add scripted test for macro mixing

Author: johnduffell

Diff for: sbt-test/scala2-compat/i16630/build.sbt

@@ -0,0 +1,24 @@
+val scala3Version = sys.props("plugin.scalaVersion")
+val scala2Version = sys.props("plugin.scala2Version")
+
+lazy val scala2 = project.in(file("scala2"))
+  .settings(
+    scalaVersion := scala2Version,
+    libraryDependencies += "org.scala-lang" % "scala-reflect" % scalaVersion.value
+  )
+
+lazy val scala3 = project.in(file("scala3"))
+  .settings(
+    scalaVersion := scala3Version
+  )
+  .dependsOn(scala2)
+
+lazy val `scala2-test` = project.in(file("scala2-test"))
+  .settings(
+    scalaVersion := scala2Version,
+    scalacOptions ++= Seq(
+      "-Ytasty-reader",
+      // TODO add an option here to let scalac read experimental tasty files
+    ),
+  )
+  .dependsOn(scala3)

Diff for: sbt-test/scala2-compat/i16630/scala2-test/TestScala2.scala

@@ -0,0 +1,9 @@
+object TestScala2 extends App {
+  private val line: Any = Macros.location.line
+  if (line != 2) {
+    println("test failed: " + line)
+    System.exit(1)
+  } else
+    println("test passed: " + line)
+  TestScala3
+}

Diff for: sbt-test/scala2-compat/i16630/scala2/Scala2MacrosCompat.scala

@@ -0,0 +1,14 @@
+import scala.reflect.macros.blackbox.Context
+import scala.language.experimental.macros
+
+case class Location(path: String, line: Int)
+
+object Scala2MacrosCompat {
+  def locationImpl[T](c: Context): c.Tree =  {
+    import c.universe._
+    val location = typeOf[Location]
+    val line = Literal(Constant(c.enclosingPosition.line))
+    val path = Literal(Constant(c.enclosingPosition.source.path))
+    q"new $location($path, $line)"
+  }
+}

Diff for: sbt-test/scala2-compat/i16630/scala3/Macros.scala

@@ -0,0 +1,19 @@
+
+import scala.quoted.{Quotes, Expr}
+import scala.language.experimental.macros
+
+case class Location[T](path: String, line: Int)
+
+class Macros[T]:
+  def location: Location[T] = macro Scala2MacrosCompat.locationImpl
+  inline def location: Location[T] = ${Macros.locationImpl}
+
+object Macros:
+
+  import scala.quoted.*
+  def locationImpl[T: Type](using quotes: Quotes): Expr[Location[T]] =
+    import quotes.reflect.Position
+    val file = Expr(Position.ofMacroExpansion.sourceFile.jpath.toString)
+    val line = Expr(Position.ofMacroExpansion.startLine + 1)
+    '{new Location[T]($file, $line)}
+

Diff for: sbt-test/scala2-compat/i16630/scala3/TestScala3.scala

@@ -0,0 +1,11 @@
+def TestScala3 = {
+  val line: Any = new Macros[Unit].location.line
+  if (line != 2) {
+    println("test failed: " + line)
+    System.exit(1)
+  } else
+    println("test passed: " + line)
+}
+object TestScala3App extends App {
+  TestScala3
+}

Diff for: sbt-test/scala2-compat/i16630/test

@@ -0,0 +1,6 @@
+# This test is based loosely on https://docs.scala-lang.org/scala3/guides/migration/tutorial-macro-mixing.html
+# Unfortunately Scala 2.13 refuses to read "experimental" tasty files, so the test is incomplete.
+# However, the original issue was a failure to compile, so the full test is not essential.
+
+# FIXME change the line below to scala2-test/run once we can make scala 2.13 read experimental scala 3 tasty files
+> scala3/run