bug compiling issue

[fabianfrz]

LC_ALL=en_US.utf8 make VERBOSE=yes all
/bin/sh: warning: setlocale: LC_ALL: cannot change locale (en_US.utf8)
/bin/sh: warning: setlocale: LC_ALL: cannot change locale (en_US.utf8)
/bin/sh: warning: setlocale: LC_ALL: cannot change locale (en_US.utf8)

TARGET all
VERBOSE yes

VERSION  0.3.602
COMMIT 5756cb38
DATE  20171108.1823
HOST  Linux
/bin/sh: warning: setlocale: LC_ALL: cannot change locale (en_US.utf8)
/bin/sh: warning: setlocale: LC_ALL: cannot change locale (en_US.utf8)
gcc -D_REENTRANT -DFORTIFY_SOURCE=2 -D_GNU_SOURCE -D_LARGEFILE64_SOURCE -DHAVE_NS_TYPE -DDIME_BUILD=0.3.602 -DDIME_STAMP=20171108.1823 -Wfatal-errors -Werror -Wall -Wextra  -Wformat-security -Warray-bounds  -Wformat=2 -Wno-format-nonliteral  -std=gnu99 -O0 -ggdb3 -rdynamic -fPIC -c -MMD   -D_REENTRANT -DFORTIFY_SOURCE=2 -D_GNU_SOURCE -D_LARGEFILE64_SOURCE -DHAVE_NS_TYPE -DDIME_BUILD=0.3.602 -DDIME_STAMP=20171108.1823  -Isrc -Isrc/providers -Ilib/local/include -I/usr/include -MF".deps/src/providers/dime/ed25519/ed25519.d" -MT".objs/src/providers/dime/ed25519/ed25519.o" -o".objs/src/providers/dime/ed25519/ed25519.o" "src/providers/dime/ed25519/ed25519.c"
/bin/sh: warning: setlocale: LC_ALL: cannot change locale (en_US.utf8)
In file included from src/providers/dime/ed25519/../ed25519/ed25519-donna.h:56:0,
                 from src/providers/dime/ed25519/ed25519.c:17:
src/providers/dime/ed25519/../ed25519/../ed25519/modm-donna-64bit.h: In function 'sub256_modm_batch':
src/providers/dime/ed25519/../ed25519/../ed25519/modm-donna-64bit.h:292:96: error: this statement may fall through [-Werror=implicit-fallthrough=]
   case 4: out[i] = (a[i] - b[i])        ; carry = (out[i] >> 63); out[i] &= 0xffffffffffffff; i++;
                                                                                               ~^~
compilation terminated due to -Wfatal-errors.
cc1: all warnings being treated as errors
make: *** [Makefile:281: .objs/src/providers/dime/ed25519/ed25519.o] Error 1

Looks like a programming issue blocks compiling the library.