Steps to reproduce:
- Use Ns3 Master
- Activate c++11 support*
- Configure with -d optimized
- Build

*I've added 
def configure(conf):
    conf.env.append_value('CXXFLAGS','-std=c++11');                                                                                                                                                    to my own module.

If I don't use "-d optimized" to configure ns3, build is successful.

Result:


In file included from ./ns3/epc-x2-header.h:24:0,
                 from ../src/lte/model/epc-x2.cc:27:
./ns3/epc-x2-sap.h: In member function ‘void ns3::EpcX2::RecvFromX2cSocket(ns3::Ptr<ns3::Socket>)’:
./ns3/epc-x2-sap.h:311:10: error: ‘params.ns3::EpcX2Sap::ResourceStatusUpdateParams::targetCellId’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
   struct ResourceStatusUpdateParams
          ^
../src/lte/model/epc-x2.cc:349:52: note: ‘params.ns3::EpcX2Sap::ResourceStatusUpdateParams::targetCellId’ was declared here
           EpcX2SapUser::ResourceStatusUpdateParams params;
                                                    ^
cc1plus: all warnings being treated as errors
Waf: Leaving directory `/home/mrueg/ns3/build'
Build failed
 -> task in 'ns3-lte' failed (exit status 1): 
        {task 140439618012304: cxx epc-x2.cc -> epc-x2.cc.1.o}
['/usr/bin/g++', '-O3', '-g', '-Wall', '-Werror', '-march=native', '-fstrict-overflow', '-std=c++11', '-Wno-error=deprecated-declarations', '-fstrict-aliasing', '-Wstrict-aliasing', '-fPIC', '-pthread', '-I.', '-I..', '-I/usr/include/libxml2', '-DHAVE_SYS_IOCTL_H=1', '-DHAVE_IF_NETS_H=1', '-DHAVE_NET_ETHERNET_H=1', '-DHAVE_PACKET_H=1', '-DHAVE_SQLITE3=1', '-DHAVE_IF_TUN_H=1', '-DHAVE_GSL=1', '../src/lte/model/epc-x2.cc', '-c', '-o', 'src/lte/model/epc-x2.cc.1.o']