C#: Address comments in the QL implementation.

csharp/ql/lib/csharp.qll

@@ -36,7 +36,7 @@ import semmle.code.csharp.controlflow.ControlFlowGraph
 import semmle.code.csharp.dataflow.DataFlow
 import semmle.code.csharp.dataflow.TaintTracking
 import semmle.code.csharp.dataflow.SSA
-private import semmle.code.csharp.Overlay
+private import semmle.code.csharp.internal.Overlay
 
 /** Whether the source was extracted without a build command. */
 predicate extractionIsStandalone() { exists(SourceFile f | f.extractedStandalone()) }

csharp/ql/lib/semmle/code/csharp/internal/Overlay.qll

@@ -10,73 +10,19 @@
 overlay[local]
 predicate isOverlay() { databaseMetadata("isOverlay", "true") }
 
+overlay[local]
+private string getLocationFilePath(@location_default loc) {
+  exists(@file file | locations_default(loc, file, _, _, _, _) | files(file, result))
+}
+
 /**
  * An abstract base class for all elements that can be discarded from the base.
  */
 overlay[local]
-abstract private class DiscardableEntity extends @locatable {
+private class DiscardableEntity extends @locatable {
   /** Gets the path to the file in which this element occurs. */
-  abstract string getPath();
-
-  /** Holds if this element exists in the base variant. */
-  predicate existsInBase() { not isOverlay() and exists(this) }
-
-  /** Holds if this element exists in the overlay variant. */
-  predicate existsInOverlay() { isOverlay() and exists(this) }
-
-  /** Gets a textual representation of this discardable element. */
-  string toString() { none() }
-}
-
-/**
- * A class of C# database entities that use `*` IDs.
- * The rest use named TRAP IDs.
- */
-overlay[local]
-private class StarEntity =
-  @expr or @stmt or @diagnostic or @extractor_message or @using_directive or @type_mention;
-
-overlay[discard_entity]
-private predicate discardStarEntity(@locatable e) {
-  e instanceof StarEntity and
-  // Entities with *-ids can exist either in base or overlay, but not both.
-  exists(DiscardableEntity de | de = e |
-    overlayChangedFiles(de.getPath()) and
-    de.existsInBase()
-  )
-}
-
-overlay[discard_entity]
-private predicate discardNamedEntity(@locatable e) {
-  not e instanceof StarEntity and
-  // Entities with named IDs can exist both in base, overlay, or both.
-  exists(DiscardableEntity de | de = e |
-    overlayChangedFiles(de.getPath()) and
-    not de.existsInOverlay()
-  )
-}
-
-overlay[local]
-private string getLocationPath(@location_default loc) {
-  exists(@file file | locations_default(loc, file, _, _, _, _) | files(file, result))
-}
-
-overlay[local]
-private predicate discardableLocation(@location_default loc, string path) {
-  not isOverlay() and
-  path = getLocationPath(loc)
-}
-
-// Discard locations that are in changed files from the base variant.
-overlay[discard_entity]
-private predicate discardLocation(@location_default loc) {
-  exists(string path | discardableLocation(loc, path) | overlayChangedFiles(path))
-}
-
-overlay[local]
-private class PossibleDiscardableEntity extends DiscardableEntity instanceof @locatable {
-  override string getPath() {
-    exists(@location_default loc | result = getLocationPath(loc) |
+  string getFilePath() {
+    exists(@location_default loc | result = getLocationFilePath(loc) |
       expr_location(this, loc) or
       stmt_location(this, loc) or
       using_directive_location(this, loc) or
@@ -104,4 +50,56 @@ private class PossibleDiscardableEntity extends DiscardableEntity instanceof @lo
       extractor_messages(this, _, _, _, _, loc, _)
     )
   }
+
+  /** Holds if this element exists in the base variant. */
+  predicate existsInBase() { not isOverlay() and exists(this) }
+
+  /** Holds if this element exists in the overlay variant. */
+  predicate existsInOverlay() { isOverlay() and exists(this) }
+
+  /** Gets a textual representation of this discardable element. */
+  string toString() { none() }
+}
+
+/**
+ * A class of C# database entities that use `*` IDs.
+ * The rest use named TRAP IDs.
+ */
+overlay[local]
+private class StarEntity =
+  @expr or @stmt or @diagnostic or @extractor_message or @using_directive or @type_mention or
+      @local_variable;
+
+overlay[discard_entity]
+private predicate discardStarEntity(@locatable e) {
+  e instanceof StarEntity and
+  // Entities with *-ids can exist either in base or overlay, but not both.
+  e =
+    any(DiscardableEntity de |
+      overlayChangedFiles(de.getFilePath()) and
+      de.existsInBase()
+    )
+}
+
+overlay[discard_entity]
+private predicate discardNamedEntity(@locatable e) {
+  not e instanceof StarEntity and
+  // Entities with named IDs can exist both in base, overlay, or both.
+  e =
+    any(DiscardableEntity de |
+      overlayChangedFiles(de.getFilePath()) and
+      not de.existsInOverlay()
+    )
+}
+
+overlay[local]
+private predicate discardableLocation(@location_default loc, string path) {
+  not isOverlay() and
+  path = getLocationFilePath(loc)
+}
+
+// Discard locations that are in changed files from the base variant.
+overlay[discard_entity]
+private predicate discardLocation(@location_default loc) {
+  exists(string path | discardableLocation(loc, path) | overlayChangedFiles(path))
 }

csharp/ql/test/library-tests/overlay/testlocations.ql

@@ -5,25 +5,22 @@ import csharp
 query predicate elementsWithMultipleSourceLocations(Element e, SourceLocation loc) {
   e.fromSource() and
   not e instanceof Namespace and
-  count(SourceLocation l0 | l0 = e.getALocation()) > 1 and
+  strictcount(SourceLocation l0 | l0 = e.getALocation()) > 1 and
   loc = e.getALocation()
 }
 
 query predicate typeMentionsWithMultipleSourceLocations(TypeMention tm, SourceLocation loc) {
-  tm.getLocation().getFile().fromSource() and
-  count(SourceLocation l0 | l0 = tm.getLocation()) > 1 and
+  strictcount(SourceLocation l0 | l0 = tm.getLocation()) > 1 and
   loc = tm.getLocation()
 }
 
 query predicate commentLinesWithMultipleSourceLocations(CommentLine cl, SourceLocation loc) {
-  cl.getLocation().getFile().fromSource() and
-  count(SourceLocation l0 | l0 = cl.getLocation()) > 1 and
+  strictcount(SourceLocation l0 | l0 = cl.getLocation()) > 1 and
   loc = cl.getLocation()
 }
 
 query predicate commentBlocksWithMultipleSourceLocations(CommentBlock cb, SourceLocation loc) {
-  cb.getLocation().getFile().fromSource() and
-  count(SourceLocation l0 | l0 = cb.getLocation()) > 1 and
+  strictcount(SourceLocation l0 | l0 = cb.getLocation()) > 1 and
   loc = cb.getLocation()
 }