satisfy the signature of HostnameRegexpSig, which doesn't understand RegExpSink

Author: erik-krogh

python/ql/lib/semmle/python/security/regexp/HostnameRegex.qll

@@ -12,7 +12,18 @@ private import codeql.regex.HostnameRegexp as Shared
 private module Impl implements Shared::HostnameRegexpSig<TreeImpl> {
   class DataFlowNode = DataFlow::Node;
 
-  class RegExpPatternSource = Regexp::RegExpPatternSource;
+  class RegExpPatternSource extends DataFlow::Node instanceof Regexp::RegExpPatternSource {
+    /**
+     * Gets a node where the pattern of this node is parsed as a part of
+     * a regular expression.
+     */
+    DataFlow::Node getAParse() { result = super.getAParse() }
+
+    /**
+     * Gets the root term of the regular expression parsed from this pattern.
+     */
+    TreeImpl::RegExpTerm getRegExpTerm() { result = super.getRegExpTerm() }
+  }
 }
 
 import Shared::Make<TreeImpl, Impl>