Merge pull request #3023 from erik-krogh/RedundantUpdate

Approved by esbena

javascript/ql/src/Expressions/RedundantExpression.ql

@@ -64,7 +64,10 @@ class RedundantIdemnecantOperand extends RedundantOperand {
  * arguments to integers. For example, `x&x` is a common idiom for converting `x` to an integer.
  */
 class RedundantIdempotentOperand extends RedundantOperand {
-  RedundantIdempotentOperand() { getParent() instanceof LogicalBinaryExpr }
+  RedundantIdempotentOperand() {
+    getParent() instanceof LogicalBinaryExpr and
+    not exists(UpdateExpr e | e.getParentExpr+() = this)
+  }
 }
 
 /**

javascript/ql/test/query-tests/Expressions/RedundantExpression/tst.js

@@ -6,4 +6,6 @@ x == 23 || x == 23;
 x & x;
 
 // this may actually be OK, but it's not good style
-pop() && pop();
+pop() && pop();
+
+foo[bar++] && foo[bar++] // OK