unified: Fix same-folder bug

Author: asgerf

unified/ql/lib/codeql/unified/internal/StaticNameBinding.qll

@@ -458,6 +458,8 @@ private module FolderHeuristic {
    */
   private predicate hasConflictingDefs(Folder folder, string name) {
     containsDef(folder, name) and
+    // Check for "two or more" using `exists(X) and not exists(unique(X))`
+    containsDef(folder.getAFolder(), name) and
     not exists(unique(Folder child | child = folder.getAFolder() and containsDef(child, name)))
   }
 

unified/ql/test/library-tests/static-name-binding/not-a-package/SiblingFiles/SubFolder1/Use.swift

@@ -1,5 +1,5 @@
 private protocol P {
-    let x4: DeclaredTwiceInSubFolder; // $ MISSING: access=Subfolder1.DeclaredTwiceInSubFolder
+    let x4: DeclaredTwiceInSubFolder; // $ access=Subfolder1.DeclaredTwiceInSubFolder
     let x5: OnlyInSubFolder1; // $ access=OnlyInSubFolder1
     let x6: OnlyInSubFolder2; // $ access=OnlyInSubFolder2
 }