"Unused const variable" build failure(s) — clang 3.6.0

With -Wall, clang detects useless const declaration:
static const int foo = 4;
and will fails with
$ clang -Werror -Wall -c foo.c 
foo.c:1:18: error: unused variable 'cbib_initial_size'
      [-Werror,-Wunused-const-variable]
static const int cbib_initial_size = 4;
                 ^
1 error generated.
PackageVersionSupposed error messageFull log Bug report
dahdi-tools 1:2.10.0.1-1astribank_usb.c:37:19: error: unused variable 'rcsid' [-Werror,-Wunused-const-variable] Log
geis 2.2.16-1geis_backend_multiplexor.c:34:24: error: unused variable 'cbib_initial_size' [-Werror,-Wunused-const-variable] Log 751539
libgdf 0.1.2-2GDFHeaderAccess.cpp:28:14: error: unused variable 'epsilon_d' [-Werror,-Wunused-const-variable] Log 751540
modemmanager 1.4.0-1test-wmc-utils.c:114:19: error: unused variable 'uml290_encap_outbuf' [-Werror,-Wunused-const-variable] Log
mongodb 1:2.4.10-5src/mongo/shell/linenoise.cpp:435:18: error: unused variable 'SPECIAL_KEY' [-Werror,-Wunused-const-variable] Log
ncap 1.9.2-2ncap_create.c:7:19: error: unused variable 'rcsid' [-Werror,-Wunused-const-variable] Log

6 errors