Diagnosing use of undefined variables takes place in
parseNumericVariableUse() and printSubstitutions() for numeric variables
but only takes place in printSubstitutions() for string variables. The
reason for the split location of diagnostics is that parsing is not
aware of the clearing of variables due to --enable-var-scope and thus
use of variables cleared in this way can only be catched by
Beyond the code level inconsistency, there is also a user facing
inconsistency since diagnostics look different between the two
functions. While the diagnostic in printSubstitutions is more verbose,
doing the diagnostic there allows to diagnose all undefined variables
rather than just the first one and error out.
This patch create dummy variable definition when encountering a use of
undefined variable so that parsing can proceed and be diagnosed by
printSubstitutions() later. Tests that were testing whether parsing
fails in such case are thus modified accordingly.