Fix owner of values with static flag

With the flag <static>, the enclosing class will be skipped.
See the documentation `SymDenotation.enclosingClass`

Author: liufengyun

compiler/src/dotty/tools/dotc/transform/init/Errors.scala

@@ -69,7 +69,7 @@ object Errors {
 
   /** Promote `this` under initialization to fully-initialized */
   case class PromoteError(msg: String, source: Tree, trace: Seq[Tree]) extends Error {
-    def show(using Context): String = "Promote the value under initialization to fully-initialized. " + msg
+    def show(using Context): String = "Promote the value under initialization to fully-initialized. " + msg + "."
   }
 
   case class AccessCold(field: Symbol, source: Tree, trace: Seq[Tree]) extends Error {

compiler/src/dotty/tools/dotc/transform/init/Semantic.scala

@@ -892,7 +892,7 @@ class Semantic {
         case Hot => Hot
         case addr: Addr =>
           val obj = heap(addr)
-          val outerCls = klass.owner.enclosingClass.asClass
+          val outerCls = klass.owner.lexicallyEnclosingClass.asClass
           if !obj.outers.contains(klass) then
             val error = PromoteError("outer not yet initialized, target = " + target + ", klass = " + klass, source, trace.toVector)
             report.error(error.show + error.stacktrace, source)

tests/init/neg/promotion-loop.check

@@ -5,5 +5,5 @@
    |
    |The unsafe promotion may cause the following problem(s):
    |
-   |1. Promote the value under initialization to fully-initialized. May only use initialized value as arguments Calling trace:
+   |1. Promote the value under initialization to fully-initialized. May only use initialized value as arguments. Calling trace:
    | -> val outer = test	[ promotion-loop.scala:12 ]

tests/init/pos/enums.scala

@@ -0,0 +1,6 @@
+enum Color(val x: Int) {
+  case Green  extends Color(3)
+  // case Red    extends Color(2)
+  case Violet extends Color(Green.x + 1)
+  // case RGB(xx: Int) extends Color(xx)
+}