Roadmap for and state of single element tuple types?

[Slava_Pestov]

Thanks for the writeup -- I didn't know canonical types were a @Douglas_Gregor invention

Minor nitpick though:

@Chris_Lattner3

I can't imagine changing this, as it would cause significant ripples throughout the type system, including source and ABI breakage.

I can't imagine that adding or removing a sugared type should have ABI impact -- mangling uses canonical types only. Or do you mean if we changed (T) to be a different type than T? That would be major breaking and quite odd from a language standpoint, I agree.

[Chris_Lattner3 (Chris Lattner)]

Yeah I mean that changing (T) to be different than T would be seriously source/ABI breaking. Similarly, any change from a sugar type to a canonical type would be a similar breaking change.