Update Py_buffer format

Use "=H" and "=I" formats.

Lib/test/test_capi/test_unicode.py

@@ -1746,13 +1746,8 @@ def test_unicode_export(self):
                    | PyUnicode_FORMAT_UCS2
                    | PyUnicode_FORMAT_UCS4)
         BUFFER_UCS1 = 'B'
-        BUFFER_UCS2 = 'H'
-        if struct.calcsize('I') == 4:
-            BUFFER_UCS4 = 'I'
-        elif struct.calcsize('L') == 4:
-            BUFFER_UCS4 = 'L'
-        else:
-            self.fail("unable to get BUFFER_UCS4 ")
+        BUFFER_UCS2 = '=H'
+        BUFFER_UCS4 = '=I'
 
         def check_ucs1(text, formats):
             if formats == PyUnicode_FORMAT_UCS1:

Objects/unicodeobject.c

@@ -2374,14 +2374,6 @@ int32_t
 PyUnicode_Export(PyObject *unicode, int32_t requested_formats,
                  Py_buffer *view)
 {
-#if SIZEOF_INT == 4
-#  define BUFFER_UCS4 "I"
-#elif SIZEOF_LONG == 4
-#  define BUFFER_UCS4 "L"
-#else
-#  error "unable to find BUFFER_UCS4"
-#endif
-
     if (!PyUnicode_Check(unicode)) {
         PyErr_Format(PyExc_TypeError, "must be str, not %T", unicode);
         return -1;
@@ -2413,7 +2405,7 @@ PyUnicode_Export(PyObject *unicode, int32_t requested_formats,
     {
         return unicode_export(unicode, view,
                               len, PyUnicode_2BYTE_DATA(unicode),
-                              2, "H", PyUnicode_FORMAT_UCS2);
+                              2, "=H", PyUnicode_FORMAT_UCS2);
     }
 
     // Convert ASCII or UCS1 to UCS2
@@ -2433,7 +2425,7 @@ PyUnicode_Export(PyObject *unicode, int32_t requested_formats,
         ucs2[len] = 0;
 
         return unicode_export_bytes(bytes, view, len,
-                                    2, "H", PyUnicode_FORMAT_UCS2);
+                                    2, "=H", PyUnicode_FORMAT_UCS2);
     }
 
     // Native UCS4
@@ -2442,7 +2434,7 @@ PyUnicode_Export(PyObject *unicode, int32_t requested_formats,
     {
         return unicode_export(unicode, view,
                               len, PyUnicode_4BYTE_DATA(unicode),
-                              4, BUFFER_UCS4, PyUnicode_FORMAT_UCS4);
+                              4, "=I", PyUnicode_FORMAT_UCS4);
     }
 
     // Convert ASCII, UCS1 or UCS2 to UCS4
@@ -2456,7 +2448,7 @@ PyUnicode_Export(PyObject *unicode, int32_t requested_formats,
         (void)as_ucs4(unicode, ucs4, len + 1, 1);
 
         return unicode_export_bytes(bytes, view, len,
-                                    4, BUFFER_UCS4, PyUnicode_FORMAT_UCS4);
+                                    4, "=I", PyUnicode_FORMAT_UCS4);
     }
 
     // Encode UCS1, UCS2 or UCS4 to UTF-8
@@ -2485,8 +2477,6 @@ PyUnicode_Export(PyObject *unicode, int32_t requested_formats,
     PyErr_SetString(PyExc_ValueError,
                     "unable to find a matching export format");
     return -1;
-
-#undef BUFFER_UCS4
 }