Traverse the types to find experimental references

compiler/src/dotty/tools/backend/jvm/BTypesFromSymbols.scala

@@ -5,7 +5,7 @@ package jvm
 import scala.tools.asm
 import scala.annotation.threadUnsafe
 import scala.collection.mutable
-import scala.collection.generic.Clearable
+import scala.collection.mutable.Clearable
 
 import dotty.tools.dotc.core.Flags._
 import dotty.tools.dotc.core.Contexts._

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

@@ -1339,7 +1339,16 @@ class RefChecks extends MiniPhase { thisPhase =>
   }
 
   override def transformTypeTree(tree: TypeTree)(using Context): TypeTree = {
-    checkExperimental(tree.symbol, tree.srcPos)
+    val tpe = tree.tpe
+    tpe.foreachPart {
+      case TypeRef(_, sym: Symbol)  =>
+        checkDeprecated(sym, tree.srcPos)
+        checkExperimental(sym, tree.srcPos)
+      case TermRef(_, sym: Symbol)  =>
+        checkDeprecated(sym, tree.srcPos)
+        checkExperimental(sym, tree.srcPos)
+      case _ =>
+    }
     tree
   }
 

tests/neg-custom-args/deprecation/14034b.scala

@@ -0,0 +1,14 @@
+
+@deprecated trait Exp
+@deprecated val exp = 1
+
+def test1 = exp // error
+def test2(a: Exp) = () // error
+
+type Foo0 = Exp // error
+type Foo = Option[Exp] // error
+type Bar = Option[exp.type] // error
+type Baz = Exp | Int // error
+type Quux = [X] =>> X match // error
+  case Exp => Int
+type Quuz[A <: Exp] = Int // error

tests/neg-custom-args/no-experimental/14034.scala

@@ -0,0 +1,12 @@
+import annotation.experimental
+
+@experimental trait Exp
+@experimental val exp = 1
+
+type Foo0 = Exp // error
+type Foo = Option[Exp] // error
+type Bar = Option[exp.type] // error
+type Baz = Exp | Int // error
+type Quux = [X] =>> X match // error
+  case Exp => Int
+type Quuz[A <: Exp] = Int // error