macros-generated private field forwardReader never has usages

[vn971]

Hi. The current implementation of Macros.handler, Macros.reader, Macros.writer define unused fields forwardReader and forwardWriter. They should be deleted (to reduce jar sizes, to make scalac warnings go away and to remove dead code from the code base).

ReactiveMongo Version 0.12.1

Also, same code in the master branch here: https://github.com/ReactiveMongo/ReactiveMongo/blob/master/macros/src/main/scala-2.12/MacroImpl.scala#L11

OpenJDK 64-Bit Server VM (build 25.121-b13, mixed mode)

openjdk version "1.8.0_121"
OpenJDK Runtime Environment (build 1.8.0_121-b13)
OpenJDK 64-Bit Server VM (build 25.121-b13, mixed mode)

Expected Behavior

No dead code in macro-generated code. No scalac warnings on unused private variables

1. define case class C(i: Int)
2. enable scalac flag "-Ywarn-unused"
3. compile

Actual Behavior

scalac shows warnings on unused private variable. The variable really has no usages in any imaginable scenario. There's just a private val defined without usages.

1. scalac shows warnings, variable really has no usages and is unnecessary

Reproducible Test Case

see above

[vn971]

I can throw in a simple PR with a fix.

[cchantep]

Hi,

This lazy variable is indeed use in some case of recursive types, so it cannot be "just" removed.

[vn971]

@cchantep thanks for the response! Where is it used? I only see definitions: https://github.com/ReactiveMongo/ReactiveMongo/search?utf8=%E2%9C%93&q=forwardWriter&type=

[cchantep]

https://github.com/ReactiveMongo/ReactiveMongo/blob/master/macros/src/main/scala-2.12/MacroImpl.scala#L603

Please first use the MailingList (to keep this tracker clean for actionable ticket).

[vn971]

Thanks, now I see it (deeply hidden). Sorry for that. Will use the ML.