This is a judgement call on Redhat's part, but there are some problems with
compiling tcl against pthreads.
To wit, with glibc2.1 (according to andreas jaeger) it is impossible to
load a shared object which is linked against pthreads.
A bit of background: I am the author of an Apache module, mod_dtcl, which
is a module for doing server-parsed Tcl, similar to PHP. I had received
numerous bug reports that there were problems with this module on redhat
So, as you can see, it's a problem if you wish to use this Apache module as
a shared object, as mod_dtcl.so is linked against tcl, which is in turn
linked against pthreads on redhat boxes.
Thanks for the comment, as I turned on --enable-threads in order to get
feedback. I will revert the change in Raw Hide, as it seems the linux world is
not quite ready for --enable-threads in tcltk. Please reopen this bug when
that time comes :-)