"Stephen J. Turnbull" <stephen(a)xemacs.org> writes:
Dmitry> Well, looking into the C99 I don't see why the
union
Dmitry> assignment could be a problem. Can you or Ben cite the gcc
Dmitry> developers reply, explaining why it is dangerous and not
Dmitry> conforming to the C standard?
Ah, we agree then. The standard _seems_ to allow our usage, but it
doesn't, and nobody (except a language lawyer trying to cover the
vendor's ass) can explain why. I say, this is bogus.
Are you absolutely sure that the bug is caused by improper union assignment
implementation by compiler vendors, not something else?
As for citing the gcc developers, since Ben mentioned
"19.13" this
would be about 1995.
Even if he could find the old message, what it comes down to is a lot
of probably useless work for Ben, no matter how you slice it. This is
not a profitable way for him to spend his time, at least in his
assessment. Ben has a long history of diving into these things once
others present evidence and narrow the field of problematic code. I
think it's reasonable to presume that his reluctance is a matter of
expert judgement, not mere laziness or arrogance, at this point.
That's why I asked for a backtrace/bug report, so that _other_ people
(not limited to you; me and Mike for sure, presumably Glynn Clements
and Valdis Kletnieks, maybe even Martin) can do the work they're
requesting to support --use-union-type, and also recognize the
"--use-union-type syndrome" when they see the symptoms.
Agree completely. The problem is that we only have Ben's conclusion
(theoretically he can be mistaken, right?) and cannot verify it ourselves
until more info is supplied.
- Dmitry Bely