SI-8044 Allow binding backquoted varid in patterns

Previously, a varid could not be backquoted, so that it was not
possible to introduce variables with names such as `type` in a
match expression.

This commit allows backquoted varids in `case x @ _` and
`case x: Int`. In neither position is a stable id accepted,
that is, an id with leading uppercase.

Therefore, this commit merely relaxes the backquoted varid to
be taken as a normal varid in these contexts.

1 files changed, 7 insertions, 0 deletions

diff --git a/test/files/pos/t8044.scala b/test/files/pos/t8044.scala
new file mode 100644
index 0000000000..8259f06a8a
--- /dev/null
+++ b/test/files/pos/t8044.scala
@@ -0,0 +1,7 @@
+
+trait T {
+  def f = 42 match { case `x` @ _ => x }
+  def g = 42 match { case `type` @ _ => `type` }
+  def h = 42 match { case `type` : Int => `type` }
+  def i = (null: Any) match { case _: Int | _: String => 17 }
+}