Merge pull request #20873 from github/shared-xml-discard

Share XML discard predicates

java/ql/lib/semmle/code/java/Overlay.qll

@@ -5,6 +5,7 @@ overlay[local?]
 module;
 
 import java
+private import internal.OverlayXml
 
 /**
  * A local predicate that always holds for the overlay variant and
@@ -18,7 +19,7 @@ predicate isOverlay() { databaseMetadata("isOverlay", "true") }
 overlay[local]
 string getRawFile(@locatable el) {
   exists(@location loc, @file file |
-    (hasLocation(el, loc) or xmllocations(el, loc)) and
+    hasLocation(el, loc) and
     locations_default(loc, file, _, _, _, _) and
     files(file, result)
   )
@@ -102,31 +103,3 @@ private predicate discardBaseConfigLocatable(@configLocatable el) {
   // property files than those included in overlayChangedFiles.
   overlayConfigExtracted(baseConfigLocatable(el))
 }
-
-/**
- * An `@xmllocatable` that should be discarded in the base variant if its file is
- * extracted in the overlay variant.
- */
-overlay[local]
-abstract class DiscardableXmlLocatable extends @xmllocatable {
-  /** Gets the raw file for an xmllocatable in base. */
-  string getRawFileInBase() { not isOverlay() and result = getRawFile(this) }
-
-  /** Gets a textual representation of this discardable xmllocatable. */
-  string toString() { none() }
-}
-
-overlay[local]
-private predicate overlayXmlExtracted(string file) {
-  isOverlay() and
-  exists(@xmllocatable el | not files(el, _) and not xmlNs(el, _, _, _) and file = getRawFile(el))
-}
-
-overlay[discard_entity]
-private predicate discardXmlLocatable(@xmllocatable el) {
-  overlayChangedFiles(el.(DiscardableXmlLocatable).getRawFileInBase())
-  or
-  // The XML extractor is currently not incremental and may extract more
-  // XML files than those included in overlayChangedFiles.
-  overlayXmlExtracted(el.(DiscardableXmlLocatable).getRawFileInBase())
-}

java/ql/lib/semmle/code/java/internal/OverlayXml.qll

@@ -0,0 +1,46 @@
+overlay[local]
+module;
+
+/**
+ * A local predicate that always holds for the overlay variant and never holds for the base variant.
+ * This is used to define local predicates that behave differently for the base and overlay variant.
+ */
+private predicate isOverlay() { databaseMetadata("isOverlay", "true") }
+
+private string getXmlFile(@xmllocatable locatable) {
+  exists(@location_default location, @file file | xmllocations(locatable, location) |
+    locations_default(location, file, _, _, _, _) and
+    files(file, result)
+  )
+}
+
+private string getXmlFileInBase(@xmllocatable locatable) {
+  not isOverlay() and
+  result = getXmlFile(locatable)
+}
+
+/**
+ * Holds if the given `file` was extracted as part of the overlay and was extracted by the HTML/XML
+ * extractor.
+ */
+private predicate overlayXmlExtracted(string file) {
+  isOverlay() and
+  exists(@xmllocatable locatable |
+    not files(locatable, _) and not xmlNs(locatable, _, _, _) and file = getXmlFile(locatable)
+  )
+}
+
+/**
+ * Holds if the given XML `locatable` should be discarded, because it is part of the overlay base
+ * and is in a file that was also extracted as part of the overlay database.
+ */
+overlay[discard_entity]
+private predicate discardXmlLocatable(@xmllocatable locatable) {
+  exists(string file | file = getXmlFileInBase(locatable) |
+    overlayChangedFiles(file)
+    or
+    // The HTML/XML extractor is currently not incremental and may extract more files than those
+    // included in overlayChangedFiles.
+    overlayXmlExtracted(file)
+  )
+}

java/ql/lib/semmle/code/xml/XML.qll

@@ -6,7 +6,6 @@ module;
 
 import semmle.files.FileSystem
 private import codeql.xml.Xml
-private import semmle.code.java.Overlay
 
 private module Input implements InputSig<File, Location> {
   class XmlLocatableBase = @xmllocatable or @xmlnamespaceable;
@@ -70,13 +69,3 @@ private module Input implements InputSig<File, Location> {
 }
 
 import Make<File, Location, Input>
-
-private class DiscardableXmlAttribute extends DiscardableXmlLocatable, @xmlattribute { }
-
-private class DiscardableXmlElement extends DiscardableXmlLocatable, @xmlelement { }
-
-private class DiscardableXmlComment extends DiscardableXmlLocatable, @xmlcomment { }
-
-private class DiscardableXmlCharacters extends DiscardableXmlLocatable, @xmlcharacters { }
-
-private class DiscardableXmlDtd extends DiscardableXmlLocatable, @xmldtd { }