Hello David,
Has anyone else gotten this error?
Never seen it before.
One thing to note though:
TclReFree
is from the tcl intepreter's regular expression library (see eg https://www.linuxquestions.org/questions/slackware-14/compiling-and-link-err...) and that one may bring its own regex.h include file (which Cactus may accidentally pick up).
My suggestion would be to to try and see if uninstalling any tcl-dev (or so) package helps.
Why Cactus picks the wrong regex.h file I do not know. In my system TCL's is in
/usr/include/tcl8.6/tcl-private/generic/regex.h
which should not be used by default (instead /usr/include/regex.h should be used).
Yours, Roland