XmStringConcatAndFree(3) on Linux
The text b4a4777953e7, as Debian 13 (Trixie), Debian 12 (Bookworm), Debian 11 (Bullseye), Debian 10 (Buster), Debian 9 (Stretch), Debian 8 (Jessie) shipped it.
A compound string function that appends one string to another and frees the original strings "XmStringConcatAndFree" "compound string functions" "XmStringConcatAndFree"