## Why?
The explanation of x and y is reversed.

https://github.com/ruby/ruby/blob/ddbd64400199fd408d23c85f9fb0d7f742ecf9e1/re.c#L251-L256
```
long
rb_memsearch(const void *x0, long m, const void *y0, long n, rb_encoding *enc)
{
    const unsigned char *x = x0, *y = y0;

    if (m > n) return -1;
```