std::string(first, last) over std::uint8_t iterators converts each byte to char implicitly, which -fsanitize=implicit-conversion reports as soon as a byte is >= 0x80 (the document size byte of the enlarged test input, and 0xFF in the new array element name test). Build the string from a const char* and a size instead. Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01N5NasCxh8jKXBaa6HBx9Xk Signed-off-by: Niels Lohmann <mail@nlohmann.me>