Why gdb is not working for this simple hello world program?

Question

Code (m1.cpp):

#include <iostream>
using namespace std;

int main (int argc, char *argv[])
{
   cout << "running m1" << endl;

   return 0;
}

GDB Version: GNU gdb (GDB) 7.6.2

Built using: g++ -g m1.cpp

Command line history:

(gdb) b main
Breakpoint 1 at 0x40087b: file m1.cpp, line 6.
(gdb) r
Starting program: .../a.out

Program received signal SIGSEGV, Segmentation fault.
0x00002aaaaaac16a0 in strcmp () from /lib64/ld-linux-x86-64.so.2
(gdb) c
Continuing.

Program terminated with signal SIGSEGV, Segmentation fault.
The program no longer exists.
(gdb)

When I run without setting any breakpoints, it runs without errors.

As requested:

(gdb) bt
#0  strcmp () from /lib64/ld-linux-x86-64.so.2
#1  in check_match.12104 () from /lib64/ld-linux-x86-64.so.2
#2  in do_lookup_x () from /lib64/ld-linux-x86-64.so.2
#3  in _dl_lookup_symbol_x () from /lib64/ld-linux-x86-64.so.2
#4  in _dl_relocate_object () from /lib64/ld-linux-x86-64.so.2
#5  in dl_main () from /lib64/ld-linux-x86-64.so.2
#6  in _dl_sysdep_start () from /lib64/ld-linux-x86-64.so.2
#7  in _dl_start () from /lib64/ld-linux-x86-64.so.2
#8  in _start () from /lib64/ld-linux-x86-64.so.2
#9  in ?? ()

Answer 1

I was able to replicate the OP's observed behavior (using the same compile and getting the same backtrace). The behavior was persistent across a range GDBs and GCCs. I noticed that the symptom goes away when I unset SHELL. In my normal environment I use tcsh (version 1.15.00). If SHELL is set, then (I believe) gdb launches using tcsh. If I unset SHELL, gdb launches using sh. This is enough for me to make forward progress. I don't have a crisp explanation for what would be different in tcsh to manifest the issue but if others have the same behavior, it may shed more light on the issue.