Identify data classes during extraction

java/kotlin-extractor/src/main/kotlin/KotlinFileExtractor.kt

@@ -386,6 +386,10 @@ open class KotlinFileExtractor(
                     } else if (kind != ClassKind.CLASS && kind != ClassKind.OBJECT) {
                         logger.warnElement("Unrecognised class kind $kind", c)
                     }
+
+                    if (c.isData) {
+                        tw.writeKtDataClasses(classId)
+                    }
                 }
 
                 val locId = tw.getLocation(c)

java/ql/lib/config/semmlecode.dbscheme

@@ -1232,3 +1232,7 @@ ktFunctionOriginalNames(
   unique int id: @method ref,
   string name: string ref
 )
+
+ktDataClasses(
+  unique int id: @class ref
+)

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

@@ -714,6 +714,13 @@ class CompanionObject extends Class {
   Field getInstance() { type_companion_object(_, result, this) }
 }
 
+/**
+ * A Kotlin data class declaration.
+ */
+class DataClass extends Class {
+  DataClass() { ktDataClasses(this) }
+}
+
 /**
  * A record declaration.
  */

java/ql/test/kotlin/library-tests/data-classes/data_classes.expected

@@ -0,0 +1 @@
+| dc.kt:1:1:1:71 | ProtoMapValue |

java/ql/test/kotlin/library-tests/data-classes/data_classes.ql

@@ -0,0 +1,5 @@
+import java
+
+from DataClass c
+where c.fromSource()
+select c