Drop retainsUniversal annotation

It can now be expressed as `@retains(caps.*)`.

Author: odersky

compiler/src/dotty/tools/dotc/core/Definitions.scala

@@ -1025,7 +1025,6 @@ class Definitions {
   @tu lazy val RequiresCapabilityAnnot: ClassSymbol = requiredClass("scala.annotation.internal.requiresCapability")
   @tu lazy val RetainsAnnot: ClassSymbol = requiredClass("scala.annotation.retains")
   @tu lazy val RetainsByNameAnnot: ClassSymbol = requiredClass("scala.annotation.retainsByName")
-  @tu lazy val RetainsUniversalAnnot: ClassSymbol = requiredClass("scala.annotation.retainsUniversal")
 
   @tu lazy val JavaRepeatableAnnot: ClassSymbol = requiredClass("java.lang.annotation.Repeatable")
 

compiler/src/dotty/tools/dotc/typer/Typer.scala

@@ -2669,16 +2669,10 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
   end typedPackageDef
 
   def typedAnnotated(tree: untpd.Annotated, pt: Type)(using Context): Tree = {
-    var annot1 = typedExpr(tree.annot, defn.AnnotationClass.typeRef)
+    val annot1 = typedExpr(tree.annot, defn.AnnotationClass.typeRef)
     val annotCls = Annotations.annotClass(annot1)
     if annotCls == defn.NowarnAnnot then
       registerNowarn(annot1, tree)
-    else if annotCls == defn.RetainsUniversalAnnot then
-      annot1 = typedExpr(
-        untpd.New(
-          untpd.TypeTree(defn.RetainsAnnot.typeRef),
-          (untpd.ref(defn.captureRoot) :: Nil) :: Nil).withSpan(tree.annot.span),
-        defn.AnnotationClass.typeRef)
     val arg1 = typed(tree.arg, pt)
     if (ctx.mode is Mode.Type) {
       val cls = annot1.symbol.maybeOwner

library/src/scala/annotation/retains.scala

@@ -13,6 +13,3 @@ package scala.annotation
  */
 @experimental
 class retains(xs: Any*) extends annotation.StaticAnnotation
-
-@experimental
-class retainsUniversal extends annotation.StaticAnnotation

tests/run-custom-args/tasty-inspector/stdlibExperimentalDefinitions.scala

@@ -51,7 +51,6 @@ val experimentalDefinitionInLibrary = Set(
   "scala.annotation.internal.WithPureFuns",
   "scala.annotation.internal.requiresCapability",
   "scala.annotation.retains",
-  "scala.annotation.retainsUniversal",
   "scala.annotation.retainsByName",
   "scala.caps",
   "scala.caps$",