Fix #8151: Make setGivenApply more flexible.

Author: odersky

compiler/src/dotty/tools/dotc/ast/Trees.scala

@@ -440,7 +440,7 @@ object Trees {
     type ThisTree[-T >: Untyped] = Apply[T]
 
     def isGivenApply = hasAttachment(untpd.ApplyGiven)
-    def setGivenApply() = { pushAttachment(untpd.ApplyGiven, ()); this }
+    def setGivenApply() = { putAttachment(untpd.ApplyGiven, ()); this }
   }
 
   /** fun[args] */

tests/pos/i8151.scala

@@ -0,0 +1,6 @@
+trait A
+trait B
+object O{
+  def m(using x:A = null)(using y:B = null) = 1
+  def n = m
+}