From 2aa68419c09ba16e4e7fdc71e4a3ad9e8b261e87 Mon Sep 17 00:00:00 2001
From: Jason Zaugg <jzaugg@gmail.com>
Date: Sat, 17 Nov 2012 22:04:19 +0100
Subject: SI-6677 Insert required cast in `new qual.foo.T`

Short version: we sometimes need to rewrite this as

    new T(qual.asInstanceOf[OwnerOfFoo].foo)

Long version:

`adaptMember` in Erasure performs a few tasks, among them:

1. adding an empty argument list to qualifiers in `new qual.T`
    for which `qual` is a val template member that has
    (post uncurry) a MethodType with an empty parameter list.

    The same rewriting was already applied in uncurry for such
    qualifiers appearing in other contexts, e.g. `qual.foo` was
    already rewritten to `qual().foo`.
2. casting, if necessary, the qualifier in `Select(qual, name)`
    to the type of owner of the symbol that this selection
    references.

    This can be neccesary with compound types:
     - some val class member has type `A with B`;
     - we instantiate `new ab.valMemberOfB.T`
     - we must pass `ab.valMemberOfB` to the constructor of `T`
       as the `$outer` pointer
     - we must cast `ab` to `B` before calling `valMemberOfB`.

    Failure to insert this cast can lead to a LinkageError or
    a VerifyError.

However, if 1) was performed, 2) was not.

The error is pretty easy to trigger with the new reflection
API:

    class Test {
      val cm: reflect.runtime.universe.Mirror
          = reflect.runtime.currentMirror
      def error {
        new cm.universe.Traverser // java.lang.VerifyError
      }

      def okay1 {
        val cm: reflect.runtime.universe.Mirror = reflect.runtime.currentMirror
        new cm.universe.Traverser
      }
    }

The fix applied here to `adaptMember` mirrors the existing
implementation of `adaptType`.
---
 test/files/run/t6677b.scala | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)
 create mode 100644 test/files/run/t6677b.scala

(limited to 'test/files/run/t6677b.scala')

diff --git a/test/files/run/t6677b.scala b/test/files/run/t6677b.scala
new file mode 100644
index 0000000000..e4fe5e3722
--- /dev/null
+++ b/test/files/run/t6677b.scala
@@ -0,0 +1,33 @@
+trait U {
+	trait U1 {
+		class X
+	}
+	type U11 <: U1
+  val u : U11 = null.asInstanceOf[U11]
+}
+trait A extends U
+
+trait B extends U {
+  def foo = ""
+  class U11 extends U1 { class X extends super.X { foo } } // refer to foo to add $outer pointer
+  override val u = new U11
+}
+class C {
+  val ab: A with B = new A with B // `B with A` works.
+
+  def foo {
+    // fails
+    new ab.u.X
+
+    // works:
+    val u = ab.u
+    new u.X
+  }
+}
+object Test {
+	def main(args: Array[String]) {
+    // java.lang.NoSuchMethodError: A.u()LB$U11;
+    // at C.foo(t6677b.scala:23)
+		new C().foo
+	}
+}
-- 
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