Choosing between __traits(compiles, { ... } ) and is(typeof( { ... } ))

[Stefan Koch]

On Wednesday, 20 September 2017 at 12:01:21 UTC, Nordlöw wrote:
> When is
>
>     __traits(compiles, { ... } )
>
> preferred over
>
>     is(typeof( { ... } ))
>
> and vice versa when writing stuff like
>
>     enum isCopyable(S) = is(typeof( { S foo = S.init; S copy = 
> foo; } ));
>
> ?
>
> Further, are there cases where the two idioms aren't 
> exchangable?

Yes there are.
Prefer __traits(compiles) it includes stricter visibility checks 
then is() does.
Also compiles does not require the expression to resolve to a 
type.