Rupert Wood wrote:
I don't know how to fight aliasing rules but as another approach you
could template the function instead, i.e.
template<typename T> T* exchange(T** ptr, T* next);
exchange<int>(&a, &v2);
since you're using C++ here.
I initially dismissed this solution since the implementation of exchange
is either a typical swap using a temporary, a compare-and-swap sequence
or a mutex, depending on various compilation options. I wanted to avoid
including the implementation in the header to avoid a bunch of #ifdefs.
However, your email made me try to avoid the warning with a template
wrapper:
template <typename T>
T* exchange_template(T** ptr, T* next) {
return reinterpret_cast<T*>(
exchange(reinterpret_cast<void**>(ptr), next));
}
...
exchange_template(&a, &v2);
I don't understand why, but this compiles without warnings. It also
avoids needing to look up the aliasing rules, and places the dangerous
cast in a single location, so this seems like a better solution.
I would still like to know if my original solution is "correct" or not,
since it would be needed for C.
Evan Jones
--
Evan Jones
http://evanjones.ca/
