SI-8044 Allow any id in explicit pattern binding

Allows arbitrary identifier in `X @ pat`, including
non-varids. This goes to regularity.

Users of this syntax are not likely to be confused
by the "backquoted var id is stable" rule.

Also for sequence pattern, `X @ _*`.

1 files changed, 8 insertions, 0 deletions

diff --git a/test/files/pos/t8044.scala b/test/files/pos/t8044.scala
index 8259f06a8a..2519a8306b 100644
--- a/test/files/pos/t8044.scala
+++ b/test/files/pos/t8044.scala
@@ -4,4 +4,12 @@ trait T {
   def g = 42 match { case `type` @ _ => `type` }
   def h = 42 match { case `type` : Int => `type` }
   def i = (null: Any) match { case _: Int | _: String => 17 }
+
+  // arbitrary idents allowed in @ syntax
+  def j = "Fred" match { case Name @ (_: String) => Name }
+  def k = "Fred" match { case * @ (_: String) => * }
+
+  // also in sequence pattern
+  def m = List(1,2,3,4,5) match { case List(1, `Rest of them` @ _*) => `Rest of them` }
+
 }