Warn unused Imports methods overload

- overloaded where not well resolved and thus not reported
- also add a tests

Author: PaulCoral

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

@@ -76,7 +76,7 @@ class CheckUnused extends Phase:
         case sel: Select =>
           unusedDataApply(_.registerUsed(sel.symbol))
           traverseChildren(tree)(using newCtx)
-        case _: (tpd.Block | tpd.Template) =>
+        case _: (tpd.Block | tpd.Template | tpd.PackageDef) =>
           unusedDataApply { ud =>
             ud.inNewScope(ScopeType.fromTree(tree))(traverseChildren(tree)(using newCtx))
           }

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

@@ -213,4 +213,27 @@ package testImportsInImports:
   package c:
     import a.b // OK
     import b.x // OK
-    val y = x
+    val y = x
+
+//-------------------------------------
+package testOnOverloadedMethodsImports:
+  package a:
+    trait A
+    trait B
+    trait C:
+      def foo(x: A):A = ???
+      def foo(x: B):B = ???
+  package b:
+    object D extends a.C
+  package c:
+    import b.D.foo // error
+  package d:
+    import b.D.foo // OK
+    def bar = foo((??? : a.A))
+  package e:
+    import b.D.foo // OK
+    def bar = foo((??? : a.B))
+  package f:
+    import b.D.foo // OK
+    def bar = foo((??? : a.A))
+    def baz = foo((??? : a.B))