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Tools/SmartCheck/Solidity/Rules/SOLIDITY_SHOULD_RETURN_STRUCT.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_SHOULD_RETURN_STRUCT
+### Rule Description
+<p>
+Consider using struct instead of multiple return values for <code>internal</code> or <code>private</code> functions. It can improve code readability.
+</p>
+
+### Solidity-Rules
+
+![](https://img.shields.io/badge/Pattern_ID-7d54ca-gold) ![](https://img.shields.io/badge/Severity-1-brown) 
+
+```
+sourceUnit
+                        [
+                            not(pragmaDirective//versionLiteral
+                                [matches(text()[1], "^0\.\s*[5-9]\s*\.|^0\.\s*[0-9]{2,}\s*\.|^[1-9]")])
+                            and not(pragmaDirective/pragmaExperimental//stringLiteral
+                                [text()[1] = "ABIEncoderV2"])
+                        ]
+                        //functionDefinition[visibleType[matches(text()[1], "internal|private")]]
+                        /returnsParameters/parameterList[count(parameter) > 3]
+```
+
+![](https://img.shields.io/badge/Pattern_ID-83hf3l-gold) ![](https://img.shields.io/badge/Severity-1-brown) 
+
+```
+sourceUnit
+                        [
+                            pragmaDirective//versionLiteral
+                                [matches(text()[1], "^0\.\s*[5-9]\s*\.|^0\.\s*[0-9]{2,}\s*\.|^[1-9]")]
+                            or pragmaDirective/pragmaExperimental//stringLiteral
+                                [text()[1] = "ABIEncoderV2"]
+                        ]
+                        //functionDefinition/returnsParameters/parameterList[count(parameter) > 3]
+```
+
+![](https://img.shields.io/badge/Pattern_ID-e5gh7l-gold) ![](https://img.shields.io/badge/Severity-1-brown) 
+
+```
+expression[text()[1] = "="]
+                        [expression[1]/tupleExpression[count(expression) > 3]]
+                        [expression[2]/functionCall]
+```
+
+### Sample Code
+
+```
+pragma solidity 0.4.24;
+
+contract C {
+    // <yes> <report> SOLIDITY_SHOULD_RETURN_STRUCT 7d54ca
+    function f1() internal returns(uint a, uint b, uint c, uint d) {
+        a = 1;
+        b = 2;
+        c = 3;
+        d = 4;
+    }
+    // <yes> <report> SOLIDITY_SHOULD_RETURN_STRUCT 7d54ca
+    function f2() private returns(uint a, uint b, uint c, uint d) {
+        a = 1;
+        b = 2;
+        c = 3;
+        d = 4;
+    }
+
+    function f5() external returns(uint a, uint b, uint c, uint d) {
+        a = 1;
+        b = 2;
+        c = 3;
+        d = 4;
+    }
+
+    function f6() returns(uint a) {
+        a = 1;
+    }
+
+    function f7() public returns(uint a, uint b, uint c, uint d) {
+        a = 1;
+        b = 2;
+        c = 3;
+        d = 4;
+    }
+
+    function f8() public returns(uint a, uint b) {
+        (a, b) = f7();
+    }
+
+    function f9() public returns(uint a, uint b, uint c, uint d) {
+    // <yes> <report> SOLIDITY_SHOULD_RETURN_STRUCT e5gh7l
+        (a, b, c, d) = f2();
+    }
+
+    function f10() public returns(uint a) {
+        (a, , , ) = f2();
+    }
+}
+```
+
+### Abstract Syntax Tree 
+
+[Click Here](https://astexplorer.net/#/gist/3600fc939d721a465259258985b48432/e0c31089dc5266ebbfcbd0ee79b07d08b98fe084) to view the AST for the above code. Code generated from AST Explorer using _solidity-parser-antlr-0.4.11_
+
+
+### Code Result
+
+```
+SOLIDITY_SHOULD_RETURN_STRUCT
+patternId: 7d54ca
+severity: 1
+line: 5
+column: 34
+content: (uinta,uintb,uintc,uintd)
+
+ruleId: SOLIDITY_SHOULD_RETURN_STRUCT
+patternId: 7d54ca
+severity: 1
+line: 12
+column: 33
+content: (uinta,uintb,uintc,uintd)
+
+ruleId: SOLIDITY_VISIBILITY
+patternId: 910067
+severity: 1
+line: 26
+column: 4
+content: functionf6()returns(uinta){a=1;}
+
+SOLIDITY_VISIBILITY :1
+SOLIDITY_SHOULD_RETURN_STRUCT :2
+
+```