Quoted codepoint is not matched while unquoted is matched

[akhomchenko]

I am using re2j (thx for library!) and use randomly generated strings to test that patterns and logic that I wrote works correctly. I recently found a weird case and I am not sure if it is a bug but feels so because golang regexp (also re2, right?) behavior is different.

Example

import com.google.re2j.Pattern;

public class Main {
    public static void main(String[] args) {
        String source = Character.toString(110781);
        System.out.println("unquoted: " + Pattern.matches(source, source));  // true
        System.out.println("quoted: " + Pattern.matches("\\Q" + source + "\\E", source));  // false
    }
}

package main

import (
	"fmt"
	"regexp"
)

func main() {
	source := string([]rune{110781})
	matched, _ := regexp.MatchString(source, source)
	fmt.Printf("unquoted: %v\n", matched)  // true
	matched, _ = regexp.MatchString(`\Q` + source + `\E`, source)
	fmt.Printf("quoted: %v\n", matched)  // true
}

(I hope I did right with that rune to string conversion)

(link: https://play.golang.org/p/EPbFTmzsZm4)

[sjamesr]

Thank you for the report, I captured the issue in a unit test and added a potential fix.

@adonovan if you could cast a quick glance over the fix to see if it's right, that would be great