From: Peter Dimov (pdimov_at_[hidden])
Date: 2007-08-25 18:24:57
Howard Hinnant:
> Just to be clear, I'm extremely well positioned to know that vendors
> are not evil, and are not adversaries.
For the record, I applied "non-evil" to the runtime checks done in a release
build, not to a vendor. :-)
> They are people, just like you
> and me. And when the standard gives them choices, they must make
> them. They try to make them in such a way as to please most of their
> customers. Sometimes they choose correctly, and sometimes they do not
> (as a vendor I admit to having chosen incorrectly sometimes). No
> vendor that I'm aware of is immune to making incorrect choices.
I accept that. So what's the problem? Vendor A ignores the mutex argument,
his users complain, so he finds a way to add checking that doesn't increase
sizeof(condition) and doesn't compromise performance for the rest of the
user base. Vendor B stores the mutex pointer in std::condition, his users
complain, he waits for the next ABI breakage and finds a way to achieve
comparable checking quality and efficiency without increasing
sizeof(condition). Everyone is happy.
...
> I don't know any more than you do, so my "forward looking" is no more
> or less valid than yours. But I strongly believe that it would be
> careless of us to be careless with sizeof(std::condition).
I'm not being careless with sizeof(condition). I already demonstrated two
ways to achieve checking without storing the pointer into the condition
itself, and hinted at another possibility (exploiting an unused void* in
pthread_cond_t). I also questioned your assertion that increasing
sizeof(condition) from 28 to 32 is of practical importance.