Why D needs tail const

[bearophile]

Stewart Gordon:

> OK, so we have std.typecons.Rebindable.  But I've found it a 
> PITA when it comes to generic programming.  Among other things, 
> if you try to pass it around, you can end up with a mess like 
> const(Rebindable!(const(....))).  This wouldn't happen with 
> built-in tail const support.

This is only partially related to your post. It's for a general 
solution.

Is it possible to invent a language construct that allows:
const(Rebindable!(const(....)))
To be defined as the same as:
Rebindable!(const(....))

Something like an onConst()/onImmutable templated methods for 
structs/classes?

Bye,
bearophile