Add a Scala 2 test sources project, and test Scala 2 macro reading.

build.sbt

@@ -5,6 +5,7 @@ import org.scalajs.jsenv.nodejs.NodeJSEnv
 
 val usedScalaCompiler = "3.3.1"
 val usedTastyRelease = usedScalaCompiler
+val scala2Version = "2.13.12"
 
 val SourceDeps = config("sourcedeps").hide
 
@@ -61,6 +62,17 @@ lazy val root = project.in(file("."))
     publish / skip := true,
   )
 
+lazy val scala2TestSources = crossProject(JSPlatform, JVMPlatform)
+  .crossType(CrossType.Pure)
+  .in(file("scala2-test-sources"))
+  .settings(commonSettings)
+  .settings(
+    scalaVersion := scala2Version,
+    publish / skip := true,
+    scalacOptions += "-Xfatal-warnings",
+    libraryDependencies += "org.scala-lang" % "scala-reflect" % scalaVersion.value % "provided",
+  )
+
 lazy val testSources = crossProject(JSPlatform, JVMPlatform)
   .crossType(CrossType.Pure)
   .in(file("test-sources"))
@@ -70,6 +82,7 @@ lazy val testSources = crossProject(JSPlatform, JVMPlatform)
     scalacOptions += "-Xfatal-warnings",
     javacOptions += "-parameters",
   )
+  .dependsOn(scala2TestSources)
 
 lazy val tastyQuery =
   crossProject(JSPlatform, JVMPlatform).in(file("tasty-query"))

scala2-test-sources/src/main/scala/scalatwo/Macros.scala

@@ -0,0 +1,11 @@
+package scalatwo
+
+import scala.language.experimental.macros
+
+import scala.reflect.macros.blackbox.Context
+
+object Macros {
+  def foo[X](x: X): Any = macro fooImpl[X]
+
+  def fooImpl[X](c: Context)(x: c.Expr[X]): c.Expr[Any] = ???
+}

tasty-query/shared/src/test/scala/tastyquery/TypeSuite.scala

@@ -3661,4 +3661,20 @@ class TypeSuite extends UnrestrictedUnpicklingSuite {
     val GenericJavaClass = ctx.findTopLevelClass("javadefined.GenericJavaClass")
     assert(clue(GenericJavaClass.getDecl(typeName("MyInner"))).exists(_.isClass))
   }
+
+  testWithContext("scala-2-macro-definition") {
+    val MacrosClass = ctx.findTopLevelModuleClass("scalatwo.Macros")
+    val macroImplAnnotClass = ctx.findTopLevelClass("scala.reflect.macros.internal.macroImpl")
+
+    val foo = MacrosClass.findNonOverloadedDecl(termName("foo"))
+    assert(foo.isMacro)
+
+    val annotImplMacro = foo.getAnnotation(macroImplAnnotClass).get
+    annotImplMacro.arguments.head match
+      case TypeApply(Apply(macroIdent @ Ident(macroName), _), _) =>
+        assert(clue(macroName) == nme.m_macro)
+        assert(clue(macroIdent.symbol) == defn.scala2MacroInfoFakeMethod)
+      case arg =>
+        fail("unexpected argument to @macroImpl", clues(arg))
+  }
 }