为什么调试器在 if 语句之后开始任意跳转？

Question

我的问题是在调试这个功能时出现的。

std::vector<patch_bundle> clean_up(std::vector<patch_bundle> vc){
    
    cout << "girdim ha";    
        for(auto itr = vc.begin(); itr != vc.end();){
    
            patch_bundle cmp_patch_bundle = *itr;
        string cmp_indices = cmp_patch_bundle.patch1_name;
        for(auto i_itr = vc.begin(); i_itr != vc.end();){
            if(i_itr != itr){
                patch_bundle tmp_patch_bundle = *i_itr; 
                string indices1 = tmp_patch_bundle.patch1_name;
                string indices2 = tmp_patch_bundle.patch2_name;
                if((indices1 == cmp_indices) || (indices2 == cmp_indices)){

                    vc.erase(i_itr);
                 }
                else{
                   ++i_itr;
                 }

               
             }
            else{
               ++i_itr;
             }
            
         }
        ++itr;
        
    }
 }

patch_bundle 结构如下

struct patch_bundle{
    int patch1[4] = {0,0,0,0};
    int patch2[4] = {0,0,0,0};
    std::string patch1_name;
    std::string patch2_name;

    std::string patch1_label;
    std::string patch2_label;

 };

这是调试器输出：

Thread 1 hit Breakpoint 1, clean_up (vc=std::vector of length 5400, capacity 5400 = {...}) at test.cpp:338
338             cout << "girdim ha";
(gdb) n
girdim ha339                    for(auto itr = vc.begin(); itr != vc.end();){
(gdb)
341                     patch_bundle cmp_patch_bundle = *itr;
(gdb)
342                     string cmp_indices = cmp_patch_bundle.patch1_name;
(gdb)
343                     for(auto i_itr = vc.begin(); i_itr != vc.end();){
(gdb)
344                             if(i_itr != itr){
(gdb)
359                                ++i_itr;
(gdb)
343                     for(auto i_itr = vc.begin(); i_itr != vc.end();){
(gdb)
344                             if(i_itr != itr){
(gdb)
345                                     patch_bundle tmp_patch_bundle = *i_itr;
(gdb)
346                                     string indices1 = tmp_patch_bundle.patch1_name;
(gdb)
347                                     string indices2 = tmp_patch_bundle.patch2_name;
(gdb)
**348                                     if((indices1 == cmp_indices) || (indices2 == cmp_indices)){
**(gdb)
353                                        ++i_itr;
(gdb)
347                                     string indices2 = tmp_patch_bundle.patch2_name;
(gdb) n
346                                     string indices1 = tmp_patch_bundle.patch1_name;
(gdb)
345                                     patch_bundle tmp_patch_bundle = *i_itr;
(gdb)
344                             if(i_itr != itr){
(gdb)
345                                     patch_bundle tmp_patch_bundle = *i_itr;
(gdb)
346                                     string indices1 = tmp_patch_bundle.patch1_name;
(gdb)

然后在粗线下方，首先读取索引 2，然后读取索引 1。看起来很奇怪。可能是什么原因？

值得注意的是，我最初只使用标准的“for(int itr = 0; ..;...)”类型的迭代。问题发生在同一粗线之后。所以我的猜测是，记忆方面有些事情不太正确。但这会影响 gdb 的行为吗？

如果需要，我正在寻求提供更多信息，

谢谢你。

Answer 1

当您观察到 GDB 进入这些行时：

353                                        ++i_itr;
(gdb)
347                                     string indices2 = tmp_patch_bundle.patch2_name;
(gdb) n
346                                     string indices1 = tmp_patch_bundle.patch1_name;

你看到它执行了

std::string

的析构函数。