4 files changed, 65 insertions, 3 deletions
diff --git a/test/files/neg/t6526.check b/test/files/neg/t6526.check
new file mode 100644
index 0000000000..606c18c301
--- /dev/null
+++ b/test/files/neg/t6526.check
@@ -0,0 +1,16 @@
+t6526.scala:8: error: could not optimize @tailrec annotated method inner: it contains a recursive call not in tail position
+    @tailrec def inner(i: Int): Int = 1 + inner(i)
+                                        ^
+t6526.scala:14: error: could not optimize @tailrec annotated method inner: it contains a recursive call not in tail position
+    @tailrec def inner(i: Int): Int = 1 + inner(i)
+                                        ^
+t6526.scala:20: error: could not optimize @tailrec annotated method inner: it contains a recursive call not in tail position
+    @tailrec def inner(i: Int): Int = 1 + inner(i)
+                                        ^
+t6526.scala:30: error: could not optimize @tailrec annotated method inner: it contains a recursive call not in tail position
+        @tailrec def inner(i: Int): Int = 1 + inner(i)
+                                            ^
+t6526.scala:39: error: could not optimize @tailrec annotated method inner: it contains a recursive call not in tail position
+    def inner(i: Int): Int = 1 + inner(i)
+                               ^
+5 errors found
diff --git a/test/files/neg/t6526.scala b/test/files/neg/t6526.scala
new file mode 100644
index 0000000000..0bc249aa98
--- /dev/null
+++ b/test/files/neg/t6526.scala
@@ -0,0 +1,41 @@
+import scala.annotation.tailrec
+
+class TailRec {
+  def bar(f: => Any) = ""
+
+  // transform the qualifier of a Select
+  bar {
+    @tailrec def inner(i: Int): Int = 1 + inner(i)
+    inner(0)
+  }.length
+
+  // transform the body of a function
+  () => {
+    @tailrec def inner(i: Int): Int = 1 + inner(i)
+    inner(0)
+  }
+
+  // transform the qualifier of a Select
+  {
+    @tailrec def inner(i: Int): Int = 1 + inner(i)
+    inner(0)
+    ""
+  }.length
+
+  // The receiver of a tail recursive call must itself be transformed
+  object X {
+    @tailrec // okay, all other annotated methods should fail.
+    def foo: Any = {
+      {
+        @tailrec def inner(i: Int): Int = 1 + inner(i)
+        inner(0)
+        this
+      }.foo
+    }
+  }
+
+  Some(new AnyRef) map { phooie =>
+    @tailrec
+    def inner(i: Int): Int = 1 + inner(i)
+  } getOrElse 42
+}
diff --git a/test/files/neg/unchecked-knowable.check b/test/files/neg/unchecked-knowable.check
index 3a6ef994b5..d279427327 100644
--- a/test/files/neg/unchecked-knowable.check
+++ b/test/files/neg/unchecked-knowable.check
@@ -1,4 +1,7 @@
-unchecked-knowable.scala:17: error: fruitless type test: a value of type Bippy cannot also be a A1
+unchecked-knowable.scala:18: error: fruitless type test: a value of type Bippy cannot also be a A1
   /*   warn */ (new Bippy).isInstanceOf[A1]
                                        ^
-one error found
+unchecked-knowable.scala:19: error: fruitless type test: a value of type Bippy cannot also be a B1
+  /*   warn */ (new Bippy).isInstanceOf[B1]
+                                       ^
+two errors found
diff --git a/test/files/neg/unchecked-knowable.scala b/test/files/neg/unchecked-knowable.scala
index 667b47f504..21624c4fb4 100644
--- a/test/files/neg/unchecked-knowable.scala
+++ b/test/files/neg/unchecked-knowable.scala
@@ -7,6 +7,7 @@ final class A4 extends A2
 /** Unknowable */
 sealed abstract class B1
 sealed abstract class B2 extends B1
+sealed trait B2B extends B1
 final class B3 extends B1
 trait B4 extends B2
 
@@ -15,6 +16,7 @@ trait Dingus
 
 class A {
   /*   warn */ (new Bippy).isInstanceOf[A1]
-  /* nowarn */ (new Bippy).isInstanceOf[B1]
+  /*   warn */ (new Bippy).isInstanceOf[B1]
+  /* nowarn */ (null: Dingus).isInstanceOf[B1]
   /* nowarn */ ((new Bippy): Any).isInstanceOf[A1]
 }