On Thu, Apr 8, 2010 at 4:52 PM, Steven Watanabe <watanabesj@gmail.com> wrote:
AMDG
Daniel Walker wrote:
True. I only meant to show that there are circumstance where successful overload resolution may require a complete type. Here's another example that doesn't use function arguments. One could imagine a scenario such as
template<class T> typename boost::enable_if< boost::is_pod<T>, T
::type foo();
template<class T> typename boost::disable_if< boost::is_pod<T>, int
::type foo();
Here the type of the expression foo<S>() cannot be determined if S is incomplete.
Again this isn't *because* S is the return type. It's because it's passed to a template that requires a complete type.
Yes, but the type of a call expression is also required to be a complete type. Maybe this isn't a good example either, since, as you point out, overload resolution can't even begin when S is incomplete due to is_pod. But it seems to me the situations are comparable, conceptually at least. But maybe things are changing. decltype allows us to put call expressions in contexts that they could never appear in before, so perhaps the type requirements for call expressions can be loosened in some of these new contexts. Daniel Walker