glib-244.1 on OS X 10.8 (xcode-5.1) gives 10 warnings in glib/tests/regex.c starting with:

  CC       regex.o
regex.c:2317:22: warning: implicit conversion from enumeration type 'GRegexCompileFlags' to different enumeration type 'GRegexMatchFlags' [-Wenum-conversion]
  TEST_MATCH("a", 0, G_REGEX_ANCHORED, "a", -1, 0, 0, TRUE);
  ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
regex.c:215:22: note: expanded from macro 'TEST_MATCH'
  data->match_opts = _match_opts;                                       \
                     ^
and the same for each of the successive 9 lines in that source. The the second parameter of TEST_MATCH, _compile_opts, is fed to a TestMatchData.compile_opts (type GRegexCompileFlags), whereas the third parameter, _match_opts, is fed to TestMatchData.match_opts (type GRegexMatchFlags). In these 10 tests, G_REGEX_ANCHORED, a GRegexCompileFlags, is in the match_opts position. Instead, should be using G_REGEX_MATCH_ANCHORED. Both are numerically equal, so the test works regardless.