docs(30): 补充两种边缘情况

30_TryCatch/TryCatch.sol

@@ -1,19 +1,32 @@
 // SPDX-License-Identifier: MIT
 pragma solidity ^0.8.21;
 
-contract OnlyEven{
+contract OnlyEven {
     constructor(uint a){
         require(a != 0, "invalid number");
         assert(a != 1);
     }
 
-    function onlyEven(uint256 b) external pure returns(bool success){
+    function onlyEven(uint256 b) external pure returns (bool success){
         // 输入奇数时revert
         require(b % 2 == 0, "Ups! Reverting");
         success = true;
     }
 }
 
+contract OnlyEven2 {
+    constructor(uint a){
+        require(a != 0, "invalid number");
+        assert(a != 1);
+    }
+
+    function onlyEven(uint256 b) external pure returns (uint256 success){
+        // 输入奇数时revert
+        require(b % 2 == 0, "Ups! Reverting");
+        success = b;
+    }
+}
+
 contract TryCatch {
     // 成功event
     event SuccessEvent();
@@ -27,12 +40,12 @@ contract TryCatch {
     constructor() {
         even = new OnlyEven(2);
     }
-    
+
     // 在external call中使用try-catch
     // execute(0)会成功并释放`SuccessEvent`
     // execute(1)会失败并释放`CatchEvent`
     function execute(uint amount) external returns (bool success) {
-        try even.onlyEven(amount) returns(bool _success){
+        try even.onlyEven(amount) returns (bool _success){
             // call成功的情况下
             emit SuccessEvent();
             return _success;
@@ -47,7 +60,7 @@ contract TryCatch {
     // executeNew(1)会失败并释放`CatchByte`
     // executeNew(2)会成功并释放`SuccessEvent`
     function executeNew(uint a) external returns (bool success) {
-        try new OnlyEven(a) returns(OnlyEven _even){
+        try new OnlyEven(a) returns (OnlyEven _even){
             // call成功的情况下
             emit SuccessEvent();
             success = _even.onlyEven(a);
@@ -59,4 +72,32 @@ contract TryCatch {
             emit CatchByte(reason);
         }
     }
+
+    // 调用非合约的方法，这里无法被try-catch捕获，会导致revert
+    function executeRevert() external {
+        try OnlyEven(address(0)).onlyEven(1){
+            // call成功的情况下
+            emit SuccessEvent();
+        } catch Error(string memory reason){
+            // catch revert("reasonString") 和 require(false, "reasonString")
+            emit CatchEvent(reason);
+        } catch (bytes memory reason){
+            // catch失败的assert assert失败的错误类型是Panic(uint256) 不是Error(string)类型 故会进入该分支
+            emit CatchByte(reason);
+        }
+    }
+
+    // 调用返回值不一致的方法，这里无法被try-catch捕获，会导致revert
+    function executeRevert2() external returns (bool success){
+        address onlyEven2 = address(new OnlyEven2(2));
+        uint256 amount = 2;
+        try OnlyEven(onlyEven2).onlyEven(amount) returns (bool _success){
+            // call成功的情况下
+            emit SuccessEvent();
+            return _success;
+        } catch Error(string memory reason){
+            // call不成功的情况下
+            emit CatchEvent(reason);
+        }
+    }
 }

30_TryCatch/readme.md

@@ -174,6 +174,46 @@ function executeNew(uint a) external returns (bool success) {
 
 ![30-5](./img/30-5.png)
 
+但是`try-catch`并不是万能的，有两种情况`try-catch`也无法捕获
+
+1.在try中调用的非合约地址的方法，即codesize为0
+```solidity
+// 调用非合约地址的方法，这里无法被try-catch捕获，会导致revert
+    function executeRevert() external {
+        //将0地址强制转换为OnlyEven合约地址，模拟调用非合约地址的方法
+        try OnlyEven(address(0)).onlyEven(1){
+            // call成功的情况下
+            emit SuccessEvent();
+        } catch Error(string memory reason){
+            // catch revert("reasonString") 和 require(false, "reasonString")
+            emit CatchEvent(reason);
+        } catch (bytes memory reason){
+            // catch失败的assert assert失败的错误类型是Panic(uint256) 不是Error(string)类型 故会进入该分支
+            emit CatchByte(reason);
+        }
+    }
+```
+![30-6](./img/30-6.png)
+
+2.函数返回值与期望的不一致
+```solidity
+ // 调用返回值不一致的方法，这里无法被try-catch捕获，会导致revert
+    function executeRevert2() external returns (bool success){
+        address onlyEven2 = address(new OnlyEven2(2));
+        uint256 amount = 2;
+        //OnlyEven2的返回值是 uint256，而这里期望的是bool,会导致revert
+        try OnlyEven(onlyEven2).onlyEven(amount) returns (bool _success){
+            // call成功的情况下
+            emit SuccessEvent();
+            return _success;
+        } catch Error(string memory reason){
+            // call不成功的情况下
+            emit CatchEvent(reason);
+        }
+    }
+```
+![30-7](./img/30-7.png)
+
 ## 总结
 
 在这一讲，我们介绍了如何在`Solidity`使用`try-catch`来处理智能合约运行中的异常：