Daniel Berlin wrote:
On Sun, 2005-07-17 at 05:13 +0200, Gabriel Dos Reis wrote:
Daniel Berlin <[EMAIL PROTECTED]> writes:
[...]
| > I think that is urgent.
| No offense, but everyone thinks the problems that affect them are the
| most urgent.
miscompilation of KDE was declared urgent; I hope bug affecting code
semantics for X is not just "request for enhancement".
Not for me to judge. That's why we have Mark.
For the record, I agree with what looks to have been the outcome of this
thread: that it makes sense to consider an object volatile iff the type
used to aspect the object is in fact volatile, regardless of its
underlying type. Certainly, the standard never requires that we remove
accesses, and I do think that this rule is what programmers who use
volatile expect, and it's an easy rule to explain, so, from a QoI point
of view I think this is a good rule, independently of what behavior
might be required by the standard.
Note that I'm explicitly not taking a position on what the standard
says. The standard is notoriously incomplete with respect to object
model issues, including volatility, so I think that trying particularly
hard to parse its words in this area is probably not a good use of time
for people trying to build a real-world compiler. Creating DRs is more
useful than trying to read the tea leaves.
Clearly, the analogous rule does not make sense for "const" in that a
"const" object can never be modified; in particular, if the compiler can
prove that "*x = 3" is an attempt to modify an object whose dynamic type
is "const int", then it can replace that with a call to "kill
(SIGSEGV)", if it likes; this is unquestionably undefined behavior.
As for putting RTH's change in 4.0.2, I'm comfortable with that,
provided the usual testing is done, as I think this is at least a QoI
regression.
Thanks,
--
Mark Mitchell
CodeSourcery, LLC
[EMAIL PROTECTED]
(916) 791-8304
