refactor of benignContext predicate based on code review

erik-krogh · erik-krogh · commit bda37b6d6f75 · 2019-10-08T11:54:56.000+02:00
diff --git a/javascript/ql/src/Statements/UseOfReturnlessFunction.ql b/javascript/ql/src/Statements/UseOfReturnlessFunction.ql
@@ -37,35 +37,36 @@ predicate benignContext(Expr e) {
   or 
   exists(ConditionalExpr cond | cond.getABranch() = e and benignContext(cond)) 
   or 
-  exists(BinaryExpr bin | (bin.getOperator() = "&&" or bin.getOperator() = "||") and bin.getAnOperand() = e and benignContext(bin)) 
+  exists(LogicalBinaryExpr bin | bin.getAnOperand() = e and benignContext(bin)) 
   or
-  exists(SeqExpr parent | parent.getAnOperand() = e and benignContext(parent))
+  exists(SeqExpr seq, int i, int n | e = seq.getOperand(i) and n = seq.getNumOperands() |
+    i < n - 1 or benignContext(seq)
+  ) 
   or
-  exists(ParExpr par | par.getExpression() = e and benignContext(par))
-  or 
-  exists(TypeAssertion assert | assert.getExpression() = e and inVoidContext(assert))
+  exists(Expr parent | parent.getUnderlyingValue() = e and benignContext(parent))
   or 
-  exists(UnaryExpr unOp | unOp.getOperator() = "void" and unOp.getOperand() = e)
+  exists(VoidExpr voidExpr | voidExpr.getOperand() = e)
+  or
+ 
+  // The call is only in a non-void context because it is in a lambda.
+  exists(ArrowFunctionExpr arrow |
+    arrow.getBody() = e
+  ) 
   or
   
   // It is ok (or to be flagged by another query?) to await a non-async function. 
-  exists(AwaitExpr await | await.getOperand() = e) 
+  exists(AwaitExpr await | await.getOperand() = e and benignContext(await)) 
   or
   
-  // Avoid double reporting. It will always evaluate to false.
+  // Avoid double reporting with js/trivial-conditional
   exists(IfStmt ifStmt | ifStmt.getCondition() = e)
   or 
-  // Avoid double reporting. `e` will always evaluate to undefined.
+  // Avoid double reporting with js/comparison-between-incompatible-types
   exists(Comparison binOp | binOp.getAnOperand() = e)
   or
-  // Avoid double reporting of "The base expression of this property access is always undefined.". 
+  // Avoid double reporting with js/property-access-on-non-object
   exists(PropAccess ac | ac.getBase() = e)
   or
-  // The call is only in a non-void context because it is in a lambda.
-  exists(ArrowFunctionExpr arrow |
-    arrow.getBody() = e
-  ) 
-  or
   // Avoid double-reporting with unused local.
   exists(VariableDeclarator v | v.getInit() = e and v.getBindingPattern().getVariable() instanceof UnusedLocal)
 }
diff --git a/javascript/ql/test/query-tests/Statements/UseOfReturnlessFunction/UseOfReturnlessFunction.expected b/javascript/ql/test/query-tests/Statements/UseOfReturnlessFunction/UseOfReturnlessFunction.expected
@@ -1,2 +1,3 @@
 | tst.js:20:17:20:33 | onlySideEffects() | the function $@ does not return anything, yet the return value is used. | tst.js:11:5:13:5 | functio ... )\\n    } | onlySideEffects |
 | tst.js:24:13:24:29 | onlySideEffects() | the function $@ does not return anything, yet the return value is used. | tst.js:11:5:13:5 | functio ... )\\n    } | onlySideEffects |
+| tst.js:30:20:30:36 | onlySideEffects() | the function $@ does not return anything, yet the return value is used. | tst.js:11:5:13:5 | functio ... )\\n    } | onlySideEffects |
diff --git a/javascript/ql/test/query-tests/Statements/UseOfReturnlessFunction/tst.js b/javascript/ql/test/query-tests/Statements/UseOfReturnlessFunction/tst.js
@@ -23,4 +23,10 @@
     
     var b = onlySideEffects();
     console.log(b);
+
+	var c = 42 + (onlySideEffects(), 42); // OK, value is thrown away. 
+	console.log(c);
+	
+	var d = 42 + (42, onlySideEffects()); // NOT OK! 
+	console.log(d);
 })();

Original file line number	Diff line number	Diff line change
`@@ -1,2 +1,3 @@`
`1`	`1`	`\| tst.js:20:17:20:33 \| onlySideEffects() \| the function $@ does not return anything, yet the return value is used. \| tst.js:11:5:13:5 \| functio ... )\\n } \| onlySideEffects \|`
`2`	`2`	`\| tst.js:24:13:24:29 \| onlySideEffects() \| the function $@ does not return anything, yet the return value is used. \| tst.js:11:5:13:5 \| functio ... )\\n } \| onlySideEffects \|`
	`3`	`+\| tst.js:30:20:30:36 \| onlySideEffects() \| the function $@ does not return anything, yet the return value is used. \| tst.js:11:5:13:5 \| functio ... )\\n } \| onlySideEffects \|`