[MCHECKSTYLE-442] Not possible to specify useful ignoreStringsRegexp property for module name MultipleStringLiterals without error

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Incomplete
• Component/s: checkstyle:check
• Assignee: Unassigned
• Reporter: Nick Williams
• Created: 26/Oct/23 21:18
• Updated: 08/Jul/24 08:36
• Resolved: 08/Jul/24 08:36

Description

The checkstyle documentation specifies this example for ignoring certain strings by regex in module MultipleStringLiterals.

    <module name="MultipleStringLiterals">
        <property name="ignoreStringsRegexp"
                  value='^(("")|(", "))$'/>
    </module>

Not only does this example not work, but no useful value for this property works. Any regex that contains a double quote ("), which is required for this property to work, results in an error:

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-checkstyle-plugin:3.3.0:check (checkstyle-verify-style) on project oss-parent:
Failed during checkstyle execution: 
Failed during checkstyle configuration: 
unable to parse configuration stream - Element type "property" must be followed by either attribute specifications, ">" or "/>".:94:85 -> [Help 1]

In addition to trying their example verbatim, I have tried all of the following, all of which result in the same error. I cannot find a workaround, so I am unable to use this property.

        <property name="ignoreStringsRegexp"
                  value='^""$' />

        <property name="ignoreStringsRegexp"
                  value="^&quot;&quot;$" />

        <property name="ignoreStringsRegexp"
                  value='^&quot;&quot;$' />

        <property name="ignoreStringsRegexp"
                  value="^((&quot;&quot;)|(&quot;, &quot;))$" />

        <property name="ignoreStringsRegexp"
                  value='^((&quot;&quot;)|(&quot;, &quot;))$' />

        <property name="ignoreStringsRegexp"
                  value="^(&quot;&quot;)|(&quot;, &quot;)$" />

        <property name="ignoreStringsRegexp"
                  value='^(&quot;&quot;)|(&quot;, &quot;)$' />

The parentheses and other symbols do not appear to be a problem, because the following do not result in any errors, they're just also not useful because checkstyle won't match on them:

        <property name="ignoreStringsRegexp"
                  value='^$' />

        <property name="ignoreStringsRegexp"
                  value='^()$' />

So it would seem that it's not possible to use legal XML techniques to insert double quotes into property values.