cmp/report_reflect.go
func formatString(s string) string {
	// Use quoted string if it the same length as a raw string literal.
	// Otherwise, attempt to use the raw string form.
	qs := strconv.Quote(s)
	if len(qs) == 1+len(s)+1 {
		return qs
	}

	// Disallow newlines to ensure output is a single line.
	// Only allow printable runes for readability purposes.
	rawInvalid := func(r rune) bool {
		return r == '`' || r == '\n' || !(unicode.IsPrint(r) || r == '\t')
	}
	if strings.IndexFunc(s, rawInvalid) < 0 {
		return "`" + s + "`"
	}
	return qs
}
func formatString(s string) string {
	// Use quoted string if it the same length as a raw string literal.
	// Otherwise, attempt to use the raw string form.
	qs := strconv.Quote(s)
	if len(qs) == 1+len(s)+1 {
		return qs
	}

	// Disallow newlines to ensure output is a single line.
	// Only allow printable runes for readability purposes.
	rawInvalid := func(r rune) bool {
		return r == '`' || r == '\n' || !(unicode.IsPrint(r) || r == '\t')
	}
	if strings.IndexFunc(s, rawInvalid) < 0 {
		return "`" + s + "`"
	}
	return qs
}
// formatString prints s as a double-quoted or backtick-quoted string.