Status quo clashing of given names in for desugar

Author: som-snytt

tests/neg/i23119.check

@@ -0,0 +1,6 @@
+-- [E161] Naming Error: tests/neg/i23119.scala:7:4 ---------------------------------------------------------------------
+7 |    given Option[List[Int]] = Some(List(x)) // error
+  |    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+  |    given_Option_List is already defined as given instance given_Option_List
+  |
+  |    Note that overloaded methods must all be defined in the same group of toplevel definitions

tests/neg/i23119.scala

@@ -0,0 +1,13 @@
+
+@main def test = println:
+  for x <- 1 to 2
+    // works with explicit name
+    //ols @ given Option[List[String]] = Some(List(x.toString))
+    given Option[List[String]] = Some(List(x.toString))
+    given Option[List[Int]] = Some(List(x)) // error
+  yield summon[Option[List[String]]].map(ss => ss.corresponds(given_Option_List.get)((a, b) => a == b.toString))
+
+// The naming clash is noticed when defining local values for "packaging":
+//  given_Option_List is already defined as given instance given_Option_List
+// Previously the naming clash was noticed when extracting values in the map or do function:
+//  duplicate pattern variable: given_Option_List