Attempting to load the for_file proc fails:
% package require Tclx
8.4
% for_file
invalid command name "for_file"
%
An ls of the package directory:
% ls
auto.tcl http1.0 ldAix opt0.4 safe.tcl tcltest2.2 encoding http2.5 ldAout.tcl package.tcl tclAppInit.c word.tcl history.tcl
init.tcl msgcat1.3 parray.tcl
doesn't include a tclIndex file (not required for
8.3 that used the TclX file tcl.tlib to wrap these).
Generating a tclIndex file solves the problem.