SI-6541 valid wildcard existentials for case-module-unapply

Instead of letting the compiler infer the return type of case module
unapply methods, provide them explicitly.

This is enabled only under -Xsource:2.12, because the change is not
source compatible.

1 files changed, 19 insertions, 0 deletions

diff --git a/test/files/run/t6541-option.scala b/test/files/run/t6541-option.scala
new file mode 100644
index 0000000000..2c10c9e09d
--- /dev/null
+++ b/test/files/run/t6541-option.scala
@@ -0,0 +1,19 @@
+import scala.tools.partest.ReplTest
+
+object Test extends ReplTest {
+  def code = """
+:setting -Xsource:2.12
+case class C12(clazz: Class[_])
+val o: Option[Class[T] forSome { type T}] = C12.unapply(C12(classOf[String]))
+
+:setting -Xsource:2.11
+import scala.language.existentials
+case class C11(clazz: Class[_])
+val o: Option[Class[T]] forSome { type T } = C11.unapply(C11(classOf[String]))
+  """
+
+  override def show() = {
+    val r = eval().mkString("\n")
+    assert(!(r.contains("warning") || r.contains("error")), r)
+  }
+}