Simple dependent types in const contexts?

[Jules-Bertholet]

I would expect this feature to come as a facet of a more general "pattern types" feature that also includes enum variant types:

What would it take to revive Enum Variant Types?

I want this too, but I don't think now is the right time to revive the feature quite yet, for the following reason. Enum variant types, where any value of an enum type that matches a specific variant is a member of a subtype corresponding to that variant, are a special case of a more general feature, where any value of a type that matches a specific pattern is a member of a subtype corresponding to that pattern. The more general feature would also encompass ranged integers, among other things. …