GDB step over function (next) doesn't seem to work

Question

I'm trying to debug a program I wrote in C++. Here is the code:

void a() { }
void b() { a(); }
int main() { b(); return 0; }

I compiled it using: g++ -g3 -O0 -o cards.exe cards.cpp.

Here is the output of my GDB session:

(gdb) b main
Breakpoint 1 at 0x401421: file cards.cpp, line 10.
(gdb) r
Starting program: C:\workspace\Cards\src/cards.exe
[New thread 1624.0xa28]
Breakpoint 1, main () at cards.cpp:10
10    int main()
(gdb) n
12        b();
(gdb) n
b () at cards.cpp:5 5
void b()
(gdb) n
7        a();
(gdb) quit
The program is running.  Exit anyway? (y or n)

Why does sending a next command to GDB still step into a function?

I'm using g++ 4.2.1-sjlj and GDB 6.8.

Answer 1

The step and next commands work one source line at a time, so when everything is all on one line a single next takes me right to the end of main().

3    int main() { b(); return 0; }
(gdb) n
0x00001faa in start ()

With the code formatted less densely I still do not see the results you see. I put the function calls on separate lines to get GDB to step over them one at a time. Here's what I get then:

jkugelman$ cat cards.cpp

void a() {
}

void b() {
    a();
}

int main() {
    b();
    return 0;
}

jkugelman$ g++ -g3 -O0 -o cards cards.cpp
jkugelman$ gdb ./cards
GNU gdb 6.3.50-20050815 (Apple version gdb-960) (Sun May 18 18:38:33 UTC 2008)
<snip>
Reading symbols for shared libraries .... done

(gdb) b main
Breakpoint 1 at 0x1ff2: file cards.cpp, line 9.
(gdb) r
Starting program: /Users/jkugelman/Development/StackOverflow/cards
Reading symbols for shared libraries +++. done

Breakpoint 1, main () at cards.cpp:9
9        b();
(gdb) n
10        return 0;
(gdb) n
11    }
(gdb) n
0x00001faa in start ()

I don't have an answer, but I just wanted to share that GDB behaves as expected on my iMac. In either case GDB treated the call to b() as one instruction and never entered the function call.