+#if defined(STRERROR_R_CHAR_P)
+// GLIBC version of strerror_r
+static const char *strerror_result(const char *a, const char *b) { (void)b; return a; }
+#elif defined(HAVE_STRERROR_R)
+// POSIX version of strerror_r
+static const char *strerror_result(int a, const char *b) { (void)a; return b; }
+#elif defined(HAVE_C__GENERIC)
+
+// what a trick!
+// http://stackoverflow.com/questions/479207/function-overloading-in-c
+static const char *strerror_result_int(int a, const char *b) { (void)a; return b; }
+static const char *strerror_result_string(const char *a, const char *b) { (void)b; return a; }
+
+#define strerror_result(a, b) _Generic((a), \
+ int: strerror_result_int, \
+ char *: strerror_result_string \
+ )(a, b)
+
+#else
+#error "cannot detect the format of function strerror_r()"
+#endif
+