Merge pull request #668 from armanbilge/issue/304

Upstream `ScalafixProject`

build.sbt

@@ -151,6 +151,7 @@ lazy val scalafix = project
     name := "sbt-typelevel-scalafix",
     tlVersionIntroduced := Map("2.12" -> "0.4.10")
   )
+  .dependsOn(noPublish)
 
 lazy val ciSigning = project
   .in(file("ci-signing"))

scalafix/src/main/scala/org/typelevel/sbt/ScalafixProject.scala

@@ -0,0 +1,126 @@
+/*
+ * Copyright 2022 Typelevel
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.typelevel.sbt
+
+import sbt._
+import scalafix.sbt._
+
+import Keys._
+import ScalafixTestkitPlugin.autoImport._
+
+final class ScalafixProject private (
+    val name: String,
+    val rules: Project,
+    val input: Project,
+    val output: Project,
+    val tests: Project
+) extends CompositeProject {
+
+  lazy val componentProjects = Seq(rules, input, output, tests)
+
+  def componentProjectReferences = componentProjects.map(x => x: ProjectReference)
+
+  def in(dir: File): ScalafixProject =
+    new ScalafixProject(
+      name,
+      rules.in(dir / "rules"),
+      input.in(dir / "input"),
+      output.in(dir / "output"),
+      tests.in(dir / "tests")
+    )
+
+  def rulesSettings(ss: Def.SettingsDefinition*): ScalafixProject =
+    rulesConfigure(_.settings(ss: _*))
+
+  def inputSettings(ss: Def.SettingsDefinition*): ScalafixProject =
+    inputConfigure(_.settings(ss: _*))
+
+  def outputSettings(ss: Def.SettingsDefinition*): ScalafixProject =
+    outputConfigure(_.settings(ss: _*))
+
+  def testsSettings(ss: Def.SettingsDefinition*): ScalafixProject =
+    testsConfigure(_.settings(ss: _*))
+
+  def rulesConfigure(transforms: (Project => Project)*): ScalafixProject =
+    new ScalafixProject(
+      name,
+      rules.configure(transforms: _*),
+      input,
+      output,
+      tests
+    )
+
+  def inputConfigure(transforms: (Project => Project)*): ScalafixProject =
+    new ScalafixProject(
+      name,
+      rules,
+      input.configure(transforms: _*),
+      output,
+      tests
+    )
+
+  def outputConfigure(transforms: (Project => Project)*): ScalafixProject =
+    new ScalafixProject(
+      name,
+      rules,
+      input,
+      output.configure(transforms: _*),
+      tests
+    )
+
+  def testsConfigure(transforms: (Project => Project)*): ScalafixProject =
+    new ScalafixProject(
+      name,
+      rules,
+      input,
+      output,
+      tests.configure(transforms: _*)
+    )
+
+}
+
+object ScalafixProject {
+  def apply(name: String): ScalafixProject = {
+
+    lazy val rules = Project(s"$name-rules", file(s"$name/rules")).settings(
+      libraryDependencies += "ch.epfl.scala" %% "scalafix-core" % _root_
+        .scalafix
+        .sbt
+        .BuildInfo
+        .scalafixVersion
+    )
+
+    lazy val input =
+      Project(s"$name-input", file(s"$name/input")).enablePlugins(NoPublishPlugin)
+
+    lazy val output =
+      Project(s"$name-output", file(s"$name/output")).enablePlugins(NoPublishPlugin)
+
+    lazy val tests = Project(s"$name-tests", file(s"$name/tests"))
+      .settings(
+        scalafixTestkitOutputSourceDirectories := (output / Compile / unmanagedSourceDirectories).value,
+        scalafixTestkitInputSourceDirectories := (input / Compile / unmanagedSourceDirectories).value,
+        scalafixTestkitInputClasspath := (input / Compile / fullClasspath).value,
+        scalafixTestkitInputScalacOptions := (input / Compile / scalacOptions).value,
+        scalafixTestkitInputScalaVersion := (input / Compile / scalaVersion).value
+      )
+      .dependsOn(rules)
+      .enablePlugins(NoPublishPlugin, ScalafixTestkitPlugin)
+
+    new ScalafixProject(name, rules, input, output, tests)
+  }
+}

scalafix/src/main/scala/org/typelevel/sbt/ScalafixProjectMacros.scala

@@ -0,0 +1,68 @@
+/*
+ * Copyright 2022 Typelevel
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.typelevel.sbt
+
+import scala.annotation.tailrec
+import scala.reflect.macros.blackbox
+
+private[sbt] object ScalafixProjectMacros {
+
+  // Copied from sbt.std.KeyMacro
+  def definingValName(c: blackbox.Context, invalidEnclosingTree: String => String): String = {
+    import c.universe.{Apply => ApplyTree, _}
+    val methodName = c.macroApplication.symbol.name
+    def processName(n: Name): String =
+      n.decodedName
+        .toString
+        .trim // trim is not strictly correct, but macros don't expose the API necessary
+    @tailrec def enclosingVal(trees: List[c.Tree]): String = {
+      trees match {
+        case ValDef(_, name, _, _) :: _ => processName(name)
+        case (_: ApplyTree | _: Select | _: TypeApply) :: xs => enclosingVal(xs)
+        // lazy val x: X = <methodName> has this form for some reason (only when the explicit type is present, though)
+        case Block(_, _) :: DefDef(mods, name, _, _, _, _) :: _ if mods.hasFlag(Flag.LAZY) =>
+          processName(name)
+        case _ =>
+          c.error(c.enclosingPosition, invalidEnclosingTree(methodName.decodedName.toString))
+          "<error>"
+      }
+    }
+    enclosingVal(enclosingTrees(c).toList)
+  }
+
+  // Copied from sbt.std.KeyMacro
+  def enclosingTrees(c: blackbox.Context): Seq[c.Tree] =
+    c.asInstanceOf[reflect.macros.runtime.Context]
+      .callsiteTyper
+      .context
+      .enclosingContextChain
+      .map(_.tree.asInstanceOf[c.Tree])
+
+  def scalafixProjectImpl(c: blackbox.Context): c.Expr[ScalafixProject] = {
+    import c.universe._
+
+    val enclosingValName = definingValName(
+      c,
+      methodName =>
+        s"""$methodName must be directly assigned to a val, such as `val x = $methodName`. Alternatively, you can use `org.typelevel.sbt.ScalafixProject.apply`"""
+    )
+
+    val name = c.Expr[String](Literal(Constant(enclosingValName)))
+
+    reify { ScalafixProject(name.splice) }
+  }
+}

scalafix/src/main/scala/org/typelevel/sbt/TypelevelScalafixPlugin.scala

@@ -19,6 +19,8 @@ package org.typelevel.sbt
 import sbt._
 import scalafix.sbt.ScalafixPlugin
 
+import scala.language.experimental.macros
+
 import Keys._
 import ScalafixPlugin.autoImport._
 
@@ -32,6 +34,8 @@ object TypelevelScalafixPlugin extends AutoPlugin {
     val tlTypelevelScalafixVersion = settingKey[Option[String]](
       "The version of typelevel-scalafix to add to the scalafix dependency classpath, or None to omit the dependency entirely."
     )
+
+    def tlScalafixProject: ScalafixProject = macro ScalafixProjectMacros.scalafixProjectImpl
   }
 
   import autoImport._