Merge pull request #2418 from max-schaefer/js/file-locatable

JavaScript: Make `File` not extend `Locatable` anymore.

javascript/ql/src/semmle/javascript/Files.qll

@@ -198,8 +198,13 @@ class Folder extends Container, @folder {
 }
 
 /** A file. */
-class File extends Container, @file, Locatable {
-  override Location getLocation() { hasLocation(this, result) }
+class File extends Container, @file {
+  /**
+   * Gets the location of this file.
+   *
+   * Note that files have special locations starting and ending at line zero, column zero.
+   */
+  Location getLocation() { hasLocation(this, result) }
 
   override string getAbsolutePath() { files(this, result, _, _, _) }
 

javascript/ql/src/semmle/javascript/JSDoc.qll

@@ -74,6 +74,7 @@ abstract class Documentable extends ASTNode {
 class JSDocTypeExprParent extends @jsdoc_type_expr_parent, Locatable {
   override Location getLocation() { hasLocation(this, result) }
 
+  /** Gets the JSDoc comment to which this element belongs. */
   JSDoc getJSDocComment() { none() }
 }
 

javascript/ql/src/semmle/javascript/Locations.qll

@@ -132,3 +132,15 @@ class Locatable extends @locatable {
     none()
   }
 }
+
+/**
+ * A `File`, considered as a `Locatable`.
+ *
+ * For reasons of backwards compatibility, @file is a subtype of @locatable. This class exists to
+ * provide an override of `Locatable.getLocation()` for @files, since it would otherwise default
+ * to `none()`, which is unhelpful.
+ */
+private class FileLocatable extends File, Locatable {
+  override Location getLocation() { result = File.super.getLocation() }
+  override string toString() { result = File.super.toString() }
+}

javascript/ql/src/semmle/javascript/dependencies/Dependencies.qll

@@ -194,7 +194,8 @@ abstract class ScriptDependency extends Dependency {
   abstract Expr getAnApiUse();
 
   override Locatable getAUse(string kind) {
-    kind = "import" and result.(HTML::HtmlFile) = this.getFile()
+    kind = "import" and
+    result = this.getFile().(HTML::HtmlFile).getATopLevel()
     or
     kind = "use" and result = getAnApiUse()
   }