The initializer of a structure variable can include a reference to itself, but this case does not work. Order is matter.

structureinitFail.c

/*
	LLVM reports a warning as follows;
	"variable 's' is uninitialized when used within its own initialization [-Wuninitialized]"
	And it shows the answer randomly.
*/
#include <stdio.h>
typedef struct {
	int a, b, c;
} S;
int sum(S s) {
	printf("sub  %d %d %d\n", s.a, s.b, s.c);
	return s.b + s.c;
}
int main() { 
	S s = {sum(s), 1, 2};
	printf("main %d %d %d\n", s.a, s.b, s.c);
	return 0;
}

So the order matter. The initializer sets the value from left to right.
As an initializer of a structure variable, it is possible to place a function that refers to the variable itself. However, the function must be aware that only member variables before itself are initialized yet.

The assembled code of above "original" source is here;
https://gist.github.com/yyasuda/c5633cea0e9c9de303f15a3af4c5d324
You can understand what happened inside. How the initializer's order matter.