JavaScript: ignore self-assignments with a JSDoc comment

asger-semmle · asger-semmle · commit 4f4ad2b942bd · 2018-11-05T11:31:02.000Z
diff --git a/javascript/ql/src/Expressions/Clones.qll b/javascript/ql/src/Expressions/Clones.qll
@@ -152,7 +152,14 @@ class SelfAssignment extends StructurallyCompared {
   }
 
   override Expr candidate() {
-    result = getParent().(AssignExpr).getRhs()
+    result = getAssignment().getRhs()
+  }
+
+  /**
+   * Gets the enclosing assignment.
+   */
+  AssignExpr getAssignment() {
+    result.getLhs() = this
   }
 }
 
diff --git a/javascript/ql/src/Expressions/SelfAssignment.ql b/javascript/ql/src/Expressions/SelfAssignment.ql
@@ -43,5 +43,7 @@ where e.same(_) and
         propName = any(AccessorMethodDeclaration amd).getName()
       ) and
       // exclude DOM properties
-      not isDOMProperty(e.(PropAccess).getPropertyName())
-select e.getParent(), "This expression assigns " + dsc + " to itself."
+      not isDOMProperty(e.(PropAccess).getPropertyName()) and
+      // exclude self-assignments with a JSDoc comment
+      not exists(e.getAssignment().getParent().(ExprStmt).getDocumentation().getATag())
+select e.getParent(), "This expression assigns " + dsc + " to itself."
diff --git a/javascript/ql/test/query-tests/Expressions/SelfAssignment/SelfAssignment.expected b/javascript/ql/test/query-tests/Expressions/SelfAssignment/SelfAssignment.expected
@@ -1,3 +1,5 @@
+| jsdoc.js:9:5:9:19 | this.y = this.y | This expression assigns property y to itself. |
+| jsdoc.js:11:5:11:23 | this.arg = this.arg | This expression assigns property arg to itself. |
 | tst.js:5:2:5:14 | width = width | This expression assigns variable width to itself. |
 | tst.js:24:1:24:19 | array[1] = array[1] | This expression assigns element 1 to itself. |
 | tst.js:27:1:27:9 | o.x = o.x | This expression assigns property x to itself. |
diff --git a/javascript/ql/test/query-tests/Expressions/SelfAssignment/jsdoc.js b/javascript/ql/test/query-tests/Expressions/SelfAssignment/jsdoc.js
@@ -0,0 +1,15 @@
+class C extends Q {
+  constructor(arg) {
+    /**
+     * Something.
+     * @type {string | undefined}
+     */
+    this.x = this.x; // OK - documentation
+
+    this.y = this.y; // NOT OK
+
+    this.arg = this.arg; // NOT OK
+  }
+}
+
+// semmle-extractor-options: --experimental

Original file line number	Diff line number	Diff line change
`@@ -152,7 +152,14 @@ class SelfAssignment extends StructurallyCompared {`
`152`	`152`	`}`
`153`	`153`
`154`	`154`	`override Expr candidate() {`
`155`		`- result = getParent().(AssignExpr).getRhs()`
	`155`	`+ result = getAssignment().getRhs()`
	`156`	`+ }`
	`157`	`+`
	`158`	`+ /**`
	`159`	`+ * Gets the enclosing assignment.`
	`160`	`+ */`
	`161`	`+ AssignExpr getAssignment() {`
	`162`	`+ result.getLhs() = this`
`156`	`163`	`}`
`157`	`164`	`}`
`158`	`165`