Merge pull request #656 from xiemaisi/js/unused-local-underscore

Approved by esben-semmle

javascript/ql/test/query-tests/Declarations/UnusedParameter/tst.js

@@ -33,4 +33,8 @@ var g = f3;
 // OK
 define(function (require, exports, module) {
 	module.x = 23;
-});
+});
+
+// OK: starts with underscore
+function f(_p) {
+}

javascript/ql/test/query-tests/Declarations/UnusedVariable/UnusedVariable.expected

@@ -9,5 +9,7 @@
 | multi-imports.js:2:1:2:42 | import  ... om 'x'; | Unused imports alphabetically, ordered. |
 | require-react-in-other-scope.js:2:9:2:13 | React | Unused variable React. |
 | typeoftype.ts:9:7:9:7 | y | Unused variable y. |
+| underscore.js:6:7:6:7 | e | Unused variable e. |
+| underscore.js:7:7:7:7 | f | Unused variable f. |
 | unusedShadowed.ts:1:1:1:26 | import  ... where'; | Unused import T. |
 | unusedShadowed.ts:2:1:2:31 | import  ... where'; | Unused import object. |

javascript/ql/test/query-tests/Declarations/UnusedVariable/underscore.js

@@ -0,0 +1,10 @@
+function f(a) {
+  const [a,  // OK: used
+	     _,  // OK: starts with underscore
+	     _c, // OK: starts with underscore
+	     d,  // OK: used
+	     e,  // NOT OK
+	     f]  // NOT OK
+         = a;
+  return a + d;
+}