seg-fault in v1.8 release

[chenziliang]

Tried using v1.8 release (the single CLI11.hpp file) in my project, got seg-fault, the following is the trace.

(gdb) bt
#0  __GI___libc_free (mem=0x93fa55d09a576) at malloc.c:3103
#1  0x000055555565846e in __gnu_cxx::new_allocator<CLI::App*>::deallocate (this=0x5555569ec7a0, __p=0x93fa55d09a576) at /usr/include/c++/8/ext/new_allocator.h:125
#2  0x000055555564efe5 in std::allocator_traits<std::allocator<CLI::App*> >::deallocate (__a=..., __p=0x93fa55d09a576, __n=18446418666927868753)
    at /usr/include/c++/8/bits/alloc_traits.h:462
#3  0x00005555556430fe in std::_Vector_base<CLI::App*, std::allocator<CLI::App*> >::_M_deallocate (this=0x5555569ec7a0, __p=0x93fa55d09a576, __n=18446418666927868753)
    at /usr/include/c++/8/bits/stl_vector.h:304
#4  0x0000555555633170 in std::_Vector_base<CLI::App*, std::allocator<CLI::App*> >::~_Vector_base (this=0x5555569ec7a0, __in_chrg=<optimized out>)
    at /usr/include/c++/8/bits/stl_vector.h:285
#5  0x0000555555621653 in std::vector<CLI::App*, std::allocator<CLI::App*> >::~vector (this=0x5555569ec7a0, __in_chrg=<optimized out>)
    at /usr/include/c++/8/bits/stl_vector.h:570
#6  0x00005555556114aa in CLI::App::~App (this=0x5555569ec640, __in_chrg=<optimized out>) at /.../CLI11.hpp:3912
#7  0x0000555555611584 in CLI::App::~App (this=0x5555569ec640, __in_chrg=<optimized out>) at /.../CLI11.hpp:3912
#8  0x0000555555678944 in std::_Sp_counted_ptr<CLI::App*, (__gnu_cxx::_Lock_policy)2>::_M_dispose (this=0x5555569f3130) at /usr/include/c++/8/bits/shared_ptr_base.h:377
#9  0x00005555556298b2 in std::_Sp_counted_base<(__gnu_cxx::_Lock_policy)2>::_M_release (this=0x5555569f3130) at /usr/include/c++/8/bits/shared_ptr_base.h:155
#10 0x0000555555618061 in std::__shared_count<(__gnu_cxx::_Lock_policy)2>::~__shared_count (this=0x5555569f2678, __in_chrg=<optimized out>)
    at /usr/include/c++/8/bits/shared_ptr_base.h:728
#11 0x00005555556092ba in std::__shared_ptr<CLI::App, (__gnu_cxx::_Lock_policy)2>::~__shared_ptr (this=0x5555569f2670, __in_chrg=<optimized out>)
    at /usr/include/c++/8/bits/shared_ptr_base.h:1167
#12 0x00005555556092d6 in std::shared_ptr<CLI::App>::~shared_ptr (this=0x5555569f2670, __in_chrg=<optimized out>) at /usr/include/c++/8/bits/shared_ptr.h:103
#13 0x0000555555658536 in std::_Destroy<std::shared_ptr<CLI::App> > (__pointer=0x5555569f2670) at /usr/include/c++/8/bits/stl_construct.h:98
#14 0x000055555564f0ff in std::_Destroy_aux<false>::__destroy<std::shared_ptr<CLI::App>*> (__first=0x5555569f2670, __last=0x5555569f2690)
    at /usr/include/c++/8/bits/stl_construct.h:108
#15 0x0000555555643244 in std::_Destroy<std::shared_ptr<CLI::App>*> (__first=0x5555569f2670, __last=0x5555569f2690) at /usr/include/c++/8/bits/stl_construct.h:137
#16 0x000055555563331f in std::_Destroy<std::shared_ptr<CLI::App>*, std::shared_ptr<CLI::App> > (__first=0x5555569f2670, __last=0x5555569f2690)
    at /usr/include/c++/8/bits/stl_construct.h:206
#17 0x0000555555621735 in std::vector<std::shared_ptr<CLI::App>, std::allocator<std::shared_ptr<CLI::App> > >::~vector (this=0x7fffffffe3c8, __in_chrg=<optimized out>)
    at /usr/include/c++/8/bits/stl_vector.h:567
#18 0x0000555555611474 in CLI::App::~App (this=0x7fffffffe1f0, __in_chrg=<optimized out>) at /.../CLI11.hpp:3912
#19 0x00005555555ed045 in main (argc=4, argv=0x7fffffffe578) at /../main.cxx:478

[henryiii]

Can you share any surrounding code? Looks a bit like Apps are trying to be deleted twice. Is this a drop in replacement for 1.7, or have you started making 1.8 related changes?

[chenziliang]

the code starts brand new and the the CLI11.hpp is a copy from the release page. The seg-fault issue is not always reproducible. The code snippet looks like below:

#include <CLI11.hpp>                                                            
#include <string>                                                               
                                                                                   
using namespace std;                                                               
                                                                                   
int main(int argc, char** argv) {                                                  
    CLI::App app{"my-ap;"};                                                        
    app.require_subcommand(1, 2);                                                  
                                                                                   
    CLI::App* cmd1 = app.add_subcommand("cmd1");                                   
    cmd1->require_option();                                                        
                                                                                   
    CLI::Option* i_flag = cmd1->add_flag("--list-i", "list interfaces");                                                                           
    CLI::Option* d_flag = cmd1->add_flag("--list-d", "list devices");              
                                                                                   
    CLI::App* cmd2 = app.add_subcommand("cmd2");                                   
    string conf_file;                                                              
    cmd2->add_option("--config", conf_file, "cmd2 configuration file")             
        ->required()                                                               
        ->check(CLI::ExistingFile);                                                
                                                                                   
    CLI11_PARSE(app, argc, argv);                                                  
                                                                                                                                                  
    if (*cmd1) {                                                                   
        if (*i_flag) {                                                             
            // do something                                            
        } else if (*d_flag) {                                                      
           // do something                                              
        }                                                                          
        return 0;                                                                  
    } 
   
    if (*cmd2) {                                                                
        // do something                                           
    }                                                                           
    return 0; 
}        

[phlptp]

what is the code around line 478?, just want to make sure that is the end of the main function, not somewhere in the middle.

[henryiii]

I'm at a workshop at NYU and didn't bring my computer (not intentionally), so can't check yet, will be high priority when I get back. Have you triggered it with the code snippet above? What platform are you on? Linux gcc?

[henryiii]

You are not storing any subcommands in smart pointers, are you? Just making sure. They are internally in smart pointers and get deleted for you. Just a thought.

[chenziliang]

1. It is gcc8 in Linux
2. No i didn't store any subcommand in smart porters. The code i posted is exactly the structure i have in my production code.
3. I run the code in my env, but it doesn't trigger any seg-fault.
4. My current workaround is new CLI::App in main to let it just leak, it will be gc by OS when my main process is gone anyway :)

[henryiii]

Ouch. I’d like to find out what is happening so you don’t have to leave the App leaking.

Can you stick a msg in the destructor of App (include the name, since subcommands are Apps) and see if it runs twice when not leaked?

I have one idea I’ll check when I can. Are you doing anything else “interesting” with subcommands the the real code?

[chenziliang]

Thanks. I will do it when available. No, I don’t do anything fancy related to subcommand. The code I show here is exactly the structure and usage in my prod code

[chenziliang]

This is probably related to my application in which there is memory overrun problem elsewhere. Will keep monitoring if the crash happens again. Thanks !

[henryiii]

Let me know if it turns out to be related to CLI11!