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syntactic Scalafix rule for unified slash syntax

In sbt 1.1.0 I implemented unified slash syntax for sbt. Today I sent a pull request to deprecate the old sbt 0.13 shell syntax #6309.

Naturally, the topic of deprecating old syntax for build.sbt also came up.

This is because “unified” slash syntax is called so because it unifies the shell syntax and the build syntax together. Thus, it makes sense to deprecate the old build.sbt syntax that uses in like skip in publish or scalacOptions in (Compile, console), if we’re deprecating the old shell syntax.

I was able to hack together a syntactic Scalafix rule to convert build.sbt to unified slash syntax -


Make sure your project is on git or make a backup.

$ cs install scalafix
$ export PATH="$PATH:$HOME/Library/Application Support/Coursier/bin"
$ scalafix --rules= *.sbt project/*.scala

It might not be precise, but it surely beats doing it by hand.

what did I just run?

This rewrite rule changes any invocation of in method with one to three arguments, and turn them into arg0 / arg1 / arg2 / lhs. Please only point the rule to *.sbt files and sbt plugin code. If you point it to ScalaTest with in, it will change it to / too.

Unlike semantic rules, syntactic rules just looks at the shape of the code and applies the rules mechanically. You can think of it as a crude IDE refactor feature, or a precise regex. It’s somewhere in between.

some examples

diff --git a/sbt-pgp/src/main/scala-sbt-0.13/Compat.scala b/sbt-pgp/src/main/scala-sbt-0.13/Compat.scala
index cf70ab2..5214226 100644
--- a/sbt-pgp/src/main/scala-sbt-0.13/Compat.scala
+++ b/sbt-pgp/src/main/scala-sbt-0.13/Compat.scala
@@ -59,7 +59,7 @@ object Compat {
       resolverName = Classpaths.getPublishTo(publishTo.value).name,
-      checksums = (checksums in publish).value,
+      checksums = (publish / checksums).value,
       logging = ivyLoggingLevel.value
@@ -68,7 +68,7 @@ object Compat {
-      (checksums in publishLocal).value,
+      (publishLocal / checksums).value,
       logging = ivyLoggingLevel.value
diff --git a/build.sbt b/build.sbt
index 22de1a398..610a4d410 100644
--- a/build.sbt
+++ b/build.sbt
@@ -78,17 +78,17 @@ def commonBaseSettings: Seq[Setting[_]] = Def.settings(
   testFrameworks += TestFramework("hedgehog.sbt.Framework"),
   testFrameworks += TestFramework("verify.runner.Framework"),
-  concurrentRestrictions in Global += Util.testExclusiveRestriction,
-  testOptions in Test += Tests.Argument(TestFrameworks.ScalaCheck, "-w", "1"),
-  testOptions in Test += Tests.Argument(TestFrameworks.ScalaCheck, "-verbosity", "2"),
-  javacOptions in compile ++= Seq("-Xlint", "-Xlint:-serial"),
+  (Global / concurrentRestrictions) += Util.testExclusiveRestriction,
+  (Test / testOptions) += Tests.Argument(TestFrameworks.ScalaCheck, "-w", "1"),
+  (Test / testOptions) += Tests.Argument(TestFrameworks.ScalaCheck, "-verbosity", "2"),
+  (compile / javacOptions) ++= Seq("-Xlint", "-Xlint:-serial"),
   Compile / doc / scalacOptions ++= {
     import scala.sys.process._
     val devnull = ProcessLogger(_ => ())
     val tagOrSha = ("git describe --exact-match" #|| "git rev-parse HEAD").lineStream(devnull).head
-      (baseDirectory in LocalRootProject).value.getAbsolutePath,
+      (LocalRootProject / baseDirectory).value.getAbsolutePath,

It puts more parentheses than I’d put sometimes, but these changes all look ok.

known issue

It does not handle chained in like contrabandFormatsForType in generateContrabands in Compile:

-    contrabandFormatsForType in generateContrabands in Compile := ContrabandConfig.getFormats,
+    (Compile / contrabandFormatsForType in generateContrabands)(generateContrabands / contrabandFormatsForType) := ContrabandConfig.getFormats,

You’d have to fix this manually: Compile / generateContrabands / contrabandFormatsForType