a. value is likely set/constructed = $$ appears in semantic action
b. value is likely destroyed = $$ appears in %destructor
That is, I think Bison shouldn't warn about !a when !b. However, Bison
currently considers a value to be likely destroyed by a %destructor
regardless of whether $$ appears in the %destructor. I think that's
inconsistent. Moreover, it might be convenient to override a per-type or
default %destructor by defining an empty per-symbol %destructor, which
would suppress the warnings:
%destructor { free ($$); }
%destructor { } symbol_with_no_value
What do you think?
Joel
