Use actual mill version in predef

[jodersky]

As of recent versions of mill, the $ivy importers support
substituting $MILL_VERSION with the current version of mill.

The changes presented here modify the predef import to use the literal
$MILL_VERSION instead of a the value read from mill's version
file. While both these values are usually equivalent, they can differ
when using a local mill wrapper script (e.g. when developing and
testing mill locally).

In essence, the changes ensure that the correct bloop plugin will
always be used.

[jodersky]

Looks like this is blocked until bloop integration with mill is fixed. I.e. until com-lihaoyi/mill#756 is merged

[tgodzik]

Thanks for the contribution! I was actually hoping for something like this. LGTM

[tgodzik]

The tests are failing though

INFO  java.lang.NoClassDefFoundError: io/circe/RootEncoder
INFO  	at mill.contrib.bloop.BloopImpl$BloopOps$bloop$.$anonfun$config$3(BloopImpl.scala:81)
INFO  	at scala.collection.mutable.HashMap.getOrElseUpdate(HashMap.scala:86)
INFO  	at mill.moduledefs.Cacher.cachedTarget(Cacher.scala:12)
INFO  	at mill.moduledefs.Cacher.cachedTarget$(Cacher.scala:10)
INFO  	at mill.define.Module.cachedTarget(Module.scala:18)
INFO  	at mill.contrib.bloop.BloopImpl$BloopOps$bloop$.config(BloopImpl.scala:81)
INFO  	at mill.contrib.bloop.BloopImpl$BloopOps$bloop$.$anonfun$writeConfig$1(BloopImpl.scala:86)
INFO  	at scala.collection.mutable.HashMap.getOrElseUpdate(HashMap.scala:86)

@jodersky any idea what is happening here?

[ckipp01]

The tests are failing though

I believe this is because com-lihaoyi/mill#756 is merged, but it will need to be released before this will work as expected.

[krotton]

The fix is currently released in a Mill's snapshot, so changing to:

override def version: String = "0.5.9-6-484657"

fixes the issue immediately.

[jodersky]

I believe this is because com-lihaoyi/mill#756 is merged, but it will need to be released before this will work as expected.

Indeed. I think the best course of action is to wait until a new "official" mill release is out (I reckon it will be 0.5.10). Once it's out I'll update the minimum version in this PR.

[tgodzik]

Let's wait for the stable Mill version.

[jodersky]

A new stable release of mill is out, I updated the version settings and pushed again. Hopefully this time the build will pass.

[ckipp01]

Awesome, this looks good. LGTM!