Fix unused imports in import stmt

Author: PaulCoral

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

@@ -69,6 +69,7 @@ class CheckUnused extends Phase:
       tree match
         case imp:tpd.Import =>
           unusedDataApply(_.registerImport(imp))
+          traverseChildren(tree)(using newCtx)
         case ident: Ident =>
           unusedDataApply(_.registerUsed(ident.symbol))
           traverseChildren(tree)(using newCtx)

tests/neg-custom-args/fatal-warnings/i15503a.scala

@@ -203,3 +203,14 @@ object testAnnotatedType:
   import annotation.switch // OK
   val a = (??? : @switch) match
     case _ => ???
+
+
+//-------------------------------------
+package testImportsInImports:
+  package a:
+    package b:
+      val x = 1
+  package c:
+    import a.b // OK
+    import b.x // OK
+    val y = x