Quoting Bernd Schmidt <ber...@codesourcery.com>:
If the point of your ENABLE_CHECKING machinery (which I also don't
really understand) is to avoid exactly that kind of bug, then the
ENABLE_CHECKING code should go away along with the use of transparent_union.
No, it does a lot more than that. It gives a sanity check that the contents
of a cumulative_args_t have actually been packed with pack_cumulative_args,
and in case more than one target is supported, the check will also
verify that the target on which get_cumulative_args is used is the same as
the one on which pack_cumulative_args was called before to pack the
cumlative_args_t.
Bugs where a target hook for the wrong target is called, or a data structure
from the wrong target is used, are hard to track down when all the optimizers
are operating in garbage-in-garbage-out mode.
