reifyAnnotations

Annotations are now supported by the reifier:
* AnnotationInfos from symbols get transformed back into mods.
* AnnotatedTypes are retained and are reified along with AnnotationInfos.

Reification is no magic, and reification of annotations especially:
* Annotations cannot refer to symbols defined inside the quasiquote.
  This restriction is due to the fact that we need to erase locally defined
  symbols before reifying to make subsequent reflective compilations succeed.
  However, while doing that, we also need to make sure that we don't make
  resulting ASTs non-compilable by removing essential information.
  This is tricky, and it more or less works for TypeTrees, but
  not for annotations that can contain arbitrary ASTs.
  For more details look into the comments to Reifiers.scala.
* Classfile annotations that contain array arguments and are applied to types,
  i.e. the ones that generate AnnotatedTypes, cannot be reified.
  This is because of limitations of manifest infrastructure.
  Typechecking "Array(mirror.LiteralAnnotArg(...))" would require the compiler
  to produce a manifest for a path-dependent type, which cannot be done now.

Review by @odersky.

1 files changed, 41 insertions, 6 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/Macros.scala b/src/compiler/scala/tools/nsc/typechecker/Macros.scala
index 48ec59234e..ed249796a8 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Macros.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Macros.scala
@@ -49,7 +49,7 @@ trait Macros { self: Analyzer =>
    *  If `foo` is declared in an object, the second parameter list is () instead of (_this: _context.Tree).
    *  If macro has no type arguments, the third parameter list is omitted (it's not empty, but omitted altogether).
    *
-   *  To find out the desugared representation of your particular macro, compile it with -Ydebug.
+   *  To find out the desugared representation of your particular macro, compile it with -Ymacro-debug.
    */
   def macroMethDef(mdef: DefDef): Tree = {
     def paramDef(name: Name, tpt: Tree) = ValDef(Modifiers(PARAM), name, tpt, EmptyTree)
@@ -86,7 +86,7 @@ trait Macros { self: Analyzer =>
 
   def addMacroMethods(templ: Template, namer: Namer): Unit = {
     for (ddef @ DefDef(mods, _, _, _, _, _) <- templ.body if mods hasFlag MACRO) {
-      val trace = scala.tools.nsc.util.trace when settings.debug.value
+      val trace = scala.tools.nsc.util.trace when settings.Ymacrodebug.value
       val sym = namer.enterSyntheticSym(trace("macro def: ")(macroMethDef(ddef)))
       trace("added to "+namer.context.owner.enclClass+": ")(sym)
     }
@@ -106,16 +106,43 @@ trait Macros { self: Analyzer =>
    *  not contain the macro implementation.
    */
   def macroImpl(mac: Symbol): Option[(AnyRef, mirror.Symbol)] = {
+    val debug = settings.Ymacrodebug.value
+    val trace = scala.tools.nsc.util.trace when debug
+    trace("looking for macro implementation: ")(mac.fullNameString)
+
     try {
       val mmeth = macroMeth(mac)
+      trace("found implementation at: ")(mmeth.fullNameString)
+
       if (mmeth == NoSymbol) None
       else {
         val receiverClass: mirror.Symbol = mirror.symbolForName(mmeth.owner.fullName)
+        if (debug) {
+          println("receiverClass is: " + receiverClass.fullNameString)
+
+          val jreceiverClass = mirror.classToJava(receiverClass)
+          val jreceiverSource = jreceiverClass.getProtectionDomain.getCodeSource
+          println("jreceiverClass is %s from %s".format(jreceiverClass, jreceiverSource))
+
+          val jreceiverClasspath = jreceiverClass.getClassLoader match {
+            case cl: java.net.URLClassLoader => "[" + (cl.getURLs mkString ",") + "]"
+            case _ => "<unknown>"
+          }
+          println("jreceiverClassLoader is %s with classpath %s".format(jreceiverClass.getClassLoader, jreceiverClasspath))
+        }
+
         val receiverObj = receiverClass.companionModule
+        trace("receiverObj is: ")(receiverObj.fullNameString)
+
         if (receiverObj == mirror.NoSymbol) None
         else {
           val receiver = mirror.companionInstance(receiverClass)
           val rmeth = receiverObj.info.member(mirror.newTermName(mmeth.name.toString))
+          if (debug) {
+            println("rmeth is: " + rmeth.fullNameString)
+            println("jrmeth is: " + mirror.methodToJava(rmeth))
+          }
+
           if (rmeth == mirror.NoSymbol) None
           else {
             Some((receiver, rmeth))
@@ -133,16 +160,21 @@ trait Macros { self: Analyzer =>
    *  tree that calls this method instead of the macro.
    */
   def macroExpand(tree: Tree, context: Context): Option[Any] = {
+    val trace = scala.tools.nsc.util.trace when settings.Ymacrodebug.value
+    trace("macroExpand: ")(tree)
+
     val macroDef = tree.symbol
     macroImpl(macroDef) match {
       case Some((receiver, rmeth)) =>
         val argss = List(global) :: macroArgs(tree)
         val paramss = macroMeth(macroDef).paramss
+        trace("paramss: ")(paramss)
         val rawArgss = for ((as, ps) <- argss zip paramss) yield {
           if (isVarArgsList(ps)) as.take(ps.length - 1) :+ as.drop(ps.length - 1)
           else as
         }
         val rawArgs: Seq[Any] = rawArgss.flatten
+        trace("rawArgs: ")(rawArgs)
         val savedInfolevel = nodePrinters.infolevel
         try {
           // @xeno.by: InfoLevel.Verbose examines and prints out infos of symbols
@@ -156,16 +188,19 @@ trait Macros { self: Analyzer =>
         } catch {
           case ex =>
             val realex = ReflectionUtils.unwrapThrowable(ex)
-            val stacktrace = new java.io.StringWriter()
-            realex.printStackTrace(new java.io.PrintWriter(stacktrace))
-            val msg = System.getProperty("line.separator") + stacktrace
+            val msg = if (settings.Ymacrodebug.value) {
+              val stacktrace = new java.io.StringWriter()
+              realex.printStackTrace(new java.io.PrintWriter(stacktrace))
+              System.getProperty("line.separator") + stacktrace
+            } else {
+              realex.getMessage
+            }
             context.unit.error(tree.pos, "exception during macro expansion: " + msg)
             None
         } finally {
           nodePrinters.infolevel = savedInfolevel
         }
       case None =>
-        val trace = scala.tools.nsc.util.trace when settings.debug.value
         def notFound() = {
           context.unit.error(tree.pos, "macro implementation not found: " + macroDef.name)
           None