blackbox restriction #4: can't customize pattern matching

When an application of a blackbox macro is used as an extractor in a
pattern match, it triggers an unconditional compiler error,
preventing customizations of pattern matching implemented with macros.

2 files changed, 26 insertions, 0 deletions

diff --git a/test/files/neg/macro-blackbox-extractor/Macros_1.scala b/test/files/neg/macro-blackbox-extractor/Macros_1.scala
new file mode 100644
index 0000000000..5c7748bec9
--- /dev/null
+++ b/test/files/neg/macro-blackbox-extractor/Macros_1.scala
@@ -0,0 +1,21 @@
+import scala.reflect.macros.BlackboxContext
+import language.experimental.macros
+
+object Extractor {
+  def unapply(x: Int) = macro Macros.unapplyImpl
+}
+
+object Macros {
+  def unapplyImpl(c: BlackboxContext)(x: c.Tree) = {
+    import c.universe._
+    q"""
+      new {
+        class Match(x: Int) {
+          def isEmpty = false
+          def get = x
+        }
+        def unapply(x: Int) = new Match(x)
+      }.unapply($x)
+    """
+  }
+}
diff --git a/test/files/neg/macro-blackbox-extractor/Test_2.scala b/test/files/neg/macro-blackbox-extractor/Test_2.scala
new file mode 100644
index 0000000000..41be6f9767
--- /dev/null
+++ b/test/files/neg/macro-blackbox-extractor/Test_2.scala
@@ -0,0 +1,5 @@
+object Test extends App {
+  42 match {
+    case Extractor(x) => println(x)
+  }
+}