printf impurity

~$ cat test.c
#include <stdio.h>

int main(int argc, const char** argv)
{
	int n;
	n = printf("value\n");
	fprintf(stderr, "n: %d\n", n);
	fclose(stdout);
	n = printf("value\n");
	fprintf(stderr, "n: %d\n", n);
}

~$ ./test
value
n: 6
n: -1