"Unused function" build failure(s) — clang 3.4

-Wall -Werror are including the option -Wunused-function. Without not the case with g++
namespace { 
   void dummy_for_semicolon_do_not_use();
}
PackageVersionSupposed error messageFull log Bug report
cdebootstrap 0.5.10../../../../src/frontend/standalone/message.c:79:12: error: unused function 'unused' [-Werror,-Wunused-function] Log 751630
curlpp 0.7.3-4example21.cpp:51:8: error: unused function 'readData' [-Werror,-Wunused-function] Log
diagnostics 0.3.3-9annotations.cpp:46:1: error: unused function 'dummy_for_semicolon_do_not_use' [-Werror,-Wunused-function] Log 751904
lxc 0.9.0~alpha3-2+deb8u1lxc_attach.c:49:1: error: unused function 'LXC_TRACE' [-Werror,-Wunused-function] Log
writerperfect 0.8.2-1FemtoZip.cxx:135:30: error: unused function 'hash' [-Werror,-Wunused-function] Log 751906

5 errors