Add DelegatedProperty QL class and use it in tests

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

@@ -713,6 +713,21 @@ class Property extends Element, Modifiable, @kt_property {
   override string getAPrimaryQlClass() { result = "Property" }
 }
 
+/** A Kotlin delegated property. */
+class DelegatedProperty extends Property {
+  Variable underlying;
+
+  DelegatedProperty() { ktPropertyDelegates(this, underlying) }
+
+  /** Holds if this delegated property is declared as a local variable. */
+  predicate isLocal() { underlying instanceof LocalVariableDecl }
+
+  /** Gets the underlying local variable or field to which this property is delegating the calls. */
+  Variable getDelegatee() { result = underlying }
+
+  override string getAPrimaryQlClass() { result = "DelegatedProperty" }
+}
+
 /** A Kotlin extension function. */
 class ExtensionMethod extends Method {
   Type extendedType;

java/ql/test/kotlin/library-tests/exprs/delegatedProperties.expected

@@ -0,0 +1,21 @@
+delegatedProperties
+| delegatedProperties.kt:6:9:9:9 | prop1 | prop1 | local | delegatedProperties.kt:6:24:9:9 | Lazy<Integer> prop1$delegate | delegatedProperties.kt:6:27:9:9 | lazy(...) |
+| delegatedProperties.kt:19:9:19:51 | varResource1 | varResource1 | local | delegatedProperties.kt:19:31:19:51 | ResourceDelegate varResource1$delegate | delegatedProperties.kt:19:34:19:51 | new ResourceDelegate(...) |
+| delegatedProperties.kt:23:9:23:31 | name | name | local | delegatedProperties.kt:23:26:23:31 | Map<String,Object> name$delegate | delegatedProperties.kt:23:29:23:31 | map |
+| delegatedProperties.kt:33:9:33:76 | readOnly | readOnly | local | delegatedProperties.kt:33:27:33:47 | ReadWriteProperty<Object,Integer> readOnly$delegate | delegatedProperties.kt:33:30:33:47 | resourceDelegate(...) |
+| delegatedProperties.kt:34:9:34:48 | readWrite | readWrite | local | delegatedProperties.kt:34:28:34:48 | ReadWriteProperty<Object,Integer> readWrite$delegate | delegatedProperties.kt:34:31:34:48 | resourceDelegate(...) |
+delegatedPropertyTypes
+| delegatedProperties.kt:6:9:9:9 | prop1 | file://:0:0:0:0 | int | file://<external>/Lazy.class:0:0:0:0 | Lazy<Integer> |
+| delegatedProperties.kt:19:9:19:51 | varResource1 | file://:0:0:0:0 | int | delegatedProperties.kt:38:1:44:1 | ResourceDelegate |
+| delegatedProperties.kt:23:9:23:31 | name | file://<external>/String.class:0:0:0:0 | String | file://<external>/Map.class:0:0:0:0 | Map<String,Object> |
+| delegatedProperties.kt:33:9:33:76 | readOnly | file://:0:0:0:0 | int | file://<external>/ReadWriteProperty.class:0:0:0:0 | ReadWriteProperty<Object,Integer> |
+| delegatedProperties.kt:34:9:34:48 | readWrite | file://:0:0:0:0 | int | file://<external>/ReadWriteProperty.class:0:0:0:0 | ReadWriteProperty<Object,Integer> |
+delegatedPropertyGetters
+| delegatedProperties.kt:6:9:9:9 | prop1 | delegatedProperties.kt:6:24:9:9 | <get-prop1> |
+| delegatedProperties.kt:19:9:19:51 | varResource1 | delegatedProperties.kt:19:31:19:51 | <get-varResource1> |
+| delegatedProperties.kt:23:9:23:31 | name | delegatedProperties.kt:23:26:23:31 | <get-name> |
+| delegatedProperties.kt:33:9:33:76 | readOnly | delegatedProperties.kt:33:27:33:47 | <get-readOnly> |
+| delegatedProperties.kt:34:9:34:48 | readWrite | delegatedProperties.kt:34:28:34:48 | <get-readWrite> |
+delegatedPropertySetters
+| delegatedProperties.kt:19:9:19:51 | varResource1 | delegatedProperties.kt:19:31:19:51 | <set-varResource1> |
+| delegatedProperties.kt:34:9:34:48 | readWrite | delegatedProperties.kt:34:28:34:48 | <set-readWrite> |

java/ql/test/kotlin/library-tests/exprs/delegatedProperties.ql

@@ -0,0 +1,38 @@
+import java
+
+// Stop external filepaths from appearing in the results
+class ClassOrInterfaceLocation extends ClassOrInterface {
+  override predicate hasLocationInfo(string path, int sl, int sc, int el, int ec) {
+    exists(string fullPath | super.hasLocationInfo(fullPath, sl, sc, el, ec) |
+      if exists(this.getFile().getRelativePath())
+      then path = fullPath
+      else path = fullPath.regexpReplaceAll(".*/", "<external>/")
+    )
+  }
+}
+
+query predicate delegatedProperties(
+  DelegatedProperty dp, string name, string isLocal, Variable underlying, Expr initializer
+) {
+  (
+    dp.isLocal() and isLocal = "local"
+    or
+    not dp.isLocal() and isLocal = "non-local"
+  ) and
+  underlying = dp.getDelegatee() and
+  name = dp.getName() and
+  underlying.getInitializer() = initializer
+}
+
+query predicate delegatedPropertyTypes(DelegatedProperty dp, Type type, Type underlyingType) {
+  dp.getGetter().getReturnType() = type and
+  dp.getDelegatee().getType() = underlyingType
+}
+
+query predicate delegatedPropertyGetters(DelegatedProperty dp, Method getter) {
+  dp.getGetter() = getter
+}
+
+query predicate delegatedPropertySetters(DelegatedProperty dp, Method setter) {
+  dp.getSetter() = setter
+}