A question about TYPE_ARG_TYPES

[Kazu Hirata]

Hi,

I keep finding places in GCC sources that check whether a member of
TYPE_ARG_TYPES is 0.  For example,

  for (link = TYPE_ARG_TYPES (function_or_method_type);
       link && TREE_VALUE (link);
       link = TREE_CHAIN (link))
    gen_type_die (TREE_VALUE (link), context_die);

Notice that TREE_VALUE (link) is part of the loop condition.

Now, do we ever allow a NULL in TYPE_ARG_TYPES?  If so, what does that
mean?  My guess is that soneone was trying to be cautious about
encountering a NULL in TYPE_ARG_TYPES.  (If that's the case, we should
be using gcc_assert instead.)

Thanks,

Kazu Hirata