problem when debug glib source code with gdb

["????" <losemyheaven qq com>]

Hi:
   Dear friend, Recently I  am curious about how glib works, so I want to debug its source code with gdb. But I got stuck...

These are steps I followed, after the source code is downloaded:
1) ./configure --enable-debug=yes
2) make
3) sudo make install

4)I created test.c in which I called glib API g_hash_table_new function
#include <glib.h>
int main(int argc, char** argv) {
 GHashTable* hash = g_hash_table_new(g_str_hash, g_str_equal);
 g_hash_table_insert(hash, "Virginia", "Richmond");
g_hash_table_insert(hash, "Ohio", "Columbus");
  return 0;
}
5)gcc test.c `pkg-config --cflags --libs glib-2.0` -g -o test

6) I used gdb to debug the output test program
gdb test

7)use gdb's directiory command to specify the source code location
directory ~/Downloads/glib-2.46.2

But when I use gdb to debug test step by step

I found that when I use gdb's step command, gdb cannot go inside the source code files which include glib APIs, such as g_hash_table_new and g_hash_table_insert

What should I do? Where am I wrong?