i, n, ok := trailingDigits(text)
	if i == 0 {
		return // ignore (not a line directive)
	}
	// i > 0

	if !ok {
		// text has a suffix :xxx but xxx is not a number
		p.errorAt(p.posAt(tline, tcol+i), "invalid line number: "+text[i:])
		return
	}

	var line, col uint
	i2, n2, ok2 := trailingDigits(text[:i-1])
	if ok2 {
		//line filename:line:col