Change 1373
A proposed fix for the bug Ian Godin reported wherein $(<[1-])
was broken.
Ian's fix was the epitome of "minimum impact surgery", which
made $(<[1-]) work properly, but which left unchanged the
undefined behavior of many other incorrect productions.
This change both fixes up the broken case, and cleans up
the handling of $(c[ ... references, such that syntax errors
in the [ ] subscripting all cause empty expansions. (Previously,
some of these syntax errors errors would return empty
expansions, other would return something (often what the
jam writer _probably_ intended, but...
was broken.
Ian's fix was the epitome of "minimum impact surgery", which
made $(<[1-]) work properly, but which left unchanged the
undefined behavior of many other incorrect productions.
This change both fixes up the broken case, and cleans up
the handling of $(c[ ... references, such that syntax errors
in the [ ] subscripting all cause empty expansions. (Previously,
some of these syntax errors errors would return empty
expansions, other would return something (often what the
jam writer _probably_ intended, but...