/* This test program is part of GDB, the GNU debugger. Copyright 2015 Free Software Foundation, Inc. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see . */ #include typedef void (*callback_t) (void); extern void process (callback_t cb); extern void parent (int first, callback_t cb); void ignore (int unused) { (void) unused; } void process (callback_t cb) { parent (0, cb); } void parent (int first, callback_t cb) { void child (void) { /* When reaching this, there are two block instances for PARENT on the stack: the one that is right in the upper frame is not the one actually used for non-local references, so GDB has to follow the static link in order to get the correct instance, and thus in order to read the proper variables. As a simple check, we can verify that under GDB, the following is true: parent_first == first (which should be one: see the IF block below). */ const int parent_first = first; ignore (parent_first); /* STOP */ ignore (first); } if (first) process (&child); else cb (); } int main () { parent (1, NULL); return 0; }