[backport] no longer warns on calls to vampire macros

As eloquently elaborated and cleverly named by Travis Brown, macros
defined in structural types are useful:
http://meta.plasm.us/posts/2013/07/12/vampire-methods-for-structural-types/.

However, since such macros are on the intersection of a number of language
features, as usual, there are bugs.

This commit fixes an unwanted interaction of macros defined in structural
types with the scala.language.reflectiveCalls guard. Since macro calls
aren't going to be carried to runtime, there's no need to warn about them.

5 files changed, 62 insertions, 1 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index e09a509839..8153766784 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -4934,7 +4934,7 @@ trait Typers extends Modes with Adaptations with Tags {
 
             if (tree.isInstanceOf[PostfixSelect])
               checkFeature(tree.pos, PostfixOpsFeature, name.decode)
-            if (tree1.symbol != null && tree1.symbol.isOnlyRefinementMember)
+            if (tree1.symbol != null && tree1.symbol.isOnlyRefinementMember && !tree1.symbol.isMacro)
               checkFeature(tree1.pos, ReflectiveCallsFeature, tree1.symbol.toString)
 
             if (qual1.hasSymbolWhich(_.isRootPackage)) treeCopy.Ident(tree1, name)
diff --git a/test/files/run/macro-vampire-false-warning.check b/test/files/run/macro-vampire-false-warning.check
new file mode 100644
index 0000000000..4792e70f33
--- /dev/null
+++ b/test/files/run/macro-vampire-false-warning.check
@@ -0,0 +1,2 @@
+2
+3
diff --git a/test/files/run/macro-vampire-false-warning.flags b/test/files/run/macro-vampire-false-warning.flags
new file mode 100644
index 0000000000..e8fb65d50c
--- /dev/null
+++ b/test/files/run/macro-vampire-false-warning.flags
@@ -0,0 +1 @@
+-Xfatal-warnings
\ No newline at end of file
diff --git a/test/files/run/macro-vampire-false-warning/Macros_1.scala b/test/files/run/macro-vampire-false-warning/Macros_1.scala
new file mode 100644
index 0000000000..a1c40a5510
--- /dev/null
+++ b/test/files/run/macro-vampire-false-warning/Macros_1.scala
@@ -0,0 +1,52 @@
+// As per http://meta.plasm.us/posts/2013/08/31/feeding-our-vampires/
+
+import scala.annotation.StaticAnnotation
+import scala.reflect.macros.Context
+import scala.language.experimental.macros
+
+class body(tree: Any) extends StaticAnnotation
+
+object Macros {
+  def selFieldImpl(c: Context) = {
+    import c.universe._
+    val field = c.macroApplication.symbol
+    val bodyAnn = field.annotations.filter(_.tpe <:< typeOf[body]).head
+    c.Expr[Any](bodyAnn.scalaArgs.head)
+  }
+
+  def mkObjectImpl(c: Context)(xs: c.Expr[Any]*) = {
+    import c.universe._
+    import Flag._
+    // val kvps = xs.toList map { case q"${_}(${Literal(Constant(name: String))}).->[${_}]($value)" => name -> value }
+    val kvps = xs.map(_.tree).toList map { case Apply(TypeApply(Select(Apply(_, List(Literal(Constant(name: String)))), _), _), List(value)) => name -> value }
+    // val fields = kvps map { case (k, v) => q"@body($v) def ${TermName(k)} = macro Macros.selFieldImpl" }
+    val fields = kvps map { case (k, v) => DefDef(
+      Modifiers(MACRO, tpnme.EMPTY, List(Apply(Select(New(Ident(newTypeName("body"))), nme.CONSTRUCTOR), List(v)))),
+      newTermName(k), Nil, Nil, TypeTree(), Select(Ident(newTermName("Macros")), newTermName("selFieldImpl"))) }
+    // q"import scala.language.experimental.macros; class Workaround { ..$fields }; new Workaround{}"
+    c.Expr[Any](Block(
+      List(
+        Import(Select(Select(Ident(newTermName("scala")), newTermName("language")), newTermName("experimental")), List(ImportSelector(newTermName("macros"), 51, newTermName("macros"), 51))),
+        ClassDef(
+          NoMods, newTypeName("Workaround"), Nil,
+          Template(
+            List(Select(Ident(newTermName("scala")), newTypeName("AnyRef"))), emptyValDef,
+            DefDef(
+              NoMods, nme.CONSTRUCTOR, Nil, List(Nil), TypeTree(),
+              Block(List(Apply(Select(Super(This(tpnme.EMPTY), tpnme.EMPTY), nme.CONSTRUCTOR), List())), Literal(Constant(()))))
+            +: fields)),
+        ClassDef(
+          Modifiers(FINAL), newTypeName("$anon"), Nil,
+          Template(
+            List(Ident(newTypeName("Workaround"))), emptyValDef,
+            List(
+              DefDef(
+                NoMods, nme.CONSTRUCTOR, Nil, List(Nil), TypeTree(),
+                Block(List(Apply(Select(Super(This(tpnme.EMPTY), tpnme.EMPTY), nme.CONSTRUCTOR), List())), Literal(Constant(())))))))),
+      Apply(Select(New(Ident(newTypeName("$anon"))), nme.CONSTRUCTOR), List())))
+  }
+}
+
+object mkObject {
+  def apply(xs: Any*) = macro Macros.mkObjectImpl
+}
diff --git a/test/files/run/macro-vampire-false-warning/Test_2.scala b/test/files/run/macro-vampire-false-warning/Test_2.scala
new file mode 100644
index 0000000000..6e44b68635
--- /dev/null
+++ b/test/files/run/macro-vampire-false-warning/Test_2.scala
@@ -0,0 +1,6 @@
+object Test extends App {
+  val foo = mkObject("x" -> "2", "y" -> 3)
+  println(foo.x)
+  println(foo.y)
+  // println(foo.z) => will result in a compilation error
+}
\ No newline at end of file