I know --disable-Werror, but I think these warnings are easy to fix.

The attached patch fixes warnings showed by clang:

gweather-timezone.c:61:27: error: declaration shadows a variable in the global scope [-Werror,-Wshadow]
parse_tzdata (const char *tzname, time_t start, time_t end,
                          ^
/usr/include/time.h:140:14: note: previous declaration is here
extern char *tzname[];
             ^
gweather-timezone.c:87:33: error: cast from 'char *' to 'guint32 *' (aka 'unsigned int *') increases required alignment from 1 to 4 [-Werror,-Wcast-align]
    timecnt = GUINT32_FROM_BE (*(guint32 *)(contents + TZ_TIMECNT_OFFSET));
                                ^
/home/lantw44/gnome/devinstall/include/glib-2.0/glib/gtypes.h:352:46: note: expanded from macro 'GUINT32_FROM_BE'
#define GUINT32_FROM_BE(val)    (GUINT32_TO_BE (val))
                                                ^
/home/lantw44/gnome/devinstall/lib/glib-2.0/include/glibconfig.h:156:49: note: expanded from macro 'GUINT32_TO_BE'
#define GUINT32_TO_BE(val)      (GUINT32_SWAP_LE_BE (val))
                                                     ^
/home/lantw44/gnome/devinstall/include/glib-2.0/glib/gtypes.h:313:67: note: expanded from macro 'GUINT32_SWAP_LE_BE'
#      define GUINT32_SWAP_LE_BE(val) (GUINT32_SWAP_LE_BE_X86_64 (val))
                                                                  ^
/home/lantw44/gnome/devinstall/include/glib-2.0/glib/gtypes.h:292:37: note: expanded from macro 'GUINT32_SWAP_LE_BE_X86_64'
         ({ guint32 __v, __x = ((guint32) (val));               \
                                           ^
gweather-timezone.c:115:23: error: cast from 'char *' to 'gint32 *' (aka 'int *') increases required alignment from 1 to 4 [-Werror,-Wcast-align]
    initial_offset = *(gint32 *)(ttinfos +
                      ^~~~~~~~~~~~~~~~~~~~
gweather-timezone.c:124:19: error: cast from 'char *' to 'gint32 *' (aka 'int *') increases required alignment from 1 to 4 [-Werror,-Wcast-align]
        second_offset = *(gint32 *)(ttinfos +
                         ^~~~~~~~~~~~~~~~~~~~
4 errors generated.