func (p *printer) commentSizeBefore(next token.Position) int {
	// save/restore current p.commentInfo (p.nextComment() modifies it)
	defer func(info commentInfo) {
		p.commentInfo = info
	}(p.commentInfo)

	size := 0
	for p.commentBefore(next) {
		for _, c := range p.comment.List {
			size += len(c.Text)
		}
		p.nextComment()
	}
	return size
}

	// (there may be a pending comment when a line comment is
	// immediately followed by a lead comment with no other
	// tokens between)
	if p.commentOffset == infinity {
		p.nextComment() // get comment ready for use
	}
}

type exprListMode uint

const (
	commaTerm exprListMode = 1 << iota // list is optionally terminated by a comma