Replace the five Unknown stubs whose NIDs hash these ICU names with the
uchar.cpp definitions of ICU 78.1 (049e0d6a), over the Zs, Zl, Zp and
White_Space code points that ICU 65.1 to 78.1 ship. Values outside
U+0000..U+10FFFF return 0, as ICU's trie error value gives.
Co-Authored-By: Claude Opus 5.5 <[email protected]>
ICU 78.1's u_unescapeAt dereferences the offset and calls the callback without checks, and u_unescape reads the source without one, so a null one faults: throw std::invalid_argument there instead of NotImplemented_nid_no_patch. A negative u_unescape capacity is clamped by _appendUChars and fails every room check, so nothing is written and the full length is returned; only a capacity whose signed difference with the output length overflows, which ICU leaves undefined, still throws.
Qu Yi