a couple more bug fixes

htmlcheck/checker.go

@@ -258,7 +258,7 @@ func (ht *htmlCheckerImpl) emitRune(ch rune, filters []outputFilter, countCols b
 	if len(filters) > 0 {
 		// try each output filter to see what we can do
 		for _, of := range filters {
-			handled = of.tryOutputRune(ht.outputBuffer, ch)
+			handled = of.tryOutputRune(&ht.outputBuffer, ch)
 			if handled {
 				break // found a filter to handle it, done
 			}
@@ -314,7 +314,7 @@ func (ht *htmlCheckerImpl) emitString(str string, filters []outputFilter, countC
 					// one of the output filters stopped us, try invoking it
 					tmpch, bsiz := utf8.DecodeRuneInString(temp[outputLen:])
 					outputLen += bsiz
-					if !stopper.tryOutputRune(ht.outputBuffer, tmpch) {
+					if !stopper.tryOutputRune(&ht.outputBuffer, tmpch) {
 						ht.outputBuffer.WriteRune(tmpch)
 					}
 					if realCountCols {

htmlcheck/filter.go

@@ -13,7 +13,7 @@ import "strings"
 
 // outputFilter is the interface for an HTML checker output filter.
 type outputFilter interface {
-	tryOutputRune(strings.Builder, rune) bool
+	tryOutputRune(*strings.Builder, rune) bool
 	matchRune(rune) bool
 	lengthNoMatch(string) int
 }
@@ -34,7 +34,7 @@ type htmlEncodingFilter struct{}
 const htmlEscapedChars = "<>&"
 
 // tryOutputRune outputs a rune that needs to be escaped.
-func (f *htmlEncodingFilter) tryOutputRune(buf strings.Builder, ch rune) bool {
+func (f *htmlEncodingFilter) tryOutputRune(buf *strings.Builder, ch rune) bool {
 	switch ch {
 	case '<':
 		buf.WriteString("&lt;")