1 files changed, 24 insertions, 0 deletions
diff --git a/test/pending/pos/t4786.scala b/test/pending/pos/t4786.scala
new file mode 100644
index 0000000000..f0579142b8
--- /dev/null
+++ b/test/pending/pos/t4786.scala
@@ -0,0 +1,24 @@
+trait Matrix[@specialized A, Repr[C] <: Matrix[C, Repr]] { // crash goes away if @specialize is removed
+  def duplicate(mb: MatrixBuilder[A, Repr]): Repr[A] = {
+    mb.zeros
+  }
+}
+trait DenseMatrix[@specialized A] extends Matrix[A, DenseMatrix]
+trait DenseMatrixFlt extends DenseMatrix[Float]
+
+trait MatrixBuilder[@specialized A, Repr[C] <: Matrix[C, Repr]] {
+  def zeros: Repr[A]
+}
+object DenseFloatBuilder extends MatrixBuilder[Float, DenseMatrix] {
+  val zeros = new Object with DenseMatrixFlt
+  // Note:
+  // - in 2.9 crash goes away if the explicit type "DenseMatrixFlt" is assigned to "zeros"
+  // - in 2.9 crash goes away if DenseMatrixFlt is a class instead of a trait:
+  //        val zeros = new DenseMatrixFlt
+}
+
+object Test extends App {
+  val m1 = DenseFloatBuilder.zeros // in 2.9 crash goes away if explicit type "DenseMatrixFlt" is assigned to m1
+  val m2 = m1.duplicate(DenseFloatBuilder)
+}
+