Preprocessor, "to string" conversion

[Classes123]

I don't know if it's a bug or it was designed that way, but the following code gives the "wrong" result:

#define TEST   15

#define _TO_STR(%0) #%0
#define TO_STR(%0)  _TO_STR(%0)

public void OnPluginStart()
{
    PrintToServer(TO_STR(TEST));
}

Result:

TEST

---

Same code in C:

#define TEST   15

#define _TO_STR(x) #x
#define TO_STR(x)  _TO_STR(x)

int main()
{
    printf(TO_STR(TEST));
    return 0;
}

Result:

15