Kotlin: Add Class.isFileClass()

java/ql/lib/change-notes/2023-07-11-file-classes.md

@@ -0,0 +1,4 @@
+---
+category: feature
+---
+* A `Class.isFileClass()` predicate, to identify Kotlin file classes, has been added.

java/ql/lib/semmle/code/java/Type.qll

@@ -709,6 +709,12 @@ class Class extends ClassOrInterface {
     )
   }
 
+  /**
+   * Holds if this class is Kotlin "file class", e.g. the class FooKt
+   * for top-level entities in Foo.kt.
+   */
+  predicate isFileClass() { file_class(this) }
+
   override string getAPrimaryQlClass() { result = "Class" }
 }