code: public function process(File $phpcsFile, $stackPtr)
      {
          $tokens = $phpcsFile->getTokens();
  
          if (empty($tokens[$stackPtr]['conditions']) === true) {
              $functionName = $phpcsFile->getDeclarationName($stackPtr);
              if ($functionName === null) {
                  return;
              }
  
              // Special exception for __autoload as it needs to be global.
              if ($functionName !== '__autoload') {
                  $error = 'Global function "%s" is not allowed';
                  $data  = [$functionName];
                  $phpcsFile->addError($error, $stackPtr, 'Found', $data);
              }
          }
      }
docs: {@inheritdoc}