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Re: [PATCH]: Fix PR tree-optimization/21407
Joseph S. Myers wrote:
On Tue, 10 May 2005, Dale Johannesen wrote:
There was quite a bit of discussion of this internal to Apple, and no
agreement was reached. Geoff strongly takes the position you say;
Mike and I disagree. The standard seems unclear.
Nick Maclaren's discussion of "What is an object?" deals more with arrays
than with structures, but the basic question of what can be done with a
given pointer remains the same.
Indeed. Geoff would perhaps seem to be recommending approaching 3, at
the bottom of Nick's message, whereas Nick recommends spproach 1.
I don't think that the situation is anywhere as clear as the type-based
aliasing rules, which were themselves sufficiently annoying to people
that we turned them off by default for a while. And, even those rules
have some areas that are still being resolved by the C committee.
It would seem rather dangerous to me to implement this optimization.