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Tools/SmartCheck/Solidity/Rules/SOLIDITY_MSGVALUE_EQUALS_ZERO.md

+# Analysis of Smart Contract Security Vulnerabilities and Tools ![](https://img.shields.io/badge/-Live-brightgreen)
+![](https://img.shields.io/badge/Batch-UG21CYS-lightgreen) ![](https://img.shields.io/badge/Batch-PG21CYS-green) ![](https://img.shields.io/badge/Batch-UG22CYS-lightgreen) ![](https://img.shields.io/badge/Batch-PG21CYS-green) ![](https://img.shields.io/badge/Batch-PhD-darkgreen) ![](https://img.shields.io/badge/-B_RIG-darkgreen)<br/>   ![](https://img.shields.io/badge/BlockchainCourse-21CY712-green)  ![](https://img.shields.io/badge/-M.Tech_Dissertation-blue) ![](https://img.shields.io/badge/Focus-Smart_Contract_Security-yellow) <br/>
+![](https://img.shields.io/badge/Blockchain-Ethereum-blue)   <br/> 
+![](https://img.shields.io/badge/Language-Solidity-blue)
+
+## SOLIDITY_MSGVALUE_EQUALS_ZERO
+### Rule Description
+<p>
+    The <code>msg.value == 0</code> condition check is meaningless in most cases.
+</p>
+
+### Solidity-Rules
+
+![](https://img.shields.io/badge/Pattern_ID-1df89a-gold) ![](https://img.shields.io/badge/Severity-1-brown) 
+
+```
+expression
+                        [expression[1]/environmentalVariable[text()[1] = "msg.value"]]
+                        [comparison[text()[1] = "=="]]
+                        [expression[2]/primaryExpression//decimalNumber[text()[1] = "0"]]
+                        [not(ancestor::functionDefinition[text()[1] = "constructor"])]
+                        [not(ancestor::functionDefinition/identifier[text()[1]
+                            = (ancestor::contractDefinition/identifier)])
+                        ]
+```
+
+### Sample Code
+
+```
+pragma solidity 0.4.24;
+
+contract MsgValue {
+
+    constructor() public {
+        require(msg.value == 0);
+    }
+
+    function myFunc() public returns(uint) {
+        // <yes> <report> SOLIDITY_MSGVALUE_EQUALS_ZERO 1df89a
+        require(msg.value == 0);
+        // <yes> <report> SOLIDITY_MSGVALUE_EQUALS_ZERO 1df89a
+        if(msg.value == 0) {
+            return(1);
+        }
+        // <yes> <report> SOLIDITY_MSGVALUE_EQUALS_ZERO 1df89a
+        assert(msg.value == 0);
+    }
+
+    function() {
+        // <yes> <report> SOLIDITY_MSGVALUE_EQUALS_ZERO 1df89a
+        require(msg.value == 0);
+    }
+}
+
+contract MsgValue2 {
+
+    function MsgValue2() {
+        require(msg.value == 0);
+    }
+}
+```
+
+### Abstract Syntax Tree 
+
+[Click Here](https://astexplorer.net/#/gist/2b6b1e6d8d56a08d4a1173aa579e2c2a/2979556ee23227a659d4cec029bf24fbff291654) to view the AST for the above code. Code generated from AST Explorer using _solidity-parser-antlr-0.4.11_
+
+### Code Result
+
+```
+SOLIDITY_MSGVALUE_EQUALS_ZERO
+patternId: 1df89a
+severity: 1
+line: 11
+column: 16
+content: msg.value==0
+
+ruleId: SOLIDITY_MSGVALUE_EQUALS_ZERO
+patternId: 1df89a
+severity: 1
+line: 13
+column: 11
+content: msg.value==0
+
+ruleId: SOLIDITY_MSGVALUE_EQUALS_ZERO
+patternId: 1df89a
+severity: 1
+line: 17
+column: 15
+content: msg.value==0
+
+ruleId: SOLIDITY_MSGVALUE_EQUALS_ZERO
+patternId: 1df89a
+severity: 1
+line: 22
+column: 16
+content: msg.value==0
+
+ruleId: SOLIDITY_VISIBILITY
+patternId: 910067
+severity: 1
+line: 20
+column: 4
+content: function(){require(msg.value==0);}
+
+ruleId: SOLIDITY_VISIBILITY
+patternId: 910067
+severity: 1
+line: 28
+column: 4
+content: functionMsgValue2(){require(msg.value==0);}
+
+SOLIDITY_VISIBILITY :2
+SOLIDITY_MSGVALUE_EQUALS_ZERO :4
+
+
+```