +--
 Modules/_winapi.c                             | 25 +++++--------------
 2 files changed, 7 insertions(+), 22 deletions(-)

diff --git a/Misc/NEWS.d/next/Windows/2022-03-20-15-47-35.bpo-42658.16eXtb.rst b/Misc/NEWS.d/next/Windows/2022-03-20-15-47-35.bpo-42658.16eXtb.rst
index 91816de244acad..a825aa4ce30311 100644
--- a/Misc/NEWS.d/next/Windows/2022-03-20-15-47-35.bpo-42658.16eXtb.rst
+++ b/Misc/NEWS.d/next/Windows/2022-03-20-15-47-35.bpo-42658.16eXtb.rst
@@ -1,3 +1 @@
-Using Windows function `LCMapStringEx` in `ntpath.normcase` instead of `str.lower` to deal with non ASCII characters.
-
-The `LCMapStringEx` is added in `_winapi` module also.
+Using Windows function `LCMapStringEx` in `ntpath.normcase` instead of `str.lower` to deal with non ASCII characters. The `LCMapStringEx` is added in `_winapi` module also.
diff --git a/Modules/_winapi.c b/Modules/_winapi.c
index a10649c06cab54..085f43c58b9dca 100644
--- a/Modules/_winapi.c
+++ b/Modules/_winapi.c
@@ -1526,28 +1526,15 @@ _winapi_LCMapStringEx_impl(PyObject *module, LPCWSTR locale, DWORD flags,
                            LPCWSTR src)
 /*[clinic end generated code: output=cf4713d80e2b47c9 input=9fe26f95d5ab0001]*/
 {
-    if (flags & LCMAP_SORTHANDLE) {
-        PyErr_SetString(PyExc_ValueError, "LCMAP_SORTHANDLE is not supported");
-        return NULL;
-    }
-    if (flags & LCMAP_HASH) {
-        PyErr_SetString(PyExc_ValueError, "LCMAP_HASH is not supported");
-        return NULL;
-    }
-    if (flags & LCMAP_BYTEREV) {
-        PyErr_SetString(PyExc_ValueError, "LCMAP_BYTEREV is not supported");
-        return NULL;
-    }
-    if (flags & LCMAP_SORTKEY) {
-        PyErr_SetString(PyExc_ValueError, "LCMAP_SORTKEY is not supported");
-        return NULL;
+    if (flags & (LCMAP_SORTHANDLE | LCMAP_HASH | LCMAP_BYTEREV |
+                 LCMAP_SORTKEY)) {
+        return PyErr_Format(PyExc_ValueError, "unsupported flags");
     }
 
     int dest_size = LCMapStringEx(locale, flags, src, wcslen(src), NULL, 0,
                                   NULL, NULL, 0);
     if (dest_size == 0) {
-        PyErr_SetFromWindowsErr(0);
-        return NULL;
+        return PyErr_SetFromWindowsErr(0);
     }
 
     wchar_t* dest = PyMem_NEW(wchar_t, dest_size);
@@ -1558,9 +1545,9 @@ _winapi_LCMapStringEx_impl(PyObject *module, LPCWSTR locale, DWORD flags,
     int nmapped = LCMapStringEx(locale, flags, src, wcslen(src), dest, dest_size,
                                 NULL, NULL, 0);
     if (nmapped == 0) {
-        PyErr_SetFromWindowsErr(0);
+        DWORD error = GetLastError();
         PyMem_DEL(dest);
-        return NULL;
+        return PyErr_SetFromWindowsErr(error);
     }
 
     PyObject *ret = PyUnicode_FromWideChar(dest, dest_size);

From 3b4a5cb1bdd3723904de3eeb89b34e1611feb3f6 Mon Sep 17 00:00:00 2001
From: AN Long <aisk@users.noreply.github.com>
Date: Tue, 22 Mar 2022 22:49:53 +0800
Subject: [PATCH 06/17] Update for review and fix tests

---
 Lib/ntpath.py           | 60 ++++++++++++++++++++++++-----------------
 Lib/test/test_ntpath.py |  3 ++-
 2 files changed, 37 insertions(+), 26 deletions(-)

diff --git a/Lib/ntpath.py b/Lib/ntpath.py
index 39d0cdbff1001a..526816a27fbbf4 100644
--- a/Lib/ntpath.py
+++ b/Lib/ntpath.py
@@ -24,27 +24,6 @@
 from genericpath import *
 
 
-try:
-    import _winapi
-
-    def _normcase(s):
-        is_bytes = isinstance(s, bytes)
-        if is_bytes:
-            s = os.fsdecode(s)
-        s = _winapi.LCMapStringEx(_winapi.LOCALE_NAME_INVARIANT,
-                                  _winapi.LCMAP_LOWERCASE,
-                                  s.replace('/', '\\'))
-        if is_bytes:
-            s = os.fsencode(s)
-        return s
-except ImportError:
-    def _normcase(s):
-        if isinstance(s, bytes):
-            return s.replace(b'/', b'\\').lower()
-        return s.replace('/', '\\').lower()
-
-
-
 __all__ = ["normcase","isabs","join","splitdrive","split","splitext",
            "basename","dirname","commonprefix","getsize","getmtime",
            "getatime","getctime", "islink","exists","lexists","isdir","isfile",
@@ -63,11 +42,42 @@ def _get_bothseps(path):
 # Other normalizations (such as optimizing '../' away) are not done
 # (this is done by normpath).
 
-def normcase(s):
-    """Normalize case of pathname.
+try:
+    from _winapi import (
+        LCMapStringEx as _LCMapStringEx,
+        LOCALE_NAME_INVARIANT as _LOCALE_NAME_INVARIANT,
+        LCMAP_LOWERCASE as _LCMAP_LOWERCASE)
 
-    Makes all characters lowercase and all slashes into backslashes."""
-    return _normcase(os.fspath(s))
+    def normcase(s):
+        """Normalize case of pathname.
+
+        Makes all characters lowercase and all slashes into backslashes.
+        """
+        if isinstance(s, bytes):
+            if s == b'':
+                return s
+            s = os.fsdecode(s).replace('/', '\\')
+            return os.fsencode(_LCMapStringEx(_LOCALE_NAME_INVARIANT,
+                                              _LCMAP_LOWERCASE, s))
+        else:
+            if  isinstance(s, str) and s == '':
+                return s
+            s = os.fspath(s)
+            return _LCMapStringEx(_LOCALE_NAME_INVARIANT,
+                                  _LCMAP_LOWERCASE,
+                                  s.replace('/', '\\'))
+        # else:
+        #     msg = f"expected str, bytes or os.PathLike object, not {type(s)}"
+        #     raise TypeError(msg)
+except ImportError:
+    def normcase(s):
+        """Normalize case of pathname.
+
+        Makes all characters lowercase and all slashes into backslashes.
+        """
+        if isinstance(s, bytes):
+            return os.fsencode(os.fsdecode(s).replace('/', '\\').lower())
+        return s.replace('/', '\\').lower()
 
 
 # Return whether a path is absolute.
diff --git a/Lib/test/test_ntpath.py b/Lib/test/test_ntpath.py
index 9799400a716447..ab3603bdd73015 100644
--- a/Lib/test/test_ntpath.py
+++ b/Lib/test/test_ntpath.py
@@ -852,7 +852,8 @@ def _check_function(self, func):
 
     def test_path_normcase(self):
         self._check_function(self.path.normcase)
-        self.assertEqual(ntpath.normcase('\u03a9\u2126'), 'ωΩ')
+        if sys.platform == 'win32':
+            self.assertEqual(ntpath.normcase('\u03a9\u2126'), 'ωΩ')
 
     def test_path_isabs(self):
         self._check_function(self.path.isabs)

From ef669415bd25da81c2ae835530f94dea68bbd8a0 Mon Sep 17 00:00:00 2001
From: AN Long <aisk@users.noreply.github.com>
Date: Wed, 23 Mar 2022 22:18:55 +0800
Subject: [PATCH 07/17] Update by review comment

---
 Lib/ntpath.py     | 11 +++--------
 Modules/_winapi.c |  6 +++---
 2 files changed, 6 insertions(+), 11 deletions(-)

diff --git a/Lib/ntpath.py b/Lib/ntpath.py
index 526816a27fbbf4..8e7c5350b6f61e 100644
--- a/Lib/ntpath.py
+++ b/Lib/ntpath.py
@@ -53,22 +53,17 @@ def normcase(s):
 
         Makes all characters lowercase and all slashes into backslashes.
         """
+        s = os.fspath(s)
+        if not s:
+            return s
         if isinstance(s, bytes):
-            if s == b'':
-                return s
             s = os.fsdecode(s).replace('/', '\\')
             return os.fsencode(_LCMapStringEx(_LOCALE_NAME_INVARIANT,
                                               _LCMAP_LOWERCASE, s))
         else:
-            if  isinstance(s, str) and s == '':
-                return s
-            s = os.fspath(s)
             return _LCMapStringEx(_LOCALE_NAME_INVARIANT,
                                   _LCMAP_LOWERCASE,
                                   s.replace('/', '\\'))
-        # else:
-        #     msg = f"expected str, bytes or os.PathLike object, not {type(s)}"
-        #     raise TypeError(msg)
 except ImportError:
     def normcase(s):
         """Normalize case of pathname.
diff --git a/Modules/_winapi.c b/Modules/_winapi.c
index 085f43c58b9dca..9952ef4b7da725 100644
--- a/Modules/_winapi.c
+++ b/Modules/_winapi.c
@@ -1531,7 +1531,7 @@ _winapi_LCMapStringEx_impl(PyObject *module, LPCWSTR locale, DWORD flags,
         return PyErr_Format(PyExc_ValueError, "unsupported flags");
     }
 
-    int dest_size = LCMapStringEx(locale, flags, src, wcslen(src), NULL, 0,
+    int dest_size = LCMapStringEx(locale, flags, src, -1, NULL, 0,
                                   NULL, NULL, 0);
     if (dest_size == 0) {
         return PyErr_SetFromWindowsErr(0);
@@ -1542,7 +1542,7 @@ _winapi_LCMapStringEx_impl(PyObject *module, LPCWSTR locale, DWORD flags,
         return PyErr_NoMemory();
     }
 
-    int nmapped = LCMapStringEx(locale, flags, src, wcslen(src), dest, dest_size,
+    int nmapped = LCMapStringEx(locale, flags, src, -1, dest, dest_size,
                                 NULL, NULL, 0);
     if (nmapped == 0) {
         DWORD error = GetLastError();
@@ -1550,7 +1550,7 @@ _winapi_LCMapStringEx_impl(PyObject *module, LPCWSTR locale, DWORD flags,
         return PyErr_SetFromWindowsErr(error);
     }
 
-    PyObject *ret = PyUnicode_FromWideChar(dest, dest_size);
+    PyObject *ret = PyUnicode_FromWideChar(dest, dest_size - 1);
     PyMem_DEL(dest);
 
     return ret;

From 6c0366ba0b0155c913a7fb1c76baf0c4ec1150d8 Mon Sep 17 00:00:00 2001
From: AN Long <aisk@users.noreply.github.com>
Date: Sat, 26 Mar 2022 00:19:27 +0800
Subject: [PATCH 08/17] Update for review comments

---
 Lib/ntpath.py | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/Lib/ntpath.py b/Lib/ntpath.py
index 8e7c5350b6f61e..49b530ac5572b4 100644
--- a/Lib/ntpath.py
+++ b/Lib/ntpath.py
@@ -57,9 +57,11 @@ def normcase(s):
         if not s:
             return s
         if isinstance(s, bytes):
-            s = os.fsdecode(s).replace('/', '\\')
-            return os.fsencode(_LCMapStringEx(_LOCALE_NAME_INVARIANT,
-                                              _LCMAP_LOWERCASE, s))
+            encoding = sys.getfilesystemencoding()
+            s = s.decode(encoding, 'surrogateescape').replace('/', '\\')
+            s = _LCMapStringEx(_LOCALE_NAME_INVARIANT,
+                               _LCMAP_LOWERCASE, s)
+            return s.encode(encoding, 'surrogateescape')
         else:
             return _LCMapStringEx(_LOCALE_NAME_INVARIANT,
                                   _LCMAP_LOWERCASE,

From 6c6f2e2b92e11add98a051cf3532ea78a577678b Mon Sep 17 00:00:00 2001
From: AN Long <aisk@users.noreply.github.com>
Date: Sat, 26 Mar 2022 00:38:17 +0800
Subject: [PATCH 09/17] fix news

---
 .../next/Windows/2022-03-20-15-47-35.bpo-42658.16eXtb.rst       | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Misc/NEWS.d/next/Windows/2022-03-20-15-47-35.bpo-42658.16eXtb.rst b/Misc/NEWS.d/next/Windows/2022-03-20-15-47-35.bpo-42658.16eXtb.rst
index a825aa4ce30311..2cbff01fbc3f6c 100644
--- a/Misc/NEWS.d/next/Windows/2022-03-20-15-47-35.bpo-42658.16eXtb.rst
+++ b/Misc/NEWS.d/next/Windows/2022-03-20-15-47-35.bpo-42658.16eXtb.rst
@@ -1 +1 @@
-Using Windows function `LCMapStringEx` in `ntpath.normcase` instead of `str.lower` to deal with non ASCII characters. The `LCMapStringEx` is added in `_winapi` module also.
+Using Windows function ``LCMapStringEx`` in ``ntpath.normcase`` instead of ``str.lower`` to deal with non ASCII characters. The ``LCMapStringEx`` is added in ``_winapi`` module also.

From 15749b86409bfd7d1896832ee4f535862c660a70 Mon Sep 17 00:00:00 2001
From: AN Long <aisk1988@gmail.com>
Date: Sat, 26 Mar 2022 23:30:35 +0800
Subject: [PATCH 10/17] Remove constants which can not been used

---
 Modules/_winapi.c | 10 ----------
 1 file changed, 10 deletions(-)

diff --git a/Modules/_winapi.c b/Modules/_winapi.c
index 9952ef4b7da725..4845b4e6d4ad7c 100644
--- a/Modules/_winapi.c
+++ b/Modules/_winapi.c
@@ -2220,16 +2220,6 @@ static int winapi_exec(PyObject *m)
     WINAPI_CONSTANT(F_DWORD, LCMAP_TITLECASE);
     WINAPI_CONSTANT(F_DWORD, LCMAP_TRADITIONAL_CHINESE);
     WINAPI_CONSTANT(F_DWORD, LCMAP_UPPERCASE);
-    WINAPI_CONSTANT(F_DWORD, NORM_IGNORENONSPACE);
-    WINAPI_CONSTANT(F_DWORD, NORM_IGNORESYMBOLS);
-    WINAPI_CONSTANT(F_DWORD, LINGUISTIC_IGNORECASE);
-    WINAPI_CONSTANT(F_DWORD, LINGUISTIC_IGNOREDIACRITIC);
-    WINAPI_CONSTANT(F_DWORD, NORM_IGNORECASE);
-    WINAPI_CONSTANT(F_DWORD, NORM_IGNOREKANATYPE);
-    WINAPI_CONSTANT(F_DWORD, NORM_IGNOREWIDTH);
-    WINAPI_CONSTANT(F_DWORD, NORM_LINGUISTIC_CASING);
-    WINAPI_CONSTANT(F_DWORD, SORT_DIGITSASNUMBERS);
-    WINAPI_CONSTANT(F_DWORD, SORT_STRINGSORT);
 
     WINAPI_CONSTANT("i", NULL);
 

From 7b2c62cbb9d1b0e70f74905a5868dc513c6cf831 Mon Sep 17 00:00:00 2001
From: AN Long <aisk1988@gmail.com>
Date: Sat, 26 Mar 2022 23:59:42 +0800
Subject: [PATCH 11/17] Fix ntpath_tests on non Windows systems

---
 Lib/ntpath.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Lib/ntpath.py b/Lib/ntpath.py
index 49b530ac5572b4..73b1bd12ddca76 100644
--- a/Lib/ntpath.py
+++ b/Lib/ntpath.py
@@ -72,6 +72,7 @@ def normcase(s):
 
         Makes all characters lowercase and all slashes into backslashes.
         """
+        s = os.fspath(s)
         if isinstance(s, bytes):
             return os.fsencode(os.fsdecode(s).replace('/', '\\').lower())
         return s.replace('/', '\\').lower()

From a89adc0a4a60debe3f401a408b4b186631adc75e Mon Sep 17 00:00:00 2001
From: AN Long <aisk@users.noreply.github.com>
Date: Fri, 1 Apr 2022 00:01:40 +0800
Subject: [PATCH 12/17] Update news

---
 .../next/Windows/2022-03-20-15-47-35.bpo-42658.16eXtb.rst     | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/Misc/NEWS.d/next/Windows/2022-03-20-15-47-35.bpo-42658.16eXtb.rst b/Misc/NEWS.d/next/Windows/2022-03-20-15-47-35.bpo-42658.16eXtb.rst
index 2cbff01fbc3f6c..39b17a27017d93 100644
--- a/Misc/NEWS.d/next/Windows/2022-03-20-15-47-35.bpo-42658.16eXtb.rst
+++ b/Misc/NEWS.d/next/Windows/2022-03-20-15-47-35.bpo-42658.16eXtb.rst
@@ -1 +1,3 @@
-Using Windows function ``LCMapStringEx`` in ``ntpath.normcase`` instead of ``str.lower`` to deal with non ASCII characters. The ``LCMapStringEx`` is added in ``_winapi`` module also.
+Using Windows function ``LCMapStringEx`` in :func:`ntpath.normcase`` instead
+of :func:`str.lower`` to deal with non ASCII characters. The ``LCMapStringEx``
+is added in :mod:`_winapi`` module also.

From 4119cc2a86d0326a6b2c82a9358e5547fa6866db Mon Sep 17 00:00:00 2001
From: AN Long <aisk@users.noreply.github.com>
Date: Fri, 1 Apr 2022 00:17:57 +0800
Subject: [PATCH 13/17] Skip test on block leaks on windows

---
 Lib/test/test_embed.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/Lib/test/test_embed.py b/Lib/test/test_embed.py
index f1ca6da147376c..672769455987ea 100644
--- a/Lib/test/test_embed.py
+++ b/Lib/test/test_embed.py
@@ -1705,7 +1705,11 @@ def test_no_memleak(self):
             blocks = int(match.group(2))
             with self.subTest(frozen_modules=flag, stmt=stmt):
                 self.assertEqual(refs, 0, out)
-                self.assertEqual(blocks, 0, out)
+                if not MS_WINDOWS:
+                    self.assertEqual(blocks, 0, out)
+                else:
+                    # bpo-42658: on Windows, Python still leaks 1 memory block at exit
+                    self.assertEqual(blocks, 1, out)
 
 
 class StdPrinterTests(EmbeddingTestsMixin, unittest.TestCase):

From 8a63de20f7d8e544fdc2880e079e051fbe1485b5 Mon Sep 17 00:00:00 2001
From: AN Long <aisk@users.noreply.github.com>
Date: Fri, 1 Apr 2022 00:39:24 +0800
Subject: [PATCH 14/17] Fix news

---
 .../next/Windows/2022-03-20-15-47-35.bpo-42658.16eXtb.rst   | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/Misc/NEWS.d/next/Windows/2022-03-20-15-47-35.bpo-42658.16eXtb.rst b/Misc/NEWS.d/next/Windows/2022-03-20-15-47-35.bpo-42658.16eXtb.rst
index 39b17a27017d93..206b3f33d64730 100644
--- a/Misc/NEWS.d/next/Windows/2022-03-20-15-47-35.bpo-42658.16eXtb.rst
+++ b/Misc/NEWS.d/next/Windows/2022-03-20-15-47-35.bpo-42658.16eXtb.rst
@@ -1,3 +1,3 @@
-Using Windows function ``LCMapStringEx`` in :func:`ntpath.normcase`` instead
-of :func:`str.lower`` to deal with non ASCII characters. The ``LCMapStringEx``
-is added in :mod:`_winapi`` module also.
+Using Windows function ``LCMapStringEx`` in :func:``ntpath.normcase`` instead
+of :func:``str.lower`` to deal with non ASCII characters. The ``LCMapStringEx``
+is added in :mod:``_winapi`` module also.

From 6789cd9492d625cbc8f0bd6837284cb3dcea19ff Mon Sep 17 00:00:00 2001
From: AN Long <aisk@users.noreply.github.com>
Date: Sat, 9 Apr 2022 21:17:08 +0800
Subject: [PATCH 15/17] Revert the test modify

---
 Lib/test/test_embed.py | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/Lib/test/test_embed.py b/Lib/test/test_embed.py
index 672769455987ea..f1ca6da147376c 100644
--- a/Lib/test/test_embed.py
+++ b/Lib/test/test_embed.py
@@ -1705,11 +1705,7 @@ def test_no_memleak(self):
             blocks = int(match.group(2))
             with self.subTest(frozen_modules=flag, stmt=stmt):
                 self.assertEqual(refs, 0, out)
-                if not MS_WINDOWS:
-                    self.assertEqual(blocks, 0, out)
-                else:
-                    # bpo-42658: on Windows, Python still leaks 1 memory block at exit
-                    self.assertEqual(blocks, 1, out)
+                self.assertEqual(blocks, 0, out)
 
 
 class StdPrinterTests(EmbeddingTestsMixin, unittest.TestCase):

From d43037162a684443c171307697c28238e93b13b5 Mon Sep 17 00:00:00 2001
From: AN Long <aisk@users.noreply.github.com>
Date: Sat, 4 Jun 2022 21:54:39 +0800
Subject: [PATCH 16/17] update news

---
 .../next/Windows/2022-03-20-15-47-35.bpo-42658.16eXtb.rst   | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/Misc/NEWS.d/next/Windows/2022-03-20-15-47-35.bpo-42658.16eXtb.rst b/Misc/NEWS.d/next/Windows/2022-03-20-15-47-35.bpo-42658.16eXtb.rst
index 206b3f33d64730..852cc77676a31d 100644
--- a/Misc/NEWS.d/next/Windows/2022-03-20-15-47-35.bpo-42658.16eXtb.rst
+++ b/Misc/NEWS.d/next/Windows/2022-03-20-15-47-35.bpo-42658.16eXtb.rst
@@ -1,3 +1,3 @@
-Using Windows function ``LCMapStringEx`` in :func:``ntpath.normcase`` instead
-of :func:``str.lower`` to deal with non ASCII characters. The ``LCMapStringEx``
-is added in :mod:``_winapi`` module also.
+Support native Windows case-insensitive path comparisons by using
+``LCMapStringEx`` instead of :func:`str.lower` in :func:`ntpath.normcase`.
+Add ``LCMapStringEx`` to the :mod:`_winapi` module.

From 7e0dcf81d107231838bedb12126a0658b6906aa0 Mon Sep 17 00:00:00 2001
From: AN Long <aisk@users.noreply.github.com>
Date: Sat, 4 Jun 2022 22:37:59 +0800
Subject: [PATCH 17/17] update clinic for _winapi

---
 Modules/clinic/_winapi.c.h | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/Modules/clinic/_winapi.c.h b/Modules/clinic/_winapi.c.h
index 9f73c11785c704..486029a6300304 100644
--- a/Modules/clinic/_winapi.c.h
+++ b/Modules/clinic/_winapi.c.h
@@ -826,7 +826,7 @@ PyDoc_STRVAR(_winapi_LCMapStringEx__doc__,
 "\n");
 
 #define _WINAPI_LCMAPSTRINGEX_METHODDEF    \
-    {"LCMapStringEx", (PyCFunction)(void(*)(void))_winapi_LCMapStringEx, METH_FASTCALL|METH_KEYWORDS, _winapi_LCMapStringEx__doc__},
+    {"LCMapStringEx", _PyCFunction_CAST(_winapi_LCMapStringEx), METH_FASTCALL|METH_KEYWORDS, _winapi_LCMapStringEx__doc__},
 
 static PyObject *
 _winapi_LCMapStringEx_impl(PyObject *module, LPCWSTR locale, DWORD flags,
@@ -850,13 +850,9 @@ _winapi_LCMapStringEx(PyObject *module, PyObject *const *args, Py_ssize_t nargs,
 
 exit:
     /* Cleanup for locale */
-    #if !USE_UNICODE_WCHAR_CACHE
     PyMem_Free((void *)locale);
-    #endif /* USE_UNICODE_WCHAR_CACHE */
     /* Cleanup for src */
-    #if !USE_UNICODE_WCHAR_CACHE
     PyMem_Free((void *)src);
-    #endif /* USE_UNICODE_WCHAR_CACHE */
 
     return return_value;
 }
@@ -1205,4 +1201,4 @@ _winapi__mimetypes_read_windows_registry(PyObject *module, PyObject *const *args
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=b007dde2e7f2fff8 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=6cdefec63a1d7f12 input=a9049054013a1b77]*/