On 3/15/26 18:49, Emanuel Spiridon via Std-Proposals wrote:
>
>
> On Sun, 15 Mar 2026 at 14:00, <std-proposals-request_at_[hidden] <mailto:std-proposals-request_at_[hidden]>> wrote:
>
> I would expect an interface that avoids "typename" and "::type",
> e.g. employing an alias template.
>
> Thank you for the suggestion. This has been implemented using a _t suffix alias template following the convention in <type_traits>.
>
> Do we get subsumption, i.e.
>
> f(is_real auto)
>
> is more specialized than
>
> f(is_number auto)
>
> ?
>
> If not, that feels like causing a bad bang-for-the-buck ratio
> of this facility.
>
> Jens
>
> Native subsumption is not achievable in a library pure form since it requires concept relationships that the compiler can trace.

Yes, and we have constraints with fold expansions.

> Subsumption could be added if this method is pursued for language level implementation.

What is the minimum feature that the language would need to add
to support subsumption? I note that we already have fold-expanded
constraints.

Jens