S5860 - Names of regular expressions named groups should be used (when they're actually...)

[Stephan_Beuze]

Hi,

An unused named group is reported while it is effectively used.

Versions

• Eclipse IDE
  Version: 2020-12 (4.18.0)
  Build id: 20201210-1552

• SonarLint
  5.6.0.25634

Sample Code

import java.util.regex.Pattern;

public static void main(String[] args) {
    Pattern pattern = Pattern.compile("\\u005C(?<escapableChars>[\\u005C.])");

    pattern.matcher("\\\\.case").replaceAll("${escapableChars}"); // returns "\\.case"
}

An info raises saying escapableChars named group isn’t used. However, it is involved in the Matcher#replaceAll call.

[alban.auzeill]

Hi Stephan,

Thanks for this feedback and the code reproducer that help me to confirm that it’s a false-positive.
I’ve created this ticket SONARJAVA-3688 to fix it.

Good luck writing regular expressions