Migration tool does not remove procedure syntax from constructors

[odersky]

I have noted code like

 def this() { this(1) }

that was not removed from the tests. It's not a big deal for now but better be consistent.

[retronym]

It isn't deprecated.

scala-hash v2.11.0-RC1 -Xfuture -deprecation
Welcome to Scala version 2.11.0-20140227-142303-fabc9f1424 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0-ea).
Type in expressions to have them evaluated.
Type :help for more information.

scala> def foo { 0 }
<console>:1: warning: Procedure syntax is deprecated. Convert procedure `foo` to method by adding `: Unit =`.
       def foo { bar }
               ^
<console>:7: warning: Procedure syntax is deprecated. Convert procedure `foo` to method by adding `: Unit =`.
       def foo { bar }
               ^

scala> class C() { def this(a: Any) = {this()} }
defined class C

scala> class C() { def this(a: Any) {this()} }
defined class C

/cc @soc I can't remember if that was intentional or not.

[samuelgruetter]

so maybe I was too fast ;-) It's already implemented, and I applied it to the scala tests (see commit). Explicit types for implicits is coming soon...

[soc]

I asked about it multiple times but got no response.
The issue is that class C() { def this(a: Any): Unit = {this()} } is no valid Scala.

[retronym]

I guess we can still decide to force the = for regularity. Looks like @samuelgruetter is making good progress with the source-rewriter tool, so we'll might be able to disable procedure syntax by default in 2.12 (albeit with an backwards compatibility command line option.)

[odersky]

I agree we should demand an "=" sign for constructors, for regularity. On the other hand, constructor definitions never have a result type, because that is always implicitly the class itself. So I think the rewrite tool now does the right thing.

[retronym]

@samuelgruetter If you're at EPFL today, I'd love to have a quick chat about your rewriting tool. I would love if we could distribute it as a compiler plugin, so that people could run it from, say, a Maven build without having to figure out the classpath to run a command line tool.