In C++ you don't have to say 'struct' or 'class' if the declaration of
the type has been seen. Some compilers will complain if you use
'struct' when 'class' should have been used and vice versa.
Fixes bugzilla #29539.
This is a zero-ing function, (like calloc), to avoid bugs due to
accessing uninitialized values. Thanks to valgrind for noticing the
use of uninitialized values.
The non-named parameter grammar understandably doesn't set the
identifier field. Fixes intermittent failures about void main(void)
{} having a named void parameter.
