blackbox restriction #1: can't refine the official return type

When an application of a blackbox macro expands into a tree `x`,
the expansion is wrapped into a type ascription `(x: T)`, where `T` is
the declared return type of the blackbox macro with type arguments and
path dependencies applied in consistency with the particular macro
application being expanded.

This invalidates blackbox macros as an implementation vehicle
of type providers.

5 files changed, 28 insertions, 4 deletions

diff --git a/test/files/neg/macro-blackbox-structural.check b/test/files/neg/macro-blackbox-structural.check
new file mode 100644
index 0000000000..86a218559c
--- /dev/null
+++ b/test/files/neg/macro-blackbox-structural.check
@@ -0,0 +1,4 @@
+Test_2.scala:4: error: value x is not a member of Any
+  println(Macros.foo.x)
+                     ^
+one error found
diff --git a/test/files/neg/macro-blackbox-structural/Impls_Macros_1.scala b/test/files/neg/macro-blackbox-structural/Impls_Macros_1.scala
new file mode 100644
index 0000000000..08f1c21e89
--- /dev/null
+++ b/test/files/neg/macro-blackbox-structural/Impls_Macros_1.scala
@@ -0,0 +1,15 @@
+import scala.language.experimental.macros
+
+object Macros {
+  def impl(c: scala.reflect.macros.BlackboxContext) = {
+    import c.universe._
+    q"""
+      trait Foo {
+        def x = 2
+      }
+      new Foo {}
+    """
+  }
+
+  def foo = macro impl
+}
\ No newline at end of file
diff --git a/test/files/neg/macro-blackbox-structural/Test_2.scala b/test/files/neg/macro-blackbox-structural/Test_2.scala
new file mode 100644
index 0000000000..ea6a817e34
--- /dev/null
+++ b/test/files/neg/macro-blackbox-structural/Test_2.scala
@@ -0,0 +1,5 @@
+import Macros._
+
+object Test extends App {
+  println(Macros.foo.x)
+}
\ No newline at end of file
diff --git a/test/files/neg/t5903a/Macros_1.scala b/test/files/neg/t5903a/Macros_1.scala
index 9fc3bfe261..7888b888e1 100644
--- a/test/files/neg/t5903a/Macros_1.scala
+++ b/test/files/neg/t5903a/Macros_1.scala
@@ -1,4 +1,4 @@
-import scala.reflect.macros.BlackboxContext
+import scala.reflect.macros.WhiteboxContext
 import language.experimental.macros
 
 trait Tree
@@ -13,7 +13,7 @@ object NewQuasiquotes {
 }
 
 object QuasiquoteMacros {
-  def unapplyImpl(c: BlackboxContext)(t: c.Tree) = {
+  def unapplyImpl(c: WhiteboxContext)(t: c.Tree) = {
     import c.universe._
     q"""
       new {
diff --git a/test/files/neg/t5903e/Macros_1.scala b/test/files/neg/t5903e/Macros_1.scala
index 13e168d529..997e6fd073 100644
--- a/test/files/neg/t5903e/Macros_1.scala
+++ b/test/files/neg/t5903e/Macros_1.scala
@@ -1,4 +1,4 @@
-import scala.reflect.macros.BlackboxContext
+import scala.reflect.macros.WhiteboxContext
 import language.experimental.macros
 
 object Interpolation {
@@ -10,7 +10,7 @@ object Interpolation {
 }
 
 object Macros {
-  def unapplyImpl(c: BlackboxContext)(x: c.Tree) = {
+  def unapplyImpl(c: WhiteboxContext)(x: c.Tree) = {
     import c.universe._
     q"""
       new {