Test fallthrough in OSSH_CHECK_CFLAG_COMPILE.

clang 10's -Wimplicit-fallthrough does not understand /* FALLTHROUGH */
comments and we don't use the __attribute__((fallthrough)) that it's
looking for.  This has the effect of turning off -Wimplicit-fallthrough
where it does not currently help (particularly with -Werror).  ok djm@

diff --git a/aclocal.m4 b/aclocal.m4
index 25ecc49a22037d58cab43891ea9a9bc7cdcee074..0193c3dccf81ebc5e397d8a16904aa35bb0d98d2 100644 (file)
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -21,6 +21,16 @@ int main(int argc, char **argv) {
        double m = l / 0.5;
        long long int n = argc * 12345LL, o = 12345LL * (long long int)argc;
        printf("%d %d %d %f %f %lld %lld\n", i, j, k, l, m, n, o);
+       /*
+        * Test fallthrough behaviour.  clang 10's -Wimplicit-fallthrough does
+        * not understand comments and we don't use the "fallthrough" attribute
+        * that it's looking for.
+        */
+       switch(i){
+       case 0: j += i;
+               /* FALLTHROUGH */
+       default: j += k;
+       }
        exit(0);
 }
        ]])],