[typing] Type-erasure re generics

[bearophile]

Jonathan M Davis:

> And maybe someday dmd will get the aforementioned optimization would be make 
> template instantiations with the same size for their type actually use one set 
> of underlying code.

LDC is already able to do it in not too much complex situations if you compile D1 code using the -mergefunc switch too. I have a LLVM bug report open on this, they say they will further improve this feature.

Bye,
bearophile