SI-6022 cleaner model of variable equality modulo <:

a more conservative "excludes": no need to reason about types

(TODO: check we don't get any spurious unreachability errors
 in the eclipse build, which is a good canary for this kind of thing)

1 files changed, 20 insertions, 0 deletions

diff --git a/test/files/pos/t6022b.scala b/test/files/pos/t6022b.scala
new file mode 100644
index 0000000000..6ceb928162
--- /dev/null
+++ b/test/files/pos/t6022b.scala
@@ -0,0 +1,20 @@
+trait A
+trait B
+trait C
+trait AB extends B with A
+
+// two types are mutually exclusive if there is no equality symbol whose constant implies both
+object Test extends App {
+  def foo(x: Any) = x match {
+    case _ : C  => println("C")
+    case _ : AB => println("AB")
+    case _ : (A with B) => println("AB'")
+    case _ : B  => println("B")
+    case _ : A  => println("A")
+  }
+
+  foo(new A {})
+  foo(new B {})
+  foo(new AB{})
+  foo(new C {})
+}