SI-5900 Fix pattern inference regression

This commit does not close SI-5900. It only addresses a regression
in 2.11 prereleases caused by SI-7886.

The fix for SI-7886 was incomplete (as shown by the last commit)
and incorrect (as shown by the regression in pos/t5900a.scala and
the fact it ended up inferring type parameters.)

I believe that the key to fixing this problem will be unifying
the inference of case class constructor patterns and extractor
patterns.

I've explored that idea:

  https://gist.github.com/retronym/7704153
  https://github.com/retronym/scala/compare/ticket/5900

But didn't quite get there.

1 files changed, 9 insertions, 0 deletions

diff --git a/test/files/pos/t5900a.scala b/test/files/pos/t5900a.scala
new file mode 100644
index 0000000000..cb02f67fb2
--- /dev/null
+++ b/test/files/pos/t5900a.scala
@@ -0,0 +1,9 @@
+case class Transition[S](x: S)
+
+object C
+
+object Test {
+  (??? : Any) match {
+    case Transition(C) =>
+  }
+}