Port sbt project naming macro for tlCrossRootProject - resolves #169

Author: DavidGregory084

.editorconfig

@@ -0,0 +1,11 @@
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[*.{scala,sbt}]
+indent_style = space
+indent_size = 2

ci/src/main/scala/org/typelevel/sbt/CrossRootProject.scala

@@ -99,11 +99,13 @@ object CrossRootProject {
   def unapply(root: CrossRootProject): Some[(Project, Project, Project, Project)] =
     Some((root.all, root.jvm, root.js, root.native))
 
-  private[sbt] def apply(): CrossRootProject = new CrossRootProject(
-    Project("root", file(".")),
-    Project("rootJVM", file(".jvm")),
-    Project("rootJS", file(".js")),
-    Project("rootNative", file(".native"))
+  def apply(): CrossRootProject = CrossRootProject("root")
+
+  def apply(name: String): CrossRootProject = new CrossRootProject(
+    Project(name, file(".")),
+    Project(s"${name}JVM", file(".jvm")),
+    Project(s"${name}JS", file(".js")),
+    Project(s"${name}Native", file(".native"))
   ).enablePlugins(NoPublishPlugin, TypelevelCiCrossPlugin)
 }
 

ci/src/main/scala/org/typelevel/sbt/CrossRootProjectMacros.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 CrossRootProjectMacros {
+
+  // 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 crossRootProjectImpl(c: blackbox.Context): c.Expr[CrossRootProject] = {
+    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.CrossRootProject.apply`"""
+    )
+
+    val name = c.Expr[String](Literal(Constant(enclosingValName)))
+
+    reify { CrossRootProject(name.splice) }
+  }
+}

ci/src/main/scala/org/typelevel/sbt/TypelevelCiPlugin.scala

@@ -21,14 +21,15 @@ import org.typelevel.sbt.gha.GenerativePlugin
 import org.typelevel.sbt.gha.GitHubActionsPlugin
 import org.typelevel.sbt.gha.GenerativePlugin.autoImport._
 import com.typesafe.tools.mima.plugin.MimaPlugin
+import scala.language.experimental.macros
 
 object TypelevelCiPlugin extends AutoPlugin {
 
   override def requires = GitHubActionsPlugin && GenerativePlugin && MimaPlugin
   override def trigger = allRequirements
 
   object autoImport {
-    def tlCrossRootProject: CrossRootProject = CrossRootProject()
+    def tlCrossRootProject: CrossRootProject = macro CrossRootProjectMacros.crossRootProjectImpl
   }
 
   override def buildSettings = Seq(