char a[true == 1 ? 1 : -1];
char b[false == 0 ? 1 : -1];
char c[__bool_true_false_are_defined == 1 ? 1 : -1];
-#if 0 /* Cannot be guaranteed with gnulib's <stdbool.h>. */
+#if 0 /* Cannot be guaranteed with gnulib's <stdbool.h>, at least,
+not for all compilers. */
char d[(bool) 0.5 == true ? 1 : -1];
bool e = &s;
-#endif
char f[(_Bool) 0.0 == false ? 1 : -1];
+#endif
char g[true];
char h[sizeof (_Bool)];
#if 0 /* See above. */