The old pcre code included with Privoxy had lots of fallthroughs
but that code is gone and the only implicit-fallthrough left is:
w32log.c: In function ‘LogWindowProc’:
w32log.c:1189:27: warning: this statement may fall through [-Wimplicit-fallthrough=]
 1189 |          g_bShowLogWindow = wParam;
      |          ~~~~~~~~~~~~~~~~~^~~~~~~~
w32log.c:1190:7: note: here
 1190 |       case WM_SIZE:  /* note: implicit-fallthrough */
      |       ^~~~
 # see: http://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
 # -Wall   doesn't actually turn on all warnings, so add  -Wextra
 #    but then plenty too many complaints by
-#      -Wimplicit-fallthrough=3
-#         too many warnings in pcre/study.c & pcre.c
 #      -Wmissing-field-initializers
 #      -Wsign-compare
 #      -Wtype-limits