Dotty uses SIP-12 syntax in output and input

[Blaisorblade]

I noticed in a #4563 comment that RefinedPrinter only uses SIP-12 syntax in output, even tho that SIP was rejected. That syntax is also accepted in input, which would still be a problem for tool authors trying to support Dotty. I couldn't dig any mention of SIP-12 in the commit logs (but only tried git log -S SIP-12 and git log -G SIP-12).

Apparently the SIP was born in 2011 and only rejected in 2016 (https://docs.scala-lang.org/sips/minutes/2016-08-16-sip-10th-august-minutes.html), so it shouldn't be surprising this is still in.

Example using while...do:

sbt:dotty> repl
scala> var i = 0; while i < 5 do { i += 1; println(i) }
1
2
3
4
5
var i: Int = 5

[SzymonPajzert]

What is the status of this ticket? I've seen in syntax doc that ‘if’ Expr ‘then’ Expr [[semi] ‘else’ Expr] is allowed syntax. Should it be removed as well, since it was proposed in SIP-12?

[Blaisorblade]

@SzymonPajzert Exactly. We have been busy, but we should certainly remove the syntax (both from the pretty-printer and the parser) to honor the SIP decision.
I don't think there's other activity on RefinedPrinter, except for #4072.

[allanrenucci]

I'll would ask @odersky first, before removing anything. I've seen him use the syntax in some of our tests

[Blaisorblade]

So while SIP-12 was rejected for Scala 2, Martin would still like to revive it. (checked with him today).

[Blaisorblade]

So I'm putting the issue on hold with stat:revisit. Sorry @SzymonPajzert for the noise!

[SzymonPajzert]

No problem, 356 to go