Do not add @experimental annotations to nested definitions

Author: nicolasstucki

compiler/src/dotty/tools/dotc/transform/SymUtils.scala

@@ -266,9 +266,6 @@ object SymUtils:
       || self.hasAnnotation(defn.ExperimentalAnnot)
       || (self.maybeOwner.isClass && self.owner.hasAnnotation(defn.ExperimentalAnnot))
 
-    def isNestedInExperimental(using Context): Boolean =
-      self.ownersIterator.drop(1).exists(_.hasAnnotation(defn.ExperimentalAnnot))
-
     /** The declared self type of this class, as seen from `site`, stripping
     *  all refinements for opaque types.
     */

compiler/src/dotty/tools/dotc/util/Experimental.scala

@@ -33,13 +33,8 @@ object Experimental:
       checker.traverse(tree.tpe)
 
   def annotateExperimental(sym: Symbol)(using Context): Unit =
-    if sym.isClass && !sym.hasAnnotation(defn.ExperimentalAnnot) then
-      // Add @experimental annotation to all classes nested in an experimental definition
-      if !sym.owner.is(Package) && sym.isNestedInExperimental then
-        sym.addAnnotation(defn.ExperimentalAnnot)
-
+    if sym.is(Enum) && sym.hasAnnotation(defn.ExperimentalAnnot) then
       // Add @experimental annotation to enum class definitions
-      val compSym = sym.companionClass
-      if compSym.is(Enum) && compSym.hasAnnotation(defn.ExperimentalAnnot) then
-        sym.addAnnotation(defn.ExperimentalAnnot)
-        sym.companionModule.addAnnotation(defn.ExperimentalAnnot)
+      val compMod = sym.companionModule.moduleClass
+      compMod.addAnnotation(defn.ExperimentalAnnot)
+      compMod.companionModule.addAnnotation(defn.ExperimentalAnnot)

tests/neg-custom-args/no-experimental/experimentalAnnotation.scala

@@ -59,9 +59,9 @@ trait ExpSAM {
 def bar(f: ExpSAM): Unit = {} // error
 
 @experimental // error
-enum E:
+enum E: // error
   case A
-  case B
+  case B // error
 
 def test(
   p1: A, // error