Backport "Fix outerSelect in Inliner" to LTS (#21094)

Backports #20313 to the LTS branch.

PR submitted by the release tooling.
[skip ci]

Author: WojciechMazur

compiler/src/dotty/tools/dotc/inlines/Inliner.scala

@@ -315,7 +315,7 @@ class Inliner(val call: tpd.Tree)(using Context):
               case Super(qual, _) => qual
               case pre => pre
             val preLevel = classNestingLevel(inlinedMethod.owner)
-            if preLevel > level then outerSelect(pre, inlinedMethod.owner, preLevel - level, selfSym.info)
+            if preLevel > level then outerSelect(pre, inlinedMethod.owner.enclosingClass, preLevel - level, selfSym.info)
             else pre
 
       val binding = accountForOpaques(

tests/pos/i20300.scala

@@ -0,0 +1,8 @@
+trait T:
+
+  def v() = ()
+
+  trait F:
+    def f(): Unit =
+      inline def op(): Unit = v()
+      op()