}

		if cap(input) != 0 && unsafe.SliceData(input) == unsafe.SliceData(clone) {
			t.Errorf("Clone(%q) return value should not reference inputs backing memory.", input)
		}
	}

	if !p.more() {
		return EOF
	}
	tok := p.input[p.inputPos]
	p.inputPos++
	return tok
}

func (p *Parser) back() {
	if p.inputPos == 0 {
		p.errorf("internal error: backing up before BOL")
	} else {
		p.inputPos--
	}
}

func (p *Parser) peek() lex.ScanToken {
	if p.more() {
		return p.input[p.inputPos].ScanToken
	}
	return scanner.EOF
}

the memory occupied by the field, not the entire struct. When passing a
pointer to an element in an array or slice, the Go memory in question is
the entire array or the entire backing array of the slice.

C code may keep a copy of a Go pointer only as long as the memory it
points to is pinned.

C code may not keep a copy of a Go pointer after the call returns,