Why opDispatch uses SFINAE implicitly?

[Stefan Koch via Digitalmars-d]

On Thursday, 2 March 2017 at 06:40:29 UTC, Dukc wrote:
> If I define an opDispatch for something, but the call does not 
> compile, the compiler currently behaves as if the opDispatch 
> didn't exist at all. Just like C++ templates as  far as I know. 
> Why is this? I think it would be better if it acted like other 
> D templates: Compilation failure is always an error, but you 
> can use preconditions if you want the "substitution failure is 
> not an error"-idiom. This would be better to detect errors.
>
> Is there any way to define a dispatching type so that it errs 
> or at least announces if the call does not compile?

All templates have SFINAE.
opDispatch as well.

you can force a compilation error by defining a catch-all 
overload that static asserts.