Compound literal and designated initializer warning from GCC but not Clang

Compiling with gcc -std=c99 -Wextra this piece of code:

#include <stdio.h>

struct T {
    int a;
    int *b;
    int c;
};

int main(void)
{
    struct T t = {.b = ((int []){1, 1})};

    printf("%d\n", t.b[1]);
    return 0;
}

Is giving me a warning:

demo.c:11:12: warning: missing initializer for field ‘c’ of ‘struct T’ [-Wmissing-field-initializers]
     struct T t = {.b = ((int []){1, 1})};
            ^
demo.c:6:9: note: ‘c’ declared here
     int c;
         ^

But designated initializers are supposed to initialize to zero the rest of the members even if they are ommited.

Why the warning? (clang compiles the same piece of code without warnings)

gcc version 6.3.0 20170516 (Debian 6.3.0-18) 
clang version 3.8.1-24 (tags/RELEASE_381/final)