gcc does not generate debugger info when using -g, -ggdb, -g3, or -ggdb3

Question

I'm using GCC 4.4.1 and GDB 7.0-ubuntu on Ubuntu 9.10. However, GCC won't generate debugger info when using any of the following switches: -g, -g3, -ggdb, or -ggdb3. So when I run the program with GDB, its as if there was no debugger information generated. I have created very simple test source files in a new, empty folder.

Here is one example:

#include <stdlib.h>
#include <stdio.h>
int main (int argc, char **argv)
{
     char    msg[4];
     // allocate 4 bytes on the stack
     strcpy (msg, "hello world");
     // overflow 
     printf ("%s\n", msg);
     return 0;
}

UPDATE: here is my command line sequence:
gcc -g ./mytest.c -o mytest
gdb ./mytest

UPDATE: I have previously turned on MALLOC_CHECK_=1 in order to test the stack overflow problem in the code. And this works so I get a stack trace. But the stack trace is no different whether I include the debug info or not. What I expected to see with the debugger information was a line number of a file for where the problem occurred under GDB. However this doesn't happen.

Answer 1

You want:

gcc -g test.c -o mytest
gdb mytest

Never call anything "test" - it clashes with a shell built in. and "test.o" would by convention be the name of an object file, not an executable.

Answer 2

Your comment says you ran:

gcc -ggdb ./test.c -o test.o

That's probably not what you want.

gcc -ggdb -o mytest test.c

is likelier to be successful. If gdb ralphs on that then you have something wrong with your installation of gcc or gdb.

Answer 3

It works fine. I ran the debugger on my computer. I had to add

#include <string.h>

to compile it though. I called the file debugger.c. Here are the steps:

gcc -g debugger.c 
gdb a.out

which will start the debugger

GNU gdb 6.3.50-20050815
... 
...
(gdb) run
Starting program: /Developer/stackoverflow/extern/a.out 
Reading symbols for shared libraries +. done

Program received signal SIGABRT, Aborted.
0x00007fff88040886 in __kill ()
(gdb) backtrace
#0  0x00007fff88040886 in __kill ()
#1  0x00007fff880e0e4f in __abort ()
#2  0x00007fff880d5693 in __chk_fail ()
#3  0x00007fff8802f851 in __strcpy_chk ()
#4  0x0000000100000f04 in main (argc=1, argv=0x7fff5fbff958) at debugger.c:9
(gdb) 

Edit: Sorry, didn't see that this was tagged c and not c++. Doesn't change anything running the debugger though. Changed it accordingly.

Edit2: Reading your edit, it seems like your problem wasn't running the debugger but getting the information where your code failed. You can use backtrace to achieve that.