Suppress warnings from CPD for C/C++ code

Question

We are using PMD Copy Paste Detector (CPD) to analyze our C and C++ code. However, there are a few parts of the code that are very similar, but with a good reason and we would like to suppress the warnings for these parts.

The documentation of PMD CPD only mentions something about annotations, but this will not work for our these languages.

How can I still ignore warnings for specific parts?

Is there a comment to do so perhaps?

[UPDATE] I'm using the following Groovy script to run CPD:

@GrabResolver(name = 'jcenter', root = 'https://jcenter.bintray.com/')
@Grab('net.sourceforge.pmd:pmd-core:5.4.+')
@Grab('net.sourceforge.pmd:pmd-cpp:5.4.+')
import net.sourceforge.pmd.cpd.CPD
import net.sourceforge.pmd.cpd.CPDConfiguration
import java.util.regex.Pattern

def tokens = 60
def scanDirs = ['./path/to/scan', './scan/this/too']
def ignores = [
    './ignore/this/path',
    './this/must/be/ignored/too'
    ].collect({ it.replace('/', File.separator) })
def rootDir = new File('.')
def outputDir = new File('./reports/analysis/')

def filename_date_format = 'yyyyMMdd'
def encoding = System.getProperty('file.encoding')
def language_converter = new CPDConfiguration.LanguageConverter()
def config = new CPDConfiguration()
config.language = new CPDConfiguration.LanguageConverter().convert('c')
config.minimumTileSize = tokens
config.renderer = config.getRendererFromString 'xml', 'UTF-8'
config.skipBlocksPattern = '//DUPSTOP|//DUPSTART'
config.skipLexicalErrors = true
def cpd = new CPD(config)

scanDirs.each { path ->
    def dir = new File(path);
    dir.eachFileRecurse(groovy.io.FileType.FILES) {
        // Ignore file?
        def doIgnore = false
        ignores.each { ignore ->
            if(it.path.startsWith(ignore)) {
                doIgnore = true
            }
        }
        if(doIgnore) {
            return
        }

        // Other checks
        def lowerCaseName = it.name.toLowerCase()
        if(lowerCaseName.endsWith('.c') || lowerCaseName.endsWith('.cpp') || lowerCaseName.endsWith('.h')) {
            cpd.add it
        }
    }
}

cpd.go();

def duplicationFound = cpd.matches.hasNext()

def now = new Date().format(filename_date_format)
def outputFile = new File(outputDir.canonicalFile, "cpd_report_${now}.xml")
println "Saving report to ${outputFile.absolutePath}"

def absoluteRootDir = rootDir.canonicalPath
if(absoluteRootDir[-1] != File.separator) {
    absoluteRootDir += File.separator
}

outputFile.parentFile.mkdirs()
def xmlOutput = config.renderer.render(cpd.matches);
if(duplicationFound) {
  def filePattern = "(<file\\s+line=\"\\d+\"\\s+path=\")${Pattern.quote(absoluteRootDir)}([^\"]+\"\\s*/>)"
  xmlOutput = xmlOutput.replaceAll(filePattern, '$1$2')
} else {
  println 'No duplication found.'
}

outputFile.write xmlOutput

Answer 1

You can define your custom markers for excluding certain blocks from analysis through the --skip-blocks-pattern option.

--skip-blocks-pattern Pattern to find the blocks to skip. Start and End pattern separated by |. Default is #if 0|#endif.

For example the following will ignore blocks between /* SUPPRESS CPD START */ and /* SUPPRESS CPD END */ comments (the comment must occupy a separate line):

$ ./run.sh cpd --minimum-tokens 100 --files /path/to/c/source --language cpp ----skip-blocks-pattern '/* SUPPRESS CPD START */|/* SUPPRESS CPD END */'

Note however, that this will cause the tool perform copy-paste-detection inside code delimited by #if 0/#endif.