bug#716: Bug in buffer-swap-text

[Stefan Monnier <monnier@iro.umontreal.ca>]

>> Your analysis sounds right, thank you.  I'd suggest to use another
>> r_alloc primitve, something like r_alloc_reset_variable, so you could do

> I've adapted your suggestion so it does not remove the consistency check in
> find_bloc (instead it does a non-checking find inline):

Thanks.  After your email, I thought we could just change
r_alloc_reset_variable to take 2 arguments: the old ptr and the
new ptr.  This way, you get more consistency checking.

BTW, if the double check (p->variable == ptr && p->data == *ptr) is
there for consistency, it would be good to add a comment about it.

Better yet: make it a real consistency check, along the lines of

  assert (*p->variable == p->data);

so it's not just checked for `ptr', but for all blocs visited in the loop.


        Stefan