Test term ref scrutinees aren't generally widened

Co-Authored-By: Matt Bovel <matthieu@bovel.net>

Author: dwijnand

tests/neg/mt-scrutinee-widen.scala

@@ -0,0 +1,24 @@
+// We widen scrutinee's that are inline proxies
+// But make sure that term refs in scrutinees are not widened in general
+
+val x: Int = 42
+val y: Int = 43
+val z: Int = 44
+
+type IsX[T] =
+    T match
+        case x.type => true
+        case _ => false
+def test = summon[IsX[y.type] =:= IsX[z.type]] // error
+
+def test2 = summon[
+  (
+    y.type match
+      case x.type => true
+      case _ => false
+  ) =:= (
+    z.type match
+          case x.type => true
+          case _ => false
+  )
+] // error