fix usage of scalafix via another task

src/main/scala/scalafix/sbt/ScalafixPlugin.scala

@@ -100,9 +100,7 @@ object ScalafixPlugin extends AutoPlugin {
         compile := Def.taskDyn {
           val oldCompile =
             compile.value // evaluated first, before the potential scalafix evaluation
-          val runScalafixAfterCompile =
-            scalafixOnCompile.value && !scalafixRunExplicitly.value
-          if (runScalafixAfterCompile)
+          if (scalafixOnCompile.value)
             scalafix
               .toTask("")
               .map(_ => oldCompile)
@@ -415,7 +413,7 @@ object ScalafixPlugin extends AutoPlugin {
       ).findErrors(files, dependencies, withScalaInterface)
       if (errors.isEmpty) {
         val task = Def.task {
-          // passively consume compilation output without triggering compile as it can result in a cyclic dependency
+          // don't use fullClasspath as it results in a cyclic dependency via compile when scalafixOnCompile := true
           val classpath =
             dependencyClasspath.in(config).value.map(_.data.toPath) :+
               classDirectory.in(config).value.toPath
@@ -428,8 +426,8 @@ object ScalafixPlugin extends AutoPlugin {
             streams.in(config, scalafix).value
           )
         }
-        if (scalafixRunExplicitly.value) task.dependsOn(compile.in(config))
-        else task
+        // sub-task of compile after which bytecode should not be modified
+        task.dependsOn(manipulateBytecode.in(config))
       } else {
         Def.task {
           if (errors.length == 1) {
@@ -563,16 +561,6 @@ object ScalafixPlugin extends AutoPlugin {
     }
   }
 
-  // Controls whether scalafix should depend on compile (true) & whether compile may depend on
-  // scalafix (false), to avoid cyclic dependencies causing deadlocks during executions (as
-  // dependencies come from dynamic tasks).
-  private val scalafixRunExplicitly: Def.Initialize[Task[Boolean]] =
-    Def.task {
-      executionRoots.value.exists { root =>
-        Seq(scalafix.key, scalafixAll.key).contains(root.key)
-      }
-    }
-
   private def isScalaFile(file: File): Boolean = {
     val path = file.getPath
     path.endsWith(".scala") ||

src/sbt-test/sbt-scalafix/wrapper/.scalafix.conf

@@ -0,0 +1 @@
+rules = [RemoveUnused]

src/sbt-test/sbt-scalafix/wrapper/build.sbt

@@ -0,0 +1,5 @@
+val V = _root_.scalafix.sbt.BuildInfo
+
+scalaVersion := V.scala212
+addCompilerPlugin(scalafixSemanticdb)
+scalacOptions ++= Seq("-Yrangepos", "-Ywarn-unused")

src/sbt-test/sbt-scalafix/wrapper/project/LintAllPlugin.scala

@@ -0,0 +1,24 @@
+import sbt._
+import scalafix.sbt.ScalafixPlugin
+import scalafix.sbt.ScalafixPlugin.autoImport._
+
+object LintAllPlugin extends AutoPlugin {
+
+  override def trigger: PluginTrigger = allRequirements
+
+  override def requires: Plugins = ScalafixPlugin
+
+  object autoImport {
+    val lintAll = taskKey[Unit]("run all linters")
+  }
+
+  import autoImport._
+
+  override def projectSettings: Seq[Def.Setting[_]] =
+    Seq(
+      lintAll := {
+        scalafix.in(Compile).toTask(" --check").value
+        // & other linters...
+      }
+    )
+}

src/sbt-test/sbt-scalafix/wrapper/project/plugins.sbt

@@ -0,0 +1,2 @@
+resolvers += Resolver.sonatypeRepo("public")
+addSbtPlugin("ch.epfl.scala" % "sbt-scalafix" % sys.props("plugin.version"))

src/sbt-test/sbt-scalafix/wrapper/src/main/scala/example/Example.scala

@@ -0,0 +1,5 @@
+package example
+
+import imported.Imported
+
+object Example

src/sbt-test/sbt-scalafix/wrapper/src/main/scala/imported/Imported.scala

@@ -0,0 +1,3 @@
+package imported
+
+object Imported

src/sbt-test/sbt-scalafix/wrapper/test

@@ -0,0 +1,14 @@
+# check that missing rewrites are detected, with or without a warm compilation cache
+> set scalafixOnCompile := false
+-> lintAll
+> compile
+-> lintAll
+
+# apply the rewrite via an explicit call
+> scalafix
+
+# confirms that `lintAll` sees that rewrite, with or without a warm compilation cache
+> clean
+> lintAll
+> compile
+> lintAll