Run Scalafix build migrations using sbt

.editorconfig

@@ -0,0 +1,5 @@
+root = true
+
+[*.{scala,sbt}]
+indent_size = 2
+indent_style = space

modules/core/src/main/scala/org/scalasteward/core/buildtool/sbt/SbtAlg.scala

@@ -17,7 +17,7 @@
 package org.scalasteward.core.buildtool.sbt
 
 import better.files.File
-import cats.data.OptionT
+import cats.data.{NonEmptyList, OptionT}
 import cats.effect.{Concurrent, Resource}
 import cats.syntax.all._
 import org.scalasteward.core.application.Config
@@ -29,6 +29,7 @@ import org.scalasteward.core.edit.scalafix.{ScalafixCli, ScalafixMigration}
 import org.scalasteward.core.io.process.SlurpOptions
 import org.scalasteward.core.io.{FileAlg, FileData, ProcessAlg, WorkspaceAlg}
 import org.scalasteward.core.util.Nel
+import org.scalasteward.core.buildtool.sbt.scalaStewardSbtScalafix
 
 final class SbtAlg[F[_]](config: Config)(implicit
     fileAlg: FileAlg[F],
@@ -107,40 +108,101 @@ final class SbtAlg[F[_]](config: Config)(implicit
     }
 
   private def runSourcesMigration(buildRoot: BuildRoot, migration: ScalafixMigration): F[Unit] =
-    OptionT(latestSbtScalafixVersion).foreachF { pluginVersion =>
-      workspaceAlg.buildRootDir(buildRoot).flatMap { buildRootDir =>
-        val plugin = scalaStewardSbtScalafix(pluginVersion)
-        fileAlg.createTemporarily(buildRootDir / project, plugin).surround {
-          val withScalacOptions = migration.scalacOptions.fold(Resource.unit[F]) { opts =>
-            val options = scalaStewardScalafixOptions(opts.toList)
-            fileAlg.createTemporarily(buildRootDir, options)
-          }
-          withScalacOptions.surround {
-            val scalafixCmds = migration.rewriteRules.map(rule => s"$scalafixAll $rule").toList
-            val slurpOptions = SlurpOptions.ignoreBufferOverflow
-            sbt(Nel(scalafixEnable, scalafixCmds), buildRootDir, slurpOptions).void
-          }
-        }
+    for {
+      buildRootDir <- workspaceAlg.buildRootDir(buildRoot)
+      _ <- runSbtScalafix(buildRootDir, migration, metaBuilds = 0, startDepth = 0)
+    } yield ()
+
+  private def runBuildMigration(buildRoot: BuildRoot, migration: ScalafixMigration): F[Unit] =
+    for {
+      buildRootDir <- workspaceAlg.buildRootDir(buildRoot)
+      metaBuilds <- metaBuildsCount(buildRootDir)
+      _ <- runSyntacticBuildMigrations(buildRootDir, migration)
+      _ <- runSbtScalafix(buildRootDir, migration, metaBuilds, startDepth = 1)
+    } yield ()
+
+  private def runSyntacticBuildMigrations(
+      buildRootDir: File,
+      migration: ScalafixMigration
+  ): F[Unit] = {
+    val rootSbtFiles =
+      fileAlg.walk(buildRootDir, 1).filter(_.extension.contains(".sbt"))
+
+    val metaBuildFiles =
+      fileAlg.walk(buildRootDir / project, 3).filter(_.extension.exists(Set(".sbt", ".scala")))
+
+    val allBuildFiles = (rootSbtFiles ++ metaBuildFiles).compile.toList
+
+    allBuildFiles.flatMap { buildFiles =>
+      Nel.fromList(buildFiles).fold(F.unit) { files =>
+        scalafixCli.runMigration(buildRootDir, files, migration)
       }
     }
+  }
 
   private def latestSbtScalafixVersion: F[Option[Version]] =
     versionsCache
       .getVersions(Scope(sbtScalafixDependency, List(config.defaultResolver)), None)
       .map(_.lastOption)
 
-  private def runBuildMigration(buildRoot: BuildRoot, migration: ScalafixMigration): F[Unit] =
-    for {
-      buildRootDir <- workspaceAlg.buildRootDir(buildRoot)
-      projectDir = buildRootDir / project
-      files0 <- (
-        fileAlg.walk(buildRootDir, 1).filter(_.extension.contains(".sbt")) ++
-          fileAlg.walk(projectDir, 3).filter(_.extension.exists(Set(".sbt", ".scala")))
-      ).compile.toList
-      _ <- Nel.fromList(files0).fold(F.unit) { files1 =>
-        scalafixCli.runMigration(buildRootDir, files1, migration)
-      }
-    } yield ()
+  private def addScalafixPluginTemporarily(
+      buildRootDir: File,
+      pluginVersion: Version,
+      metaBuilds: Int,
+      startDepth: Int
+  ): Resource[F, Unit] = {
+    val buildsDepth = metaBuilds + startDepth
+    val plugin = scalaStewardSbtScalafix(pluginVersion)
+    List
+      .iterate(buildRootDir / project, buildsDepth + 1)(_ / project)
+      .drop(startDepth)
+      .collectFold(fileAlg.createTemporarily(_, plugin))
+  }
+
+  private def addScalacOptionsTemporarily(
+      buildRootDir: File,
+      scalacOptions: Option[Nel[String]],
+      metaBuilds: Int,
+      startDepth: Int
+  ): Resource[F, Unit] =
+    scalacOptions.fold(Resource.unit[F]) { opts =>
+      val buildsDepth = metaBuilds + startDepth
+      val options = scalaStewardScalafixOptions(opts.toList)
+      List
+        .iterate(buildRootDir, buildsDepth + 1)(_ / project)
+        .drop(startDepth)
+        .collectFold(fileAlg.createTemporarily(_, options))
+    }
+
+  private def runSbtScalafix(
+      buildRootDir: File,
+      migration: ScalafixMigration,
+      metaBuilds: Int,
+      startDepth: Int
+  ): F[Unit] =
+    OptionT(latestSbtScalafixVersion).foreachF { pluginVersion =>
+      addScalafixPluginTemporarily(buildRootDir, pluginVersion, metaBuilds, startDepth)
+        .surround {
+          addScalacOptionsTemporarily(buildRootDir, migration.scalacOptions, metaBuilds, startDepth)
+            .surround {
+              val scalafixCmds = migration.rewriteRules.map(rule => s"$scalafixAll $rule").toList
+              val slurpOptions = SlurpOptions.ignoreBufferOverflow
+              val buildsDepth = metaBuilds + startDepth
+              val scalafixCommands = scalafixEnable :: scalafixCmds
+              val commandLists =
+                (scalafixCommands :: List.fill(buildsDepth)(reloadPlugins :: scalafixCommands))
+                  .drop(startDepth)
+              val commands = NonEmptyList.fromList(commandLists.flatten)
+              commands.fold(F.unit) { cmds =>
+                sbt(
+                  cmds,
+                  buildRootDir,
+                  slurpOptions
+                ).void
+              }
+            }
+        }
+    }
 
   private def sbt(
       sbtCommands: Nel[String],

modules/core/src/main/scala/org/scalasteward/core/edit/scalafix/ScalafixCli.scala

@@ -31,7 +31,7 @@ final class ScalafixCli[F[_]](implicit
 ) {
   def runMigration(workingDir: File, files: Nel[File], migration: ScalafixMigration): F[Unit] = {
     val rules = migration.rewriteRules.map("--rules=" + _)
-    val cmd = scalafixBinary :: rules ::: files.map(_.pathAsString)
+    val cmd = scalafixBinary :: "--syntactic" :: rules ::: files.map(_.pathAsString)
     processAlg.exec(cmd, workingDir, slurpOptions = SlurpOptions.ignoreBufferOverflow).void
   }
 

modules/core/src/main/scala/org/scalasteward/core/io/FileAlg.scala

@@ -136,7 +136,13 @@ object FileAlg {
         Resource.fromAutoCloseable(source).use(src => F.blocking(src.mkString))
 
       override def walk(dir: File, maxDepth: Int): Stream[F, File] =
-        Stream.eval(F.delay(dir.walk(maxDepth))).flatMap(Stream.fromBlockingIterator(_, 1))
+        Stream.force(
+          F.blocking(dir.exists)
+            .ifF(
+              Stream.eval(F.delay(dir.walk(maxDepth))).flatMap(Stream.fromBlockingIterator(_, 1)),
+              Stream.empty.covary[F]
+            )
+        )
 
       override def writeFile(file: File, content: String): F[Unit] =
         logger.debug(s"Write $file") >>