"How do I calculate the line number of ...?" is a '''very'''
frequently-asked question.

There's no satisfying answer, in general.  While [introspection] is
generally one of Tcl's strengths, no one has yet invested what's
necessary to implement a line-number calculation satisfyingly.





[[Explain difficulties (byte-coded vs. not, in script vs. proc body vs. eval)?]]






[[Various ways to instrument existing procedures ... ]]






[[Tom Tromey once wrote extension (?) to do this.  Arjen Markus' Tclcov (?)
does a nearly (?) identical instrumentation.]]





[[tclguy's summary:  "it is going to have to be somebody's
science project"]]