Use of deprecated interp->result makes VTK un-buildable on Tcl/Tk 8.6
This issue was created automatically from an original Mantis Issue. Further discussion may take place here.
The use of interp->result has been deprecated in Tcl for many years, and with 8.6 they're finally making it not work by default. Using this method will result in an error when building against Tcl/Tk 8.6 unless you do #define USE_INTERP_RESULT before including tcl.h - that, however, is a hack intended to aid migration, the expectation is that the code should be fixed. For Tcl/Tk 9.0 it will be made completely impossible to use interp->result.