Do not accept splices and holes in annotations

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

@@ -1449,12 +1449,6 @@ trait Checking {
       case Typed(expr, _) => validAnnotArg(expr)
       // TODO(mbovel): should probably be handled by `tpd.allTermArguments` instead.
       case NamedArg(_, arg) => validAnnotArg(arg)
-      // TODO(mbovel): we should probably not allow `Splice` and `Hole`.
-      // How to encode them as types?
-      // When removing those cases, tests/pos-macros/i7519b.scala and
-      // tests/pos-macros/i7052.scala fail.
-      case Splice(_) => true
-      case Hole(_, _, _, _) => true
       case _ => false
 
   /** 1. Check that all case classes that extend `scala.reflect.Enum` are `enum` cases

tests/neg-macros/i7052.scala

@@ -1,7 +1,7 @@
 import scala.quoted.*
 class Test {
   def foo(str: String)(using Quotes) = '{
-    @deprecated(str, "") // error
+    @deprecated(str, "") // error: not a valid annotation 
     def bar = ???
   }
 }

tests/neg-macros/i7052b.scala

@@ -4,7 +4,7 @@ class Test {
     val qctx: Quotes = ???
     given qctx.type = qctx
     '{
-      @deprecated(str, "") // error
+      @deprecated(str, "") // error: not a valid annotation 
       def bar = ???
     }
   }

tests/pos-macros/i7052.scala → tests/neg-macros/i7052c.scala

@@ -1,7 +1,7 @@
 import scala.quoted.*
 class Test {
   def foo(str: Expr[String])(using Quotes) = '{
-    @deprecated($str, "")
+    @deprecated($str, "") // error: not a valid annotation 
     def bar = ???
   }
 }

tests/pos-macros/i7519b.scala → tests/neg-macros/i7519b.scala

@@ -9,5 +9,5 @@ inline def quote[T]: Quoted[T] = ${ quoteImpl[T] }
 
 def quoteImpl[T: Type](using Quotes): Expr[Quoted[T]] = {
   val value: Expr[Int] = '{ 42 }
-  '{ new Quoted[T @Annot($value)] }
+  '{ new Quoted[T @Annot($value)] } // error: not a valid annotation
 }