}
		if must != 0 {
			// Conflicts found; need to finish final span.
			addSpan(re.Sub[start], re.Sub[last], must, flags)
		}
		return 0, allCant
	}
}

// writeRegexp writes the Perl syntax for the regular expression re to b.
func writeRegexp(b *strings.Builder, re *Regexp, f printFlags, flags map[*Regexp]printFlags) {
	f |= flags[re]
	if f&flagPrec != 0 && f&^(flagOff|flagPrec) != 0 && f&flagOff != 0 {