child-wait.c:66:32: warning: arithmetic on a null pointer treated as a cast from integer to pointer is a GNU extension [-Wnull-pointer-arithmetic]
        hash_table_insert(child_pids, POINTER_CAST(pid), wait);
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
./macros.h:42:27: note: expanded from macro 'POINTER_CAST'
        ((void *) ((char *) NULL + (i)))
                                 ^
./hash.h:111:20: note: expanded from macro 'hash_table_insert'
                (void *)((char*)(key) + COMPILE_ERROR_IF_TYPES_NOT_COMPATIBLE((table)._key, key)), \
                                 ^~~
child-wait.c:66:32: warning: arithmetic on a null pointer treated as a cast from integer to pointer is a GNU extension [-Wnull-pointer-arithmetic]
        hash_table_insert(child_pids, POINTER_CAST(pid), wait);
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
./macros.h:42:27: note: expanded from macro 'POINTER_CAST'
        ((void *) ((char *) NULL + (i)))
                                 ^
./hash.h:111:79: note: expanded from macro 'hash_table_insert'
                (void *)((char*)(key) + COMPILE_ERROR_IF_TYPES_NOT_COMPATIBLE((table)._key, key)), \
                                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~
./macros.h:178:52: note: expanded from macro 'COMPILE_ERROR_IF_TYPES_NOT_COMPATIBLE'
                !__builtin_types_compatible_p(typeof(_a), typeof(_b)))
                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~
./macros.h:170:25: note: expanded from macro 'COMPILE_ERROR_IF_TRUE'
        (sizeof(char[1 - 2 * ((condition) ? 1 : 0)]) - 1)
                               ^~~~~~~~~
child-wait.c:72:32: warning: arithmetic on a null pointer treated as a cast from integer to pointer is a GNU extension [-Wnull-pointer-arithmetic]
        hash_table_remove(child_pids, POINTER_CAST(pid));
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~
./macros.h:42:27: note: expanded from macro 'POINTER_CAST'
        ((void *) ((char *) NULL + (i)))
                                 ^
./hash.h:124:46: note: expanded from macro 'hash_table_remove'
                if (unlikely(!hash_table_try_remove(table, key))) \
                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~
./hash.h:121:33: note: expanded from macro 'hash_table_try_remove'
                (const void *)((const char *)(key) + COMPILE_ERROR_IF_TYPES2_NOT_COMPATIBLE((table)._const_key, (table)._key, key)))
                                              ^
./macros.h:189:45: note: expanded from macro 'unlikely'
#  define unlikely(expr) (__builtin_expect((expr) ? 1 : 0, 0) != 0)
                                            ^~~~
child-wait.c:72:32: warning: arithmetic on a null pointer treated as a cast from integer to pointer is a GNU extension [-Wnull-pointer-arithmetic]
        hash_table_remove(child_pids, POINTER_CAST(pid));
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~
./macros.h:42:27: note: expanded from macro 'POINTER_CAST'
        ((void *) ((char *) NULL + (i)))
                                 ^
./hash.h:124:46: note: expanded from macro 'hash_table_remove'
                if (unlikely(!hash_table_try_remove(table, key))) \
                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~
./hash.h:121:113: note: expanded from macro 'hash_table_try_remove'
                (const void *)((const char *)(key) + COMPILE_ERROR_IF_TYPES2_NOT_COMPATIBLE((table)._const_key, (table)._key, key)))
                                                                                                                              ^
./macros.h:181:53: note: expanded from macro 'COMPILE_ERROR_IF_TYPES2_NOT_COMPATIBLE'
                !__builtin_types_compatible_p(typeof(_a1), typeof(_b)) && \
                                                                  ^
./macros.h:170:25: note: expanded from macro 'COMPILE_ERROR_IF_TRUE'
        (sizeof(char[1 - 2 * ((condition) ? 1 : 0)]) - 1)
                               ^
./macros.h:189:45: note: expanded from macro 'unlikely'
#  define unlikely(expr) (__builtin_expect((expr) ? 1 : 0, 0) != 0)
                                            ^~~~
child-wait.c:72:32: warning: arithmetic on a null pointer treated as a cast from integer to pointer is a GNU extension [-Wnull-pointer-arithmetic]
        hash_table_remove(child_pids, POINTER_CAST(pid));
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~
./macros.h:42:27: note: expanded from macro 'POINTER_CAST'
        ((void *) ((char *) NULL + (i)))
                                 ^
./hash.h:124:46: note: expanded from macro 'hash_table_remove'
                if (unlikely(!hash_table_try_remove(table, key))) \
                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~
./hash.h:121:113: note: expanded from macro 'hash_table_try_remove'
                (const void *)((const char *)(key) + COMPILE_ERROR_IF_TYPES2_NOT_COMPATIBLE((table)._const_key, (table)._key, key)))
                                                                                                                              ^
./macros.h:182:53: note: expanded from macro 'COMPILE_ERROR_IF_TYPES2_NOT_COMPATIBLE'
                !__builtin_types_compatible_p(typeof(_a2), typeof(_b)))
                                                                  ^
./macros.h:170:25: note: expanded from macro 'COMPILE_ERROR_IF_TRUE'
        (sizeof(char[1 - 2 * ((condition) ? 1 : 0)]) - 1)
                               ^
./macros.h:189:45: note: expanded from macro 'unlikely'
#  define unlikely(expr) (__builtin_expect((expr) ? 1 : 0, 0) != 0)
                                            ^~~~
child-wait.c:82:7: warning: arithmetic on a null pointer treated as a cast from integer to pointer is a GNU extension [-Wnull-pointer-arithmetic]
                                                POINTER_CAST(status.pid));
                                                ^~~~~~~~~~~~~~~~~~~~~~~~~
./macros.h:42:27: note: expanded from macro 'POINTER_CAST'
        ((void *) ((char *) NULL + (i)))
                                 ^
./hash.h:80:33: note: expanded from macro 'hash_table_lookup'
                (const void *)((const char *)(key) + COMPILE_ERROR_IF_TYPES2_NOT_COMPATIBLE((table)._key, (table)._const_key, key)))
                                              ^~~
child-wait.c:82:7: warning: arithmetic on a null pointer treated as a cast from integer to pointer is a GNU extension [-Wnull-pointer-arithmetic]
                                                POINTER_CAST(status.pid));
                                                ^~~~~~~~~~~~~~~~~~~~~~~~~
./macros.h:42:27: note: expanded from macro 'POINTER_CAST'
        ((void *) ((char *) NULL + (i)))
                                 ^
./hash.h:80:113: note: expanded from macro 'hash_table_lookup'
                (const void *)((const char *)(key) + COMPILE_ERROR_IF_TYPES2_NOT_COMPATIBLE((table)._key, (table)._const_key, key)))
                                                     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~
./macros.h:181:53: note: expanded from macro 'COMPILE_ERROR_IF_TYPES2_NOT_COMPATIBLE'
                !__builtin_types_compatible_p(typeof(_a1), typeof(_b)) && \
                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~
./macros.h:170:25: note: expanded from macro 'COMPILE_ERROR_IF_TRUE'
        (sizeof(char[1 - 2 * ((condition) ? 1 : 0)]) - 1)
                               ^~~~~~~~~
child-wait.c:82:7: warning: arithmetic on a null pointer treated as a cast from integer to pointer is a GNU extension [-Wnull-pointer-arithmetic]
                                                POINTER_CAST(status.pid));
                                                ^~~~~~~~~~~~~~~~~~~~~~~~~
./macros.h:42:27: note: expanded from macro 'POINTER_CAST'
        ((void *) ((char *) NULL + (i)))
                                 ^
./hash.h:80:113: note: expanded from macro 'hash_table_lookup'
                (const void *)((const char *)(key) + COMPILE_ERROR_IF_TYPES2_NOT_COMPATIBLE((table)._key, (table)._const_key, key)))
                                                     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~
./macros.h:182:53: note: expanded from macro 'COMPILE_ERROR_IF_TYPES2_NOT_COMPATIBLE'
                !__builtin_types_compatible_p(typeof(_a2), typeof(_b)))
                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~
./macros.h:170:25: note: expanded from macro 'COMPILE_ERROR_IF_TRUE'
        (sizeof(char[1 - 2 * ((condition) ? 1 : 0)]) - 1)
                               ^~~~~~~~~
8 warnings generated.