2.0.10 in EL6 and Fedora 21 (Rawhide):

fatal.c:23:0: warning: "_GNU_SOURCE" redefined [enabled by default]

1. define _GNU_SOURCE /* required for getting at program counter */
   ^
   <command-line>:0:0: note: this is the location of the previous definition
   fatal.c: In function 'print_fatal_info':
   fatal.c:206:14: warning: unused variable 'uctx' [-Wunused-variable]
   ucontext_t *uctx = (ucontext_t *)context;
   ^
   fatal.c: At top level:
   fatal.c:65:20: warning: 'get_register_name' defined but not used [-Wunused-function]
   static const char *get_register_name(int reg)

comms.c: In function 'zbx_tcp_check_security':
comms.c:1136: warning: dereferencing pointer 'name4' does break strict-aliasing rules
comms.c:1122: note: initialized from here

2.2.1 in EL6 and Fedora 21 (Rawhide):

modules.c: In function 'load_modules':
modules.c:123: warning: dereferencing type-punned pointer will break strict-aliasing rules
modules.c:139: warning: dereferencing type-punned pointer will break strict-aliasing rules
modules.c:156: warning: dereferencing type-punned pointer will break strict-aliasing rules
modules.c:165: warning: dereferencing type-punned pointer will break strict-aliasing rules
modules.c: In function 'unload_modules':
modules.c:237: warning: dereferencing type-punned pointer will break strict-aliasing rules
modules.c:237: warning: dereferencing pointer 'func_uninit.52' does break strict-aliasing rules
modules.c:237: note: initialized from here
modules.c: In function 'load_modules':
modules.c:123: warning: dereferencing pointer 'func_version.39' does break strict-aliasing rules
modules.c:123: note: initialized from here
modules.c:139: warning: dereferencing pointer 'func_init.42' does break strict-aliasing rules
modules.c:139: note: initialized from here
modules.c:156: warning: dereferencing pointer 'func_timeout.44' does break strict-aliasing rules
modules.c:156: note: initialized from here
modules.c:165: warning: dereferencing pointer 'func_list.46' does break strict-aliasing rules
modules.c:165: note: initialized from here

evalfunc.c: In function 'evaluate_COUNT':
evalfunc.c:479: warning: 'op' may be used uninitialized in this function

dbupgrade.c:128:13: warning: 'parse_db_monitor_item_params' defined but not used [-Wunused-function]
static void parse_db_monitor_item_params(const char *params, char **dsn, char **user, char **password, char **sql)
^

lld_host.c: In function 'DBlld_update_hosts':
lld_host.c:2540:16: warning: 'interface' may be used uninitialized in this function [-Wmaybe-uninitialized]
if (interface->main != main)
^
lld_host.c:2501:23: note: 'interface' was declared here
zbx_lld_interface_t *interface;
^
lld_host.c:995:16: warning: 'group' may be used uninitialized in this function [-Wmaybe-uninitialized]
group->name = buffer;
^
lld_host.c:921:19: note: 'group' was declared here
zbx_lld_group_t *group;
^
lld_host.c:651:23: warning: 'host' may be used uninitialized in this function [-Wmaybe-uninitialized]
if (0 != strcmp(host->name, buffer))
^
lld_host.c:591:18: note: 'host' was declared here
zbx_lld_host_t *host;
^

checks_simple_vmware.c: In function 'check_vcenter_vm_hv_name':
checks_simple_vmware.c:1266:31: warning: 'hv' may be used uninitialized in this function [-Wmaybe-uninitialized]
name = zbx_xml_read_value(hv->details, ZBX_XPATH_LN2("config", "name"));