Fix #2333: Check if class is deprecated

Author: nicolasstucki

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

@@ -257,8 +257,11 @@ class PostTyper extends MacroTransform with IdentityDenotTransformer { thisPhase
         case tree: MemberDef =>
           transformMemberDef(tree)
           super.transform(tree)
-        case tree: New if isCheckable(tree) =>
-          Checking.checkInstantiable(tree.tpe, tree.pos)
+        case tree: New =>
+          if (tree.tpe.classSymbol.hasAnnotation(defn.DeprecatedAnnot))
+            ctx.deprecationWarning(s"${tree.tpe.typeSymbol} is deprecated", tree.pos)
+          if (isCheckable(tree))
+            Checking.checkInstantiable(tree.tpe, tree.pos)
           super.transform(tree)
         case tree @ Annotated(annotated, annot) =>
           cpy.Annotated(tree)(transform(annotated), transformAnnot(annot))

tests/neg-custom-args/i2333.scala

@@ -0,0 +1,5 @@
+@deprecated("bla", "2.11.0") class Foo
+
+object Test {
+  new Foo // error
+}