In a post from yesterday (see http://tinyurl.com/hzk5w), Alexei Alexandrov found a rather serious problem with is_convertible in at least MSVC 7.1 and Intel 9.0, namely that is_convertible<From,To> fails to compile when
From is non-copyable, emitting an error message like this:
Wait a second, I've just looked at the original error messages, and the test case is very specific, it fails for: is_convertible<const noncopyable, const noncopyable> That is known not to work, *and will never work*, there is no way we can define a trait that detects whether a type is copy-constructable or not. In other words the From and To parameters must be different types. Likewise is_convertible<From, To> will fail if To has a private constructor taking a From as argument. Sorry but it's an inherent limitation of the trait implemented without core-language support. John.