-Wformat cannot use const struct fields as format strings on purpose?

Question

Here's a small piece of code:

 static struct {
 const char fmt[10];
 } const x = { "%dn" };
 static const char * const fmt = "%dn";
 printf(fmt, 1);
 printf(x.fmt, 1);

The second printf produces a warning:

 test.c:105:10: warning: format string is not a string literal
[-Wformat-nonliteral]
 printf(x.fmt, 1);
 ^~~~~

From my point of view both format strings are identical. Why can't gcc deduce the format string in the second case?