Merge pull request #1818 from scalamacros/topic/auto-duplicate-expansions

macro expansions are now auto-duplicated

6 files changed, 46 insertions, 5 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/Macros.scala b/src/compiler/scala/tools/nsc/typechecker/Macros.scala
index 6ed879af14..768d739b4b 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Macros.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Macros.scala
@@ -694,9 +694,11 @@ trait Macros extends scala.tools.reflect.FastTrack with Traces {
 
             var expectedTpe = expandee.tpe
             if (isNullaryInvocation(expandee)) expectedTpe = expectedTpe.finalResultType
-            var typechecked = typecheck("macro def return type", expanded, expectedTpe)
-            typechecked = typecheck("expected type", typechecked, pt)
-            typechecked
+            // also see http://groups.google.com/group/scala-internals/browse_thread/thread/492560d941b315cc
+            val expanded0 = duplicateAndKeepPositions(expanded)
+            val expanded1 = typecheck("macro def return type", expanded0, expectedTpe)
+            val expanded2 = typecheck("expected type", expanded1, pt)
+            expanded2
           } finally {
             popMacroContext()
           }
diff --git a/src/reflect/scala/reflect/internal/Trees.scala b/src/reflect/scala/reflect/internal/Trees.scala
index 2029fb67b3..35e10d73c8 100644
--- a/src/reflect/scala/reflect/internal/Trees.scala
+++ b/src/reflect/scala/reflect/internal/Trees.scala
@@ -1501,15 +1501,18 @@ trait Trees extends api.Trees { self: SymbolTable =>
     }
   }
 
-  private lazy val duplicator = new Transformer {
+  private lazy val duplicator = new Duplicator(focusPositions = true)
+  private class Duplicator(focusPositions: Boolean) extends Transformer {
     override val treeCopy = newStrictTreeCopier
     override def transform(t: Tree) = {
       val t1 = super.transform(t)
-      if ((t1 ne t) && t1.pos.isRange) t1 setPos t.pos.focus
+      if ((t1 ne t) && t1.pos.isRange && focusPositions) t1 setPos t.pos.focus
       t1
     }
   }
 
+  def duplicateAndKeepPositions(tree: Tree) = new Duplicator(focusPositions = false) transform tree
+
   // ------ copiers -------------------------------------------
 
   def copyDefDef(tree: Tree)(
diff --git a/test/files/run/macro-duplicate.check b/test/files/run/macro-duplicate.check
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/test/files/run/macro-duplicate.check
diff --git a/test/files/run/macro-duplicate.flags b/test/files/run/macro-duplicate.flags
new file mode 100644
index 0000000000..cd66464f2f
--- /dev/null
+++ b/test/files/run/macro-duplicate.flags
@@ -0,0 +1 @@
+-language:experimental.macros
\ No newline at end of file
diff --git a/test/files/run/macro-duplicate/Impls_Macros_1.scala b/test/files/run/macro-duplicate/Impls_Macros_1.scala
new file mode 100644
index 0000000000..de81923330
--- /dev/null
+++ b/test/files/run/macro-duplicate/Impls_Macros_1.scala
@@ -0,0 +1,29 @@
+import scala.reflect.macros.Context
+
+object Macros {
+  def impl(c: Context) = {
+    import c.universe._
+    val Expr(Block((cdef: ClassDef) :: Nil, _)) = reify { class C { def x = 2 } }
+    val cdef1 =
+      new Transformer {
+        override def transform(tree: Tree): Tree = tree match {
+          case Template(_, _, ctor :: defs) =>
+            val defs1 = defs collect {
+              case ddef @ DefDef(mods, name, tparams, vparamss, tpt, body) =>
+                val future = Select(Select(Select(Ident(newTermName("scala")), newTermName("concurrent")), newTermName("package")), newTermName("future"))
+                val Future = Select(Select(Ident(newTermName("scala")), newTermName("concurrent")), newTypeName("Future"))
+                val tpt1 = if (tpt.isEmpty) tpt else AppliedTypeTree(Future, List(tpt))
+                val body1 = Apply(future, List(body))
+                val name1 = newTermName("async" + name.toString.capitalize)
+                DefDef(mods, name1, tparams, vparamss, tpt1, body1)
+            }
+            Template(Nil, emptyValDef, ctor +: defs ::: defs1)
+          case _ =>
+            super.transform(tree)
+        }
+      } transform cdef
+    c.Expr[Unit](Block(cdef1 :: Nil, Literal(Constant(()))))
+  }
+
+  def foo = macro impl
+}
\ No newline at end of file
diff --git a/test/files/run/macro-duplicate/Test_2.scala b/test/files/run/macro-duplicate/Test_2.scala
new file mode 100644
index 0000000000..6dbd4382d3
--- /dev/null
+++ b/test/files/run/macro-duplicate/Test_2.scala
@@ -0,0 +1,6 @@
+import scala.concurrent._
+import ExecutionContext.Implicits.global
+
+object Test extends App {
+  Macros.foo
+}
\ No newline at end of file