"spir" <denis.s...@gmail.com> wrote in message news:mailman.157.1289146124.21107.digitalmar...@puremagic.com... I'd like to know, aside user-side semantics, whether the compiler uses the "in" qualifier for efficiency (pass arrays & structs by ref under the hood?). Well, seems obvious, but there may be some hidden constraint I'm unable to realise.
The spec states: "The in storage class is equivalent to const scope." So, no, the compiler never implicitly uses ref to pass in parameters. It could be possible with a rule like "pass by const ref if param.sizeof > x bytes", but I think this would require an abi change.