const unicode.ReplacementChar

8 uses

	unicode (current package)
		letter.go#L11: 	ReplacementChar = '\uFFFD'     // Represents invalid code points.
		letter.go#L209: 		return ReplacementChar, false // as reasonable an error as any

	encoding/json
		decode.go#L1269: 					if dec := utf16.DecodeRune(rr, rr1); dec != unicode.ReplacementChar {
		decode.go#L1276: 					rr = unicode.ReplacementChar

	github.com/google/safehtml
		html.go#L83: 			runes = append(runes, unicode.ReplacementChar)

	google.golang.org/protobuf/internal/encoding/json
		decode_string.go#L72: 						r == unicode.ReplacementChar || err != nil {

	google.golang.org/protobuf/internal/encoding/text
		decode_string.go#L134: 					if in[0] != '\\' || in[1] != 'u' || r == unicode.ReplacementChar || err != nil {

	mime
		encodedword.go#L336: 				buf.WriteRune(unicode.ReplacementChar)