Failing to build tests when CMAKE_BUILD_TYPE MinSizeRel on Linux

[palerikm]

First discovered when building spudlib on Ubuntu.

OS: Linux ubuntu 3.19.0-16-generic #16-Ubuntu SMP Thu Apr 30 16:09:58 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
CC: cc (Ubuntu 4.9.2-10ubuntu13) 4.9.2

Diff to reproduce bug (Sorry about my lack of cmake understanding but
cmake .. -DCMAKE_BUILD_TYPE=MinRelSize -Dcoveralls=OFF -Dcoveralls_send=OFF -Dverbose=ON did not provoke the bug)

-if (NOT CMAKE_BUILD_TYPE)

• if ( optimize )
• set ( CMAKE_BUILD_TYPE MinSizeRel )
• set ( coveralls OFF )
• set ( coveralls_send OFF )
• else ()
• set ( CMAKE_BUILD_TYPE Debug )
• endif ()
  -endif()
  +set ( CMAKE_BUILD_TYPE MinSizeRel )
  +set ( coveralls OFF )
  +set ( coveralls_send OFF )

+#if (NOT CMAKE_BUILD_TYPE)
+# if ( optimize )
+# set ( CMAKE_BUILD_TYPE MinSizeRel )
+# set ( coveralls OFF )
+# set ( coveralls_send OFF )
+# else ()
+# set ( CMAKE_BUILD_TYPE Debug )
+# endif ()
+#endif()

Gives following compile warnings:
d /home/palmarti/development/cn-cbor/build/test && /usr/bin/cc -Os -DNDEBUG -I/home/palmarti/development/cn-cbor/test/../include -I/home/palmarti/development/cn-cbor/src/../include -std=gnu99 -Wall -Wextra -pedantic -Werror -o CMakeFiles/cbor_test.dir/cbor_test.c.o -c /home/palmarti/development/cn-cbor/test/cbor_test.c
/home/palmarti/development/cn-cbor/test/cbor_test.c: In function ‘_ctest_cbor_parse_normalize_run’:
/home/palmarti/development/cn-cbor/test/cbor_test.c:168:9: error: iteration 18ul invokes undefined behavior [-Werror=aggressive-loop-optimizations]
CTEST_LOG("%s: %s", tests[i], cn_cbor_error_str[err.err]);
^
/home/palmarti/development/cn-cbor/test/cbor_test.c:163:5: note: containing loop
for (i=0; i<sizeof(tests)/sizeof(char); ) {
^
cc1: all warnings being treated as errors
test/CMakeFiles/cbor_test.dir/build.make:57: recipe for target 'test/CMakeFiles/cbor_test.dir/cbor_test.c.o' failed
make[2]: *_* [test/CMakeFiles/cbor_test.dir/cbor_test.c.o] Error 1