If MS_WIN64 is defined, MS_WINDOWS is also defined: #ifdef can be simplified.

Include/pyport.h

@@ -263,7 +263,7 @@ typedef size_t Py_uhash_t;
  */
 #ifdef HAVE_LONG_LONG
 #   ifndef PY_FORMAT_LONG_LONG
-#       if defined(MS_WIN64) || defined(MS_WINDOWS)
+#       ifdef MS_WINDOWS
 #           define PY_FORMAT_LONG_LONG "I64"
 #       else
 #           error "This platform's pyconfig.h needs to define PY_FORMAT_LONG_LONG"

Modules/_io/_iomodule.h

@@ -77,7 +77,7 @@ extern int _PyIO_trap_eintr(void);
    long with "%lld" even when both long and long long have the same
    precision. */
 
-#if defined(MS_WIN64) || defined(MS_WINDOWS)
+#ifdef MS_WINDOWS
 
 /* Windows uses long long for offsets */
 typedef PY_LONG_LONG Py_off_t;

Modules/_io/fileio.c

@@ -533,7 +533,7 @@ fileio_readinto(fileio *self, PyObject *args)
         len = pbuf.len;
         Py_BEGIN_ALLOW_THREADS
         errno = 0;
-#if defined(MS_WIN64) || defined(MS_WINDOWS)
+#ifdef MS_WINDOWS
         if (len > INT_MAX)
             len = INT_MAX;
         n = read(self->fd, pbuf.buf, (int)len);
@@ -602,7 +602,7 @@ fileio_readall(fileio *self)
     if (!_PyVerify_fd(self->fd))
         return PyErr_SetFromErrno(PyExc_IOError);
 
-#if defined(MS_WIN64) || defined(MS_WINDOWS)
+#ifdef MS_WINDOWS
     pos = _lseeki64(self->fd, 0L, SEEK_CUR);
 #else
     pos = lseek(self->fd, 0L, SEEK_CUR);
@@ -645,7 +645,7 @@ fileio_readall(fileio *self)
         Py_BEGIN_ALLOW_THREADS
         errno = 0;
         n = bufsize - bytes_read;
-#if defined(MS_WIN64) || defined(MS_WINDOWS)
+#ifdef MS_WINDOWS
         if (n > INT_MAX)
             n = INT_MAX;
         n = read(self->fd, PyBytes_AS_STRING(result) + bytes_read, (int)n);
@@ -706,7 +706,7 @@ fileio_read(fileio *self, PyObject *args)
         return fileio_readall(self);
     }
 
-#if defined(MS_WIN64) || defined(MS_WINDOWS)
+#ifdef MS_WINDOWS
     if (size > INT_MAX)
         size = INT_MAX;
 #endif
@@ -718,7 +718,7 @@ fileio_read(fileio *self, PyObject *args)
     if (_PyVerify_fd(self->fd)) {
         Py_BEGIN_ALLOW_THREADS
         errno = 0;
-#if defined(MS_WIN64) || defined(MS_WINDOWS)
+#ifdef MS_WINDOWS
         n = read(self->fd, ptr, (int)size);
 #else
         n = read(self->fd, ptr, size);
@@ -766,7 +766,7 @@ fileio_write(fileio *self, PyObject *args)
         Py_BEGIN_ALLOW_THREADS
         errno = 0;
         len = pbuf.len;
-#if defined(MS_WIN64) || defined(MS_WINDOWS)
+#ifdef MS_WINDOWS
         if (len > 32767 && isatty(self->fd)) {
             /* Issue #11395: the Windows console returns an error (12: not
                enough space error) on writing into stdout if stdout mode is
@@ -839,7 +839,7 @@ portable_lseek(int fd, PyObject *posobj, int whence)
 
     if (_PyVerify_fd(fd)) {
         Py_BEGIN_ALLOW_THREADS
-#if defined(MS_WIN64) || defined(MS_WINDOWS)
+#ifdef MS_WINDOWS
         res = _lseeki64(fd, pos, whence);
 #else
         res = lseek(fd, pos, whence);

Modules/posixmodule.c

@@ -361,7 +361,7 @@ static int win32_can_symlink = 0;
 #undef STAT
 #undef FSTAT
 #undef STRUCT_STAT
-#if defined(MS_WIN64) || defined(MS_WINDOWS)
+#ifdef MS_WINDOWS
 #       define STAT win32_stat
 #       define LSTAT win32_lstat
 #       define FSTAT win32_fstat
@@ -7425,7 +7425,7 @@ static PyObject *
 posix_lseek(PyObject *self, PyObject *args)
 {
     int fd, how;
-#if defined(MS_WIN64) || defined(MS_WINDOWS)
+#ifdef MS_WINDOWS
     PY_LONG_LONG pos, res;
 #else
     off_t pos, res;
@@ -7453,7 +7453,7 @@ posix_lseek(PyObject *self, PyObject *args)
     if (!_PyVerify_fd(fd))
         return posix_error();
     Py_BEGIN_ALLOW_THREADS
-#if defined(MS_WIN64) || defined(MS_WINDOWS)
+#ifdef MS_WINDOWS
     res = _lseeki64(fd, pos, how);
 #else
     res = lseek(fd, pos, how);
@@ -7659,7 +7659,7 @@ posix_write(PyObject *self, PyObject *args)
     }
     len = pbuf.len;
     Py_BEGIN_ALLOW_THREADS
-#if defined(MS_WIN64) || defined(MS_WINDOWS)
+#ifdef MS_WINDOWS
     if (len > INT_MAX)
         len = INT_MAX;
     size = write(fd, pbuf.buf, (int)len);

Modules/socketmodule.c

@@ -2553,7 +2553,7 @@ sock_recv_guts(PySocketSockObject *s, char* cbuf, Py_ssize_t len, int flags)
     Py_BEGIN_ALLOW_THREADS
     timeout = internal_select_ex(s, 0, interval);
     if (!timeout) {
-#if defined(MS_WIN64) || defined(MS_WINDOWS)
+#ifdef MS_WINDOWS
         if (len > INT_MAX)
             len = INT_MAX;
         outlen = recv(s->sock_fd, cbuf, (int)len, flags);
@@ -3251,7 +3251,7 @@ sock_send(PySocketSockObject *s, PyObject *args)
     if (!timeout) {
 #ifdef __VMS
         n = sendsegmented(s->sock_fd, buf, len, flags);
-#elif defined(MS_WIN64) || defined(MS_WINDOWS)
+#elif defined(MS_WINDOWS)
         if (len > INT_MAX)
             len = INT_MAX;
         n = send(s->sock_fd, buf, (int)len, flags);
@@ -3308,7 +3308,7 @@ sock_sendall(PySocketSockObject *s, PyObject *args)
         if (!timeout) {
 #ifdef __VMS
             n = sendsegmented(s->sock_fd, buf, len, flags);
-#elif defined(MS_WIN64) || defined(MS_WINDOWS)
+#elif defined(MS_WINDOWS)
             if (len > INT_MAX)
                 len = INT_MAX;
             n = send(s->sock_fd, buf, (int)len, flags);
@@ -3407,7 +3407,7 @@ sock_sendto(PySocketSockObject *s, PyObject *args)
     Py_BEGIN_ALLOW_THREADS
     timeout = internal_select_ex(s, 1, interval);
     if (!timeout) {
-#if defined(MS_WIN64) || defined(MS_WINDOWS)
+#ifdef MS_WINDOWS
         if (len > INT_MAX)
             len = INT_MAX;
         n = sendto(s->sock_fd, buf, (int)len, flags,

Objects/fileobject.c

@@ -390,7 +390,7 @@ stdprinter_write(PyStdPrinter_Object *self, PyObject *args)
 
     Py_BEGIN_ALLOW_THREADS
     errno = 0;
-#if defined(MS_WIN64) || defined(MS_WINDOWS)
+#ifdef MS_WINDOWS
     if (n > INT_MAX)
         n = INT_MAX;
     n = write(self->fd, c, (int)n);

Python/fileutils.c

@@ -16,13 +16,13 @@ extern wchar_t* _Py_DecodeUTF8_surrogateescape(const char *s, Py_ssize_t size);
 PyObject *
 _Py_device_encoding(int fd)
 {
-#if defined(MS_WINDOWS) || defined(MS_WIN64)
+#if defined(MS_WINDOWS)
     UINT cp;
 #endif
     if (!_PyVerify_fd(fd) || !isatty(fd)) {
         Py_RETURN_NONE;
     }
-#if defined(MS_WINDOWS) || defined(MS_WIN64)
+#if defined(MS_WINDOWS)
     if (fd == 0)
         cp = GetConsoleCP();
     else if (fd == 1 || fd == 2)