Using typedefed types as covariant return types

[Rick Mann]

Bill Baxter Wrote:

> What are you reading that makes you think CFStringRef is "derived" from 
> CFTypeRef?

It seems to be implied by the "Implicit Conversions" section of <http://www.digitalmars.com/d/type.html>:

"A typedef or enum can be implicitly converted to its base type, but going the other way requires an explicit conversion. "