for {
		tok := p.lex.Next()
		if tok == lex.BuildComment {
			if p.sawCode {
				p.errorf("misplaced //go:build comment")
			}
			continue
		}
		if tok != '\n' {
			p.sawCode = true
		}
		if tok == '#' {
			// A leftover wisp of a #include/#define/etc,
			// to let us know that p.sawCode should be true now.
			// Otherwise ignored.
			continue
		}
		return tok
	}
}