Map escape sequence name to uppercase before calling into unicodedata

Author: SnoopJ

Misc/NEWS.d/next/Core and Builtins/2023-07-26-00-03-00.gh-issue-80667.N7Dh8B.rst

@@ -0,0 +1,2 @@
+Literals using the ``\N{name}`` escape syntax can now construct CJK
+ideographs and Hangul syllables using case-insensitive names.

Objects/unicodeobject.c

@@ -6011,9 +6011,18 @@ _PyUnicode_DecodeUnicodeEscapeInternal(const char *s,
                 if (namelen) {
                     /* found a name.  look it up in the unicode database */
                     s++;
+
+                    /* map to uppercase before calling getcode, which does
+                     * case-sensitive comparisons */
+                    char buffer[namelen];
+                    size_t i;
+                    for (i = 0; i < namelen; i++) {
+                        buffer[i] = Py_TOUPPER(start[i]);
+                    }
+
                     ch = 0xffffffff; /* in case 'getcode' messes up */
                     if (namelen <= INT_MAX &&
-                        ucnhash_capi->getcode(start, (int)namelen,
+                        ucnhash_capi->getcode(buffer, (int)namelen,
                                               &ch, 0)) {
                         assert(ch <= MAX_UNICODE);
                         WRITE_CHAR(ch);