alignment declarations don't work if they precede the struct keyword

$ cat t.c

#include <inttypes.h>

#include <stdio.h>

#include <stdlib.h>

__attribute__((aligned(64))) struct xx {

	int a;

};

typedef struct xx XX;

struct __attribute__((aligned(64))) yy {

	int a;

};

typedef struct yy YY;

int

main(void)

{

	XX *a;

	YY *b;

        printf("sizeof XX: %zu\n", sizeof(XX));

        a = malloc(10 * sizeof(XX));

        printf("XX array element size: %zu\n", 

            (char *)&a[1] - (char *)&a[0]);

        printf("sizeof YY: %zu\n", sizeof(YY));

        b = malloc(10 * sizeof(YY));

        printf("YY array element size: %zu\n", 

            (char *)&b[1] - (char *)&b[0]);

	return (0);

}

$ gcc48 t.c; ./a.out

sizeof XX: 4

XX array element size: 4

sizeof YY: 64

YY array element size: 64

$ gcc5 t.c; ./a.out

sizeof XX: 4

XX array element size: 4

sizeof YY: 64

YY array element size: 64

$ clang t.c; ./a.out

t.c:5:16: warning: attribute 'aligned' is ignored,

place it after "struct" to apply attribute to type

declaration [-Wignored-attributes]

__attribute__((aligned(64))) struct xx {

               ^

1 warning generated.

sizeof XX: 4

XX array element size: 4

sizeof YY: 64

YY array element size: 64

typedef __attribute__((aligned(64))) struct xx {

        int a;

} XX;

typedef struct __attribute__((aligned(64))) yy {

        int a;

} YY;

$ clang t.c; ./a.out

sizeof XX: 4

XX array element size: 4

sizeof YY: 64

YY array element size: 64