+#define CCAN_STR_DEBUG 1
+#include <ccan/str/str.h>
+
+int main(int argc, char *argv[])
+{
+#ifdef FAIL
+#if !HAVE_BUILTIN_TYPES_COMPATIBLE_P || !HAVE_TYPEOF
+#error We need typeof to check islower.
+#endif
+ char
+#else
+ unsigned char
+#endif
+ c = argv[0][0];
+
+#ifdef FAIL
+ /* Fake fail on unsigned char platforms. */
+ c = 255;
+ BUILD_ASSERT(c < 0);
+#endif
+
+ return islower(c);
+}