Why doesn't GDB show line numbers or function names?

I was trying to use GDB to troubleshoot a segfault in code I'm writing. GDB does not show line numbers or function names when I use the backtrace command. Here's a short sample program that illustrates my problem:

void segfault(int *b) {    // This causes a segfault on CentOS7 Intel 64-bit    b[-1] = 5;}void main() {    int a[10];    segfault(a);}

However when I compile with

gcc -ggdb -O0 test.c -o segfaulttest

And use gdb segfaulttest to run it, when I use gdb's backtrace command I don't get any line numbers or function names. I would expect it to list main() and segfault() in the trace.

Sample output

Reading symbols from /home/user/test/segfaulttest...done.(gdb) runStarting program: /home/user/test/segfaulttest Program received signal SIGSEGV, Segmentation fault.0x000000050040051c in ?? ()(gdb) bt#0  0x000000050040051c in ?? ()#1  0x0000000000000000 in ?? ()(gdb) 

I'm using:

• CentOS 7 (64 bit)
• GCC: gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-4)
• GDB is gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-4)

(Aside: I fixed the actual bug in my code, I just don't understand why gdb backtrace doesn't show me more information).